JP2014134316A - Refrigeration unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigeration unit which utilizes condensed exhaust heat to enable a drain pan to be heated at given timing during any of cooling operation and hot gas defrosting operation thereby achieving good efficiency and shortening the defrosting time.SOLUTION: A refrigeration unit 100 includes: a drain pan 22 disposed below a cooler 20; a drain pan heating pipeline 25 attached to the drain pan 22; a hot gas bypass pipe 15 which is branched from the downstream side of a two-stage compressor 5 and is united to the upstream side of the cooler 20; a second branch pipeline 3b which is branched from the upstream side of a main expansion valve 18 and is united to the upstream side of the cooler 20; and a heat recovery device 23 which heats a refrigerant flowing between a heat recovery expansion valve 24 and the drain pan heating pipeline 25.

Description

  The present invention relates to a refrigeration apparatus that cools and maintains, for example, the inside of a refrigerated warehouse at a predetermined temperature, and particularly relates to a refrigeration apparatus that includes a drain pan heater.

  Conventionally, for example, there are refrigeration apparatuses that cool and maintain the inside of a refrigerated warehouse at a predetermined temperature. In such a refrigeration apparatus, in general, frost grows in the cooler during the cooling operation and hinders heat transfer, so that the defrosting operation is performed at a predetermined cycle. In general, it is assumed that the drain water generated at this time is frozen again on the drain pan, and the drain pan is also provided with heating means such as an electric heater.

  In the method of heating the drain pan with an electric heater, a large amount of electric input is required. Further, a large amount of drain water evaporates at a location where the temperature is locally high, and recondensation occurs on the inner wall surface. Because of these problems, there has been proposed a method of performing drain pan heating by using a refrigerant pipe as a drain pan heater and circulating a high-temperature refrigerant therethrough.

  For example, a system is known in which a drain pan heater (drain pan heater 20) is interposed in a bypass pipe when performing a defrosting operation using hot gas, thereby heating the drain pan with a hot gas bypass refrigerant (for example, Patent Documents). 1).

  In addition, the drain pan heater (drain pan heater 17) is used as a pipe through which the high-pressure liquid refrigerant flows before decompressing, and the liquid refrigerant is cooled to near the drain pan ambient temperature by an economizer. There is known a method for suppressing heat dissipation (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 9-318229 (page 3, FIG. 1, etc.) JP 2011-137602 A (page 7-11, FIG. 2 etc.)

  However, in the refrigeration apparatus shown in Patent Document 1, the drain pan can be heated only during the hot gas defrosting operation. Therefore, immediately after the start of defrosting, drain water may freeze on the drain pan, resulting in poor drainage. In addition, the condensed exhaust heat during the cooling operation cannot be used as a heat source for the drain pan heating, and both the drain pan and the cooler are heated by the electric input of the compressor.

  Further, in the refrigeration apparatus as shown in Patent Document 2, the liquid refrigerant circulates through the drain pan heater pipe during the cooling operation, and the gas refrigerant circulates during the defrosting operation. In addition, since the high-temperature discharged gas refrigerant flows through the drain pan heater during the defrosting operation, the amount of drain water evaporated increases. Furthermore, since the liquid refrigerant is cooled only to the intermediate pressure refrigerant temperature, the heat radiation into the warehouse cannot be suppressed under the condition that the temperature in the refrigerated warehouse to be cooled is sufficiently lower than the intermediate pressure refrigerant temperature. .

  An object of the present invention is to solve the above-described problems, and in any operation state during the cooling operation and the hot gas defrosting operation, the condensed exhaust heat is used at an arbitrary timing. An object of the present invention is to obtain a refrigeration apparatus that can efficiently heat the drain pan and shorten the defrosting time.

