JP5764736B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus for cooling a cooling storage facility in a store or the like, for example.

  Conventionally, cooling storage facilities such as refrigeration cases and refrigeration cases have been installed in stores (indoors) of stores such as supermarkets and convenience stores. And the inside of these warehouses is cooled by a refrigerator, and displayed and sold while cooling the product.

  In such a refrigeration apparatus, in recent years, it has become impossible to use chlorofluorocarbon refrigerants due to natural environmental problems and the like. For this reason, the thing using the carbon dioxide which is a natural refrigerant | coolant is developed as a substitute of a fluorocarbon refrigerant | coolant. It is known that the carbon dioxide refrigerant is a refrigerant having a high and low pressure difference, and the high pressure side of the refrigeration cycle is brought into a supercritical state by compression (see, for example, Patent Document 1).

  Also, in such a supercritical refrigeration cycle, under conditions where the refrigerant temperature at the gas cooler outlet becomes high due to a high heat source temperature on the gas cooler side (for example, the outside air temperature that is a heat medium that exchanges heat with the gas cooler). Since the specific enthalpy at the inlet of the evaporator is increased, there has been a problem that the refrigeration effect is significantly reduced. In this case, in order to ensure the refrigerating capacity, it is necessary to increase the high-pressure pressure, which causes a disadvantage that the compression power increases and the coefficient of performance also decreases.

  Therefore, the refrigerant cooled by the gas cooler is divided into two refrigerant flows, one of the divided refrigerant flows (first refrigerant flow) is throttled by the auxiliary throttle means, and then one of the passages of the intermediate heat exchanger (first And the other refrigerant flow (second refrigerant flow) is provided in a heat exchange manner with the first flow path of the intermediate heat exchanger (second flow path). A so-called split cycle (two-stage compression, one-stage expansion intermediate refrigeration cycle) refrigeration apparatus is also proposed in which the refrigerant is evaporated by an evaporator via a main throttle means.

  In the split cycle refrigeration apparatus, the refrigerant after radiating heat by the gas cooler can be divided, and the second refrigerant flow can be cooled by the first refrigerant flow expanded under reduced pressure. Enthalpy can be reduced. As a result, the refrigeration effect can be increased and the performance can be effectively improved as compared with the conventional apparatus.

Japanese Patent Publication No. 7-18602

  By the way, in the refrigeration system in which the carbon dioxide refrigerant is enclosed and the high pressure side becomes supercritical pressure as described above, the high pressure side becomes extremely high pressure, so a large receiver tank is attached as in the case of using a normal HFC refrigerant. It is impossible to enclose a relatively large amount of refrigerant with a margin. Therefore, it is indispensable for efficient and effective operation that an appropriate amount of refrigerant is enclosed in the refrigerant circuit. Conventionally, the amount of refrigerant is determined at the time of initial refrigerant charging and when the refrigerant leaks during the subsequent operation. It was extremely difficult to do.

  In view of the situation as described above, it is an object of the present invention to appropriately manage the amount of refrigerant in a refrigerant circuit in a refrigeration apparatus in which a high pressure side has a supercritical pressure.

In the refrigeration apparatus of the present invention, a refrigerant circuit is configured by the compression means, the gas cooler, the auxiliary throttle means, the intermediate heat exchanger, the main throttle means, and the evaporator, and the refrigerant discharged from the gas cooler is divided into two flows. After the first refrigerant flow is divided, the first refrigerant flow is passed through the auxiliary throttle means to the first flow path of the intermediate heat exchanger, and the second refrigerant flow is flowed to the second flow path of the intermediate heat exchanger. The first refrigerant flow and the second refrigerant flow are exchanged in the intermediate heat exchanger by flowing to the evaporator through the throttle means, and the refrigerant discharged from the evaporator is sucked into the low pressure portion of the compression means. The first refrigerant flow from the intermediate heat exchanger is sucked into the intermediate pressure part of the compression means, and the high pressure side becomes supercritical pressure, and is connected to the high pressure side of the refrigerant circuit via the recovery switching means A refrigerant recovery tank connected to the intermediate pressure region of the refrigerant circuit via the opening / closing means for discharge, And a control means for recovering the refrigerant in the refrigerant recovery tank by opening the recovery opening and closing means based on the increase in the high pressure side pressure based on the high pressure side pressure of the refrigerant circuit. Based on the decrease in the side pressure, the discharge opening / closing means is opened to release the refrigerant from the refrigerant recovery tank, and the temperature difference between the second refrigerant flow and the first refrigerant flow through the intermediate heat exchanger and the recovery The refrigerant amount in the refrigerant circuit is determined according to the state of the opening / closing means .

In the refrigeration apparatus according to the second aspect of the present invention, when the temperature difference between the second refrigerant flow and the first refrigerant flow is large and the collection opening / closing means is frequently closed, the refrigerant circuit The rotation speed of the blower that air-cools the gas cooler with a low frequency of occurrence of a state in which the temperature difference between the second refrigerant flow and the first refrigerant flow is large is determined. When the frequency of occurrence of a state where the recovery opening / closing means is open is high, it is determined that the amount of refrigerant in the refrigerant circuit is excessive.

In the refrigeration apparatus according to a third aspect of the present invention, in each of the above inventions, the control means determines the amount of refrigerant in the refrigerant circuit according to the temperature difference between the refrigerant that has passed through the gas cooler and the second refrigerant flow that has passed through the intermediate heat exchanger. It is characterized by.

In the refrigeration apparatus according to the fourth aspect of the present invention, when the temperature difference between the refrigerant that has passed through the gas cooler and the second refrigerant flow that has passed through the intermediate heat exchanger is small, the amount of refrigerant in the refrigerant circuit is insufficient. It is characterized by determining that it is a thing.

The refrigeration apparatus according to a fifth aspect of the present invention is characterized in that, in each of the above inventions, the control means includes means for displaying a determination result of the refrigerant amount.

The refrigeration apparatus according to a sixth aspect of the invention is characterized in that, in each of the above inventions, the control means issues a predetermined alarm when the determined refrigerant amount is insufficient or excessive.

A refrigeration apparatus according to a seventh aspect of the present invention is characterized in that, in each of the above inventions, the refrigerant circuit includes a high-pressure service port and a low-pressure service port, and the control unit has a refrigerant sealing operation mode in which the operation of the compression unit is continued. .

The refrigeration apparatus of the invention of claim 8 is characterized in that carbon dioxide is used as a refrigerant in the refrigerant circuit in each of the above inventions.

  In the present invention, a refrigerant circuit is composed of a compression means, a gas cooler, an auxiliary throttle means, an intermediate heat exchanger, a main throttle means, and an evaporator, and the refrigerant discharged from the gas cooler is divided into two flows. The first refrigerant flow is passed through the auxiliary throttle means to the first flow path of the intermediate heat exchanger, the second refrigerant flow is flowed to the second flow path of the intermediate heat exchanger, and then the main throttle means is Then, the first refrigerant flow and the second refrigerant flow are exchanged in the intermediate heat exchanger, and the refrigerant discharged from the evaporator is sucked into the low-pressure portion of the compression means. Since the first refrigerant flow coming out of the vessel is sucked into the intermediate pressure part of the compression means and the high pressure side is a supercritical pressure, the refrigerant after radiating heat from the gas cooler is shunted and depressurized by the auxiliary throttle means The expanded first refrigerant stream cools the second refrigerant stream in the intermediate heat exchanger. You will be able to, by reducing the specific enthalpy of the evaporator inlet it is possible to increase the refrigerating effect, effectively it is possible to improve performance as compared with the conventional device.

  At this time, when the amount of refrigerant in the refrigerant circuit is not an appropriate amount, or when the amount of refrigerant has changed from the appropriate amount, the cooling effect of the second refrigerant flow by the first refrigerant flow changes, so in the intermediate heat exchanger By monitoring the cooling effect of the second refrigerant flow by the first refrigerant flow, it is possible to determine the amount of refrigerant in the refrigerant circuit.

Therefore, in the present invention, the amount of refrigerant in the refrigerant circuit is determined according to the cooling effect of the second refrigerant flow by the first refrigerant flow in the intermediate heat exchanger. That is, the present invention includes a refrigerant recovery tank connected to the high-pressure side of the refrigerant circuit via the recovery opening / closing means and connected to the intermediate pressure region of the refrigerant circuit via the discharge opening / closing means, and the control means includes Based on the high-pressure side pressure of the refrigerant circuit, the refrigerant is recovered in the refrigerant recovery tank by opening the recovery opening / closing means based on the increase in the high-pressure side pressure, and based on the decrease in the high-pressure side pressure. Control is performed to release the refrigerant from the refrigerant recovery tank by opening the opening / closing means .

In this case, if the amount of refrigerant in the refrigerant circuit is insufficient, the high-pressure side pressure of the refrigerant circuit does not increase, and the collection opening / closing means is often closed. In addition, since the first refrigerant flow that the auxiliary throttle means flows also tends to decrease, the cooling effect of the second refrigerant flow by the first refrigerant flow in the intermediate heat exchanger is reduced, and the first refrigerant flow that has passed through the intermediate heat exchanger is reduced. The state where the temperature difference between the second refrigerant flow and the first refrigerant flow becomes large increases.

Therefore, in the present invention, the amount of refrigerant in the refrigerant circuit is determined according to the temperature difference between the second refrigerant flow and the first refrigerant flow that have passed through the intermediate heat exchanger, and the state of the recovery switching means. When the temperature difference between the second refrigerant flow and the first refrigerant flow is large and the collection opening / closing means is frequently closed as in Item 2 , the refrigerant amount in the refrigerant circuit is insufficient. By determining that the refrigerant is present, the refrigerant shortage in the refrigerant circuit or the refrigerant leakage from the refrigerant circuit can be accurately detected.

  On the other hand, when the amount of refrigerant in the refrigerant circuit is excessive, the pressure on the high-pressure side of the refrigerant circuit becomes high, so that the recovery opening / closing means is often open, and the auxiliary throttle means is also an intermediate heat exchanger. Since the first refrigerant flow tends to increase in order to further cool the second refrigerant flow, the second refrigerant flow receives a stronger cooling action from the first refrigerant flow in the intermediate heat exchanger, and the intermediate heat The temperature difference between the second refrigerant flow and the first refrigerant flow that has passed through the exchanger is reduced. In addition, since the rotation speed of the blower that air-cools the gas cooler also increases, the frequency of occurrence of a state in which the temperature difference between the second refrigerant flow and the first refrigerant flow increases is low, and the rotation speed of the blower that air-cools the gas cooler. When the frequency of occurrence of the state in which the recovery opening / closing means is open is high, it is accurately detected that the refrigerant amount is excessive in the refrigerant circuit by determining that the refrigerant amount in the refrigerant circuit is excessive. Will be able to.

  Also, if the amount of refrigerant in the refrigerant circuit is insufficient, the cooling effect of the second refrigerant flow by the first refrigerant flow in the intermediate heat exchanger is simply reduced as described above, so that the refrigerant is diverted through the gas cooler. The temperature difference between the refrigerant before passing through and the second refrigerant flow that has passed through the intermediate heat exchanger becomes small.

Therefore, the amount of refrigerant in the refrigerant circuit is determined according to the temperature difference between the refrigerant before being diverted through the gas cooler by the control means and the second refrigerant flow through the intermediate heat exchanger, as in claim 3. When the temperature difference between the refrigerant before being diverted through the gas cooler and the second refrigerant flow through the intermediate heat exchanger is small as in claim 4 , it is determined that the refrigerant amount in the refrigerant circuit is insufficient. Even so, it becomes possible to accurately detect refrigerant shortage in the refrigerant circuit or refrigerant leakage from the refrigerant circuit.

  This realizes an appropriate amount of refrigerant enclosed in the refrigerant circuit at the time of initial refrigerant encapsulation, ensures efficient operation and refrigeration capacity, and prevents unnecessary refrigerant encapsulation and wasteful refrigerant consumption Can be reduced. Furthermore, since leakage of refrigerant from the refrigerant circuit after sealing can be detected, smooth and efficient operation management can be realized.

