JP4624223B2 - Refrigeration system - Google Patents

Description

  The present invention relates to a refrigeration system for performing indoor air conditioning and internal cooling of a cooling storage facility in a store, for example.

Conventionally, the inside of a store such as a convenience store is air-conditioned (air-conditioned) by an air conditioner. In addition, there are refrigerated or refrigerated open showcases and showcases with doors (cooling storage facilities) that display and sell products, and these are cooled by the refrigerator (patents). Reference 1).
JP 2002-174470 A

  By the way, the evaporator which cools the inside (cooled space) of the cooling storage facility or the like constitutes a refrigerant circuit together with a decompression device such as a compressor, a condenser and an expansion valve. The compressor can be controlled in capacity by controlling the operating frequency, and the expansion valve is constituted by a temperature expansion valve or an electric expansion valve whose valve opening can be adjusted, and the degree of superheat of the refrigerant in the evaporator can be controlled. It is controlled to be constant.

Therefore, when the interior is sufficiently cooled, the expansion valve throttles the valve opening, so the low pressure side pressure of the compressor decreases. When this low pressure side pressure becomes low on average, the COP of the compressor is lowered and the operation efficiency is deteriorated. Therefore, conventionally, a set pressure is provided, and when the low pressure side pressure decreases to the lower limit value between the upper limit value and the lower limit value set above and below this set pressure, the operating frequency of the compressor is lowered to reduce the capacity, While controlling the opening degree of the expansion valve in the expanding direction, the set pressure is changed based on the temperature deviation between the temperature of the cooled space cooled by the evaporator and the set temperature of the cooled space.

  On the other hand, the temperature in the cooled space fluctuates greatly due to the opening and closing of the door of the cooled space and the loading and unloading of products, so the temperature deviation from the set temperature of the cooled space also varies greatly, making it difficult to control the compressor There was a problem. Therefore, conventionally, the temperature in the space to be cooled is treated as an average value at a constant interval, thereby suppressing fluctuations in temperature deviation.

  Therefore, during the averaging process, the temperature of the cooled space is not reflected in the operation control as needed, and the actual temperature is maintained lower than the set temperature, leading to a decrease in operation efficiency.

  The present invention has been made in order to solve the conventional technical problem, and can effectively eliminate the deterioration of the operation efficiency of the compressor due to the long update time of the average temperature of the space to be cooled. Is to provide.

  The present invention includes a compressor circuit, a condenser, an expansion valve, and an evaporator that form a refrigerant circuit, a cooled space that is cooled by the evaporator, and the compression based on the low-pressure side pressure and the set pressure of the compressor. In a refrigeration system that controls the capacity of the machine and changes the set pressure based on a deviation between the temperature of the cooled space and a set temperature at a predetermined cycle, a signal indicating that the cooling of the cooled space by the evaporator is stopped The set pressure is changed to a predetermined value regardless of the predetermined cycle, and the capacity of the compressor is controlled.

The refrigeration system according to a second aspect of the invention is characterized in that the temperature deviation is replaced with a predetermined value and recorded by a signal indicating that the cooling of the cooled space by the evaporator is stopped.

  The refrigeration system according to a third aspect of the invention is characterized in that, in the above, an actual temperature deviation is recorded by a signal indicating that the temperature of the space to be cooled exceeds a predetermined temperature.

  The refrigeration system according to a fourth aspect of the present invention is the actual temperature deviation after the cooling of the cooled space by the evaporator is stopped and the capacity of the compressor is controlled in each of the first to third aspects of the present invention. Is recorded.

  A refrigeration system according to a fifth aspect of the present invention has a refrigerant circuit including a compressor, a condenser, an expansion valve, and a plurality of evaporators, and has a plurality of cooling spaces that are cooled by these evaporators. In the refrigeration system that controls the capacity of the compressor based on the low-pressure side pressure and the set pressure, and changes the set pressure based on the maximum temperature deviation among the deviations of the temperature of the cooled space and the set temperature at a predetermined cycle. The set pressure is changed to a predetermined value regardless of the predetermined period, and the capacity of the compressor is controlled by a signal indicating that the cooling of the cooled space by all the evaporators is stopped.

  According to a sixth aspect of the present invention, the refrigeration system according to the sixth aspect is characterized in that the corresponding temperature deviation is recorded with a predetermined value in accordance with a signal indicating that the cooling of the cooled space by the evaporator is stopped.

  The refrigeration system of the invention of claim 7 is characterized in that the actual temperature deviation corresponding to the space to be cooled is recorded by a signal in which the temperature of the space to be cooled exceeds a predetermined temperature.

  The refrigeration system according to an eighth aspect of the present invention is the refrigeration system according to the fifth to seventh aspects of the present invention, wherein the cooling of the cooled space by all the evaporators is stopped and the capacity control of the compressor is performed. The actual temperature deviation is recorded.

In the present invention, when the evaporator stops cooling the cooled space, the temperature deviation is replaced with a predetermined value and recorded, and the temperature deviation is set by the signal that all the evaporators stop cooling the cooled space. Reflect in pressure. Thus, for example, in order to change the set pressure in the direction of increasing the set pressure in response to a signal that the evaporator has stopped cooling the cooled space, the operating frequency of the compressor is reduced regardless of the predetermined cycle, and the valve It is possible to promote an increase in the low-pressure side pressure by controlling the opening degree in the expanding direction. Therefore, it is possible to improve the operation efficiency of the refrigeration system by improving the COP of the compressor by preventing the cold in the refrigeration equipment from being overcooled and eliminating the disadvantage that the low pressure side pressure of the compressor is reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a system configuration including a refrigerant circuit of a refrigeration system 1 according to an embodiment to which the present invention is applied. The refrigeration system 1 of the embodiment realizes, for example, air conditioning in a store 2 of a convenience store and cooling of a plurality of refrigerated cases 3 and a refrigerator case 4 as a cooling storage facility installed therein. It is.

  In an actual convenience store or the like, a plurality of refrigeration cases 3 are installed, but only two of the first and second refrigeration cases 3 are shown in the drawing. The refrigerated case 3 and the refrigerated case 4 are open showcases whose front and upper surfaces are open, as well as showcases whose openings are closed with a transparent glass door so that the openings can be freely opened and closed. Cooled to a temperature (+ 3 ° C. to + 10 ° C.) and chilled foods such as beverages and sandwiches are displayed, and the inside of the freezer case 4 is cooled to a freezing temperature (−10 ° C. to −20 ° C.). Ice cream and other frozen desserts will be displayed.