  A refrigeration apparatus according to the present invention includes a compressor, a condenser, a first flow path opening / closing means, a first expansion means, a refrigerant circuit connected to an evaporator, a drain pan disposed below the evaporator, The first drain pan heating means which is a refrigerant pipe attached to the drain pan, and the evaporator branches from the downstream side of the compressor and passes through the second flow path opening / closing means and the first drain pan heating means. The first bypass circuit that joins upstream of the first branch circuit and the first expansion means branch from upstream of the first expansion means, and then the second expansion means and the first drain pan heating means flow in this order, and then join upstream of the evaporator. And a refrigerant heating means for heating the refrigerant flowing between the second expansion means and the first drain pan heating means.

  The refrigeration apparatus according to the present invention can distribute the hot gas refrigerant to the drain pan heating means at an arbitrary timing even when the cooling operation is performed. Therefore, according to the refrigeration apparatus according to the present invention, the drain pan is heated at the timing immediately before the start of the defrosting, whereby the increase in the load in the warehouse can be minimized, and the drain pan is sufficiently heated at the start of the defrosting. Therefore, it is possible to suppress the occurrence of problems due to drain overflow and residual frost. Further, since the drain pan heating heat source during the cooling operation is a part of the condensed exhaust heat, it does not require an input for drain pan heating and is energy saving.

It is a schematic block diagram which shows an example of the refrigerant circuit structure of the freezing apparatus which concerns on Embodiment 1 of this invention. It is a refrigerant circuit block diagram which shows the valve | bulb operation | movement and refrigerant | coolant flow direction at the time of the normal cooling operation mode of the freezing apparatus which concerns on Embodiment 1 of this invention. It is a pressure-enthalpy diagram which shows the refrigerating-cycle operation | movement at the time of the normal cooling operation mode of the freezing apparatus which concerns on Embodiment 1 of this invention. It is a refrigerant circuit block diagram which shows the valve operation at the time of the defrost preparation operation mode of the freezing apparatus which concerns on Embodiment 1 of this invention, and a refrigerant | coolant flow direction. It is a pressure-enthalpy diagram which shows the refrigerating cycle operation at the time of the defrost preparation operation mode of the freezing apparatus which concerns on Embodiment 1 of this invention. It is a refrigerant circuit block diagram which shows the valve | bulb operation | movement of the hot gas defrost operation mode of the refrigeration apparatus which concerns on Embodiment 1 of this invention, and a refrigerant | coolant flow direction. It is a pressure-enthalpy diagram which shows the refrigerating cycle operation | movement at the time of the hot gas defrost operation mode of the refrigerating apparatus which concerns on Embodiment 1 of this invention. It is a schematic block diagram which shows an example of the refrigerant circuit structure of the freezing apparatus which concerns on Embodiment 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one. Further, in the following drawings including FIG. 1, the same reference numerals denote the same or equivalent parts, and this is common throughout the entire specification. Furthermore, the forms of the constituent elements shown in the entire specification are merely examples, and are not limited to these descriptions.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram illustrating an example of a refrigerant circuit configuration of a refrigeration apparatus 100 according to Embodiment 1 of the present invention. Based on FIG. 1, the structure of the freezing apparatus 100 is demonstrated. This refrigeration apparatus 100 cools the inside of a refrigerated warehouse by circulating a refrigerant.

<Circuit configuration>
In FIG. 1, a refrigeration apparatus 100 has a heat source unit 1 placed outdoors and a cooling unit 2 placed in a refrigerated warehouse. The heat source unit 1 and the cooling unit 2 are connected by a liquid pipe 3 and a gas pipe 4 to form a refrigeration cycle. In addition, although the refrigerant | coolant enclosed in the refrigerant circuit of the freezing apparatus 100 is not specifically limited, In the following description, the case where R410A is used is made into the example.

  The heat source unit 1 has a low-stage compressor 6 and a high-stage compressor 7, and a two-stage compressor 5, an air-cooled condenser 8, which includes an intermediate pressure port 5a through which refrigerant can be injected into the intermediate pressure part during compression, The liquid receiver 10, the economizer 11, and the liquid electromagnetic valve 29 are arranged in series. A refrigerant is injected into the intermediate pressure port 5 a of the two-stage compressor 5 through the injection pipe 14. The air-cooled condenser 8 is provided with an outdoor fan 9 that adjusts the amount of heat exchange between the outdoor air and the refrigerant. Further, the heat source unit 1 is provided with an injection pipe 14 that branches from the economizer 11 and the liquid electromagnetic valve 29 and is connected to the intermediate pressure port 5 a of the two-stage compressor 5.