Further, if the control means is provided with a means for displaying the determination result of the refrigerant amount as in the invention of claim 5 , it is possible to improve workability at the time of initial refrigerant filling and to accurately grasp the refrigerant leakage. become able to.

Further, when the amount of refrigerant determined by the control means is insufficient or excessive as in the invention of claim 6 , if a predetermined alarm is issued, a quick response can be realized. become.

In this case, the high pressure service port and the low pressure service port are provided in the refrigerant circuit as in the invention of claim 7 , and the control means is provided with a refrigerant sealing operation mode in which the operation of the compression means is continued, so that when the refrigerant is insufficient or leaked The sealing operation can be performed smoothly.

In particular, in a refrigeration apparatus in which carbon dioxide is used as the refrigerant in the refrigerant circuit and the high pressure side is at a supercritical pressure as in claim 8 , the refrigerant is not liquefied on the high pressure side, so that it is difficult to determine the appropriate amount of refrigerant. By applying, it becomes possible to achieve significant improvements in refrigerant quantity management.

It is a system block diagram containing the refrigerant circuit of the freezing apparatus of the Example to which this invention is applied. It is a figure which shows the example of a display of the display apparatus of the refrigerator unit controller of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram including a refrigerant circuit of a refrigeration apparatus R according to an embodiment of the present invention. The refrigeration apparatus R according to the embodiment includes, for example, air conditioning in a room 152 (store) of a convenience store or a supermarket, and a refrigeration case 5A that is a refrigeration facility or a refrigeration case 5B that is a refrigeration facility installed therein. It achieves internal cooling.

  The refrigerated case 5A and the refrigerated case 5B are open showcases whose front and upper surfaces are open, as well as showcases whose openings are closed by a transparent glass door, and the inside of the freezer case 5A is predetermined. Is cooled to a freezing temperature (for example, −20 ° C. to −30 ° C.), and frozen desserts such as frozen food and ice cream are displayed, and the inside of the refrigerator case 5B has a predetermined refrigerating temperature (for example, 0 ° C. to + 10 ° C.) Chilled foods such as beverages and sandwiches are displayed.

  In this figure, reference numeral 153 denotes an air conditioning system including an air conditioning refrigerant circuit 154 for air conditioning the room 152, and reference numeral 156 denotes a refrigeration refrigerant circuit 1 for cooling the inside of the refrigeration case 5A and the refrigeration case 5B. The refrigeration system provided. The air conditioning system 153 includes an indoor unit 157 installed on the ceiling or the like of the room 152, an outdoor unit 158 installed outside the store, a hot water use air conditioner 159, and the like. In the embodiment, 1 is referred to as a refrigeration refrigerant circuit, but any one of refrigeration only, refrigeration only, or a refrigerant circuit intended for refrigeration and refrigeration as in the embodiment may be used.

  The air conditioning side refrigerant circuit 154 is provided in the outdoor unit 158 and includes a compressor (compression unit) 161 (COMP4), a radiator 162, an air conditioning expansion valve (throttle unit) 163, an evaporator 164, and an accumulator. A refrigeration cycle is configured by sequentially connecting the pipes 166 in an annular shape. The refrigerant used in the air-conditioning side refrigerant circuit 154 is carbon dioxide used in the cooling and storage refrigerant circuit 1 described later in the embodiment, but may be a normal HFC refrigerant. However, it goes without saying that a carbon dioxide refrigerant is suitable for generating hot water, which will be described later, in view of natural environmental problems.

  The refrigerant compressed and discharged by the compressor 161 enters the radiator 162 and radiates heat there. At this time, the heating effect is exhibited. The refrigerant that has exited the radiator 162 passes through the high-pressure side pipe 167, is throttled by the expansion valve 163, and then is evaporated by the evaporator 164. At this time, the endothermic effect is exhibited, and the cycle of passing through the low pressure side pipe 168 and sucking into the compressor 161 through the accumulator 166 is repeated. In this case, the high-pressure side pipe 167 and the low-pressure side pipe 168 are arranged in a heat exchange relationship to constitute an internal heat exchanger 169. Thereby, the refrigerant reaching the expansion valve 163 via the high-pressure side pipe 167 is supercooled, and gasification of the refrigerant entering the accumulator 166 via the low-pressure side pipe 168 is promoted.

  In FIG. 1, reference numeral 171 denotes a hot water storage tank provided in the outdoor unit 158. City water is supplied to the hot water storage tank 171 from the water tap 172, and water (hot water) in the hot water storage tank 171 is circulated to the water circulation pipe 174 by the pump 173. This water circulation pipe 174 is arranged in a heat exchange relationship with the radiator 162 of the air conditioning side refrigerant circuit 154 to constitute a water heat exchanger 176. Thereby, the water circulating in the water circulation pipe 174 is heated by the heating action by heat radiation from the radiator 162, and hot water is generated and stored in the hot water storage tank 171.

  Hot water generated in the hot water storage tank 171 is circulated to the hot water use air conditioner 159 through the hot water circulation pipe 177. This hot water use air conditioner 159 is configured by a desiccant air conditioner or an absorption air conditioner. The desiccant air conditioner exhibits a cooling action using a desiccant, and the heat of the hot water circulated through the hot water circulation pipe 177 is used to regenerate the desiccant. In the case of an absorption air conditioner, hot water circulating through the hot water circulation pipe 177 is used for heating the regenerator. And the indoor 152 is air-conditioned using the utilization side heat exchanger 178 and the air blower 179 of the indoor unit 157 by the cooling capacity of these desiccant air conditioners or absorption type air conditioners.

  In the figure, 181 is an indoor unit controller provided in the indoor unit 157, and 182 is an outdoor unit controller provided in the outdoor unit 158. Reference numeral 183 denotes a master controller (control means) for performing integrated control of the refrigeration apparatus R, and is installed in a store management room or the like. These controllers 181 to 183 are all constituted by a microcomputer, and the master controller 183, the indoor unit controller 181 and the outdoor unit controller 183 are connected so as to perform data communication with each other.

  On the other hand, the refrigeration system 156 includes a refrigerator unit 3 installed outdoors and the refrigeration case 5A and the refrigeration case 5B. The refrigerator unit 3 and the cases 5A and 5B are connected by refrigerant pipes 7 and 9. A predetermined refrigeration cycle of the refrigeration refrigerant circuit 1 is configured.

  The refrigeration cycle of the refrigeration refrigerant circuit 1 uses, as a refrigerant, carbon dioxide whose high-pressure side refrigerant pressure (high pressure) is equal to or higher than its critical pressure (supercritical). This carbon dioxide refrigerant is a natural refrigerant that is friendly to the global environment and takes into consideration flammability and toxicity. As the lubricating oil, existing oils such as mineral oil (mineral oil), alkylbenzene oil, ether oil, ester oil, and PAG (polyalkyl glycol) are used.

  The refrigerator unit 3 includes two compressors (compression means) 11 and 11 (COMP2, COMP3) arranged in parallel. In the present embodiment, the compressor 11 is an internal intermediate pressure type multi-stage compression rotary compressor, and includes a cylindrical sealed container 12 made of a steel plate, an electric element disposed and housed in the inner space of the sealed container 12, and the electric motor. Rotary compression mechanism comprising a first (low stage side) rotary compression element (first compression element) and a second (high stage side) rotary compression element (second compression element) driven by the rotary shaft of the element It consists of parts.

  The first rotary compression element compresses the low-pressure refrigerant sucked into the compressor 11 from the low-pressure side of the refrigeration refrigerant circuit 1 through the refrigerant pipe 9, discharges it to an intermediate pressure, and discharges the second rotary compression element. Further sucks in the intermediate pressure refrigerant compressed and discharged by the first rotary compression element, compresses it to a high pressure, and discharges it to the high pressure side of the refrigeration refrigerant circuit 1. The compressor 11 is a variable frequency compressor, and can control the rotational speeds of the first rotary compression element and the second rotary compression element by changing the operating frequency of the electric element.

  On the side surface of the hermetic container 12 of the compressor 11, a low-stage suction port 22 and a low-stage discharge port 24 that communicate with the first rotary compression element, and a high-stage side that communicates with the second rotary compression element A suction port 26 and a high-stage discharge port 28 are formed. Refrigerant introduction pipes 30 are connected to the low-stage suction ports 22, 22 of the compressors 11, 11, respectively, and merge at the upstream side of each, and are connected to the refrigerant pipe 9.

  The low pressure (LP: about 4 MPa in a normal operation state) refrigerant gas sucked into the low pressure portion of the first rotary compression element by the low-stage side suction port 22 causes the intermediate pressure (MP: The pressure is increased to about 8 MPa in a normal operation state and discharged into the sealed container 12. Thereby, the inside of the airtight container 12 becomes an intermediate pressure (MP).

  Intermediate pressure discharge pipes 36 and 36 are respectively connected to the low-stage discharge ports 24 and 24 of the compressors 11 and 11 from which the intermediate-pressure refrigerant gas in the hermetic container 12 is discharged. And is connected to one end of the intercooler 38. The intercooler 38 cools the intermediate pressure refrigerant discharged from the first rotary compression element by air, and an intermediate pressure suction pipe 40 is connected to the other end of the intercooler 38. The suction pipe 40 is branched into two and then connected to the high-stage suction ports 26 and 26 of the compressors 11 and 11.

  The medium-pressure (MP) refrigerant gas sucked into the intermediate pressure portion of the second rotary compression element by the high-stage suction port 26 is compressed at the second stage by the second rotary compression element and is heated to a high temperature. The refrigerant gas becomes a high pressure (HP: a supercritical pressure of about 12 MPa in a normal operation state).

  High pressure discharge pipes 42 and 42 are connected to the high stage discharge ports 28 and 28 provided on the high pressure chamber side of the second rotary compression element of the compressors 11 and 11, respectively. Are connected to the refrigerant pipe 7 via an oil separator 44, a gas cooler 46, and an intermediate heat exchanger 80 and an exhaust heat recovery pipe 70 constituting a split cycle, which will be described in detail later. The exhaust heat recovery pipe 70 is arranged in a heat exchange relationship with the evaporator 164 of the air conditioning refrigerant circuit 154 of the air conditioning system 153, and constitutes a cascade heat exchanger 90.

  The gas cooler 46 cools the high-pressure discharged refrigerant discharged from the compressor 11, and a gas cooler blower 47 for air-cooling the gas cooler 46 is disposed in the vicinity of the gas cooler 46. In this embodiment, the gas cooler 46 is juxtaposed with the above-described intercooler 38 and an oil cooler 74, which will be described in detail later, and these are arranged in the same air passage. The air passage is provided with an outside air temperature sensor (outside air temperature detecting means) 56 that detects the outside air temperature where the refrigerator unit 3 is disposed.

  The high-stage discharge ports 28, 28 have a high-pressure sensor (high-pressure detector) 48 that detects the discharge pressure of the refrigerant discharged from the second rotary compression element, and a discharge that detects the discharge refrigerant temperature. A temperature sensor (discharge temperature detecting means) 50 is provided. Furthermore, the oil separator 44 separates and captures the oil contained in the high-pressure discharged refrigerant discharged from the compressor 11 from the refrigerant. The oil separator 44 receives the captured oil in the compressor 11. An oil return circuit 73 for returning is connected. The oil return circuit 73 is provided with an oil cooler 74 that cools the captured oil. The oil return circuit 73 is branched into two systems on the downstream side of the oil cooler 74, and each has a flow rate adjusting valve (motor valve). It is connected to the hermetic container 12 of the compressor 11 through 76. Since the inside of the sealed container 12 of the compressor 11 is maintained at an intermediate pressure as described above, the trapped oil is caused by the differential pressure between the high pressure in the oil separator 44 and the intermediate pressure in the sealed container 12. 12 is returned.

  On the other hand, the refrigeration case 5A and the refrigeration case 5B are respectively installed in the room 152 and connected in parallel to the refrigerant pipes 7 and 9, respectively. The refrigeration case 5A and the refrigeration case 5B have case-side refrigerant pipes 60A and 60B that connect the refrigerant pipe 7 and the refrigerant pipe 9, and the case-side refrigerant pipes 60A and 60B include solenoid valves 61A and 61B, respectively. The main throttle means 62A and 62B and the evaporators 63A and 63B are sequentially connected. Each of the evaporators 63A and 63B is adjacent to an air circulation fan 65A and 65B for blowing air to the evaporator.