  6 is an air conditioner (air conditioning system) including an air conditioning refrigerant circuit 7, and 8 is a cooling device including a cooling storage facility refrigerant circuit 9 for cooling the inside of the refrigerator case 3 and the freezing case 4. Cooling storage equipment system). The air conditioner 6 includes an indoor unit 11 installed on the ceiling of the store 2 and the like, and an outdoor unit 12 installed outside the store, and an air-conditioning refrigerant circuit 7 is piped between these units. Yes.

  The refrigerant circuit for air conditioning 7 includes two compressors 13A (frequency control operation by an inverter) and 13B (constant speed operation) installed in the exterior case of the outdoor unit 12, check valves 5A and 5B, oil Separator 10, four-way valve 14, heat source side heat exchanger 16, expansion valve (pressure reduction means comprising an electric expansion valve whose valve opening can be adjusted) 17, 18 and 19, cascade heat exchanger 21, reverse The stop valve 22, the accumulator 23, and the like, and a use side heat exchanger 27 installed on the indoor unit 11 side are systematically configured.

  Reference numeral 26 denotes an outdoor unit controller (configured by a general-purpose microcomputer) for controlling equipment on the outdoor unit 12 side of the air conditioner 6 based on temperature and pressure, and is provided in the outdoor unit 12. Reference numeral 24 denotes a blower for ventilating the outside air to the heat source side heat exchanger 16 and is provided at a position corresponding to the heat source side heat exchanger 16 in the outdoor unit 12. 28 is an indoor unit controller (consisting of a general-purpose microcomputer) for controlling the equipment on the indoor unit 11 side of the air conditioner 6 based on temperature and pressure, and is provided in each indoor unit 11 ( One not shown). Reference numeral 15 denotes a blower for ventilating the air in the store 2 to the use side heat exchanger 27 and is provided at a position corresponding to each of the use side heat exchangers 27 in the indoor unit 11.

  The compressors 13A and 13B are connected in parallel to each other, and the discharge sides of the compressors 13A and 13B are joined via check valves 5A and 5B, respectively, and one inlet of the four-way valve 14 is passed through the oil separator 10. It is connected to the. The check valves 5A and 5B have the four-way valve 14 in the forward direction. One outlet of the four-way valve 14 is connected to the inlet of the heat source side heat exchanger 16. The heat source side heat exchanger 16 includes an inlet side 16A having a relatively small flow resistance composed of a large number of parallel pipes and an outlet side 16B in which these are aggregated into a small number of parallel pipes or a single pipe. The outlet on the outlet side 16B of the heat source side heat exchanger 16 is connected to the inlet of the expansion valve 18 via the expansion valve 17, and the outlet of the expansion valve 18 is diverted across the indoor unit 11, so that each use side heat It is connected to the inlet of the exchanger 27.

  After the outlets of the respective use side heat exchangers 27 are joined, they cross the outdoor unit 12 and are connected to the other inlet of the four-way valve 14, and the other outlet of the four-way valve 14 is connected to the accumulator 23 via the check valve 22. Has been. And the exit of this accumulator 23 is connected to the suction side of compressor 13A, 13B. The check valve 22 has a forward direction on the accumulator 23 side.

  The piping between the expansion valves 17 and 18 is connected to the inlet of the expansion valve 19, and the outlet of the expansion valve 19 is connected to the inlet of the air conditioning side passage 21 </ b> A of the cascade heat exchanger 21. The outlet of the air conditioning side passage 21A of the cascade heat exchanger 21 is connected to the suction side of the compressors 13A and 13B via an accumulator 23.

  On the other hand, in the cooling device 8, a refrigerant circuit 9 for a cooling storage facility is constructed by piping between the outdoor unit 12 and the refrigeration case 3 and the refrigeration case 4 installed in the store 2. The refrigerant circuit 9 for the cooling storage facility includes a first compressor 37 installed in the exterior case of the outdoor unit 12, a condenser (heat exchanger) 38, two four-way valves 39 and 41, and a check. A valve 42, an oil separator 31, a receiver tank 36, and the like; a refrigeration evaporator 43 that is installed in the refrigeration case 3 to cool the interior of the refrigeration case 3; and an expansion valve (electrical expansion with adjustable valve opening) Valve) 44, solenoid valves 46 and 47, check valve 48, refrigeration evaporator 49 that is installed in the refrigeration case 4 and cools the inside of the refrigeration case 4, an expansion valve (electrical expansion with adjustable valve opening) Valve) 51, electromagnetic valves 52 and 53, a second compressor 54, a check valve 30, an oil separator 45, and the like.

  Reference numeral 32 denotes a refrigerator controller (configured by a general-purpose microcomputer) that controls equipment on the outdoor unit 12 side of the cooling device 8 based on temperature and pressure, and is provided in the outdoor unit 12. Reference numeral 35 denotes a blower for passing outside air through the condenser 38, and is provided at a position corresponding to the condenser 38 of the outdoor unit 12. Reference numeral 50 denotes a refrigeration case controller (configured by a general-purpose microcomputer) that controls equipment on the refrigeration case 3 side based on temperature and pressure, and is provided in each refrigeration case 3 (one is not shown). ). The refrigeration case controller 50 and the refrigerator controller 32 constitute a control device according to the present invention. Further, 55 is a refrigeration case controller (a controller constituting a cooling storage facility system control means, which is constituted by a general-purpose microcomputer) that controls equipment on the refrigeration case 4 side based on temperature and pressure. 4 is provided.

  Reference numeral 20 denotes a blower for ventilating the cool air in each refrigerator case 3 to the refrigerator 43 for cooling, and is provided at a position corresponding to each evaporator 43 in the refrigerator case 3. Reference numeral 25 denotes a blower for passing cold air in the refrigerator case 4 through the freezer evaporator 49, and is provided at a position corresponding to the freezer evaporator 49 in the freezer case 4.

  The discharge side of the compressor 37 is connected to one inlet of the four-way valve 39 via the oil separator 31, and one outlet of the four-way valve 39 is connected to the inlet of the condenser 38. The condenser 38 includes an inlet side 38A having a relatively small flow resistance composed of a large number of parallel pipes, and an outlet side 38B in which these are aggregated into a small number of parallel pipes or a single pipe. The outlet on the outlet side 38B of the condenser 38 is connected to the inlet of the receiver tank 36, and the outlet of the receiver tank 36 is connected to one inlet of the four-way valve 41.