  The injection pipe 14 includes a first branch injection pipe 14 a that guides the refrigerant to the low pressure side of the economizer 11 and a second branch injection pipe 14 b that bypasses the economizer 11. The first branch injection pipe 14 a and the second branch injection pipe 14 b are connected on the downstream side of the economizer 11.

  On the low pressure side of the economizer 11, a bypass refrigerant (refrigerant flowing through the first branch injection pipe 14 a) branched from the liquid pipe 3 through which the high-pressure liquid refrigerant flows flows through the economizer expansion valve 12. The economizer expansion valve 12 is connected to the first branch injection pipe 14 a on the upstream side of the economizer 11. A liquid bypass expansion valve 13 for bypassing the high-pressure liquid refrigerant directly to the intermediate pressure port 5a is installed in the second branch injection pipe 14b.

  Further, in the heat source unit 1, a hot gas bypass pipe 15 that connects the outlet side of the two-stage compressor 5 and the downstream side of the flow of the high-pressure refrigerant in the economizer 11 is provided. That is, a part of the refrigerant discharged from the two-stage compressor 5 can be flowed to the hot gas bypass pipe 15 and can be merged downstream of the economizer 11 that is the high-pressure refrigerant outlet via the heat source side hot gas valve 16. It has become.

  In the cooling unit 2, a liquid electromagnetic valve 17, a heat recovery unit 23, a main expansion valve 18, a distributor 19, and a cooler 20 are arranged in series. The cooler 20 is provided with an internal fan 21 that adjusts the amount of heat exchange between the air in the refrigerated warehouse and the refrigerant. A drain pan 22 is provided at the lower part of the cooler 20. The drain pan 22 receives drain water falling from the cooler 20 during the defrosting operation and drains it outside the warehouse. A drain pan heating pipe 25 and a drain pan heater 27 are attached to the lower surface of the drain pan 22. The drain pan heater 27 is connected to a heater power supply 28 and is supplied with power.

  Further, the cooling unit 2 is provided with a first branch pipe 3 a that branches the liquid pipe 3 on the upstream side of the high-pressure refrigerant flow of the liquid electromagnetic valve 17 and connects to the drain pan heating pipe 25. An internal hot gas valve 26 is installed in the first branch pipe 3a. The downstream side of the drain pan heating pipe 25 is connected between the main expansion valve 18 and the distributor 19.

  Further, in the cooling unit 2, the liquid pipe 3 is branched between the heat recovery unit 23 and the main expansion valve 18, and is connected to the downstream side of the internal hot gas valve 26 in the first branch pipe 3a. A pipe 3b is provided. A heat recovery expansion valve 24 is installed in the second branch pipe 3b.

  On the low pressure side of the heat recovery unit 23, the refrigerant branched on the upstream side of the main expansion valve 18 (refrigerant flowing through the second branch pipe 3 b) flows through the heat recovery expansion valve 24. . The refrigerant flowing through the second branch pipe 3 b joins the first branch pipe 3 a upstream of the drain pan heating pipe 25, flows through the drain pan heating pipe 25, and joins downstream of the main expansion valve 18. . Further, during the defrosting operation in which hot gas from the liquid pipe 3 is sent to the first branch pipe 3a, the drain pan heating pipe 25 and the cooling are not passed through the expansion valves (the main expansion valve 18 and the heat recovery expansion valve 24). The refrigerant is circulated through the vessel 20.

The “two-stage compressor 5” corresponds to the “compressor” of the present invention.
The “air-cooled condenser 8” corresponds to the “condenser” of the present invention.
The “heat source side hot gas valve 16” corresponds to the “second flow path opening / closing means” of the present invention.
The “hot gas bypass pipe 15” and the “first branch pipe 3a” correspond to the “first bypass circuit” of the present invention.
The “injection tube 14” corresponds to the “third bypass circuit” of the present invention.
“Economizer expansion valve 12” corresponds to “third expansion means” of the present invention.
The “economizer 11” corresponds to the “second internal heat exchanger” of the present invention.