  A refrigeration amplifier 186 is connected between the outlet of the evaporator 63A of the refrigeration case 5A and the refrigerant pipe 9. The refrigeration amplifier 186 includes a compressor 187 and an oil separator 188. The refrigeration amplifier 186 compresses the refrigerant that has reached the inlet to increase the pressure, and then discharges the refrigerant from the outlet. The inlet of the refrigeration amplifier 186 is connected to the evaporator 63A. The outlet of the refrigeration amplifier 186 is connected to the refrigerant pipe 9. The refrigerant pipe 9 is connected to the low-stage suction port 22 communicating with the first rotary compression element of each of the compressors 11 and 11 through the refrigerant introduction pipe 30 as described above. Thereby, the refrigeration refrigerant circuit 1 of the refrigeration system of the refrigeration apparatus R in the present embodiment is configured.

  In the figure, 191 and 192 are refrigeration case controllers and refrigeration case controllers provided in the refrigeration case 5A and the refrigeration case 5B, respectively, and 193 is a refrigeration amplifier controller provided in the refrigeration amplifier 186. Reference numeral 194 denotes a refrigerator unit controller (control means) provided in the refrigerator unit 3, and these controllers 191 to 194 are constituted by a microcomputer and can communicate data with each other and the master controller 159. Connected to be.

  In the refrigerator unit controller 194, various sensors are connected to the input side, and various valve devices, compressors 11 and 11, a fan motor of the gas cooler blower 47, and the like are connected to the output side. The refrigerator unit controller 194 controls the operating frequency of the compressors 11 and 11 based on the low pressure side pressure LT detected by the low pressure sensor 32 described later and a predetermined low pressure control value LPS, and the low pressure LP is reduced. Thus, the operating number of the compressors 11 is reduced, or the operating number is increased by stopping and rising. The details of the refrigerator unit controller 194 will be described later according to each control.

(A) Refrigerant amount adjustment control Next, refrigerant amount adjustment control of the refrigeration refrigerant circuit 1 constituting the refrigeration system 156 of the refrigeration apparatus R in the present embodiment will be described. The refrigerant recovery tank 100 is connected via the first communication circuit 101 to the high pressure side which is the supercritical pressure of the refrigeration refrigerant circuit 1, in this embodiment, to the downstream side of the intermediate heat exchanger 80 of the refrigerator unit 3. Has been. The refrigerant recovery tank 100 has a predetermined volume, and a first communication circuit (recovery communication circuit) 101 is connected to the upper portion of the tank 100. In the first communication circuit 101, an electric expansion valve 102 is interposed as a collection opening / closing means (first opening / closing means) having a throttling function. The opening / closing means having the restriction function is not limited to this. For example, the first communication circuit 101 may be constituted by, for example, a capillary tube and an electromagnetic valve (open / close valve) as the restriction means.

  The refrigerant recovery tank 100 is connected to a second communication circuit 103 that communicates the upper part of the tank 100 with the intermediate pressure region of the refrigeration refrigerant circuit 1. In the present embodiment, the other end of the second communication circuit 103 is connected to an intermediate pressure suction pipe 40 on the outlet side of the intercooler 38 of the refrigeration refrigerant circuit 1 as an example of the intermediate pressure region. The second communication circuit 103 is provided with an electromagnetic valve 104 as a second opening / closing means.

  The refrigerant recovery tank 100 is connected to a third communication circuit (discharge communication circuit) 105 that communicates the lower portion of the tank 100 with the intermediate pressure region of the refrigeration refrigerant circuit 1. In the present embodiment, the other end of the third communication circuit 105 is an intermediate pressure suction pipe on the outlet side of the intercooler 38 of the refrigeration refrigerant circuit 1, as in the second communication circuit 103 as an example of the intermediate pressure region. 40 to communicate. The third communication circuit 105 is provided with an electromagnetic valve 106 as a discharge opening / closing means (third opening / closing means).

  The refrigerator unit controller 194 has a unit outlet side pressure sensor (unit outlet side pressure detecting means) 58 and an outside air temperature sensor 56 connected to the input side. This unit outlet side pressure sensor 58 detects the pressure of the refrigerant toward the refrigeration case 5A and the refrigeration case 5B via the exhaust heat recovery pipe 70 on the downstream side of the refrigerant recovery tank 100. On the output side of the refrigerator unit controller 194, there are an electric expansion valve (first opening / closing means) 102, an electromagnetic valve (second opening / closing means) 104, an electromagnetic valve (third opening / closing means) 106, and the gas cooler 46. The fan motor of the blower 47 is connected. The refrigerator unit controller 194 controls the rotational speed of the fan motor of the gas cooler blower 47 based on the temperature detected by the outside air temperature sensor 56 (outside air temperature) as will be described in detail later.

(A-1) Refrigerant Recovery Operation Hereinafter, the refrigerant recovery operation of the refrigeration refrigerant circuit 1 will be described. The refrigerator unit controller 194 determines whether or not the detected pressure of the unit outlet side pressure sensor 58 (high pressure side pressure HP) has exceeded a predetermined recovery threshold, or whether the detected pressure of the unit outlet side pressure sensor 58 is the previous recovery threshold. It is determined whether or not a predetermined recovery protection value lower than that is exceeded and the rotational speed of the gas cooler blower 47 is the maximum value.

  In the present embodiment, the intermediate pressure (MP) of the refrigeration refrigerant circuit 1 has an appropriate value of about 8 MPa as an example, so that the value is set as the recovery protection value, and the recovery threshold is higher than the recovery protection value. ) Set to 9 MPa. Moreover, the maximum value of the rotation speed of the gas cooler blower 47 in this embodiment is set to 800 rpm as an example. Further, it may be a condition that a predetermined time elapses after the rotation number of the gas cooler blower 47 reaches the maximum value.

  Thereby, the refrigerator unit controller 194 exceeds the recovery protection value of 8 MPa when the detected pressure of the unit outlet side pressure sensor 58 exceeds the recovery threshold of 9 MPa, or even if the detected pressure is equal to or lower than the recovery threshold. When the rotational speed of the gas cooler blower 47 reaches the maximum value of 800 rpm, it is determined that the high-pressure side pressure has abnormally increased due to excess gas refrigerant in the refrigeration refrigerant circuit 1. A collection operation is executed.

  In this refrigerant recovery operation, the refrigerator unit controller 194 opens the electric expansion valve (recovery opening / closing means) 102 and the electromagnetic valve 104 with the electromagnetic valve (release opening / closing means) 106 closed. As a result, the high-temperature and high-pressure refrigerant discharged from the high-stage discharge port 28 of the compressors 11 and 11 passes through the oil separator 44 and is cooled by the gas cooler 46 and the intermediate heat exchanger 80, and then a part thereof is opened. The refrigerant flows into the refrigerant recovery tank 100 through the first communication circuit 101 in which the electric expansion valve 102 is provided.

  At this time, since the electromagnetic valve 104 is opened, the inside of the refrigerant recovery tank 100 is connected via the second communication circuit 103 that connects the upper part of the refrigerant recovery tank 100 and the intermediate pressure region of the refrigeration refrigerant circuit 1. Pressure can be released out of the tank. Therefore, even when the refrigerant in the refrigeration refrigerant circuit 1 is operated in a gas cycle in which the refrigerant in the refrigeration refrigerant circuit 1 is not liquefied, such as when the outside air temperature becomes high, the refrigerant in the tank 100 decreases in pressure and flows into the tank. Liquefies and accumulates in the tank 100. That is, when the pressure in the refrigerant recovery tank 100 drops below the supercritical pressure, the refrigerant changes from the gas region to the saturation region, and the liquid level can be secured.

  As a result, the refrigerant in the refrigeration refrigerant circuit 1 can be quickly and efficiently recovered in the refrigerant recovery tank 100. Therefore, it is possible to eliminate the disadvantage of the abnormally high pressure caused by the refrigerant having a surplus on the high pressure side in the refrigeration refrigerant circuit 1, and to prevent overload operation of the compressors 11 and 11 due to the high pressure abnormality. In particular, unlike the case where the upper part of the refrigerant recovery tank 100 and the intermediate pressure region of the refrigeration refrigerant circuit 1 are communicated with each other via the second communication circuit 103, the lower pressure side region of the refrigeration refrigerant circuit 1 is communicated. It is possible to avoid a decrease in cooling efficiency due to an increase in the low-pressure side pressure.

  Further, in this embodiment, even if the pressure on the high pressure side detected by the unit outlet side pressure sensor 58 is equal to or lower than the recovery threshold, the predetermined recovery protection value is exceeded, and the blower 47 that air-cools the gas cooler 46 is used. When the rotational speed is the maximum value, the refrigerant recovery operation is performed, and therefore, the efficiency due to the state in which the high-pressure side of the refrigeration refrigerant circuit 1 is abnormally high in consideration of the operation state of the blower 47 continues. It is possible to prevent the decrease.

(A-2) Refrigerant holding operation On the other hand, the refrigerator unit controller 194 determines whether or not the high-pressure side pressure detected by the unit outlet side pressure sensor 58 has become a recovery protection value, which is 8 MPa or less in this embodiment. However, when the value falls below the recovery protection value, the refrigerant recovery operation is terminated and the operation proceeds to the refrigerant holding operation. In this refrigerant holding operation, the refrigerator unit controller 194 maintains a state where the electromagnetic valve (release opening / closing means) 106 is closed, closes the electromagnetic valve 104, and increases the opening degree of the electric expansion valve (recovery opening / closing means) 102. The opening degree in the refrigerant recovery operation is maintained.

  The opening degree of the electric expansion valve 102 may be smaller than the opening degree in the refrigerant recovery operation. As a result, when the electromagnetic valve 104 is closed, the liquid level in the refrigerant recovery tank 100 can be maintained by the pressure of the high-pressure side region of the refrigeration refrigerant circuit 1 via the opened electric expansion valve 102. Become. Therefore, liquid sealing in the refrigerant recovery tank 100 can be avoided, and safety can be ensured. Thereby, it becomes possible to maintain the amount of circulating refrigerant in the refrigeration refrigerant circuit 1 appropriately.

  The refrigerator unit controller 194 also sets the opening of the electric expansion valve 102 in the refrigerant holding operation to be smaller than the opening in the refrigerant recovery operation, so that the refrigeration refrigerant is stored in the refrigerant recovery tank 100 in the refrigerant holding operation. When the refrigerant in the circuit 1 is recovered excessively, it is possible to effectively eliminate the disadvantage that the refrigerant in the refrigeration refrigerant circuit 1 is insufficient.

(A-3) Refrigerant discharge operation Then, the refrigerator unit controller 194 has a predetermined discharge threshold (7 MPa in this embodiment) in which the detected pressure of the unit outlet side pressure sensor 58 is lower than the recovery protection value (in this case, about 8 MPa). Or the detected pressure of the unit outlet side pressure sensor 58 is equal to or lower than the previous recovery protection value, and the rotational speed of the gas cooler blower 47 is equal to or lower than a predetermined specified value lower than the maximum value. Judge whether or not. In this embodiment, the predetermined specified value is about 3/8 of the maximum value, that is, about 300 rpm when the maximum value is 800 rpm. Further, it may be a condition that a predetermined time elapses after the rotational speed of the gas cooler blower 47 becomes equal to or less than a predetermined specified value.

  As a result, the refrigerator unit controller 194 allows the gas cooler blower when the detected pressure of the unit outlet side pressure sensor 58 is less than the discharge threshold value of 7 MPa, or when the detected pressure is 8 MPa or less which is the recovery protection value. If the rotational speed of 47 is a predetermined specified value, in this case 300 rpm or less, it is determined that the refrigerant in the refrigeration refrigerant circuit 1 has become insufficient, and the refrigerant discharge operation is executed.

