JP2013137123A - Refrigerating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating apparatus which does not require hot gas piping for the exclusive use of defrosting for connecting a heat source unit with a plurality of cooling units, supplies a high-temperature coolant only to a part of cooler while continuing cooling operation without disposing a stop valve for channel switching on a piping part through which a low-pressure coolant flows and can perform defrosting operation.SOLUTION: A coolant branch unit 3 is connected between a liquid main pipe 4 extended from a heat source unit 1 and liquid branch pipes 40a, 40b extended from the plurality of cooling units 2, respectively. The coolant branch unit 3 has a defrosting coolant circuit B which branches a part of a liquid coolant flowing out of a condenser 7, causes makes branched liquid coolant flow into the low pressure side of an inner heat exchanger 13 via a defrosting flow adjusting valve 14, makes the liquid coolant having flown into the low pressure side of the inner heat exchanger 13 perform heat exchange with the liquid coolant (cooling coolant) of the high pressure side of the inner heat exchanger 13 and to be heated to produce the defrosting coolant. The cooling coolant or the defrosting coolant after passing through the high pressure side of the inner heat exchanger is selectively supplied to each of the plurality of cooling units 2 by the defrosting solenoid valves 15a, 15b.

Description

  The present invention relates to a refrigeration apparatus including a plurality of coolers for cooling a freezer such as a refrigerated warehouse.

  In this type of refrigeration apparatus, as a defrosting method for removing frost attached to a cooler during a cooling operation, an external heating method is known in which a heater is brought into close contact with the cooler to perform defrosting. However, in this method, although the frost in the portion near the heater can be removed, the heat is not sufficiently transmitted to the far portion, so that there is a problem that the frost remains unmelted. In order to eliminate unmelted residue, the heating amount of the heater may be increased, but it is necessary to heat to a considerably high temperature. For this reason, problems such as an increase in cooling load due to the heat of the heater, and condensation of moisture evaporated by heating on the inner wall surface may occur. For this reason, there are many examples that employ the internal heating method.

  A refrigeration apparatus that employs an internal heating system includes a compressor, a condenser, an expansion valve, and a cooler, and includes a refrigerant circuit that circulates the refrigerant. And the cooler is heated and defrosted by flowing a part of hot gas refrigerant (henceforth hot gas refrigerant | coolant) discharged from the compressor directly to a cooler (refer patent document 1). Thus, while the hot gas refrigerant is passed through the cooler and defrosting, the cooler cannot cool the object to be cooled. For this reason, in the refrigeration apparatus provided with a plurality of coolers as in Patent Document 1, the cooling operation can be continued with other coolers while the defrosting operation is performed with some coolers. .

  Specifically, in Patent Document 1, one end of a hot gas pipe for guiding the hot gas refrigerant to the cooler is connected to the discharge side of the compressor, and a flow path switching device is provided at the other end to each cooler. It is configured to allow hot gas to flow independently. With this configuration, the cooling operation and the defrosting operation can be independently switched in each cooler, and the cooling operation can be continued while performing the defrosting.

  As a refrigeration apparatus that can continue the cooling operation with another cooler even during the defrosting operation, for example, the high-temperature refrigerant that has passed through the condenser is circulated to the defrosting target cooler without depressurization to remove the defrosting. A defrosting operation method is also known in which the refrigerant after passing through the defroster target cooler is decompressed and then circulated to another cooler to perform a cooling operation (see, for example, Patent Document 2).

JP 2010-255921 (page 14, FIG. 3) Japanese Patent Laying-Open No. 2005-274057 (page 9, FIG. 7)

  By the way, there is a refrigeration apparatus in which a heat source unit having a compressor and a plurality of cooling units having a cooler are connected via two pipes of a liquid main pipe and a gas main pipe. In this type of refrigeration apparatus, when a method of performing defrosting by flowing hot gas refrigerant discharged from a compressor to a cooler as in Patent Document 1, a heat source unit and a plurality of cooling units are connected to a liquid main pipe. In addition to the gas main pipe, it is necessary to connect via a hot gas pipe. That is, it is necessary to install a total of three pipes between the heat source unit and the plurality of cooling units, which causes a problem that the cost of installation work increases.

  Moreover, in the defrosting method of the refrigerating apparatus of patent document 2, the gas branch pipe requires a switching valve for switching the flow path. The gas branch pipe is a portion through which the low-pressure gas refrigerant flowing out of the cooler passes, and a slight pressure loss in this portion leads to deterioration of the equipment performance. For this reason, it is necessary to use a valve with the largest possible opening / closing valve provided in the gas branch pipe, and there is a problem that the size and cost of the cooling unit having the cooler are increased.