  One outlet of the four-way valve 41 is connected to the inlet of the case side passage 21 </ b> B of the cascade heat exchanger 21. The cascade heat exchanger 21 exchanges heat between the refrigerant that passes through the air conditioning side passage 21A and the case side passage 21B that are formed inside, thereby cooling the low pressure side of the air conditioning refrigerant circuit 7 and cooling it. The high-pressure side of the storage facility refrigerant circuit 9 is thermally coupled. Note that the refrigerant flows through the air conditioning side passage 21A and the case side passage 21B are counterflows.

  The outlet of the case side passage 21 </ b> B of the cascade heat exchanger 21 is connected to the other inlet of the four-way valve 39, and the other outlet of the four-way valve 39 is connected to the other inlet of the four-way valve 41. The other outlet of the four-way valve 41 exits from the outdoor unit 12 and branches into the store 2. One of the branched pipes is further branched, and one of the branched pipes is connected to the inlet of the expansion valve 44 via the solenoid valves 47 and 46 in order, and the outlet of the expansion valve 44 is the refrigeration evaporator 43 of the first refrigeration case 3. Connected to the entrance. The other branched portion is connected to the inlet of the expansion valve 44 via the electromagnetic valve 46, and the outlet of the expansion valve 44 is connected to the inlet of the refrigeration evaporator 43 of the second refrigeration case 3.

  The other pipe branched into the store 2 is connected to the inlet of the expansion valve 51 via the electromagnetic valve 52, and the outlet of the expansion valve 51 is connected to the inlet of the refrigeration evaporator 49. The solenoid valve 53 connects the inlet of the solenoid valve 52 and the outlet of the expansion valve 51 in parallel with the series circuit of the solenoid valve 52 and the expansion valve 51.

  The outlet of the freezing evaporator 49 is connected to the suction side of the compressor 54 via the check valve 30. The check valve 30 has a forward direction on the compressor 54 side. The compressor 54 is a compressor having a smaller output than the compressor 37, and its discharge side is connected to the suction side of the compressor 37 via an oil separator 45. That is, the compressor 37 and the compressor 54 are connected in series on the refrigerant circuit. The outlet of the refrigeration evaporator 43 joins and is connected to the outlet side of the oil separator 45 disposed on the discharge side of the compressor 54. The check valve 48 is connected between the check valve 30 before the compressor 54 and the solenoid valves 46 and 47, and the directions of the solenoid valves 46 and 47 are the forward directions. Further, the check valve 42 is connected between the suction side of the compressor 37 and the pipe that exits the oil separator 31, and the oil separator 31 direction is the forward direction. A predetermined amount of refrigerant such as R-410A and R-404A is sealed in the refrigerant circuits 7 and 9, for example.

  The operation of the refrigeration system 1 of the present invention will be described with the above configuration. The compressors 37 and 13A perform capacity control by controlling the operation frequency by an inverter, and the compressor 13B and the compressor 54 are operated at a constant speed. The operation of the entire refrigeration system 1 is controlled by a main controller (main control means) 56 composed of a general-purpose microcomputer.

  Here, the main controller 56 is connected to the outdoor unit controller 26, the indoor unit controller 28, the refrigerator controller 32, the refrigeration case controller 50, and the refrigeration case controller 55 so as to be able to perform data communication. Receive and collect data. Then, based on the received data, an optimum operation pattern at that time, which will be described later, is determined. It transmits to the case controller 50 and the freezing case controller 55. The outdoor unit controller 26, the indoor unit controller 28, the refrigerator controller 32, the refrigeration case controller 50, and the refrigeration case controller 55 perform control operations to be described later based on the data regarding the optimum operation pattern received from the main controller 56 and the operation data of each device. Execute.

(1) Optimal operation pattern 1: Air conditioner cooling operation (Fig. 1)
First, when the main controller 56 determines that the cooling operation of the air conditioner 6 is optimal in summer or the like, the data related to the optimal operation pattern 1 is the outdoor unit controller 26, the indoor unit controller 28, the refrigerator controller 32, the refrigeration case controller. 50 and the refrigeration case controller 55.

  Based on the received data, the outdoor unit controller 26 causes the inlet on the outlet side of the oil separator 10 of the four-way valve 14 to communicate with the outlet on the inlet side of the heat source side heat exchanger 16 and the other inlet to the other outlet. Further, the expansion valve 17 is fully opened. Then, the compressors 13A and 13B are operated. The outdoor unit controller 26 controls the capacity by adjusting the operating frequency of the compressor 13A.

  When the compressors 13A and 13B are operated, the high-temperature and high-pressure gas refrigerant discharged from the discharge sides of the compressors 13A and 13B enters the inlet side 16A of the heat source side heat exchanger 16 through the four-way valve 14. Outside air is ventilated by the air blower 24 to the heat source side heat exchanger 16, and the refrigerant dissipates heat here to be condensed and liquefied. That is, in this case, the heat source side heat exchanger 16 functions as a condenser. This liquid refrigerant exits from the outlet side 16B from the inlet side 16A of the heat source side heat exchanger 16 via the outlet side 16B. And after passing the expansion valve 17, it branches. One of the branches reaches the expansion valve 18, where it is throttled and depressurized, and then branches and flows into each use side heat exchanger 27 where it evaporates.

  The air in the store 2 is ventilated by the blower 15 to the use side heat exchanger 27, and the air in the store 2 is cooled by an endothermic action due to evaporation of the refrigerant. As a result, the store 2 is cooled. The low-temperature gas refrigerant exiting from the use-side heat exchanger 27 merges and then passes from the other inlet of the four-way valve 14 to the other outlet, and sequentially passes through the check valve 22 and the accumulator 23, and then the compressors 13A and 13B. Repeat the circulation sucked into the suction side. Based on the temperature of the use side heat exchanger 27 and the air temperature sucked into the indoor unit controller 28, the indoor unit controller 28 controls the blower 15 that ventilates the use side heat exchanger 27 so that the temperature in the store 2 becomes the set temperature. Information from the indoor unit controller 28 is transmitted to the main controller 56, and the outdoor unit controller 26 controls the operation of the compressors 13A and 13B based on this information.