  In this refrigerant discharge operation, the refrigerator unit controller 194 closes the electric expansion valve (recovery opening / closing means) 102 and the electromagnetic valve 104 and opens the electromagnetic valve (release opening / closing means) 106. As a result, the liquid refrigerant accumulated in the refrigerant recovery tank 100 is discharged to the refrigeration refrigerant circuit 1 through the third communication circuit 105 in which the electromagnetic valve 106 connected to the lower portion of the tank 100 is opened. Therefore, unlike the case where gas refrigerant is mixed from the upper part of the refrigerant recovery tank 100 and discharged to the refrigeration refrigerant circuit 1, the refrigerant in the refrigerant recovery tank 100 can be quickly released to the refrigeration refrigerant circuit 1. Thereby, it is possible to operate the refrigeration refrigerant circuit 1 of the refrigeration system 156 with high efficiency.

(A-4) Refrigerant holding operation Thereafter, the refrigerator unit controller 194 determines whether or not the high-pressure side pressure detected by the unit outlet-side pressure sensor 58 has reached a recovery protection value, which is 8 MPa or more in this embodiment. If the recovery protection value is exceeded, the refrigerant discharge operation is terminated and the operation proceeds to the refrigerant holding operation as described above. Thereafter, based on the high-pressure side pressure of the refrigeration refrigerant circuit 1, the refrigerant recovery operation-refrigerant holding operation-refrigerant discharge operation-refrigerant holding operation is repeatedly executed to control refrigerant recovery / release based on the high-pressure side pressure. It is possible to accurately prevent high pressure protection and overload operation. Thereby, the cooling capacity of the refrigeration refrigerant circuit 1 can be ensured, and the COP can be optimized.

  In particular, in this embodiment, it is possible to control the refrigerant recovery / release operation in consideration of not only the high-pressure side pressure but also the rotational speed of the gas cooler blower 47 that air-cools the gas cooler 46, and the high-pressure of the refrigeration refrigerant circuit 1. It is possible to prevent a decrease in efficiency due to a state in which the side becomes abnormally high. In the present embodiment, the second communication circuit 103 and the third communication circuit 105 are both in communication with the outlet side of the intercooler 38 of the refrigeration refrigerant circuit 1. Thereby, pressure loss in the intercooler 38 can be prevented, and the refrigerant can be smoothly discharged from the refrigerant recovery tank 100 to the refrigeration refrigerant circuit 1.

  In addition, when the compressors 11 and 11 stop operation, the refrigerator unit controller 194 performs a refrigerant discharge operation. Thereby, the disadvantage that the refrigerant amount in the refrigeration refrigerant circuit 1 is insufficient at the time of starting the compressors 11 and 11 can be solved, and an appropriate high pressure side pressure according to the pressure on the high pressure side by the compressor 11 to be operated. Can be realized. In this case, the compressor 11 (compression means) employs a two-stage compression rotary compressor in which the first and second compression elements and the electric element are incorporated in the sealed container 12. In addition, it may be of a type in which the refrigerant can be taken out and introduced from the intermediate pressure section with two single-stage rotary compressors or other types of compressors.

(B) Split cycle Next, the split cycle of the refrigeration refrigerant circuit 1 of the refrigeration system 156 of the refrigeration apparatus R in the present embodiment will be described. The refrigerant circuit 1 for refrigeration in the present embodiment includes a merger 81 as a merger that merges the first rotary compression element (low stage side) of each of the compressors 11, 11, the intercooler 38, and the two fluid flows. , The second rotary compression element (higher stage side) of each compressor 11, 11, oil separator 44, gas cooler 46, flow divider 82, auxiliary throttle means (auxiliary expansion valve) 83, intermediate heat exchanger 80, main throttle The means (main expansion valves) 62A and 62B, the evaporators 63A and 63B, and the refrigeration amplifier 193 constitute a refrigeration cycle.

  The flow divider 82 is a flow dividing device that divides the refrigerant from the gas cooler 46 into two flows. That is, the flow divider 82 of the present embodiment diverts the refrigerant that has exited the gas cooler 46 into the first refrigerant flow and the second refrigerant flow, the first refrigerant flow through the auxiliary circuit, and the second refrigerant flow. In the main circuit.

  The main circuit in FIG. 1 includes the first rotary compression element of the compressors 11 and 11, the intercooler 38, the merger 81, the second rotary compression element 20 of the compressors 11 and 11, the gas cooler 46, and the flow divider. 82, an annular refrigerant circuit comprising the second flow path 80B of the intermediate heat exchanger 80, the main throttle means 62A, 62B, the evaporators 63A, 63A, etc. The auxiliary circuit refers to the auxiliary throttle means 83 from the flow divider 82. 3 shows a circuit that reaches the junction 81 through the first flow path 80A of the intermediate heat exchanger 80 in sequence.

  The auxiliary throttle means 83 diverts the first refrigerant flow that is diverted by the flow divider 82 and flows through the auxiliary circuit. The intermediate heat exchanger 80 is a heat exchanger that performs heat exchange between the first refrigerant flow in the auxiliary circuit decompressed by the auxiliary throttle means 83 and the second refrigerant flow divided by the flow divider 82. In the intermediate heat exchanger 80, a second flow path 80B through which the second refrigerant flow flows and a first flow path 80A through which the first refrigerant flow flows are provided in a heat exchangeable relationship. Since the second refrigerant flow is cooled by the first refrigerant flow flowing through the first flow path 80A by passing through the second flow path 80B of the intermediate heat exchanger 80, the evaporators 63A, 63B The specific enthalpy in can be reduced.

  The refrigerator unit controller 194 includes a discharge temperature sensor (discharge temperature detecting means) 50, a unit outlet side pressure sensor (unit outlet side pressure detecting means) 58, an intermediate pressure sensor (intermediate pressure pressure detecting means) 49, a split on the input side. Outlet temperature sensor (split outlet temperature detection means) 64, low pressure sensor (suction pressure detection means) 32, gas cooler outlet temperature sensor (gas cooler outlet temperature detection means) 52, unit outlet temperature sensor (unit outlet temperature detection means) 54, unit An inlet temperature sensor (inlet temperature detection means) 34 is connected.

  The discharge temperature sensor 50 is provided in the high-stage discharge port 28 of the compressors 11 and 11, and detects the discharge temperature (DT) of the refrigerant discharged from the second rotary compression element. The unit outlet side pressure sensor 58 is a downstream side of the refrigerant recovery tank 100 and detects the pressure of the refrigerant toward the refrigeration case 5A and the refrigeration case 5B through the exhaust heat recovery pipe 70 (cascade heat exchanger 90). It is. The low-pressure sensor 32 is connected to the low-stage suction ports 22 and 22 of the compressors 11 and 11 on the low-pressure side of the refrigeration refrigerant circuit 1, which is downstream of the evaporators 63A and 63B in this embodiment. The suction pressure of the refrigerant that is provided in the refrigerant pipe 9 and moves toward the refrigerant introduction pipe 30 is detected. The intermediate pressure sensor 49 is an intermediate pressure region of the refrigeration refrigerant circuit 1, which is an auxiliary circuit of the split cycle in this embodiment, and is the first circuit after passing through the first flow path 80A of the intermediate heat exchanger 80. Detect the pressure of the refrigerant flow. The split outlet temperature sensor 64 detects the temperature (Tsp) of the first refrigerant flow after passing through the first flow path 80A of the intermediate heat exchanger 80.

  The gas cooler outlet temperature sensor 52 is provided on the outlet side of the gas cooler 46 and detects the temperature (GCT) of the refrigerant before leaving the gas cooler 46 and being divided. The unit outlet temperature sensor 54 is provided on the outlet side of the intermediate heat exchanger 80 connected to the refrigerant pipe 7 and is the temperature of the second refrigerant flow after passing through the second flow path 80B of the intermediate heat exchanger 80. A unit outlet temperature (LT) is detected. The unit inlet temperature sensor 34 is provided in the refrigerant pipe 9 connected to the lower stage suction port 22 of the compressor 11 and detects the refrigerant suction temperature toward the refrigerant introduction pipe 30. The auxiliary throttle means 83 constituting the split cycle is connected to the output side of the refrigerator unit controller 194. The opening degree of the auxiliary throttle means 83 is controlled by a step motor.

  Hereinafter, the opening degree control of the auxiliary throttle means 83 will be described in detail. The auxiliary throttle means 83 has a predetermined initial valve opening when the compressor 11 starts operating. Thereafter, the refrigerator unit controller 194 determines an operation amount for increasing the valve opening degree of the auxiliary throttle means 83 based on the following first control amount, second control amount, and third control amount.

(B-1) Valve Opening Increase Control of Auxiliary Throttle Means The first control amount (DTcont) is obtained based on the discharge refrigerant temperature DT of the compressor 11. The refrigerator unit controller 194 determines whether or not the temperature DT detected by the discharge temperature sensor 50 is higher than a predetermined value DT0. If the discharge refrigerant temperature DT is higher than the predetermined value DT0, the auxiliary throttle means A control amount acting in the direction of increasing the opening degree of 83 is set. The predetermined value DT0 is set to a temperature (for example, + 95 ° C.) that is slightly lower than a limit temperature (for example, + 100 ° C.) that enables proper operation of the compressor 11. When the temperature rises, the auxiliary throttle means 83 is opened. By increasing the degree, the temperature rise of the compressor 11 is suppressed, and control is performed so that the compressor 11 does not reach the limit temperature.

  The second control amount (MPcont) is a control amount for adjusting the amount of refrigerant flowing through the auxiliary circuit of the split cycle to optimize the intermediate pressure (MP). In this embodiment, it is calculated from the high pressure side pressure HP of the refrigeration refrigerant circuit 1 detected by the unit outlet side pressure sensor 58 and the low pressure side pressure LP of the refrigeration refrigerant circuit 1 detected by the low pressure sensor 32. It is determined whether or not the pressure MP in the intermediate pressure region of the refrigeration refrigerant circuit 1 detected by the intermediate pressure sensor 49 is higher than the (determined) appropriate intermediate pressure value, and the pressure MP in the intermediate pressure region is appropriate. When the pressure is lower than the intermediate pressure value, the auxiliary throttle means 83 is actuated to increase the opening.

  The appropriate intermediate pressure value may be calculated from the geometric mean of the detected high-pressure side pressure HP and the low-pressure side pressure LP. In addition, an appropriate intermediate pressure value may be calculated from the high-pressure side pressure HP and the low-pressure side pressure LP in advance. The intermediate pressure value may be obtained experimentally and determined from a data table constructed based on this.

  In the present embodiment, the second control amount (MPcont) is determined by comparing the appropriate intermediate pressure value obtained from the high pressure side pressure HP and the low pressure side pressure LP with the pressure MP in the intermediate pressure region. However, the present invention is not limited to this. For example, the following may be adopted. That is, the overcompression determination value MPO is calculated from the pressure MP in the intermediate pressure region of the refrigeration refrigerant circuit 1 detected by the intermediate pressure sensor 49 and the low pressure side pressure LP of the refrigeration refrigerant circuit 1 detected by the low pressure sensor 32. Then, it is determined whether or not the overcompression determination value MPO is lower than the high pressure side pressure HP of the refrigeration refrigerant circuit 1 detected by the unit outlet side pressure sensor 58, and the overcompression determination value MPO is higher than the high pressure side pressure HP. If it is lower, the auxiliary throttle means 83 is actuated to increase the opening. By reflecting the second control amount in the opening degree control of the auxiliary throttle means 83, the pressure difference among the high pressure side pressure HP, the intermediate pressure region pressure MP, and the low pressure side pressure LP can be appropriately maintained, and the refrigeration cycle The operation can be stabilized.

  The third control amount (SPcont) is a control amount for optimizing the refrigerant temperature LT that has come out of the second flow path of the intermediate heat exchanger 80. In the present embodiment, the refrigerator unit controller 194 includes the refrigerant temperature GCT before being diverted through the gas cooler 46 detected by the gas cooler outlet temperature sensor 52 and the intermediate heat exchanger 80 detected by the unit outlet temperature sensor 54. It is determined whether or not the difference (GCT−LT) from the temperature LT of the second refrigerant flow that has passed through is smaller than a predetermined value SP, and if it is smaller, the opening degree of the auxiliary throttle means 83 is increased. .