  The present invention has been made in order to solve the above-described problems, and does not require a defrosting hot gas pipe for connection between a heat source unit and a plurality of cooling units, and a pipe through which a low-pressure refrigerant flows. An object is to obtain a refrigeration apparatus capable of performing a defrosting operation by supplying a high-temperature refrigerant only to some coolers while continuing a cooling operation without installing an on-off valve for switching a channel in a part. And

  A refrigeration apparatus according to the present invention includes a cooling refrigerant circuit connected to a compressor, a condenser, a high-pressure side of an internal heat exchanger, a decompression apparatus, and a cooler so that the cooling refrigerant circulates, and a cooling refrigerant circuit A heat source unit having a compressor and a condenser; a gas main pipe extending from the heat source unit via a gas branch pipe; a plurality of cooling units having a decompression device and a cooler; and a liquid main pipe extending from the heat source unit A refrigerant branch portion connected between each of the plurality of cooling units and a liquid branch pipe extending from each of the cooling units. The refrigerant branch portion flows out of the internal heat exchanger and the condenser and flows out of the condenser. A part of the liquid refrigerant before flowing into the high-pressure side is branched, flows into the low-pressure side of the internal heat exchanger via the defrosting flow control device, flows out of the condenser, and flows into the high-pressure side of the internal heat exchanger Heat-exchange with cooling refrigerant to heat and defrost The defrosting refrigerant circuit that generates the medium and the cooling refrigerant after passing through the high-pressure side of the internal heat exchanger of the cooling refrigerant circuit or the defrosting refrigerant generated by the defrosting refrigerant circuit And a refrigerant flow switching device that selectively supplies each of them.

  According to the present invention, the heat source unit and the plurality of cooling units are connected by the gas main pipe, and the refrigerant branch portion is provided between the liquid main pipe extending from the heat source unit and the plurality of cooling units, and the refrigerant branch portion is A part of the high-pressure liquid refrigerant flowing from the liquid main pipe is used as a cooling refrigerant by the internal heat exchanger and the defrost flow rate adjusting device, and the defrosting refrigerant is removed from the remaining high-pressure liquid refrigerant using this cooling refrigerant. Thus, the cooling refrigerant or the defrosting refrigerant can be selectively supplied to each cooling unit independently. As a result, the cooling operation can be performed without connecting the heat source unit and a plurality of cooling units with hot gas piping dedicated to defrosting, or without providing an on-off valve for switching the flow path in the piping portion through which the low-pressure refrigerant flows. It is possible to perform the defrosting operation by supplying the defrosting refrigerant only to some of the coolers while continuing the operation.

It is a figure which shows an example of the refrigerant circuit of the freezing apparatus in Embodiment 1 of this invention. It is a Mollier diagram which shows the relationship between the enthalpy and the pressure at the time of the normal operation mode of the freezing apparatus in Embodiment 1 of this invention. It is a refrigerant circuit figure at the time of the defrost operation mode of the freezing apparatus in Embodiment 1 of this invention. It is a Mollier diagram which shows the relationship between the enthalpy and pressure at the time of the defrost operation mode in the freezing apparatus in Embodiment 1 of this invention. FIG. 2 is a characteristic diagram showing the behavior of the defrosting refrigerant when the opening degree of the defrosting flow rate adjusting valve in FIG. 1 is changed, (a) is the defrosting heat quantity characteristic, (b) is the defrosting at the outlet of the internal heat exchanger. It is the figure which respectively showed the refrigerant | coolant temperature (state G) characteristic for water, and (c) defrost flow volume characteristic. It is a figure which shows an example of the refrigerant circuit of the freezing apparatus in Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating an example of a refrigerant circuit of a refrigeration apparatus in Embodiment 1 of the present invention. In FIG. 1 and the drawings to be described later, the same reference numerals denote the same or corresponding parts, which are common throughout the entire specification. Furthermore, the forms of the constituent elements appearing in the entire specification are merely examples and are not limited to these descriptions.
The refrigeration apparatus includes a heat source unit 1 and a plurality of (here, two) cooling units 2a and 2b (hereinafter sometimes collectively referred to as a cooling unit 2) for cooling a freezer (including a refrigerated warehouse and a cooling chamber). And a refrigerant branching unit 3 as a refrigerant branching unit.

  The heat source unit 1 and the cooling units 2a and 2b are installed at positions separated from each other, and the cooling units 2a and 2b are connected to the gas main pipe 5 extending from the heat source unit 1 via the gas branch pipes 50a and 50b. In addition to the gas main pipe 5, the liquid main pipe 4 also extends from the heat source unit 1, and the refrigerant branch unit 3 is connected between the liquid main pipe 4 and the liquid branch pipes 40a and 40b extending from the cooling units 2a and 2b. Has been.

  A configuration in which the heat source unit 1 and the plurality of cooling units 2a and 2b are connected by the liquid main pipe 4 and the gas main pipe 5 is more general than before, and the refrigeration apparatus according to the first embodiment is a so-called general configuration. 2 corresponds to a configuration in which the refrigerant branch unit 3 is connected between the liquid main pipe 4 and the cooling units 2a and 2b. Although the details of the configuration of the refrigerant branch unit 3 will be described later, the refrigerant branch unit 3 enables the cooling operation and the defrosting operation to be performed simultaneously.