  The other refrigerant branched after passing through the expansion valve 17 reaches the expansion valve 19, where it is throttled and depressurized, and then flows into the air conditioning side passage 21A of the cascade heat exchanger 21, where it evaporates. The cascade heat exchanger 21 is cooled by the endothermic action due to the evaporation of the refrigerant in the air-conditioning refrigerant circuit 7 and becomes a low temperature. The low-temperature gas refrigerant exiting the cascade heat exchanger 21 repeats circulation that is sucked into the suction sides of the compressors 13A and 13B via the accumulator 23.

  The outdoor unit controller 26 adjusts the refrigerant temperature at the entrance / exit of the use side heat exchanger 27, the temperature of the use side heat exchanger 27, the refrigerant temperature at the entrance / exit of the cascade heat exchanger 21, or the temperature of the cascade heat exchanger 21. Based on this, the valve openings of the expansion valves 18 and 19 are adjusted so as to obtain an appropriate degree of superheat.

  On the other hand, the refrigerator controller 32 causes the inlet on the outlet side of the oil separator 31 of the four-way valve 39 in the refrigerant circuit 9 for the cooling storage facility of the cooling device 8 to communicate with the outlet on the inlet side of the heat source side heat exchanger 38. To the other outlet. Further, the inlet on the outlet side of the receiver tank 36 of the four-way valve 41 is communicated with the outlet on the inlet side of the case side passage 21B of the cascade heat exchanger 21, and the other inlet is communicated with the other outlet. Then, the compressor 37 and the compressor 54 are operated. The high-temperature and high-pressure gas refrigerant discharged from the compressor 37 is separated by the oil separator 31 and then enters the inlet side 38 </ b> A of the condenser 38 through the four-way valve 39. Outside air is also passed through the condenser 38 by the blower 35, and the refrigerant flowing into the condenser 38 dissipates heat and condenses there.

  The refrigerant that has passed through the inlet side 38A of the condenser 38 reaches the outlet side 38B and exits there. The refrigerant discharged from the condenser 38 enters the receiver tank 36 from the inlet side of the receiver tank 36 and is temporarily stored therein to separate the gas / liquid. The separated liquid refrigerant exits from the outlet of the receiver tank 36, passes through the four-way valve 41, and then enters the case side passage 21 </ b> B of the cascade heat exchanger 21. The refrigerant in the refrigerant circuit 9 for the cooling storage facility that has entered the case side passage 21B is cooled by the cascade heat exchanger 21 that is at a low temperature due to the evaporation of the refrigerant in the air conditioning side passage 21A as described above. Increase.

  The refrigerant supercooled in the cascade heat exchanger 21 is branched after sequentially passing through the four-way valve 39 and the four-way valve 41, one is further branched, and the other is sequentially passed through the electromagnetic valves 47 and 46, and then the expansion valve 44. After being squeezed and depressurized there, it flows into the refrigeration evaporator 43 of the first refrigeration case 3 and evaporates there. The other branched portion passes through the electromagnetic valve 46 and reaches the expansion valve 44, where it is throttled and depressurized, and then flows into the refrigerating evaporator 43 of the second refrigerating case 3, where it evaporates. In each refrigeration evaporator 43, the air in the refrigerator case 3 is ventilated and circulated by the blower 20, and the air in each refrigerator is cooled by the endothermic action due to the evaporation of the refrigerant. Thereby, the inside cooling of the refrigeration case 3 is performed. The low-temperature gas refrigerant exiting the refrigeration evaporator 43 joins and then reaches the outlet side of the oil separator 45 of the compressor 54.

  The other refrigerant branching out of the four-way valve 41 passes through the electromagnetic valve 52 and reaches the expansion valve 51 where it is throttled and depressurized, and then flows into the freezing evaporator 49 where it evaporates. The internal air of the refrigeration case 4 is also ventilated and circulated by the blower 25 to the freezing evaporator 49, and the internal air is cooled by the endothermic action due to the evaporation of the refrigerant. Thereby, the inside cooling of the freezing case 4 is performed.

  The low-temperature gas refrigerant exiting the freezing evaporator 49 passes through the check valve 30 and reaches the compressor 54 where it is compressed and increased to the pressure on the outlet side of the refrigerating evaporator 43 (low-pressure side pressure of the refrigerating system). After being discharged from the compressor 54 and separated by the oil separator 45, the oil is combined with the refrigerant from the refrigeration evaporator 43. The merged refrigerant repeats circulation that is sucked into the suction side of the compressor 37.

  Thus, since the high pressure side refrigerant of the refrigerant circuit 9 for the cooling storage facility can be supercooled by the low pressure side refrigerant of the air conditioning refrigerant circuit 7 flowing through the air conditioning side passage 21A of the cascade heat exchanger 21, the refrigeration case 3 or The cooling capacity in the evaporators 43 and 49 of the refrigeration case 4 and the operation efficiency of the refrigerant circuit 9 for the cooling storage facility are improved. In this case, since the refrigerant on the high pressure side of the refrigerant circuit 9 for the cooling storage facility flows into the case side passage 21B of the cascade heat exchanger 21 via the condenser 38, the degree of superheat of the air conditioning refrigerant circuit 7 is also in an appropriate range. Can be maintained.

  In addition, the pressure of the refrigerant discharged from the refrigeration evaporator 49 of the refrigerant circuit 9 for the cooling storage facility is lower than that of the refrigerant discharged from the refrigeration evaporator 43 because the evaporation temperature becomes lower, but the refrigeration evaporator 43 Before being merged with the refrigerant discharged from the refrigerant, the compressor 54 compresses and pressurizes the refrigerant, and the inside of the refrigerator case 3 and the refrigerator case 4 is cooled smoothly by the evaporators 43 and 49, respectively, for the cooling storage facility. It becomes possible to operate without any trouble by adjusting the pressure of the refrigerant sucked into the compressor 37 of the refrigerant circuit 9.

(2) Control for changing the set pressure of the low-pressure side pressure Here, the refrigeration case controller 50 is the refrigeration case 3 internal temperature (temperature of the space to be cooled) TP or the discharge cold air temperature through the refrigeration evaporator 43 or refrigeration evaporation. The opening degree of each expansion valve 44 is adjusted based on the temperature of the cold air sucked into the cooler 43, the refrigerant temperature on the outlet side of the refrigerating evaporator 43, or the temperature of the refrigerating evaporator 43. Thereby, the superheat degree of the refrigerant in each refrigeration evaporator 43 is set to an appropriate constant value while keeping the inside of each refrigeration case 3 cooled to the refrigeration temperature described above.