  Here, the predetermined value SP is different depending on whether the high-pressure side pressure HP is in the supercritical region or the saturation region of the refrigerant. In the present embodiment, whether the high-pressure side pressure HP is a supercritical region or a saturated region is based on the outside air temperature detected by the outside air temperature sensor 56, and when the outside air temperature is high, for example, at + 31 ° C. or higher, If it is determined that the temperature is in the supercritical region and the outside air temperature is low, for example, if it is less than + 31 ° C., it is determined that the region is a saturated region. If it is determined that the region is a supercritical region, the predetermined value SP is set to be increased, and if it is determined to be a saturated region, the predetermined value SP is decreased. In this embodiment, the predetermined value SP is + 35 ° C. in the supercritical region and + 20 ° C. in the saturation region.

  The refrigerator unit controller 194 uses the three control amounts obtained as described above, that is, the first control amount (DTcont), the second control amount (MPcont), and the third control amount (SPcont). In addition, the operation amount of the valve opening of the auxiliary throttle means 83 is determined, and the valve opening is increased based on this.

(B-2) Valve Opening Reduction Control of Auxiliary Throttle Means Further, the refrigerator unit controller 194 is configured such that the second refrigerant flow temperature LT passed through the intermediate heat exchanger 80 or the refrigerant discharge temperature DT from the compressor 11. The operation amount for reducing the valve opening degree of the auxiliary throttle means 83 is determined from the difference between the refrigerant temperature GCT and the refrigerant temperature GCT before being diverted through the gas cooler 46.

  That is, the refrigerator unit controller 194 determines whether the temperature LT of the second refrigerant flow that has passed through the intermediate heat exchanger 80 detected by the unit outlet temperature sensor 54 is lower than a predetermined value. In the present embodiment, the predetermined value is set to −5 ° C. as an example. Accordingly, when the unit outlet temperature is −5 ° C. or lower, the second refrigerant flow cooled in the intermediate heat exchanger 80 is excessively cooled by operating in the direction of reducing the opening degree of the auxiliary throttle means 83. It is possible to eliminate the inconvenience.

  The refrigerator unit controller 194 also determines the difference (DT−) between the temperature DT detected by the discharge temperature sensor 50 and the refrigerant temperature GCT before being diverted through the gas cooler 46 detected by the gas cooler outlet temperature sensor 52. It is determined whether or not (GCT) is lower than a predetermined value TDT, and if it is lower, the opening of the auxiliary throttle means 83 is acted in the direction of reducing.

  Here, the predetermined value TDT differs depending on whether the high-pressure side pressure HP is in the supercritical region or the saturation region of the refrigerant. In the present embodiment, as in the case of obtaining the third control amount, whether the high-pressure side pressure HP is in the supercritical region or the saturated region is determined based on the outside air temperature. When it is determined that the region is a supercritical region, the predetermined value TDT is set to be lowered. When it is determined that the region is a saturated region, the predetermined value TDT is increased. In this embodiment, the predetermined value TDT is + 10 ° C. in the supercritical region and + 35 ° C. in the saturation region.

  When the temperature LT of the second refrigerant flow that has passed through the intermediate heat exchanger 80 is equal to or lower than a predetermined value (0 ° C.), the refrigerator unit controller 194 passes through the refrigerant temperature DT discharged from the compressor 11 and the gas cooler 46. When the difference from the refrigerant temperature GCT before diversion is lower than the predetermined value TDT, the operation amount of the valve opening of the auxiliary throttle means 83 is determined, and the valve opening is based on this regardless of the valve opening increase control. Reduce the degree.

  In the refrigeration refrigerant circuit 1 of the refrigeration system 156 of the refrigeration apparatus R having the split cycle as described above, the first refrigerant flow that has been decompressed and expanded by the auxiliary throttle means 83 is divided by the refrigerant after having been radiated by the gas cooler 46. Thus, the second refrigerant flow can be cooled, and the specific enthalpy at the inlets of the evaporators 63A and 63B can be reduced. As a result, the refrigeration effect can be increased and the performance can be effectively improved as compared with the conventional apparatus. In addition, since the divided first refrigerant flow is returned to the second rotary compression element (intermediate pressure portion) from the high-stage suction port 26 of the compressor 11, the first refrigerant flow from the low-stage suction port 22 of the compressor 11 is returned. The amount of the second refrigerant flow sucked into the first rotary compression element (low pressure part) is reduced, and the compression work in the first rotary compression element (low stage part) for compressing from the low pressure to the intermediate pressure is reduced. Decrease. As a result, the compression power in the compressor 11 is reduced and the coefficient of performance is improved.

  Here, the effect of the so-called split cycle depends on the amounts of the first refrigerant flow and the second refrigerant flow flowing through the intermediate heat exchanger 80. That is, if the amount of the first refrigerant flow is too large, the amount of the second refrigerant flow that finally evaporates in the evaporators 63A and 63B is insufficient, and conversely if the amount of the first refrigerant flow is too small. The effect of the split cycle fades. On the other hand, the pressure of the first refrigerant flow reduced by the auxiliary throttle means 83 is the intermediate pressure of the refrigeration refrigerant circuit 1, and controlling the intermediate pressure controls the amount of the first refrigerant flow. .

  Here, in this embodiment, as described above, when the temperature DT (discharge temperature sensor 50) of the refrigerant discharged from the compressor 11 is higher than the predetermined value DT0, the opening of the auxiliary throttle means 83 is increased. Assist when the pressure MP in the intermediate pressure region of the refrigeration refrigerant circuit 1 is lower than the appropriate intermediate pressure value obtained from the first control amount and the high pressure side pressure HP and the low pressure side pressure LP of the refrigeration refrigerant circuit 1 The second control amount acting in the direction of increasing the opening degree of the throttle means 83, the temperature GCT of the refrigerant before being diverted through the gas cooler 46, and the temperature LT of the second refrigerant flow through the intermediate heat exchanger 80 When the difference (GCT−LT) is smaller than the predetermined value SP, the third control amount acting in the direction of increasing the opening degree of the auxiliary throttle means 83 is calculated, and these first to third control amounts are added together. Therefore, the auxiliary throttle means 83 Determining a manipulated variable for increasing the opening degree. Further, when the temperature LT is lower than a predetermined value, or when the temperature DT-GCT is lower than the predetermined value TDT, the operation amount is determined in a direction to reduce the valve opening degree of the auxiliary throttle means 83.

  As a result, the temperature DT of the discharged refrigerant can be kept at a predetermined value DT0 or less by the first control amount, and the intermediate pressure MP of the refrigeration refrigerant circuit 1 can be optimized by the second control amount. The pressure difference among the side pressure LP, the intermediate pressure MP, and the high pressure side pressure HP can be properly maintained. In addition, the temperature LT of the second refrigerant flow that has passed through the intermediate heat exchanger 80 can be lowered by the third control amount, and the refrigeration effect can be maintained. As a result, it is possible to achieve high efficiency and stabilization of the refrigeration apparatus as a whole.

  The refrigerator unit controller 194 increases the predetermined value SP and lowers the predetermined value TDT when the high-pressure side pressure HP is in the supercritical region, and decreases the predetermined value SP when the high-pressure side pressure HP is in the saturation region. By increasing the predetermined value TDT, the third control amount and the predetermined values SP and TDT of the first control amount are changed depending on whether the high-pressure side pressure HP is in the supercritical region or the saturation region. Can be controlled.

  Thereby, even when the high-pressure side pressure HP is in the saturation region, the degree of superheat in the intermediate heat exchanger 80 can be reliably ensured, and the inconvenience of causing a liquid back in the compressor 11 can be avoided. Further, when the high-pressure side pressure HP is in the supercritical region, such a liquid back does not occur, and therefore, the efficiency can be set as a priority.

  When the over-compression determination value MPO obtained from the pressure MP and the low-pressure side pressure LP in the intermediate pressure region of the refrigeration refrigerant circuit 1 is lower than the high-pressure side pressure HP of the refrigerant circuit. As the second control amount acting in the direction of increasing the opening degree of the auxiliary throttle means, the operation amount of the valve opening degree of the auxiliary throttle means is determined by adding the first to third control quantities. In the same manner as described above, the intermediate pressure MP of the refrigerant circuit can be optimized, and thereby the pressure difference among the low pressure side pressure LP, the intermediate pressure MP, and the high pressure side pressure HP can be properly maintained.

  In addition, the first refrigerant flow output from the intermediate heat exchanger 80 in this embodiment can be returned to the outlet side of the intercooler 38 by the merger 81 provided on the outlet side of the intercooler 38. Thus, it is possible to prevent the pressure loss at 38 and smoothly merge the refrigerant flow from the intermediate heat exchanger 80 to the intermediate pressure side of the refrigeration refrigerant circuit 1.

(C) Cascade heat exchanger Next, the cascade heat exchanger 90 employed in the refrigeration apparatus R will be described. In the present embodiment, the cascade heat exchanger 90 is divided by the flow divider 82 through the gas cooler 46 and flows through the exhaust heat recovery pipe 70 through the intermediate heat exchanger 80 (the refrigeration refrigerant of the refrigeration system 156). This is a heat exchanger that performs heat exchange between the high-pressure side of the circuit 1 and the refrigerant flowing through the evaporator 164 of the air-conditioning refrigerant circuit 154 of the air-conditioning system 153 (low-pressure side of the air-conditioning refrigerant circuit 154 of the air-conditioning system 153). . Thus, the second refrigerant flow that has passed through the intermediate heat exchanger 80 of the refrigeration refrigerant circuit 1 is cooled by the refrigerant that evaporates in the evaporator 164 of the air conditioning refrigerant circuit 154, and the evaporator 164 of the air conditioning refrigerant circuit 154 is The heat of the second refrigerant flow in the refrigeration refrigerant circuit 1 is pumped up by the flowing refrigerant.

  As described above, the cascade heat exchanger 90 for exchanging heat between the low pressure side of the air conditioning refrigerant circuit 154 of the air conditioning system 153 and the high pressure side of the refrigeration refrigerant circuit 1 of the refrigeration system 156 is provided. The exhaust heat recovery pipe 70 through which the second refrigerant flow before reaching the main throttle means 62A and 62B via the intermediate heat exchanger 80 of the refrigeration system 156 flows, and the evaporator 164 of the air conditioning system 153, Since the refrigerant flowing through the evaporator 164 and the second refrigerant flow of the refrigeration system 156 are heat-exchanged, the refrigerant evaporated in the evaporator 164 of the air conditioning refrigerant circuit 154 of the air conditioning system 153 causes the refrigerant of the refrigeration system 156 to The second refrigerant flow reaching the main throttle means 62A and 62B of the refrigeration refrigerant circuit 1 is supercooled, and the inside of the refrigeration case 5A or the refrigeration case 5B in a so-called split cycle supercritical refrigeration cycle. It is possible to improve the operating efficiency and capacity of the refrigeration system 156, each cooled further.

  On the other hand, in the air conditioning system 153, the evaporator 164 effectively sucks up the exhaust heat of the refrigeration system 156, generates hot water in the hot water storage tank 171 by heat radiation from the radiator 162, and uses the hot water to generate a desiccant air conditioner or an absorption type. By performing air conditioning of the room 152 with the hot water use air conditioner 159 composed of an air conditioner, it is possible to significantly improve the air conditioning efficiency and capacity. In general, it is possible to improve the energy balance and efficiency of the refrigeration apparatus R that cools indoor air conditioning and cooling storage facilities, and achieves significant energy saving. In particular, when carbon dioxide is used as the refrigerant in the refrigeration refrigerant circuit 1 of the refrigeration system 156, the refrigerating capacity can be effectively improved and the performance can be improved.

  Although not shown in FIG. 1, the hot water in the hot water storage tank 171 may be directly supplied to a cooking room or the like at the store. Moreover, the floor heating of the room (store) 152 may be performed using hot water in the hot water storage tank 171. The concept of the indoor air conditioning in the air conditioning system 153 is not limited to the hot water use air conditioner 159, and such floor heating is also applicable. Shall be included.