  Hereinafter, each structure of the heat-source unit 1, the cooling unit 2, and the refrigerant | coolant branch unit 3 which comprises a freezing apparatus is demonstrated sequentially.

  The heat source unit 1 includes a compressor 6, a condenser 7, and a liquid receiver 8, which are connected by a refrigerant pipe. The cooling unit 2 includes a liquid electromagnetic valve 9, an expansion valve 10 as a pressure reducing device whose opening degree can be adjusted by a pulse motor, and a cooler 11, which are connected by a refrigerant pipe. The ends of the liquid branch pipes 40 a and 40 b extending from the cooling units 2 a and 2 b are connected to the liquid branch pipe side connection ports 3 b and 3 c of the refrigerant branch unit 3.

  The refrigerant branching unit 3 is a cooling refrigerant for performing cooling operation or defrosting for defrosting operation of the high-pressure liquid refrigerant that has flowed into the refrigerant branching unit 3 from the liquid main pipe 4 through the liquid main pipe side connection port 3a. It has the function of supplying it selectively to each cooler 11 as a refrigerant for use. The refrigerant branching unit 3 includes an internal heat exchanger 13, a defrosting flow rate adjustment valve 14, defrosting electromagnetic valves 15a and 15b as refrigerant flow switching devices, and check valves 16a and 16b. Connected with refrigerant piping.

  The specific connection configuration in the refrigerant branch unit 3 will be described. The upstream side of the internal heat exchanger 13 is connected to the liquid main pipe side connection port 3a connected to the liquid main pipe 4, and the downstream side of the internal heat exchanger 13 is The cooling units 2a and 2b are branched to the same number, and the branched branches are connected to the liquid branch pipe side connection ports 3b and 3c via the defrosting electromagnetic valves 15a and 15b, respectively. With this configuration, the compressor 6, the condenser 7, the liquid receiver 8, the high pressure side of the internal heat exchanger 13, the defrosting solenoid valves 15a and 15b, the liquid solenoid valve 9, the expansion valve 10, and the cooler 11 are arranged in this order. The cooling refrigerant circuit A is configured by being connected in an annular shape. For example, a refrigerant R410A is sealed in the cooling refrigerant circuit A. Hereinafter, the refrigerant circulating in the cooling refrigerant circuit A may be referred to as a cooling refrigerant.

  The refrigerant branching unit 3 is further branched from between the liquid main pipe side connection port 3a and the internal heat exchanger 13, and through the defrosting flow rate adjusting valve 14 and the low pressure side of the internal heat exchanger 13, the defrosting electromagnetic wave. A defrosting refrigerant circuit B that merges between the valves 15a and 15b and the liquid branch pipe side connection ports 3b and 3c is formed. Hereinafter, the refrigerant passing through the defrosting refrigerant circuit B may be referred to as a defrosting refrigerant.

  In the defrosting refrigerant circuit B configured as described above, a part of the liquid refrigerant before flowing into the high pressure side of the internal heat exchanger 13 is branched, and after the pressure is reduced by the defrosting flow rate adjusting valve 14, the internal heat exchanger 13 It flows into the low-pressure side, flows out of the condenser 7 and heat-exchanges with the cooling refrigerant that flows into the high-pressure side of the internal heat exchanger 13 as it is to produce defrosting refrigerant. The defrosting refrigerant generated in the defrosting refrigerant circuit B flows into the liquid branch pipes 40a and 40b via the check valves 16a and 16b, and is supplied to the cooling units 2a and 2b.

  The defrosting solenoid valves 15a and 15b selectively use the cooling refrigerant flowing out from the high pressure side of the internal heat exchanger 13 or the defrosting refrigerant generated by the defrosting refrigerant circuit B for each of the cooling units 2a and 2b. To supply. That is, when supplying the cooling refrigerant to the cooling unit 2a and supplying the defrosting refrigerant to the cooling unit 2b, the defrosting electromagnetic valve 15a is opened, the defrosting electromagnetic valve 15b is closed, and the cooling unit 2a is closed. When supplying the defrosting refrigerant and supplying the cooling refrigerant to the cooling unit 2b, the defrosting electromagnetic valve 15a is closed and the defrosting electromagnetic valve 15b is opened. Further, when supplying the cooling refrigerant to both the cooling units 2a and 2b, both the defrosting electromagnetic valves 15a and 15b are opened.

  The refrigeration apparatus is further provided with a control device 60 that controls the entire refrigeration apparatus. The control device 60 is constituted by a microcomputer and includes a CPU, a RAM, a ROM, and the like. The control device 60 switches between a normal operation mode or a defrosting operation mode, which will be described later, the opening degree control of the defrosting flow rate adjustment valve 14, the opening / closing control of the defrosting electromagnetic valves 15a, 15b, and the opening / closing control of the liquid electromagnetic valve 9. Then, the opening degree of the expansion valve 10 is controlled. The control device 60 may be provided in the heat source unit 1, may be provided in the cooling unit 2 or the refrigerant branching unit 3, and is configured separately for each unit, and performs cooperative processing with each other. You may make it the structure to perform.