  That is, when the internal temperature TP of the refrigeration case 3 is high and cooling is necessary, the refrigeration case controller 50 increases the valve opening degree of the expansion valve 44 corresponding to the refrigeration evaporator 43 of the refrigeration case 3. More refrigerant flows through the refrigeration evaporator 43. Further, when the internal temperature TP of the refrigeration case 3 is low and cooling is not so necessary, the opening degree of the expansion valve 44 is reduced to reduce the amount of refrigerant flowing into the refrigeration evaporator 43. As a result, the internal temperature TP of each refrigeration case 3 is controlled to the set temperature TS, the superheat degree of the refrigerant in the refrigeration evaporator 43 is kept constant, and the internal temperature TP is stored below a predetermined lower limit temperature lower than the set temperature TS. When the cooling is unnecessary, such as when the internal temperature TP is lowered, the expansion valve 44 is finally closed.

  The refrigeration case controller 55 is configured such that the inside temperature of the refrigeration case 4, the temperature of the discharged cold air passing through the refrigeration evaporator 49, or the temperature of the suction cold air into the refrigeration evaporator 49, Alternatively, the valve opening of the expansion valve 51 is adjusted based on the temperature of the freezing evaporator 49. As a result, while maintaining the inside of the freezing case 4 to be cooled to the above-described freezing temperature, an appropriate degree of superheat (constant superheat) is obtained. The control of the expansion valve 51 is the same as that of the expansion valve 44 described above.

  The refrigerator controller 32 controls the operating frequency CHz of the compressor 37 based on the low pressure LP of the refrigerant circuit 9 for the cooling storage facility. In this case, in the refrigerator controller 32, a preset low pressure side pressure LPS is defined by default. The upper limit LPSH and the lower limit LPSL are automatically set with a certain differential above and below the set pressure LPS. When the set pressure LPS is changed, the upper limit LPSH is automatically set by parallel movement. The lower limit value LPSL is also changed. And when the low-pressure side pressure LP of the refrigerant circuit 9 for cooling storage facilities falls to the said lower limit LPSL, the operating frequency CHz of the compressor 37 is lowered to the low frequency LHz.

  Thus, when the low-pressure side pressure LP of the refrigerant circuit 9 for the cooling storage facility is reduced to the lower limit value LPSL, the refrigerant to the refrigeration evaporator 43 of the refrigeration case 3 is reduced by reducing the operating frequency CHz of the compressor 37. Since the inflow amount also decreases, the cooling capacity also decreases. As a result, the refrigeration case controller 50 controls the expansion valve 44 so as to expand the opening of the expansion valve 44, thereby preventing a decrease in the low-pressure side pressure LP of the refrigerant circuit 9 for the cooling storage facility. Therefore, the COP of the compressor 37 is prevented from decreasing due to the decrease in the low pressure LP.

  When all the expansion valves 44 and 51 are fully closed and the low-pressure side pressure LP is lowered to a very low value, the compressor 37 is stopped. Thereafter, if any one of the expansion valves 44 and 51 is opened and the low-pressure side pressure LP increases, the refrigerator controller 32 starts the compressor 37. When the low-pressure side pressure LP increases to the upper limit value LPSH, the compressor The operation frequency CHz of 37 is increased to a high frequency HHz.

  In addition, when the set pressure LPS is constant, the operating frequency CHz of the compressor 37 is frequently switched, particularly in a situation where the load in each refrigerator case 3 is light, and the low pressure side pressure LP is averaged. Since it becomes low and overshoot occurs, operation / stop is repeated in a state where the operation frequency CHz is high.

  Therefore, the refrigerator controller 32 receives the internal temperature TP and the set temperature TS of the refrigeration case 3 from the refrigeration case controller 50, and calculates the moving average temperature TPA of the internal temperature TP per fixed time t (for example, 15 minutes). To do. Next, the set pressure LPS is changed based on the temperature deviation e (e = TPA−TS) between the moving average temperature TPA and the set temperature TS. The change control of the set pressure LPS of the low pressure LP will be described below.

  In this case, the control is to calculate the saturation temperature-temperature deviation e at the current set pressure LPS, and convert this to a pressure to obtain the changed set pressure LPS. That is, when the internal temperature TP is higher than the set temperature TS, the temperature deviation e is positive. Therefore, the refrigerator controller 32 changes the setting pressure LPS to lower and the larger the temperature deviation e is, the more positive it is. That is, as the internal temperature TP is higher than the set temperature TS, the set pressure LPS is changed so as to greatly decrease. On the other hand, when the internal temperature TP is lower than the set temperature TS, the temperature deviation e becomes negative. Therefore, the refrigerator controller 32 changes the direction so as to increase the set pressure LPS, and the larger the temperature deviation e becomes negative. That is, as the internal temperature TP is lower than the set temperature TS, the set pressure LPS is changed in a direction to be increased.

  As described above, the set pressure LPS is changed based on the temperature deviation e between the inside temperature TP of the refrigerated case 3 and the set temperature TS in the inside, and the set pressure when the inside temperature TP is higher than the set temperature TS. When LPS is lowered and the internal temperature TP is lower than the set temperature TS, the set pressure LPS is changed in the direction of increasing the set pressure LPS. Therefore, when the internal temperature TP is high, the operating frequency CHz (capacity) of the compressor 37 is increased. Thus, the cooling capacity of the refrigeration evaporator 43 can be maintained.

  On the other hand, in the situation where the internal temperature TP is sufficiently cooled and the expansion valve 44 reduces the valve opening, and the low pressure side pressure of the refrigerant circuit 9 for the cooling storage facility decreases, the operating frequency of the compressor 37 is earlier. It is possible to reduce the CHz and control the expansion valve 44 in the direction of expanding the valve opening degree to promote an increase in the low-pressure side pressure. As a result, the disadvantage that the low-pressure side pressure LP of the refrigerant circuit 9 for the cooling storage facility decreases on average can be solved, and the COP of the compressor 37 can be improved and the operating efficiency of the refrigeration system 1 can be improved. become.