The “liquid electromagnetic valve 17” corresponds to the “first flow path opening / closing means” of the present invention.
The “main expansion valve 18” corresponds to the “first expansion means” of the present invention.
The “cooler 20” corresponds to the “evaporator” of the present invention.
The “drain pan heating pipe 25” corresponds to the “first drain pan heating means” of the present invention.
The “heat recovery expansion valve 24” corresponds to the “second expansion means” of the present invention.
The “second branch pipe 3b” corresponds to the “second bypass circuit” of the present invention.
The “heat recovery unit 23” corresponds to the “refrigerant heating means” and the “first internal heat exchanger” of the present invention.
The “drain pan heater 27” corresponds to the “second drain pan heater” of the present invention.

<Driving action>
(Normal cooling operation mode)
FIG. 2 is a refrigerant circuit configuration diagram showing valve operation and refrigerant flow direction when the refrigeration apparatus 100 is in the normal cooling operation mode. FIG. 3 is a pressure-enthalpy diagram showing the refrigeration cycle operation of the refrigeration apparatus 100 in the normal cooling operation mode. Based on FIG.2 and FIG.3, the refrigerating cycle operation | movement at the time of the normal cooling operation of the freezing apparatus 100 is demonstrated. FIG. 2 is a schematic configuration diagram of FIG. 1 in which arrows indicating valve operation and refrigerant flow are additionally described. Note that FIG. 2 shows that the blacked-out valve is closed. The alphabet shown in FIG. 2 corresponds to the alphabet shown in FIG.

  In the normal cooling operation mode, the high-temperature and high-pressure refrigerant (state A) discharged from the two-stage compressor 5 dissipates heat to the outside air in the air-cooled condenser 8 and condenses to become a high-pressure liquid refrigerant (state B). This high-pressure liquid refrigerant flows through the receiver 10 to the economizer 11 and is cooled by the intermediate-pressure refrigerant (state F) decompressed by the economizer expansion valve 12 to increase the degree of supercooling (state). C).

  The liquid refrigerant having increased the degree of supercooling (state C) flows through the liquid pipe 3 and flows into the cooling unit 2, passes through the liquid electromagnetic valve 17 and the main expansion valve 18, and is depressurized. It becomes a low-pressure two-phase refrigerant (state D) of about 30 ° C. and flows into the cooler 20. This low-pressure two-phase refrigerant (state D) is heated and evaporated by air at about −20 ° C. in the refrigerated warehouse sent by the internal fan 21 to become a low-pressure gas refrigerant (state E). The low-pressure gas refrigerant returns to the heat source unit 1 again via the gas pipe 4 and is sucked into the two-stage compressor 5 again.

  On the other hand, in the economizer 11 of the heat source unit 1, the refrigerant (state F) that flows through the first injection pipe 4 a and is decompressed to the intermediate pressure by the economizer expansion valve 12 flows into the economizer 11 again and enters the high-pressure liquid refrigerant (state B). ) And heat exchange. Here, it is conceivable that the refrigerant flowing into the intermediate pressure port 5a of the two-stage compressor 5 has a high degree of dryness and cannot sufficiently cool the discharge gas temperature. Therefore, the economizer expansion valve 12 adjusts the flow rate so that the discharge gas temperature of the two-stage compressor 5 does not become abnormally high.

  As a result, the refrigerant (state G) injected into the intermediate pressure port 5a of the two-stage compressor 5 is a combination of the gas refrigerant evaporated by the economizer 11 and the liquid refrigerant flowing through the liquid bypass expansion valve 13. . This intermediate pressure two-phase refrigerant (state G) and the refrigerant that has been sucked into the two-stage compressor 5 as the low-pressure gas refrigerant (state E) and increased to the intermediate pressure are merged inside the two-stage compressor 5, H.