(D) Control of Gas Cooler Blower Next, control of the gas cooler blower 47 for air-cooling the gas cooler 46 as described above will be described. The refrigerator unit controller (control means) 194 in the present embodiment is connected to the high temperature pressure sensors (high pressure detection means) 48, 48 and the low pressure sensor 32 on the input side, and the outside air temperature sensor 56 is connected to the output side. A blower 47 is connected.

  The refrigerator unit controller 194 has a blower control mode 1 that is controlled based on the high pressure side pressure HP as a control mode of the blower 47 for the gas cooler, and a blower control mode 2 that is controlled by an outside air temperature AT and a basic rotational speed BHz described later. In the blower control mode 1, the refrigerator unit controller 194 performs control to increase the rotational speed of the gas cooler blower 47 when the high pressure side pressure HP detected by the high pressure sensor 48 increases, and to decrease the rotational speed when it decreases. Run. The switching of the blower control mode can be performed by a switch operation of the refrigerator unit controller 194 or the master controller 183.

  Here, the high pressure side pressure HP of the refrigeration refrigerant circuit 1 varies depending on the outside air temperature AT, and the higher the outside air temperature AT, the higher the high pressure side pressure HP. Further, if the rotational speed of the gas cooler blower 47 is increased, the air cooling capacity of the gas cooler 46 is increased, so that the high pressure side pressure HP is decreased. Therefore, it is experimentally determined in advance how many rotations of the gas cooler blower 47 with respect to various outdoor temperature AT conditions will cause the high pressure side pressure HP to reach a predetermined target value (target high pressure: THP). It is possible to ask for it.

  Therefore, when the gas cooler blower 47 is operated at the outside air temperature AT in a state where an appropriate amount of refrigerant is sealed in the refrigeration refrigerant circuit 1, the high pressure side pressure HP detected by the high pressure sensor 48 is The number of revolutions of the gas cooler blower 47 that becomes a predetermined target value (target high pressure: THP) is obtained in advance by experiments, and the number of revolutions is stored (stored) in the refrigerator unit controller 194 as data of the basic number of revolutions BHz. Let me.

  The data on the basic rotational speed BHz of the gas cooler blower 47 may be written as a data table of the basic rotational speed BHz respectively obtained corresponding to each assumed outdoor air temperature AT. The refrigerator unit controller 194 may be programmed as a function of the basic rotation speed BHz.

  In the blower control mode 2, the refrigerator unit controller 194 reads or calculates the basic rotation speed BHz corresponding to the outside air temperature AT detected by the outside air temperature sensor 56. Then, the gas cooler blower 47 is controlled so that the rotational speed becomes the basic rotational speed BHz. In this way, the refrigerator unit controller 194 stores data related to the basic rotation speed BHz of the gas cooler blower 47 according to the outside air temperature AT, and the basic rotation speed is based on the outside air temperature AT detected by the outside air temperature sensor 56. If the rotational speed of the gas cooler blower 47 is controlled so as to be BHz, the basic rotational speed BHz of the gas cooler blower 47 is operated at the basic rotational speed BHz corresponding to the outdoor air temperature AT. By setting the rotation speed at which the high-pressure side pressure HP of the refrigeration refrigerant circuit 1 becomes the target value THP, even if the refrigeration refrigerant circuit 1 of the refrigeration apparatus R has a supercritical pressure on the high-pressure side, The rotation speed of the gas cooler blower 47 can be controlled so that the high pressure side pressure HP becomes the target value THP.

  Here, since the high-pressure side pressure HP of the refrigeration refrigerant circuit 1 detected by the high-pressure sensor 48 fluctuates in a short time, if the rotation speed of the gas cooler blower 47 is controlled based on this high-pressure side pressure HP, the fluctuation of the rotation speed The width increases and noise increases.

  However, as described above, the rotational speed of the gas cooler blower 47 is not controlled based on the high-pressure side pressure HP of the refrigeration refrigerant circuit 1 detected by the high-pressure sensor 48, and the gas cooler is used at a basic rotational speed BHz corresponding to the outside temperature AT in advance. By controlling the blower 47, it is possible to avoid the disadvantage that the fluctuation range of the rotation speed of the gas cooler blower 47 becomes large due to the short-term fluctuation of the high pressure side pressure HP, and the noise due to the operation of the gas cooler blower 47 is reduced as a whole. However, highly efficient and stable operation can be realized. Note that when the outside air temperature AT exceeds the control range, the rotation speed of the gas cooler blower 47 naturally becomes the maximum value, so that the refrigerator unit controller 194 recovers the refrigerant in the refrigerant recovery tank 100 as described above. The refrigerant recovery operation is executed, and the amount of refrigerant circulating in the refrigeration refrigerant circuit 1 is adjusted to prevent the high pressure side pressure HP from rising abnormally.

  In particular, in the supercritical refrigeration cycle using carbon dioxide as the refrigerant in the refrigeration refrigerant circuit 1, either the saturation cycle or the gas cycle is performed depending on the outside air temperature AT. Since the refrigerant is not liquefied when the gas cycle is performed, the temperature and pressure are not uniquely determined by the amount of refrigerant in the refrigeration refrigerant circuit 1 at that time. Therefore, the target value THP, which is an appropriate high-pressure side pressure HP, differs depending on the outside air temperature AT. Therefore, data on the basic rotation speed BHz of the gas cooler blower 47 that becomes an appropriate high-pressure side pressure HP according to the outside air temperature AT is held. However, the rotational speed of the gas cooler blower 47 is controlled so as to be the basic rotational speed BHz based on the outside air temperature AT, which is extremely effective.

(E) Refrigerant amount determination and adjustment Next, the refrigerant amount determination operation in the refrigeration refrigerant circuit 1 in the refrigeration system 156 of the refrigeration apparatus R will be described. In the refrigeration refrigerant circuit 1 in which the carbon dioxide refrigerant is sealed and the high pressure side becomes supercritical pressure as in the embodiment, the high pressure side becomes extremely high pressure, so that a large receiver tank is used as in the case of using a normal HFC refrigerant. It is not possible to enclose a relatively large amount (excess) of refrigerant by attaching the refrigerant, and even if the refrigerant recovery tank 100 is attached and the amount of circulating refrigerant is adjusted as in the embodiment, the appropriate amount of refrigerant is refrigerated. It is indispensable for efficient and effective operation to be enclosed in the refrigerant circuit 1 and to accurately detect refrigerant leakage from the refrigeration refrigerant circuit 1 during the subsequent operation.

  Therefore, the refrigerator unit controller 194 always executes the refrigerant amount determination operation described below at a predetermined sampling period. This determination operation includes two types of modes (a first determination operation mode (E-1) and a second determination operation mode (E-2) to be described later), and either or both of them are executed. Switching of the determination operation mode in this case is also performed by a switch operation of the refrigerator unit controller 194 or the master controller 183.

  A high-pressure service port 196 is connected to the high-pressure side exhaust heat recovery refrigerant pipe 70 of the refrigeration refrigerant circuit 1 located at the unit outlet of the refrigerator unit 3, and the low-pressure side refrigerant pipe located at the unit inlet. 9 is connected to a low-pressure service port 197. The refrigerator unit controller 194 is provided with a display (display means) 198 as shown in FIG. The display 198 of the embodiment is provided with a four-digit 7-segment LED 201, four decimal point LEDs 202, and a refrigerant amount LED 203 that functions as an alarm means.

(E-1) Refrigerant amount determination operation mode 1 based on outside air temperature and high pressure side pressure
As described above, in the blower control mode 2, the refrigerator unit controller 194 controls the gas cooler blower 47 so that the basic rotation speed BHz is obtained by the outside air temperature AT and the corresponding basic rotation speed BHz of the gas cooler blower 47. This basic rotational speed BHz is the high pressure of the refrigeration refrigerant circuit 1 under the condition that an appropriate amount of refrigerant (carbon dioxide) is sealed in the refrigeration refrigerant circuit 1 as described above under the condition that the outside air temperature AT at that time. This is the rotational speed of the gas cooler blower 47 at which the side pressure HP becomes the target value THP.

  Accordingly, when the high-pressure side pressure HP of the refrigeration refrigerant circuit 1 detected by the high-pressure sensor 48 cannot be maintained at the target value THP while the gas cooler blower 47 is being controlled, the refrigeration refrigerant circuit It can be determined that the amount of refrigerant in 1 is not an appropriate amount. In this case, if the refrigerant amount is insufficient, the high pressure side pressure HP is lower than the target value THP. Conversely, if the refrigerant amount is excessive, the high pressure side pressure HP is higher than the target value THP.

  Therefore, the refrigerator unit controller 194 constantly monitors the high pressure side pressure HP detected by the high pressure sensor 48 at a predetermined sampling period. Then, after the user encloses the refrigerant in the refrigeration refrigerant circuit 1 and starts the operation of the refrigeration apparatus R (immediately after the encapsulation and during the subsequent operation), a predetermined switch connected to the refrigerator unit controller 194 is turned on. When operated, the refrigerator unit controller 194 switches the display unit 198 to the refrigerant amount display mode and displays the determination result.

  FIG. 2B shows that the determination is being performed. In this case, the refrigerator unit controller 194 turns on the decimal point 202. In this case, the refrigerator unit controller 194 displays the elapsed time during determination by sequentially turning on the light from the decimal point 202 at the right end (one end) toward the left (the other end). If the determination cannot be made, a bar is displayed on the 7-segment LED 201 in the lower first digit as shown in FIG.

  On the other hand, when the high-pressure side pressure HP is the target value THP or within an upper and lower allowable range Y (for example, within 5%), the refrigerator unit controller 194 determines that the refrigerant amount is an appropriate amount and displays it. The display on the device 198 is shown in FIG. In this case, the refrigerator unit controller 194 turns on the lower half of the lower three-digit 7-segment LED 201 and sequentially turns on the decimal point 202 as described above to turn on the four decimal points 202. The refrigerant amount LED 203 is also lit. As a result, the user can confirm that an appropriate amount of refrigerant has been sealed in the refrigeration refrigerant circuit 1.

  On the other hand, when the high-pressure side pressure HP does not reach the target value THP and is extremely lower than the target value THP and the difference is equal to or greater than a predetermined threshold value X (for example, 20%), the refrigerator unit controller 194 It is determined that the refrigerant is insufficient, and the display on the display unit 198 is shown in FIG. In this case, the refrigerator unit controller 194 illuminates the lower half of the 7-segment LED 201 in the first digit, sequentially lights the decimal point 202 as described above, and lights the four decimal points 202. Thereby, the user can confirm that the refrigerant | coolant in the refrigerant circuit 1 for refrigeration is remarkably insufficient.

  Further, when the high pressure side pressure HP does not reach the target value THP and is slightly lower than the target value THP and the difference is smaller than the threshold value X, but larger than the allowable range Y (5%), the refrigerator The unit controller 194 determines that the refrigerant is deficient, and sets the display on the display 198 to (e) in FIG. In this case, the refrigerator unit controller 194 illuminates the lower half of the lower two-digit 7-segment LED 201 and sequentially illuminates the decimal point 202 as described above to illuminate the four decimal points 202. Thereby, the user can confirm that the refrigerant | coolant in the refrigerant circuit 1 for refrigeration is short.

  On the contrary, when the high pressure side pressure HP is higher than the target value THP and the difference is larger than the allowable range Y (5%), the refrigerator unit controller 194 determines that the refrigerant is excessive and displays the display on the display 198. It is assumed as (g) in FIG. In this case, the refrigerator unit controller 194 illuminates the lower half of all four digits of the 7-segment LED 201 and sequentially illuminates the decimal point 202 as described above to illuminate the four decimal points 202. Further, the refrigerant amount LED 203 is blinked. As a result, the user can confirm that the refrigerant in the refrigeration refrigerant circuit 1 is excessive (overfilled).