Here, a thermo switch is used as a device for detecting the internal temperature of the refrigerated case 3. Many thermoswitches use thermophysical properties such as bimetal and thermistor. When the internal temperature TP of the refrigeration case 3 is higher than the set temperature TS, the thermoswitch is turned on and the expansion valve 44 of the evaporator is operated to cool. When the internal temperature TP is lower than the set temperature TS, control is performed to turn off and close the expansion valve 44 to stop cooling. This control can also be performed by an electrical control method based on the temperature measured by the temperature sensor.

In the present invention, based on the flowchart of FIG. 4, the thermoswitch is controlled by ON / OFF. The refrigeration case controller 50 receives the ON / OFF state of the thermo switch (not shown) of the refrigeration case 3 (S100), and confirms the state (S101). When the thermo switch with the refrigerated case 3 is turned off, the thermo switch off state is recorded (S102). Subsequently, it is confirmed whether all the thermoswitches of the refrigeration case 3 are in the OFF state (S103). If all the thermoswitches in the refrigeration case 3 are not in the OFF state, the refrigeration in which the thermoswitch is OFF. For case 3, the temperature deviation e is replaced with a set deviation eS (eg, −1 ° C.) having a negative value and recorded (S108). After the maximum value of the temperature deviation e is transmitted to the refrigeration controller (S109), the actual temperature deviation of the refrigeration case 3 in which the thermo switch is OFF is confirmed (S110). If the actual temperature deviation is equal to or greater than a predetermined temperature deviation eM (here, + 2 ° C.), the temperature deviation e of the refrigeration case 3 is replaced with the actual temperature deviation (S111). Thereafter, the state of the thermo switch is confirmed again for the whole (S101).

On the other hand, when all the thermoswitches of the refrigeration case 3 are in the OFF state, the refrigeration case controller 50 transmits the set deviation eS as the temperature deviation e to the main controller 56 (S104). Thereby, the main controller 56 changes the set pressure LPS by an amount corresponding to the received temperature deviation e (S105). Further, the OFF state record is deleted for all the thermoswitches in the refrigeration case 3 (S106), and the temperature deviation e recorded in the refrigeration case controller 50 is returned from the set deviation eS to the actual temperature deviation and recorded (S107).

Thereby, when the internal temperature TP of all the refrigeration cases 3 is lower than the set temperature TS, that is, the expansion valve 44 throttles the valve opening, and the low pressure side pressure of the refrigerant circuit 9 for the cooling storage facility decreases. In the situation, the operating frequency CHz (capacity) of the compressor 37 can be lowered at an earlier stage, and the valve opening degree of the expansion valve 44 can be controlled to be increased to promote an increase in the low-pressure side pressure. As a result, the disadvantage that the low-pressure side pressure LP of the refrigerant circuit 9 for the cooling storage facility decreases on average can be solved, and the COP of the compressor 37 can be improved and the operating efficiency of the refrigeration system 1 can be improved. become.

(3) Control of change of set pressure of low-pressure side pressure during defrosting of refrigeration evaporator Next, the refrigeration case controller 50 defrosts the refrigeration evaporator 43 at a predetermined time or every predetermined time. This defrosting is performed by fully closing the expansion valve 44 and ventilating the refrigerant into the refrigeration evaporator 43 by passing air through the refrigeration evaporator 43 by the blower 20. The start of defrosting of the evaporator 43 is also notified to the main controller 56. During defrosting of the refrigeration evaporator 43, the main controller 56 does not perform change control of the set pressure LPS of the low-pressure side pressure LP, and maintains the set pressure LPS before the start of defrosting.

  For example, after a predetermined time has elapsed, the refrigeration case controller 50 ends the defrosting of the refrigeration evaporator 43 and resumes the control of the valve opening degree of the expansion valve 44 described above. After the defrosting of the evaporator 43 is completed, the set pressure LPS of the low pressure LP is returned to the default low value described above.

  Here, after the defrosting is completed, the internal temperature TP of the refrigeration case 3 is high, and when the expansion valve 44 is opened, the load increases rapidly for the refrigerant circuit 9 for the cooling storage facility. Therefore, if the set pressure LPS before the start of defrosting is set to a high value, the operating frequency CHz of the compressor 37 is lowered early and cannot follow the load increase, but the default is low after the end of the defrosting. By returning the set pressure LPS to the value, it becomes possible to cope with a rapid load increase after defrosting.

  Here, as described above, by returning the set pressure LPS of the low pressure side pressure LP to the default low value after the defrosting is completed, the compressor 37 can be operated at a high frequency HHz for a long time or during the whole process during the pulldown after the defrosting is completed. Will be driving. Therefore, the internal temperature TP of the refrigeration case 3 is quickly lowered to the lower limit temperature, and the expansion valve 44 is closed accordingly. Therefore, if the expansion valve 51 is closed, the compressor 37 also stops early, and the compressor 37 repeats frequent operation-stop as it is.

  Therefore, the operation time TO corresponding to the time from the start of the operation of the compressor 37 after the defrosting to the stop is measured, and when this operation time TO is shorter than 12 minutes, for example, the evaporation for refrigeration The set pressure LPS is increased by an amount corresponding to 2 ° C. at the refrigerant evaporation temperature in the vessel 43. Further, when the operation time TO is, for example, 12 minutes or more and less than 15 minutes, the set pressure LPS is increased by an amount corresponding to 1 ° C. as the refrigerant evaporation temperature in the refrigeration evaporator 43. That is, the shorter the operating time TO is, the larger the increase range of the set pressure LPS is.

  Thereby, the operating time of the compressor 37 is shortened while the set pressure LPS of the low pressure side pressure LP is gradually increased based on the operating time of the compressor 37, thereby shortening the time required for pull-down after the completion of the defrosting. To improve driving efficiency by eliminating frequent operation-stops. Then, when the operation time TO of the compressor 37 becomes 15 minutes or longer, the main controller 56 shifts to set pressure LPS change control (2-1) based on the temperature deviation e.

(4) Optimal operation pattern 2: Heating operation of the air conditioner (Fig. 2)
Next, the heating operation of the air conditioner 6 in winter will be described with reference to FIG. In this case as well, the above-described change control of the set pressure of the low-pressure side pressure is performed. When the main controller 56 determines that the heating operation of the air conditioner 6 is optimal, data regarding the optimal operation pattern 2 is the outdoor unit controller 26, the indoor unit controller 28, the refrigerator controller 32, the refrigeration case controller 50, and the refrigeration case controller. 55.