  Since the air in the refrigerated warehouse is cooled and dehumidified by the cooler 20 having a surface temperature of about −30 ° C., the condensed moisture freezes and becomes frost and is stacked on the surface of the cooler 20. This frost grows with the passage of time, and eventually reduces the ventilation rate of the cooler 20. Therefore, defrosting operation is required at regular time intervals.

(Defrost preparation operation mode (drain pan heating operation mode))
FIG. 4 is a refrigerant circuit configuration diagram showing the valve operation and the refrigerant flow direction when the refrigeration apparatus 100 is in the defrost preparation operation mode. FIG. 5 is a pressure-enthalpy diagram showing the refrigeration cycle operation of the refrigeration apparatus 100 in the defrost preparation operation mode. Based on FIG.4 and FIG.5, operation | movement of the refrigerating cycle at the time of the defrost preparation operation of the freezing apparatus 100 is demonstrated. FIG. 4 is a schematic configuration diagram of FIG. 1 in which arrows indicating valve operation and refrigerant flow are additionally described. Note that FIG. 4 shows that the blacked-out valve is closed. The alphabet shown in FIG. 4 corresponds to the alphabet shown in FIG.

  In the refrigeration apparatus 100, frost grows in the cooler 20, for example, the cooling unit 2 performs a cooling operation continuously for a predetermined time, or the temperature difference between the internal air temperature and the refrigerant evaporation temperature spreads beyond a predetermined value. When it is determined, first, the defrost preparation operation mode is entered. The basic operation of the defrost preparation operation is the same as the normal cooling operation mode described above, but heat is not exchanged by the economizer 11 and heat is recovered from the high-temperature and high-pressure liquid refrigerant by the heat recovery unit 23 in the cooling unit 2. However, it is different from the normal cooling operation in that the drain pan 22 is heated by the heat.

  Inside the heat source unit 1, the refrigerant flow rate injected into the intermediate pressure port 5a is adjusted only by the liquid bypass expansion valve 13 that does not pass through the economizer 11, and the economizer expansion valve 12 is fully closed. Thereby, the high-pressure liquid refrigerant (state B) that has passed through the air-cooled condenser 8 flows into the cooling unit 2 without being cooled by the economizer 11.

  In the cooling unit 2, the liquid refrigerant (state C) whose pressure has been slightly lowered from the state B is partially branched after passing through the heat recovery device 23 and is reduced to a low pressure by the heat recovery expansion valve 24. Heat exchange with (State J) results in a liquid refrigerant (State I) with an increased degree of supercooling. On the other hand, the branched low-pressure refrigerant (state J) is heated by the high-temperature liquid refrigerant in the heat recovery unit 23 to become a high-temperature low-pressure gas refrigerant (state K), and the drain pan 22 is circulated through the drain pan heating pipe 25 to raise the temperature of the drain pan 22. At the same time, the refrigerant (state L) is slightly reduced in temperature and merged with the mainstream refrigerant. Subsequent operations are the same as those in the normal cooling operation mode.

  By operating in this way, the drain pan 22 can be heated to about 30 ° C. before starting the defrosting operation, and even if the drain water falls, it can be prevented from being frozen again. In addition, since the heat source at this time is a part of the condensed exhaust heat discharged to the outdoor air by the heat source unit 1, no new electric input is required, and highly efficient heating can be performed. Further, the low-pressure refrigerant branched to heat the drain pan 22 collects the cold heat of the drain pan 22 and contributes to an increase in cooling capacity.

(Hot gas defrosting operation mode)
FIG. 6 is a refrigerant circuit configuration diagram showing the valve operation and the refrigerant flow direction in the hot gas defrosting operation mode of the refrigeration apparatus 100. FIG. 7 is a pressure-enthalpy diagram showing the refrigeration cycle operation in the hot gas defrosting operation mode of the refrigeration apparatus 100. Based on FIG.6 and FIG.7, operation | movement of the refrigerating cycle of the hot gas defrosting operation mode of a freezing apparatus is demonstrated. Note that FIG. 6 shows that the blacked-out valve is closed. Further, the alphabet shown in FIG. 6 corresponds to the alphabet shown in FIG.