(Normal operation mode)
FIG. 2 is a Mollier diagram showing the relationship between enthalpy and pressure in the normal operation mode in the refrigeration apparatus in Embodiment 1 of the present invention. The refrigerant states indicated by points A to E and H in FIG. 2 correspond to refrigerant states at points A to E and H in the refrigeration apparatus of FIG. Moreover, the arrow of FIG. 1 has shown the flow of the refrigerant | coolant at the time of normal operation mode. In FIG. 1, the white valve is open, and the black valve is closed. This also applies to the drawings described later.

  Hereinafter, the refrigeration cycle operation in the normal operation mode of the refrigeration apparatus will be described with reference to FIGS. 1 and 2. The normal operation mode is an operation mode in which the cooling units 2a and 2b perform the cooling operation. In the normal operation mode, the defrosting flow rate adjustment valve 14 of the refrigerant branching unit 3 is closed, and the defrosting electromagnetic valves 15a and 15b are opened. Further, the liquid electromagnetic valves 9 of the cooling units 2a and 2b are also opened.

  The high-temperature and high-pressure gas refrigerant (state B) discharged from the compressor 6 dissipates heat to the outside air in the condenser 7 and condenses, and flows into the liquid receiver 8. Since the liquid receiver 8 stores excess liquid refrigerant in this refrigeration cycle, the liquid and gas coexist in this state, and the liquid refrigerant flowing out of the liquid receiver 8 becomes a saturated liquid (state C).

  The high-pressure liquid refrigerant that has flowed out of the liquid receiver 8 flows out of the heat source unit 1, passes through the liquid main pipe 4, and flows into the refrigerant branching unit 3 from the liquid main pipe side connection port 3 a. In normal operation, since the defrost flow rate adjusting valve 14 is closed, all the liquid refrigerant that has flowed into the refrigerant branch unit 3 flows into the internal heat exchanger 13 and is branched without performing heat exchange. It flows into the cooling units 2a and 2b via the electromagnetic valves 15a and 15b.

  The high-pressure liquid refrigerant that has flowed into the cooling unit 2 flows into the expansion valve 10 via the liquid electromagnetic valve 9, and is decompressed mainly by the expansion valve 10 to become a low-pressure two-phase refrigerant (states E and H). Flow into. The low-pressure two-phase refrigerant that has flowed into the cooler 11 evaporates by exchanging heat with the internal air, and becomes low-pressure gas refrigerant (state A) and flows out of the cooling unit 2.

  The low-pressure gas refrigerant that has flowed out of the cooling units 2a and 2b flows into the gas main pipe 5 through the gas branch pipes 50a and 50b, and is sucked into the compressor 6 again. In this manner, the refrigerant in the cooling refrigerant circuit A circulates to cool the air in the warehouse.

  If the above-described normal operation mode is continued for a long time, frost gradually accumulates in the cooler 11, and when the accumulation amount exceeds a predetermined amount, the cooling capacity is significantly reduced. For this reason, the defrosting operation is performed at predetermined intervals. Hereinafter, the defrosting operation will be described.

(Defrost operation mode)
FIG. 3 is a refrigerant circuit diagram in the defrosting operation mode of the refrigeration apparatus in Embodiment 1 of the present invention. FIG. 4 is a Mollier diagram showing the relationship between enthalpy and pressure in the defrosting operation mode in the refrigeration apparatus in Embodiment 1 of the present invention. Moreover, each refrigerant | coolant state which the point A-point H in FIG. 4 shows respond | corresponds to each state of the refrigerant | coolant in the point A-point H in the refrigeration apparatus of FIG.

  In the defrosting operation mode, the defrosting flow rate adjustment valve 14 is opened, and the defrosting electromagnetic between the cooler 11 that performs the defrosting operation and the internal heat exchanger 13 among the defrosting electromagnetic valves 15a and 15b. The valve is closed, and the defrosting solenoid valve between the cooler 11 and the internal heat exchanger 13 that continues the cooling operation is opened. Further, the expansion valve 10 of the cooler 11 that performs the defrosting operation is fully opened. The expansion valve 10 of the cooler 11 that continues the cooling operation is controlled according to the operating state of the cooling unit 2.

  Hereinafter, an example in which the cooling unit 2a is cooled and the cooling unit 2b is defrosted will be described in detail. In this case, the defrosting solenoid valve 15a is opened, the defrosting solenoid valve 15b is closed, the expansion valve 10 of the cooling unit 2b is fully opened, and the liquid solenoid valves 9 of the cooling units 2a and 2b are opened. .