  Based on the received data, the outdoor unit controller 26 switches so that the inlet on the outlet side of the oil separator 10 of the four-way valve 14 is in communication with the outlet on the inlet side of the use side heat exchanger 27 and the other inlet is in communication with the other outlet. The expansion valve 17 is fully closed and the expansion valve 18 is fully opened. Then, the compressors 13A and 13B are operated. When the compressors 13 </ b> A and 13 </ b> B are operated, the high-temperature and high-pressure gas refrigerant discharged from the discharge sides of the compressors 13 </ b> A and 13 </ b> B enters the use-side heat exchanger 27 through the four-way valve 14 from the oil separator 10. As described above, the air in the store 2 is ventilated by the blower 15 to the use side heat exchanger 27, and the refrigerant dissipates heat here and heats the air in the store 2 while it condenses into liquid. Thereby, the inside of the store 2 is heated.

  The refrigerant liquefied in the use side heat exchanger 27 exits from the use side heat exchanger 27, passes through the expansion valve 18, reaches the expansion valve 19, and is throttled and decompressed there, and then the air conditioning side passage of the cascade heat exchanger 21. After flowing into 21A, where it evaporates and absorbs heat, the circulation is repeated through the accumulator 23 and sucked into the suction sides of the compressors 13A and 13B.

  The outdoor unit controller 26 adjusts the valve opening degree of the expansion valve 19 based on the refrigerant temperature at the inlet / outlet of the cascade heat exchanger 21 or the temperature of the cascade heat exchanger 21 so that the degree of superheat is appropriate. Moreover, the indoor unit controller 28 controls the blower 15 that ventilates the use side heat exchanger 27 so that the temperature in the store 2 is set to the set temperature based on the temperature of the use side heat exchanger 27 and the air temperature sucked therein. Further, the operation of the compressors 13A and 13B is controlled by the outdoor unit controller 26 as described above.

  On the other hand, the refrigerator controller 32 uses the outlet on the outlet side of the case side passage 21B of the cascade heat exchanger 21 of the four-way valve 39 in the refrigerant circuit 9 for the cooling storage facility of the cooling device 8 as the outlet on the inlet side of the condenser 38. The inlet of the receiver tank 36 of the four-way valve 41 is switched to communicate with the other outlet, the inlet of the receiver tank 36 of the four-way valve 41 is communicated with the outlet of the solenoid valves 46, 47 and 52, and the other inlet is communicated with the other outlet. Switch so that The other solenoid valves and the like are the same as in the cooling operation described above. That is, the electromagnetic valves 46 and 47 and 52 are opened, and the compressors 37 and 54 are operated.

  Thus, the high-temperature and high-pressure gas refrigerant discharged from the compressor 37 sequentially passes through the four-way valves 39 and 41 and first enters the case side passage 21B of the cascade heat exchanger 21. That is, the high-temperature and high-pressure gas refrigerant discharged from the compressor 37 is directly supplied to the case side passage 21 </ b> B of the cascade heat exchanger 21 before going to the condenser 38. Since the refrigerant of the refrigerant circuit 9 for the cooling storage facility that has entered the case side passage 21B dissipates heat in the cascade heat exchanger 21, it is cooled by the refrigerant of the air conditioning refrigerant circuit 7 that evaporates in the air conditioning side passage 21A as described above. Deliver heat. As a result, the refrigerant in the air conditioning refrigerant circuit 7 pumps up the waste heat of the refrigerant in the refrigerant circuit 9 for the cooling storage facility.

  The refrigerant that has passed through the case side passage 21B of the cascade heat exchanger 21 then enters the inlet side 38A of the condenser 38 via the four-way valve 39. Outside air is also ventilated by the blower 35 to the condenser 38, and the refrigerant flowing into the condenser 38 dissipates heat.

  The refrigerant that has passed through the inlet side 38A of the condenser 38 reaches the outlet side 38B and exits there. The refrigerant discharged from the condenser 38 enters the receiver tank 36 from the inlet side of the receiver tank 36 and is temporarily stored therein to separate the gas / liquid. The separated liquid refrigerant exits from the outlet of the receiver tank 36, passes through the four-way valve 41, and then branches, and goes to the electromagnetic valves 46, 47, and 52 as described above.

  By such operation, during the heating operation of the air conditioning refrigerant circuit 7 of the air conditioner 6, the waste heat of the high-pressure side refrigerant of the refrigerant circuit 9 for the cooling storage facility is recovered by the cascade heat exchanger 21 and the air conditioning refrigerant circuit 7. It becomes possible to convey to the use side heat exchanger 27. As a result, the heating capacity of the air conditioner 6 can be improved. In general, the efficiency of the refrigeration system 1 that cools the in-store air-conditioning and the refrigeration case 3 and the refrigeration case 4 is improved and energy is saved. Can be achieved.

  Particularly in this case, since the refrigerant on the high pressure side of the refrigerant circuit 9 for the cooling storage facility is passed through the cascade heat exchanger 21 before the condenser 38, the waste heat recovery from the high pressure side refrigerant of the refrigerant circuit 9 for the cooling storage facility is performed. Efficiently, the heating capability in the use side heat exchanger 27 of the air conditioning refrigerant circuit 7 can be further improved.

  Here, when the air conditioner 6 is lightly loaded, such as when the store 2 is relatively warm, the outdoor unit controller 26 reduces the refrigerant flow rate by reducing the valve opening of the expansion valve 19, so that cascade heat exchange is performed. However, in the present invention, the refrigerant on the high pressure side of the refrigerant circuit 9 for the cooling storage facility is passed through the cascade heat exchanger 21 and then condensed. Therefore, when the heat radiation amount of the refrigerant in the cascade heat exchanger 21 of the cooling storage facility refrigerant circuit 9 becomes excessive during the heating operation of the air conditioning refrigerant circuit 7, the condenser 38. This excess amount of heat is released. As a result, a stable waste heat recovery operation can be realized.

  Further, as described above, the flow path is switched using the four-way valves 39 and 41, and is connected to the condenser 38 and the outlet of the refrigerant circuit 9 for the cooling storage facility during the cooling operation and the heating operation of the air conditioning refrigerant circuit 7. The flow direction of the refrigerant flowing through the receiver tank 36 is the same. As a result, the pressure loss of the refrigerant flowing in the refrigerant circuit 9 for the cooling storage facility is reduced compared to the case where the refrigerant flows in the condenser 38 and the receiver tank 36 are opposite between the cooling operation and the heating operation. It becomes possible to prevent or suppress, and efficient operation becomes possible. In particular, since the flow path is switched by the two four-way valves 39 and 41, the configuration of the refrigerant circuit 9 for the cooling storage facility can be simplified.