  In the hot gas defrosting operation mode, the liquid electromagnetic valve 29 in the heat source unit 1 is closed and the heat source side hot gas valve 16 is opened. On the cooling unit 2 side, the internal fan 21 is stopped, the liquid electromagnetic valve 17 is closed, and the internal hot gas valve 26 is opened.

  As a result, most of the high-temperature and high-pressure discharged gas refrigerant (state A) flowing out of the two-stage compressor 5 is directly carried to the cooling unit 2 and used for defrosting of the cooler 20. The part returns to the intermediate pressure port 5a of the two-stage compressor 5 via the air-cooled condenser 8, the liquid receiver 10, and the liquid bypass expansion valve 13. The flow rate of the refrigerant that is slightly branched and circulated in the heat source unit 1 is adjusted by the liquid bypass expansion valve 13 so that the discharge gas temperature of the two-stage compressor 5 is properly maintained.

  The hot gas refrigerant flowing to the cooling unit 2 side is mainly depressurized by the heat source side hot gas valve 16 on the heat source unit 1 side and reaches a drain pan heating pipe 25 as a low-pressure gas refrigerant (state K) of about 30 ° C. To do. At this time, since the drain pan 22 is sufficiently heated in the defrost preparation operation mode, the hot gas refrigerant flowing through the drain pan heating pipe 25 flows into the cooler 20 with almost no change in state.

  The hot gas refrigerant that has flowed into the cooler 20 decreases its temperature while melting the frost attached to the cooler 20, becomes a gas refrigerant (state E) of approximately 0 ° C., then flows out of the cooler 20, and gas piping 4 is again sucked into the two-stage compressor 5.

  In the refrigeration apparatus 100, a drain pan heater 27 is attached to the drain pan 22 as an auxiliary heat source for increasing the amount of defrost heat. The drain pan heater 27 heats the drain pan 22 in the hot gas defrosting operation mode. The amount of heat of the heater at this time is transmitted to the hot gas refrigerant flowing through the drain pan heating pipe 25 and is used as the amount of defrosting heat of the cooler 20.

  Since the drain pan heater 27, which is an auxiliary heat source for defrosting, heats the cooler 20 via the hot gas refrigerant, the local high temperature portion can be reduced as compared with the case where the electric heater is directly heated. In addition, problems such as condensation on the inner wall surface due to evaporation of drain water can be avoided.

  In the first embodiment, the case of a two-stage compressor in which the compression process is divided into a low stage and a high stage has been described, but the return refrigerant from the economizer 11 is used even in the case of a normal compressor without an intermediate pressure port. By using the suction side of the two-stage compressor 5, the same effect as the refrigeration apparatus 100 can be obtained.

  As described above, according to the refrigeration apparatus 100 according to the first embodiment, the hot gas refrigerant can be circulated through the drain pan heating pipe 25 even in the cooling operation state. The generated drain water is not frozen in the drain pan 22 and the reliability of the defrosting operation is improved. Further, since the drain pan heating heat source during the cooling operation is a part of the condensed exhaust heat, it does not require an input for drain pan heating and is energy saving.

  In addition, since the drain pan heating medium is a hot gas refrigerant, it does not overheat unlike an electric heater, and an increase in the load due to evaporation of drain water and contamination due to dew condensation in the warehouse are unlikely to occur.

  Even when the electric heater is defrosted as an auxiliary heat source, by arranging the electric heater so as to heat the drain pan heating pipe 25, abnormal overheating due to heat radiation unevenness of the electric heater can be suppressed, and drain water evaporation It is possible to make it difficult for contamination due to increased load in the cabinet and condensation in the cabinet.

  In addition, since the refrigerant flowing through the drain pan heating pipe 25 is always a low-pressure gas refrigerant, there is little fluctuation in the required refrigerant amount with respect to the normal operation state, and the liquid pan does not accumulate in the drain pan heating pipe 25 and is enclosed. The amount of refrigerant does not increase and the liquid receiver for storing surplus refrigerant does not become large, and the equipment cost is reduced.