  Hereinafter, the refrigeration cycle operation will be described separately for a cooling side cycle by the cooling refrigerant circuit A and a defrosting side cycle by the defrosting refrigerant circuit B. The solid line arrows in FIG. 3 indicate the refrigerant flow in the cooling side cycle, and the dotted line arrows indicate the refrigerant flow in the defrosting side cycle. Moreover, the continuous line of FIG. 4 has shown the Mollier diagram in a cooling side cycle, and the dotted line has shown the Mollier diagram of the defrost side cycle.

(Cooling cycle: cooling operation)
First, the operation of the cooling side cycle will be described. As in the normal operation mode described above, the high-temperature and high-pressure gas refrigerant (state B) discharged from the compressor 6 radiates heat to the outside air by the condenser 7 and becomes a high-pressure liquid refrigerant (state C). leak. The high-pressure liquid refrigerant flows into the refrigerant branching unit 3 from the liquid main pipe side connection port 3a through the liquid main pipe 4. The refrigerant that has flowed into the refrigerant branching unit 3 branches into two, one flows directly into the high-pressure side of the internal heat exchanger 13, and the other flows into the defrosting refrigerant circuit B and enters the defrosting flow rate adjustment valve 14. The pressure is reduced and then flows into the low pressure side of the internal heat exchanger 13.

  The cooling refrigerant that has flowed into the high-pressure side of the internal heat exchanger 13 is cooled by exchanging heat with the defrosting refrigerant from the defrosting refrigerant circuit B, and has a high degree of supercooling (state D). Become. This high-pressure liquid refrigerant flows out of the refrigerant branch unit 3 from the liquid branch pipe side connection port 3b via the defrosting electromagnetic valve 15a and flows into the cooling unit 2a. The refrigerant that has flowed into the cooling unit 2 a passes through the liquid electromagnetic valve 9, and then is decompressed by the expansion valve 10 to become a low-pressure two-phase refrigerant (state E) and flows into the cooler 11. The low-pressure two-phase refrigerant that has flowed into the cooler 11 evaporates by exchanging heat with the internal air, and becomes low-pressure gas refrigerant (state A) and flows out of the cooling unit 2a. The low-pressure gas refrigerant that has flowed out of the cooling unit 2 a is again sucked into the compressor 6 through the gas branch pipe 50 a and the gas main pipe 5. As described above, the cooling refrigerant circulates in the cooling refrigerant circuit A to cool the inside of the warehouse.

(Defrost side cycle: Defrost operation)
The defrosting refrigerant flowing into the defrosting refrigerant circuit B is depressurized by the defrosting flow rate adjusting valve 14 as described above, and then flows into the low pressure side of the internal heat exchanger 13. The defrosting refrigerant flowing into the low pressure side of the internal heat exchanger 13 is heated by exchanging heat with the high pressure liquid refrigerant (cooling refrigerant) on the high pressure side of the internal heat exchanger 13. Thereby, the defrosting refrigerant | coolant (state G) which is a hot gas refrigerant raised to the temperature close | similar to a condensation temperature is produced | generated. The defrosting refrigerant flows out of the refrigerant branch unit 3 from the liquid branch pipe side connection port 3c via the check valve 16b, and flows into the cooling unit 2b.

  The defrosting refrigerant that has flowed into the cooling unit 2 b is slightly reduced in pressure due to pressure loss when passing through the liquid electromagnetic valve 9 and the expansion valve 10 (state H) and flows into the cooler 11. The defrosting refrigerant that has flowed into the cooler 11 proceeds through the cooler 11 while melting the frost adhering to the cooler 11, and loses the ability to defrost when the temperature falls to 0 ° C., which is the frost temperature, and gas branching occurs. It is sucked again into the compressor 6 through the pipe 50b and the gas main pipe 5. Defrosting is performed by supplying the defrosting refrigerant to the cooling unit 2b as described above.

  When the defrosting of the cooling unit 2b proceeds and it is determined that the defrosting is finished, the defrosting operation of the cooling unit 2a is started in the same procedure as described above, and the cooling unit 2b is switched to the cooling operation. In this way, the cooling units 2 are defrosted one by one, and at least one of the two cooling units 2 continues the cooling operation, so that the temperature inside the chamber varies (specifically, the temperature inside the chamber rises). Can be suppressed.

The defrosting refrigerant in the defrosting side cycle acquires the amount of heat for defrosting by internal heat exchange with the liquid refrigerant (cooling refrigerant) in the cooling side cycle, so that an external heat source such as a heater is not used. Highly efficient defrosting can be performed. At this time, in the cooling side cycle, the enthalpy difference before and after the cooler is expanded by ΔH _CD (see FIG. 4) due to heat exchange with the defrosting refrigerant, so that the cooling capacity is increased and highly efficient cooling operation is performed. It can be carried out.