  In this way, the refrigerator unit controller 194 determines the amount of refrigerant in the refrigeration refrigerant circuit 1 based on the high pressure side pressure HP of the refrigeration refrigerant circuit 1, so that the high pressure of the refrigeration refrigerant circuit 1 as in the embodiment. When the side pressure HP does not reach the target value THP, it is determined that the refrigerant amount in the refrigeration refrigerant circuit 1 is insufficient, and the high pressure side pressure HP of the refrigeration refrigerant circuit 1 becomes higher than the target value THP. By determining that the refrigerant amount in the refrigeration refrigerant circuit 1 is excessive, the refrigerant in the refrigeration refrigerant circuit 1 is insufficient, or the refrigerant leaks from the refrigeration refrigerant circuit 1 and the refrigeration refrigerant circuit 1. It is possible to accurately detect refrigerant overfilling.

(E-2) Refrigerant amount determination operation mode 2 based on the temperature difference before and after the intermediate heat exchanger
Next, another refrigerant quantity determination operation will be described. Since the refrigerant circuit 1 for refrigeration is in a split cycle, the first refrigerant separated from the gas cooler 46 and diverted by the flow divider 82 when the refrigerant in the circuit is not in an appropriate amount or has changed from the appropriate amount. Since the cooling effect of the second refrigerant flow due to the flow also changes (the cooling effect decreases when the refrigerant is insufficient), the cooling effect of the second refrigerant flow due to the first refrigerant flow in the intermediate heat exchanger 80 is monitored. By doing so, it is possible to determine the amount of refrigerant in the refrigeration refrigerant circuit 1.

  Therefore, the amount of refrigerant in the refrigeration refrigerant circuit 1 is determined according to the cooling effect of the second refrigerant flow by the first refrigerant flow in the intermediate heat exchanger 80. In this case, as described above, the refrigerator unit controller 194 is electrically operated based on the increase in the high pressure side pressure HP based on the high pressure side pressure HP detected by the unit outlet side pressure sensor 58. The refrigerant is recovered in the refrigerant recovery tank 100 by opening the expansion valve (recovery opening / closing means) 102, and the solenoid valve (discharge opening / closing means) 106 is opened to recover the refrigerant based on the decrease in the high pressure side pressure HP. When the control for discharging the refrigerant from the tank 100 is executed, the electric expansion valve 102 is not provided because the high-pressure side pressure HP of the refrigeration refrigerant circuit 1 cannot be increased if the refrigerant amount in the refrigeration refrigerant circuit 1 is insufficient. The number of closed states increases.

  Further, when the opening degree of the auxiliary throttle unit 83 is controlled based on the discharge refrigerant temperature DT of the compressor 11, if the refrigerant amount in the refrigeration refrigerant circuit 1 is insufficient, the discharge refrigerant temperature DT of the compressor 11 is also reduced. Since the first refrigerant flow that the auxiliary throttling means 83 flows also decreases, the cooling effect of the second refrigerant flow by the first refrigerant flow in the intermediate heat exchanger 80 decreases, and the intermediate heat exchanger 80 The difference between the temperature LT of the second refrigerant flow that has passed through and the temperature Tsp of the first refrigerant flow increases. Therefore, refrigeration is performed according to the temperature difference (for example, the absolute value of LT-Tsp) between the second refrigerant flow and the first refrigerant flow passed through the intermediate heat exchanger 80 and the state of the electric expansion valve (recovery opening / closing means) 102. Insufficient refrigerant amount in the refrigerant circuit 1 can be determined.

  Conversely, when the refrigerant amount in the refrigeration refrigerant circuit 1 is excessive, the high-pressure side pressure HP of the refrigeration refrigerant circuit 1 is also increased, so that the electric expansion valve 102 (recovery opening / closing means) is open. And the auxiliary throttle means 83 tends to increase the first refrigerant flow in order to further cool the second refrigerant flow in the intermediate heat exchanger 80. Therefore, the second refrigerant flow in the intermediate heat exchanger 80 is increased. Receives a stronger cooling action from the first refrigerant flow, and the temperature difference between the second refrigerant flow and the first refrigerant flow passed through the intermediate heat exchanger 80 (for example, the absolute value of LT-Tsp) becomes smaller. Further, when the gas cooler blower 47 is controlled with the high pressure side pressure HP as in the blower control mode 1 described above, the rotation speed of the gas cooler blower 47 increases as the high pressure side pressure HP increases due to excess refrigerant. Thus, it can be determined that the amount of refrigerant in the refrigeration refrigerant circuit 1 is excessive.

  Therefore, the refrigerator unit controller 194 detects the temperature difference between the second refrigerant flow and the first refrigerant flow that has passed through the intermediate heat exchanger 80 detected by the unit outlet temperature sensor 54 and the split outlet temperature sensor 64 at a predetermined sampling period ( For example, the absolute value of LT-Tsp) and the state of the electric expansion valve 102 are constantly monitored. Then, after the user encloses the refrigerant in the refrigeration refrigerant circuit 1 and starts the operation of the refrigeration apparatus R (immediately after the encapsulation and during the subsequent operation), a predetermined switch connected to the refrigerator unit controller 194 is turned on. When operated, the refrigerator unit controller 194 switches the display unit 198 to the refrigerant amount display mode and displays the determination result. 2B and 2C are the same as described above.

  On the other hand, when the occurrence frequency per predetermined time in a state where the absolute value of LT-Tsp is larger than the predetermined threshold value Xd is within a predetermined threshold value Z% (for example, 5%), the refrigerator unit controller 194 has the refrigerant amount. It is determined that the amount is appropriate, and the display on the display unit 198 is set to (f) in FIG. In this case, the refrigerator unit controller 194 lights the lower half of the lower three-digit 7-segment LED 201, and the four decimal points 202 are also turned on as described above. The refrigerant amount LED 203 is also lit. As a result, the user can confirm that an appropriate amount of refrigerant has been sealed in the refrigeration refrigerant circuit 1.

  On the other hand, when the absolute value of LT-Tsp is greater than the predetermined threshold value Xd and the frequency of occurrence of the electric expansion valve 102 in the closed state per predetermined time is higher than a predetermined threshold value W% (for example, 70%). The refrigerator unit controller 194 determines that the refrigerant is insufficient, and displays the display 198 as (d) in FIG. In this case, the refrigerator unit controller 194 lights the lower half of the 7-segment LED 201 of the lower first digit, and also lights the four decimal points 202 as described above. Thereby, the user can confirm that the refrigerant | coolant in the refrigerant circuit 1 for refrigeration is remarkably insufficient.

  Further, when the absolute value of LT-Tsp is larger than the predetermined threshold value Xd and the frequency of occurrence of the electric expansion valve 102 in the closed state per predetermined time is higher than the threshold value Z% and lower than the threshold value W%, The machine unit controller 194 determines that the refrigerant is insufficient and sets the display on the display 198 to (e) in FIG. In this case, the refrigerator unit controller 194 lights the lower half of the lower two-digit 7-segment LED 201, and the four decimal points 202 are also turned on as described above. Thereby, the user can confirm that the refrigerant | coolant in the refrigerant circuit 1 for refrigeration is short.

  Conversely, the occurrence rate per predetermined time when the absolute value of LT-Tsp is greater than the predetermined threshold value Xd is equal to or less than the threshold value Z%, and the predetermined time during which the rotational speed of the gas cooler blower 47 is higher than the predetermined threshold value QHz. The occurrence rate of hit is equal to or higher than a predetermined threshold value P% (when the gas cooler blower 47 is controlled by the high pressure side pressure HP in the blower control mode 1) and the electric expansion valve 102 is open per predetermined time When the occurrence frequency is equal to or higher than the predetermined threshold N%, the refrigerator unit controller 194 determines that the refrigerant is excessive and displays the display on the display unit 198 as (g) in FIG. In this case, the refrigerator unit controller 194 lights the lower half of the seven-segment LED 201 of all four digits, and the four decimal points 202 are also lit as described above. Further, the refrigerant amount LED 203 is blinked. As a result, the user can confirm that the refrigerant in the refrigeration refrigerant circuit 1 is excessive (overfilled).

  Thus, the frequency with which the temperature difference (absolute value of LT-Tsp) between the second refrigerant flow and the first refrigerant flow is large and the electric expansion valve (recovery opening / closing means) 102 is closed occurs. Is high, the refrigerant amount in the refrigeration refrigerant circuit 1 is determined to be insufficient, so that the refrigerant shortage in the refrigeration refrigerant circuit 1 or the refrigerant leakage from the refrigeration refrigerant circuit 1 is accurately detected. Will be able to. Further, the frequency of occurrence of a state in which the temperature difference between the second refrigerant flow and the first refrigerant flow (absolute value of LT-Tsp) increases is low, and the rotational speed of the gas cooler blower 46 is high (the gas cooler blower). 46 only by controlling the high pressure side pressure HP), when the frequency of occurrence of the open state of the electric expansion valve 102 is high, by determining that the amount of refrigerant in the refrigeration refrigerant circuit 1 is excessive, It becomes possible to accurately detect overfilling of the refrigerant into the refrigeration refrigerant circuit 1.

  If the amount of refrigerant cannot be determined even by the above determination operation, the refrigerator unit controller 194 uses the refrigerant temperature GCT before diverting through the gas cooler 46 detected by the gas cooler outlet temperature sensor 52 and the unit outlet temperature sensor 54. The refrigerant amount in the refrigeration refrigerant circuit 1 is determined according to the difference with the temperature LT of the second refrigerant flow that has passed through the intermediate heat exchanger 80 detected by the above.

  If the refrigerant amount in the refrigeration refrigerant circuit 1 is insufficient, the cooling effect of the second refrigerant flow by the first refrigerant flow in the intermediate heat exchanger 80 is simply reduced as described above. The temperature difference (GCT-LT) between the refrigerant having passed through and the second refrigerant flow having passed through the intermediate heat exchanger 80 becomes small. Therefore, the refrigerator unit controller 194 monitors this temperature difference (GCT-LT) at a predetermined sampling period, and when GCT-LT is higher than the predetermined threshold Mdeg, it is determined that the amount is an appropriate amount and the display unit 198 The display is shown in FIG. On the other hand, if it is equal to or less than Mdeg, it is determined that the refrigerant is insufficient, and the result is shown in FIG.

  Thus, when the temperature difference GCT-LT between the refrigerant before being diverted through the gas cooler 46 and the second refrigerant flow through the intermediate heat exchanger 80 is small, the refrigerant amount in the refrigeration refrigerant circuit 1 is insufficient. Even if it is determined to be a thing, the refrigerant shortage in the refrigeration refrigerant circuit 1 or the refrigerant leakage from the refrigeration refrigerant circuit 1 can be accurately detected.

  With these refrigerant amount determination operations, an appropriate amount of refrigerant is sealed in the refrigeration refrigerant circuit 1 at the time of initial refrigerant charging, ensuring efficient operation and refrigerating capacity, and unnecessary refrigerant sealing This also prevents wasteful refrigerant consumption. Furthermore, since leakage of the refrigerant from the refrigeration refrigerant circuit 1 after the enclosure can be detected, smooth and efficient operation management can be realized.

  In this case, the display unit 198 is provided in the refrigerator unit controller 194 to display the refrigerant amount determination result, so that the workability at the time of initial refrigerant charging is improved and the refrigerant leakage is accurately grasped. Will be able to. When the determined refrigerant amount is excessive, the refrigerant amount LED 203 is blinked to issue an alarm, so that it is possible to realize a quick response when refrigerant leakage occurs. Although not turned on in the embodiment, it goes without saying that a similar alarm is obtained if the refrigerant amount LED 203 is blinked or the like even when the refrigerant is insufficient.

  In addition, the refrigerator unit controller 194 displays a predetermined alarm on the display unit 198 when the display of FIG. In addition, even when the display of (g) in FIG. 2 occurs continuously a plurality of times, a predetermined alarm display different from this is displayed on the display 198. As a result, it is possible to prompt quick response of replenishment and purging described later.

(E-3) Refrigerant Encapsulation When it is determined that the refrigerant amount is insufficient as described above, the user connects a refrigerant cylinder to the high-pressure service port 196 and performs liquid charging. At this time, the refrigerator unit controller 194 has a refrigerant charging operation mode, and shifts to the refrigerant charging operation mode by a predetermined switch operation. In this refrigerant charging operation mode, the refrigerator unit controller 194 sends instructions to the refrigeration case controller 191 and the refrigeration case controller 192, and is set to a value lower than the internal temperature setting value of each case where the compressor 11 stops at the low pressure control value. Change the set value to a sufficiently low value. Further, the upper limit of the opening degree of the main throttle means 62A, 62B is restricted, and only the control for reducing the opening degree by eliminating the degree of superheat is allowed.