  Moreover, since the discharge gas temperature of the two-stage compressor 5 is adjusted by two systems of the economizer circuit and the liquid bypass circuit, a sufficient supercooling degree is imparted to the liquid refrigerant during the normal cooling operation so that the cooling is highly efficient. You can drive. In addition, in the defrost preparation operation mode, a hot gas refrigerant having a high temperature can be generated without using an economizer, and the drain pan heating time can be shortened.

Embodiment 2. FIG.
FIG. 8 is a schematic configuration diagram showing an example of a refrigerant circuit configuration of the refrigeration apparatus 100A according to Embodiment 2 of the present invention. Based on FIG. 8, the refrigeration apparatus 100A will be described. Similar to the refrigeration apparatus 100 according to Embodiment 1, the refrigeration apparatus 100A cools the inside of the refrigerated warehouse by circulating the refrigerant. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and differences from the first embodiment will be mainly described.

  The refrigeration apparatus 100A shown in FIG. 8 has a refrigerant circuit configured on the assumption that a plurality of cooling units 2 (two in FIG. 8) are connected. Moreover, in FIG. 8, the operation | movement at the time of a hot gas defrost operation is shown. Note that FIG. 8 shows that the blacked-out valve is closed. That is, the cooling unit 2 shown on the upper side of FIG. 8 performs the defrosting operation, and the cooling unit 2 shown on the lower side of FIG. 8 does not execute the defrosting operation.

  In the refrigerating apparatus 100 </ b> A, the liquid electromagnetic valve 29 is unnecessary, and a hot gas pipe 30 that is a third connection pipe that connects the heat source unit 1 and the cooling unit 2 is additionally installed. A hot gas refrigerant flows through the hot gas pipe 30. The hot gas pipe 30 is connected to the hot gas bypass pipe 15 and connected to the internal hot gas valve 26. That is, the hot gas pipe 30 corresponds to the “first branch pipe 3a” of the refrigeration apparatus 100 according to the first embodiment.

  The same high pressure liquid refrigerant as in the normal cooling operation mode is circulated in the liquid pipe 3. Therefore, in the refrigeration apparatus 100A, the liquid refrigerant for the cooling operation can be supplied to the cooling unit 2 not performing the defrosting operation (for example, the cooling unit 2 shown on the lower side of FIG. 8). With such a configuration, even when a plurality of cooling units 2 are connected, each of them can independently perform a hot gas defrosting operation.

  The “hot gas bypass pipe 15” and the “hot gas pipe 30” correspond to the “first bypass circuit” of the present invention.

  As described above, according to the refrigeration apparatus 100A according to the second embodiment, even if the cooling unit 2 is added, the drain pan heating pipe can be used in the cooling operation as in the refrigeration apparatus 100. Since the hot gas refrigerant can be circulated through the drain 25, the drain water generated during the defrosting is not frozen in the drain pan 22, and the reliability of the defrosting operation is improved. Further, since the drain pan heating heat source during the cooling operation is a part of the condensed exhaust heat, it does not require an input for drain pan heating and is energy saving.

  In addition, since the drain pan heating medium is a hot gas refrigerant, it does not overheat unlike an electric heater, and an increase in the load due to evaporation of drain water and contamination due to dew condensation in the warehouse are unlikely to occur.

  Even when the electric heater is defrosted as an auxiliary heat source, by arranging the electric heater so as to heat the drain pan heating pipe 25, abnormal overheating due to heat radiation unevenness of the electric heater can be suppressed, and drain water evaporation It is possible to make it difficult for contamination due to increased load in the cabinet and condensation in the cabinet.

  In addition, since the refrigerant flowing through the drain pan heating pipe 25 is always a low-pressure gas refrigerant, there is little fluctuation in the required refrigerant amount with respect to the normal operation state, and the liquid pan does not accumulate in the drain pan heating pipe 25 and is enclosed. The amount of refrigerant does not increase and the liquid receiver for storing surplus refrigerant does not become large, and the equipment cost is reduced.