(Control of refrigerant flow for defrosting)
Next, a method for controlling the defrosting refrigerant flow rate will be described with reference to FIGS. 4 and 5. FIG. 5 is a characteristic diagram showing the behavior of the defrosting refrigerant when the opening degree of the defrosting flow rate adjusting valve in FIG. 1 is changed, (a) is the defrosting heat quantity characteristic, and (b) is the internal heat exchange. The defrosting refrigerant temperature (state G) characteristic at the vessel outlet, and (c) the defrosting flow rate characteristic are shown.

As shown in FIG.5 (c), a defrost flow volume increases monotonously as the opening degree of the defrost flow control valve 14 is enlarged. When the defrost flow rate increases, the enthalpy change width ΔH _FG (difference of enthalpy between the state F and the state G) (see FIG. 4) of the refrigerant for defrosting in the internal heat exchanger 13 becomes small, and the internal heat exchanger 13 outlet The defrosting refrigerant temperature (state G) decreases monotonously as shown in FIG. When the defrosting flow rate is extremely small, the defrosting refrigerant temperature (state G) becomes a value close to the condensation temperature, but as the defrosting flow rate is increased, the defrosting refrigerant temperature (state G) gradually increases. It will fall and will eventually fall below 0 ° C.

The amount of defrosting heat is determined by the enthalpy difference ΔH _HA (see FIG. 4) between the state H and the state A and the defrosting flow rate. In the temperature region where the defrosting refrigerant temperature (state G) is sufficiently high, the larger the defrosting flow rate, the larger the defrosting heat amount. Therefore, when the defrosting flow rate increases as shown in FIG. It increases as shown in FIG. On the other hand, when the refrigerant temperature for defrosting (state G) approaches 0 ° C., the temperature difference from the frost becomes small, the amount of defrosting heat is reduced regardless of the defrosting flow rate, and the temperature at the cooler inlet (state H). When the temperature reaches 0 ° C., the defrosting heat becomes zero.

  Therefore, as shown to Fig.5 (a), there exists a defrost flow volume which becomes the maximum amount of defrost heat. In the first embodiment, the opening degree of the defrosting flow rate adjusting valve 14 is adjusted aiming at the flow rate at which the defrosting heat amount is maximized. By maximizing the amount of heat for defrosting, defrosting can be completed in a short time, and fluctuations in the internal temperature can be suppressed. The opening degree of the defrosting flow rate adjustment valve 14 is specifically adjusted so that the temperature difference between the state C and the state G does not fall below a predetermined value (for example, about 10 [K]). The opening is determined.

  As described above, according to the first embodiment, the refrigerant branch unit 3 is provided between the liquid main pipe 4 and the cooling units 2a and 2b, and the internal heat exchanger 13 provided in the refrigerant branch unit 3 and the defrosting are provided. A part of the high-pressure liquid refrigerant flowing in from the liquid main pipe 4 is used as a cooling refrigerant by the flow rate adjusting valve 14, and a defrosting refrigerant is generated from the remaining high-pressure liquid refrigerant using the cooling refrigerant. A refrigerant or a defrosting refrigerant is selectively supplied to each cooling unit 2a, 2b independently. With this configuration, it is possible to perform the cooling operation with other cooling units even while the defrosting operation is performed with a certain cooling unit, and the temperature change of the freezer can be reduced.

  In addition, since the refrigeration apparatus that can perform the defrosting operation while continuing the cooling operation can be configured only by providing the refrigerant branching unit 3 between the liquid main tube 4 and the cooling units 2a and 2b, In addition to the gas main pipe 5, there is no need to add a hot gas pipe dedicated to defrosting. Therefore, the time and cost required for installation work can be reduced.

  The refrigerant branch unit 3 is provided on the liquid main pipe 4 side, and the gas main pipe 5 side may be connected to the gas main pipe 5 via the gas branch pipes 50a and 50b. Therefore, unlike patent document 2, it is not necessary to install the on-off valve for flow path switching in the piping part through which the low-pressure refrigerant flows.

  Moreover, since it is the internal heating system by a refrigerant | coolant, the cooler 11 can be heated comparatively uniformly compared with the external heating system which sticks a heater to the cooler 11 and performs defrosting. Therefore, the amount of extra input heat that does not contribute to defrosting is reduced, and the defrosting time can be shortened.

  Further, the heat source unit 1 does not need to recognize whether the cooling unit 2 is performing the cooling operation or the defrosting operation, and the cooling operation and the defrosting operation can be switched only by the refrigerant branch unit 3. Therefore, by additionally installing the refrigerant branching unit 3 in the existing refrigeration apparatus, it can be renewed to a refrigeration apparatus capable of performing defrosting during the cooling operation.

  In the first embodiment, the refrigerant branching unit 3 in which all of the internal heat exchanger 13, the defrosting flow rate adjustment valve 14, the defrosting electromagnetic valves 15a and 15b and the check valves 16a and 16b are unitized is provided. Although shown, it does not necessarily need to be unitized, in short, what is necessary is just to set it as the structure provided with each element which comprises the refrigerant | coolant branch unit 3. FIG.