(5) Optimal operation pattern 3: Control when almost no heat is required in the cascade heat exchanger of the cooling device during heating operation of the air conditioner (FIG. 3)
Here, during the heating operation of the air conditioner 6 as described above, if the load of the store air is further reduced and the heating capacity becomes excessive, the outdoor unit controller 26 sets the operation frequency of the compressor 13B based on the store temperature information. Reduce the heating capacity. On the other hand, even if such control is performed and an excessive amount of heat is released in the condenser 38 as described above, the heat radiation in the cascade heat exchanger 21 of the refrigerant circuit 9 for the cooling storage facility of the cooling device 8 is reduced. In a situation that is hardly required, the heating capacity of the air conditioner 6 becomes excessive with the circuit of FIG.

  In such a case, the refrigerator controller 32 switches the four-way valves 39 and 41 from the state shown in FIGS. That is, in this case, the refrigerator controller 32 switches the inlet of the four-way valve 39 on the outlet side of the oil separator 31 to communicate with the outlet on the inlet side of the condenser 38 and the other inlet to the other outlet. In addition, the outlet side inlet of the receiver tank 36 of the four-way valve 41 is switched to the inlet side outlet of the case side passage 21B of the cascade heat exchanger 21 and the other inlet is communicated with the other outlet.

  As a result, the high-temperature and high-pressure refrigerant discharged from the compressor 37 passes through the condenser 38 and dissipates heat in the same manner as in FIG. 1, and then flows into the cascade heat exchanger 21, so that the air-conditioning refrigerant circuit It is possible to avoid the disadvantage that the refrigerant No. 7 is excessively heated in the cascade heat exchanger 21 and to improve the efficiency by overcooling the cooling storage facility. Here, also in this case, the above-described change control of the set pressure of the low-pressure side pressure is performed.

  In the embodiment, the present invention has been described with the refrigeration system that cools the air conditioning and the cooling storage facility in the store at the convenience store. However, the present invention is not limited to this, and the present invention is effective even when only the cooling storage facility is cooled. . Further, in the embodiment, the capacity control of the compressor is realized by controlling the operation frequency by the inverter. However, the present invention is not limited to this, and various capacity controls can be applied. Furthermore, the change control of the set pressure LPS is based on the evaporation temperature and the set temperature when the evaporation temperature of the refrigerant in the refrigeration evaporator 43 can be measured regardless of the internal temperature TP and the set temperature TS. You may go. Further, in the above embodiment, the compressors 37 and 13A are controlled in capacity by controlling the operation frequency by an inverter. However, the meaning of capacity control is not limited to this, and a plurality of compressors are connected in parallel (for example, a plurality of constants). This includes the case of switching the number of units operated by parallel connection of high-speed compressors, parallel connection of one constant-speed compressor and one inverter-controlled compressor, or controlling the operation frequency in addition to that.

It is a figure explaining the structure of the refrigerating system containing the refrigerant circuit at the time of the cooling operation of the air conditioner in the Example to which this invention is applied. It is a figure explaining the structure of the refrigerating system containing the refrigerant circuit at the time of the heating operation of the air conditioner in the Example to which this invention is applied. It is a figure explaining the structure of the refrigerating system containing a refrigerant circuit when the heat radiation in a cascade heat exchanger is hardly required in the heating operation of the air conditioner in the Example to which this invention is applied. It is a flowchart regarding the control method of the refrigeration system to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigeration system 3 Refrigeration case 4 Refrigeration case 6 Air conditioner 7 Air-conditioning refrigerant circuit 8 Cooling device 9 Refrigerating circuit 13A, 13B, 37, 54 Compressor 14 Four-way valve 16 Heat source side heat exchanger 21 Cascade heat exchange 27 Use side heat exchanger 32 Refrigerator controller 38 Condensers 39, 41 Four-way valve (flow path control means)
43 Refrigerating evaporators 44 and 51 Expansion valve 49 Refrigerating evaporator 50 Refrigerating case controller

Claims (8)

A refrigerant circuit is composed of a compressor, a condenser, an expansion valve, and an evaporator, and has a space to be cooled that is cooled by the evaporator.
Control the capacity of the compressor based on the low pressure side pressure and the set pressure of the compressor,
In the refrigeration system that changes the set pressure based on a deviation between the temperature of the space to be cooled and the set temperature at a predetermined cycle,
A refrigeration system that controls the capacity of the compressor by changing the set pressure to a predetermined value regardless of the predetermined period by a signal indicating that the cooling of the cooled space by the evaporator is stopped.   2. The refrigeration system according to claim 1, wherein the deviation is recorded with a predetermined value replaced by a signal indicating that the cooling of the cooled space by the evaporator is stopped.   The refrigeration system according to claim 2, wherein an actual deviation is recorded by a signal indicating that the temperature of the cooled space exceeds a predetermined temperature.   4. The refrigeration system according to claim 1, wherein the actual deviation is recorded after the cooling of the space to be cooled by the evaporator is stopped and the capacity of the compressor is controlled. A refrigerant circuit is constituted by a compressor, a condenser, an expansion valve, and a plurality of evaporators, and has a plurality of cooled spaces that are cooled by these evaporators.
Control the capacity of the compressor based on the low pressure side pressure and the set pressure of the compressor,
In the refrigeration system that changes the set pressure based on a maximum deviation among the deviation between the temperature of the cooled space and the set temperature at a predetermined cycle,
A refrigeration system that controls the capacity of the compressor by changing the set pressure to a predetermined value regardless of the predetermined period based on a signal that cooling of the cooling space by all the evaporators is stopped. 6. The refrigeration system according to claim 5, wherein the corresponding deviation is recorded with a predetermined value by a signal indicating that the cooling of the cooled space by the evaporator is stopped.   The refrigeration system according to claim 6, wherein an actual deviation corresponding to the cooled space is recorded by a signal indicating that the temperature of the cooled space exceeds a predetermined temperature. The refrigeration according to any one of claims 5 to 7, wherein all actual deviations are recorded after cooling of the cooled space by all the evaporators is stopped and capacity control of the compressor is performed. system.