  That is, since the refrigerator unit controller 194 continues the operation of the compressors 11 and 11 in the refrigerant charging operation mode, the charging operation at the time of refrigerant shortage or leakage can be performed smoothly. Then, it is sealed with a display 198 until an appropriate amount is obtained.

(E-4) Refrigerant purge Conversely, when it is determined that the refrigerant amount is overfilled (overfilled), the user purges the refrigerant from the low pressure service port 197. Then, the display 198 is purged until an appropriate amount is reached.

  In the above embodiment, the refrigerator unit controller 198 executes the refrigerant amount determination operation, and the display unit 198 shown in FIG. 2 is provided in the refrigerator unit controller 194. However, the determination is not limited thereto, or these determinations are made accordingly. The operation may be performed by the master controller 183, and the display device 198 may be provided in the master controller 183.

(F) Compressor startability improvement (bypass circuit)
Next, the startability improvement control of the compressor 11 will be described. As shown in FIG. 2, the intermediate pressure region of the refrigeration refrigerant circuit 1 on the outlet side of the intercooler 38 of the refrigeration apparatus R as described above, in the present embodiment, the second or the second connected to the outlet side of the intercooler 38. A bypass circuit 84 is provided that communicates the third communication circuits 103 and 105 with the refrigerant pipe 9 that is the refrigerant outlet side of the evaporators 63A and 63B in this embodiment. . An electromagnetic valve (valve device) 85 is interposed in the bypass circuit 84. The compressors 11 and 11 and the electromagnetic valve 85 are connected to the output side of the refrigerator unit controller 194. The refrigerator unit controller 194 can detect (acquire) the operating frequency of the compressor 11.

  With the above configuration, the startability improvement control operation of the compressor 11 will be described. In the state where the compressor 11 is operating as described above, the low-pressure refrigerant gas sucked into the low-pressure portion of the first rotary compression element 18 by the low-stage suction port 22 is the first rotary compression element 18. Thus, the pressure is increased to an intermediate pressure and discharged into the sealed container 12. The intermediate-pressure refrigerant gas in the hermetic container 12 is discharged from the low-stage discharge port 24 of the compressor 11 to the intermediate-pressure discharge pipe 36 and is connected to the high-stage side via the intermediate-pressure suction pipe 40 to which the intercooler 38 is connected. It is sucked into the suction port 26. A region from the first rotary compression element 18 until it is sucked into the second rotary compression element 20 through the high-stage suction port 26 is defined as an intermediate pressure region.

  The medium-pressure refrigerant gas sucked into the intermediate pressure portion of the second rotary compression element 20 by the high stage side suction port 26 is compressed by the second stage by the second rotary compression element 20, and the Refrigerant gas is discharged from the high-stage discharge port 28 to the high-pressure discharge pipe 42, and the oil separator 44, gas cooler 46, exhaust heat recovery heat exchanger 70, intermediate heat exchanger 80, refrigerant pipe 7, and showcase units 5A, 5B. The region up to the main throttle means 62A, 62B is the high pressure side.

  Then, by being decompressed and expanded by the main throttle means 62A and 62B, the refrigerant circuit 1 for refrigeration extends from the evaporators 63A and 63B downstream thereof to the lower stage suction port 22 communicating with the first rotary compression element 18. The low pressure side.

  When the compressor 11 is restarted after the operation of the compressor 11 is stopped, the refrigerator unit controller 194 switches the electromagnetic valve 85 from the start of the compressor 11 to a predetermined operating frequency. The flow path of the bypass circuit 84 is opened by opening. The predetermined operating frequency is an operating frequency at which the compressor 11 can perform effective torque control, and is set to 35 Hz as an example in the present embodiment.

  As a result, the electromagnetic valve 85 is opened until the compressor 11 is started from the stopped state and rises to the predetermined operating frequency, so that the first rotary compression element 18 boosts the pressure to an intermediate pressure. The refrigerant in the intermediate pressure region discharged from the stage side discharge port 24 to the intermediate pressure discharge pipe 36 and passing through the intercooler 38 flows into the low pressure side region of the refrigeration refrigerant circuit 1 through the bypass circuit 84. As a result, the pressure in the intermediate pressure region and the low pressure side region of the refrigeration refrigerant circuit 1 is equalized.

  Thereby, at the time of starting from the start of the compressor 11 until it rises to a predetermined operating frequency, a predetermined torque cannot be ensured. During this time, by setting the intermediate pressure region and the low pressure side region to equal pressure, the outside temperature Therefore, even if the intermediate pressure tends to be high, the inconvenience of the intermediate pressure approaching the high pressure can be solved.

  Therefore, it is possible to avoid a start failure due to the pressure in the intermediate pressure region and the pressure in the high pressure region approaching while torque shortage at the start of the compressor 11 occurs, In addition, highly efficient operation can be realized. The refrigerator unit controller 194 closes the solenoid valve 85 and closes the flow path of the bypass circuit 84 after the detected operating frequency of the compressor 11 has risen to a predetermined operating frequency. Perform a normal refrigeration cycle.

(G) Compressor startability improvement (frequency control)
As described above, the refrigerator unit controller 194 controls the operation frequency and the number of the compressors 11 and 11 to be operated based on the low pressure LP detected by the low pressure sensor 32 and the predetermined low pressure control value LPS. That is, the refrigerator unit controller 194 increases the operating frequency of the compressor 11 when the low-pressure side pressure LP increases, and decreases the operating frequency when it decreases. Further, when the low-pressure side pressure LP does not fall below the control value LPS even when the operation frequency of the compressor 11 reaches the maximum value while operating with any one compressor 11, another compression is performed. The machine 11 is also started and shifts to a state in which the two compressors 11 are operated.

  In that case, the refrigerator unit controller 194 reduces the operating frequency of the one compressor 11 currently operating at the maximum frequency to a predetermined specified frequency Hzs lower than the maximum frequency. In the process of lowering or after lowering, the refrigerator unit controller 194 starts the other compressor 11 that is currently stopped, and raises the operating frequency to the specified frequency Hzs. After that, after operating the two compressors 11 and 11 at the specified frequency Hzs for a predetermined period, the refrigerator unit controller 194 performs control for determining the operating frequency of the compressors 11 and 11 based on the low pressure LP. Transition.

  As described above, when the one compressor 11 is in operation and the other compressor 11 is started to move to the state in which the two compressors 11 and 11 are operated, the refrigerator unit controller 194 is currently operated. Since the operating frequency of the compressor 11 on the one hand is once lowered, the high / low pressure difference of the refrigeration refrigerant circuit 1 is reduced. As a result, the starting load of the other compressor 11 that starts from the stopped state is reduced, which can contribute to energy saving and reduce noise.

  The refrigerator unit controller 194 has a control amount (step) of the operating frequency when operating the two compressors 11 and 11 smaller than a control amount (step) when operating the one compressor 11. To do. For example, when the operation frequency is changed in fHz steps when operating one compressor 11, the operation frequency is changed in f / 2 Hz steps when operating two compressors 11 and 11. As a result, a large capacity change during operation of two units is prevented and noise is reduced.

R Refrigeration equipment 1 Refrigeration refrigerant circuit 3 Refrigerator unit 5A Refrigeration case (refrigeration equipment)
5B refrigerated case (refrigerated equipment)
7, 9 Refrigerant piping 11 Compressor (compression means)
32 Low pressure sensor (suction pressure detection means)
34 Unit inlet temperature sensor (inlet temperature detection means)
46 Gas cooler 47 Blower for gas cooler (blower)
48 High pressure sensor (High pressure detector)
49 Intermediate pressure sensor (Intermediate pressure detection means)
50 Discharge temperature sensor (Discharge temperature detection means)
52 Gas cooler outlet temperature sensor (gas cooler outlet temperature detection means)
54 Unit outlet temperature sensor (unit outlet temperature detection means)
56 Outside temperature sensor (outside temperature detection means)
58 Unit outlet pressure sensor (Unit outlet pressure detector)
62A, 62B Main throttle means 63A, 63B Evaporator 70 Waste heat recovery piping 80 Intermediate heat exchanger 80A First flow path 80B Second flow path 83 Auxiliary throttle means 90 Cascade heat exchanger 100 Refrigerant recovery tank 102 Electric expansion Valve (recovery opening / closing means)
106 Solenoid valve (release opening / closing means)
153 Air conditioning system 154 Refrigerant circuit for air conditioning 156 Refrigeration system 159 Air conditioner using hot water 161 Compressor (compression means)
162 Radiator 163 Expansion valve (throttle means)
164 Evaporator 171 Hot water storage tank 178 User side heat exchanger 183 Master controller 194 Refrigerator unit controller 196 High pressure service port 197 Low pressure service port 198 Display (display means)

Claims (8)

The compression means, the gas cooler, the auxiliary throttle means, the intermediate heat exchanger, the main throttle means, and the evaporator constitute a refrigerant circuit, and the refrigerant discharged from the gas cooler is divided into two flows, and the first The refrigerant flow is passed through the auxiliary throttle means to the first flow path of the intermediate heat exchanger, the second refrigerant flow is flowed to the second flow path of the intermediate heat exchanger, and then the main throttle means The first refrigerant flow and the second refrigerant flow are exchanged in the intermediate heat exchanger, and the refrigerant discharged from the evaporator is transferred to the low pressure portion of the compression means. In the refrigerating apparatus in which the first refrigerant flow discharged from the intermediate heat exchanger is sucked into the intermediate pressure portion of the compression means, and the high pressure side is supercritical pressure.
A refrigerant recovery tank connected to the high pressure side of the refrigerant circuit via a recovery opening and closing means, and connected to an intermediate pressure region of the refrigerant circuit via a discharge opening and closing means;
Control means,
The control means recovers the refrigerant in the refrigerant recovery tank by opening the recovery opening / closing means based on the increase in the high pressure side pressure based on the high pressure side pressure of the refrigerant circuit, and the high pressure side pressure. Based on the decrease, the release opening and closing means is opened to release the refrigerant from the refrigerant recovery tank,
A refrigeration apparatus that determines a refrigerant amount in the refrigerant circuit according to a temperature difference between the second refrigerant flow and the first refrigerant flow that have passed through the intermediate heat exchanger, and a state of the recovery switching means. . When the temperature difference between the second refrigerant flow and the first refrigerant flow is large and the collection opening / closing means is frequently closed, the refrigerant amount in the refrigerant circuit is insufficient. The frequency of occurrence of a temperature difference between the second refrigerant flow and the first refrigerant flow is low, and the rotational speed of the blower for air-cooling the gas cooler is high, and the recovery opening / closing 2. The refrigeration apparatus according to claim 1 , wherein when the frequency of occurrence of the state in which the means is open is high, it is determined that the amount of refrigerant in the refrigerant circuit is excessive . The control means determines an amount of refrigerant in the refrigerant circuit according to a temperature difference between the refrigerant before being diverted through the gas cooler and the second refrigerant flow through the intermediate heat exchanger. The refrigeration apparatus according to claim 1 or 2. When the temperature difference between the refrigerant before being diverted through the gas cooler and the second refrigerant flow through the intermediate heat exchanger is small, the control means has an insufficient amount of refrigerant in the refrigerant circuit. The refrigeration apparatus according to claim 3 , wherein the determination is performed . The refrigeration apparatus according to any one of claims 1 to 4, wherein the control means includes means for displaying a determination result of the refrigerant amount . The refrigeration according to any one of claims 1 to 5, wherein the control unit issues a predetermined alarm when the determined amount of the refrigerant is insufficient or excessive. apparatus. The refrigerant circuit includes a high pressure service port and a low pressure service port,
The refrigeration apparatus according to any one of claims 1 to 6, wherein the control means has a refrigerant sealing operation mode in which the operation of the compression means is continued . The refrigeration apparatus according to any one of claims 1 to 7, wherein carbon dioxide is used as a refrigerant in the refrigerant circuit .

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