Embodiment 2. FIG.
Embodiment 2 relates to a measure for increasing the amount of defrost heat for shortening the defrosting time.

  FIG. 6 is a diagram illustrating an example of a refrigerant circuit of the refrigeration apparatus according to Embodiment 2 of the present invention. FIG. 6 shows an example in which the cooling unit 2a is cooled and the cooling unit 2b is defrosted. Moreover, the solid line arrow of FIG. 6 has shown the flow of the refrigerant | coolant of a cooling side cycle, and the dotted line arrow has shown the flow of the refrigerant | coolant of a defrost side cycle. In the second embodiment, the difference from the first embodiment will be mainly described. Further, the modification applied to the same part as in the first embodiment is also applied to the second embodiment.

  Hereinafter, with reference to FIG. 6, measures 1 to 4 for increasing the amount of defrost heat will be described in order.

(Measures for increasing defrosting heat 1)
A refrigerant heater 17 as a first auxiliary heating device is incorporated in the refrigerant branch unit 3, and the refrigerant for defrost that has flowed out of the internal heat exchanger 13 is further heated by the refrigerant heater 17. Thereby, a defrost calorie | heat amount can be enlarged.

  When the cooler 11 is heated, as described above, the heat is transmitted more uniformly when heated from the inside than when heated from the outside, and it is possible to suppress the remaining frost from melting. Therefore, if the heat quantity is the same, the cooler 11 can be heated more uniformly by directly heating the defrosting refrigerant than by installing the cooler heater 18 outside the cooler 11 and heating it. And the time required for defrosting can be further shortened.

(Measure 2 for increasing defrosting heat)
A cooler heater 18 as a second auxiliary heating device is fixed and provided in close contact with the heat transfer portion to which frost adheres in the cooler 11. Then, the cooler heater 18 is energized simultaneously with the start of the defrosting operation.

  Conventionally, a method of defrosting by heating the cooler 11 with the cooler heater 18 is generally known. In this method, as described above, it is necessary to heat to a considerably high temperature in order to eliminate unmelted frost far from the cooler heater 18, and problems such as an increase in cooling load and condensation may occur. On the other hand, in this Embodiment 2, when using the cooler heater 18, the refrigerant flows through the cooler 11. For this reason, when the refrigerant | coolant which distribute | circulated the cooler 11 passes the cooler heater 18 vicinity, it absorbs the heat | fever of the cooler heater 18 and the refrigerant | coolant which absorbed the heat | fever distribute | circulates to the low temperature part with which frost melt | dissolves. To do. Therefore, the heat of the cooler heater 18 is effectively spread over the entire cooler 11, and the entire cooler 11 can be heated uniformly. Therefore, the amount of defrosting heat can be increased without increasing the cooling load, and the defrosting operation can be completed in a shorter time.

(Measure 3 for increasing defrosting heat)
A blower fan 19 that blows air is provided in the condenser 7, and the heat dissipation capability of the condenser 7 is adjusted by controlling the rotational speed of the blower fan 19.

  Since the defrosting refrigerant temperature does not exceed the condensation temperature, for example, when the outside air temperature is low in winter and the condensation temperature is reduced to, for example, about 30 ° C, the defrosting refrigerant temperature is also lower than 30 ° C. . Thus, if the refrigerant temperature for defrosting is low, sufficient defrosting heat quantity cannot be obtained. Therefore, when the defrosting operation is performed with at least one unit, if the condensation temperature falls below a predetermined temperature (for example, 50 ° C.), the rotation speed of the blower fan 19 is reduced to suppress the condensation heat radiation, and the condensation temperature is reduced. By preventing the temperature from falling below a predetermined temperature, the amount of defrosting heat is increased.

(Measure 4 for increasing defrosting heat)
As shown in the cooling unit 2b of FIG. 6, a bypass circuit 12 is provided that bypasses the expansion valve 10 (when the liquid electromagnetic valve 9 is provided, bypasses both the liquid electromagnetic valve 9 and the expansion valve 10). The bypass circuit 12 is provided with a bypass valve 12a, and the bypass valve 12a is opened during the defrosting operation of the cooling unit 2b.

  The bypass circuit 12 is provided for the purpose of minimizing the pressure drop caused by passing through the liquid electromagnetic valve 9 and the expansion valve 10 during the defrosting operation. FIG. 6 shows a configuration in which the bypass circuit 12 is provided only on the cooling unit 2b side. However, a configuration in which the bypass circuit 12 is also provided on the cooling unit 2a side may be used.

  When defrosting the cooling unit 2b, the pressure drop from the state G to the state H can be reduced by opening the bypass valve 12a of the bypass circuit 12 and allowing the refrigerant to pass through the bypass circuit 12. For this reason, the heat exchange driving force in the internal heat exchanger 13, that is, the temperature difference between the state C and the state F is increased, and the amount of heat exchange in the internal heat exchanger 13 can be increased. Therefore, the temperature of the defrosting refrigerant flowing into the cooler 11 of the cooling unit 2b can be made higher than when the bypass circuit 12 is not provided, and the time required for defrosting can be shortened.