  Moreover, since the discharge gas temperature of the two-stage compressor 5 is adjusted by two systems of the economizer circuit and the liquid bypass circuit, a sufficient supercooling degree is imparted to the liquid refrigerant during the normal cooling operation so that the cooling is highly efficient. You can drive. In addition, in the defrost preparation operation mode, a hot gas refrigerant having a high temperature can be generated without using an economizer, and the drain pan heating time can be shortened.

  1 heat source unit, 2 cooling unit, 3 liquid piping, 4 gas piping, 4a first injection tube, 5 two-stage compressor, 5a intermediate pressure port, 6 low-stage compression section, 7 high-stage compression section, 8 air-cooled condenser, 9 outdoor blower, 10 liquid receiver, 11 economizer, 12 economizer expansion valve, 13 liquid bypass expansion valve, 14 injection pipe, 15 hot gas bypass pipe, 16 heat source side hot gas valve, 17 liquid electromagnetic valve, 18 main expansion valve, 19 Distributor, 20 Cooler, 21 Blower, 22 Drain pan, 23 Heat recovery unit, 24 Heat recovery expansion valve, 25 Drain pan heating piping, 26 Inside hot gas valve, 27 Drain pan heating heater, 28 Heater power supply, 29 liquid Solenoid valve, 30 hot gas piping, 100 refrigeration equipment, 100A refrigeration equipment.

Claims (6)

A refrigerant circuit connected to a compressor, a condenser, a first flow path opening / closing means, a first expansion means, and an evaporator;
A drain pan disposed below the evaporator;
A first drain pan heating means which is a refrigerant pipe attached to the drain pan;
A first bypass circuit branched from the downstream of the compressor, and joined to the upstream of the evaporator via second flow path opening / closing means and the first drain pan heating means;
A second bypass circuit that branches from the upstream side of the first expansion means, flows in the order of the second expansion means, and the first drain pan heating means, and then merges upstream of the evaporator;
Refrigerant heating means for heating the refrigerant flowing between the second expansion means and the first drain pan heating means;
A refrigeration apparatus comprising: The refrigerant heating means includes
A refrigerant flowing through the condenser and flowing between the first flow path opening and closing means and the first expansion means;
A refrigerant flowing between the second expansion means and the first drain pan heating means;
The refrigeration apparatus according to claim 1, wherein the refrigeration apparatus is an internal heat exchanger that exchanges heat. A third bypass circuit branched from the downstream of the condenser and joined to the suction or intermediate pressure of the compressor via a third expansion means;
A second internal heat exchanger for exchanging heat between the refrigerant flowing through the third bypass circuit and the refrigerant flowing out of the condenser;
The refrigeration apparatus according to claim 1 or 2, further comprising: A normal cooling operation mode for closing the second flow path opening / closing means and closing the second expansion means;
A drain pan heating operation mode in which the second expansion means is opened and the refrigerant flows through the second bypass circuit, and the refrigerant heating means is operated to heat the drain pan;
A hot gas defrosting operation mode in which the first flow path opening / closing means is closed and the second flow path opening / closing means is opened to allow the refrigerant to flow through the first bypass circuit;
The refrigeration apparatus according to any one of claims 1 to 3, wherein the drain pan heating operation mode is executed between the normal cooling operation mode and the hot gas defrosting operation mode. Comprising a second drain pan heating means by an external heat source;
The refrigeration apparatus according to claim 4, wherein the second drain pan heating means is operated during the hot gas defrosting operation mode. The first bypass circuit includes:
The downstream of the compressor and the upstream of the first flow path opening and closing means are connected to join the upstream of the evaporator,
Or
The downstream of the said compressor and the downstream of the said refrigerant | coolant heating means in the said 2nd bypass circuit are connected, It has joined the upstream of the said evaporator. The any one of Claims 1-5 characterized by the above-mentioned. The refrigeration apparatus described in 1.

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