  Although FIG. 6 shows a configuration in which all the above-described increasing measures are taken, a configuration in which a part of them is combined may be used.

  Moreover, in each embodiment, although the case where two cooling units 2 were connected was demonstrated, the structure by which about 10 cooling units 2 were connected to one heat source unit like a food store showcase, for example Also, the present invention can be applied. In the case of such a configuration, when the amount of defrost heat required by the cooler 11 to be defrosted is much smaller than the cooling capacity of the other coolers 11, the refrigerant heater 17 or the cooler heater Even if an auxiliary heating device such as 18 is not installed, a sufficiently large amount of defrosting heat can be obtained, and a highly efficient defrosting operation can be performed with a simple configuration.

  The refrigeration apparatus may be an air conditioner including an indoor unit (cooling unit) and an outdoor unit (heat source unit). Of course, the present invention may be applied to a multi-system configuration including a plurality of outdoor units.

  The features of the present invention have been described above in each embodiment. For example, the configuration of refrigerant circuit elements such as a compressor, a heat exchanger, and a pressure reducing device is limited to the contents described in each embodiment. However, the present invention can be changed as appropriate within the scope of the present invention.

  1 Heat source unit, 2 (2a, 2b) Cooling unit, 3 Refrigerant branch unit, 3a Liquid main pipe side connection port, 3b Liquid branch pipe side connection port, 3c Liquid branch pipe side connection port, 4 Liquid main pipe, 5 Gas main pipe, 6 Compressor, 7 Condenser, 8 Liquid receiver, 9 Liquid solenoid valve, 10 Expansion valve, 11 Cooler, 12 Bypass circuit, 12a Bypass valve, 13 Internal heat exchanger, 14 Defrost flow control valve, 15a For defrost Solenoid valve, 15b solenoid valve for defrosting, 16a check valve, 16b check valve, 17 refrigerant heater, 18 cooler heater, 19 blower fan, 40a liquid branch pipe, 40b liquid branch pipe, 50a gas branch pipe, 50b Gas branch pipe, 60 control device, A cooling refrigerant circuit, B defrosting refrigerant circuit.

Claims (6)

A refrigerant circuit for cooling connected to the compressor, the condenser, the high-pressure side of the internal heat exchanger, the decompression device and the cooler so that the cooling refrigerant circulates;
A heat source unit having the compressor and the condenser of the cooling refrigerant circuit;
A plurality of cooling units connected to a gas main pipe extending from the heat source unit via a gas branch pipe, and having the pressure reducing device and the cooler;
A refrigerant branch connected to a liquid main pipe extending from the heat source unit and a liquid branch pipe extending from each of the plurality of cooling units;
The refrigerant branch is
The internal heat exchanger;
Branching a part of the liquid refrigerant before flowing out from the condenser and flowing into the high-pressure side of the internal heat exchanger, flowing into the low-pressure side of the internal heat exchanger via the defrosting flow control device, A refrigerant circuit for defrosting that generates heat by defrosting and heat-exchanging with a cooling refrigerant flowing out of the condenser and flowing into the high-pressure side of the internal heat exchanger;
The cooling refrigerant after passing through the high pressure side of the internal heat exchanger of the cooling refrigerant circuit or the defrosting refrigerant generated by the defrosting refrigerant circuit is selectively supplied to each of the plurality of cooling units. A refrigeration apparatus comprising a refrigerant flow switching device.   The opening degree of the defrosting flow rate adjusting device is adjusted so that the temperature difference between the outlet temperature of the condenser of the cooling refrigerant circuit and the outlet temperature of the internal heat exchanger of the defrosting refrigerant circuit becomes a predetermined value. The refrigeration apparatus according to claim 1.   The refrigeration apparatus according to claim 1 or 2, further comprising a first auxiliary heating device that heats the defrosting refrigerant that has flowed out of the internal heat exchanger.   4. The second auxiliary heating device is fixedly provided on at least one of the plurality of coolers so as to be in close contact with a heat transfer portion to which frost adheres. 5. The refrigeration apparatus according to one item.   When the defrosting operation is performed with at least one of the plurality of cooling units, the rotation speed of the blower fan is provided so that the condensation temperature does not fall below a predetermined temperature. The refrigeration apparatus according to any one of claims 1 to 4, wherein the heat dissipation capacity of the condenser is adjusted by control.   Among the plurality of cooling units, at least one of the predetermined cooling units has a bypass circuit that bypasses the pressure reducing device of the self, and the bypass valve of the bypass circuit of the self in the defrosting operation. The refrigeration apparatus according to any one of claims 1 to 5, wherein the refrigeration apparatus is opened.

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