JP2024089045A - Refrigerating device and defrosting method for load cooler - Google Patents

Abstract

To provide a refrigerating device and a defrosting method for a load cooler that can improve defrosting performance while securing reliability by reducing an increase in size of a structure of the load cooler and complexity of defrosting control.SOLUTION: A refrigerating device comprises a defrosting circuit 72 for defrosting a load cooler. The defrosting circuit 72 comprises a heat exchanger 200 for exchanging heat between a cooling refrigerant of a cooling circuit 70 and a defrosting heat medium of the defrosting circuit 72. The defrosting circuit 72 for circulating heat via the heat exchanger 200 between the load cooler 12 and a heat accumulator 16 is provided. The defrosting circuit 72 comprises a heat absorbing part 74 for absorbing heat from a heat accumulating agent via the defrosting heat medium in the heat accumulator 16, and a defrosting part 76 for dissipating heat by using the cooling refrigerant of the cooling circuit 70 in the load cooler 12. The cooling circuit 70 comprises a heat dissipating part for dissipating heat into the heat accumulating agent in the heat accumulator 16, and a cooling part for cooling a load fluid in the load cooler 12.SELECTED DRAWING: Figure 1

Description

The present invention relates to a defrosting method for a refrigeration device and a load cooler, and more specifically to a defrosting method for a refrigeration device and a load cooler that can improve defrosting performance while ensuring reliability by reducing the size of the load cooler structure and the complexity of the defrosting control.

Conventionally, in order to defrost a cooled load cooler, the applicant of the present invention has proposed a defrosting method for a refrigeration system or a load cooler that uses exhaust heat during cooling operation to defrost the load cooler from the viewpoint of energy saving, for example in Patent Documents 1 and 2. This method uses a loop thermosiphon type defrosting technology.
Specifically, the refrigeration device proposed in Patent Document 1 is a refrigeration device in which a load cooler, a compressor, a heat accumulator, a condenser, a receiver, and an expansion valve are connected in this order by refrigerant piping to form a cooling circuit, the heat accumulator is installed at a level below the heat exchanger, and a first bypass pipe connects the refrigerant piping that forms an inflow portion to the load cooler or the refrigerant piping that forms an outflow portion from the load cooler to the refrigerant piping that forms an inflow portion to the heat accumulator or the refrigerant piping that forms an outflow portion from the heat accumulator, and a second bypass pipe connects the other refrigerant piping to the one of the refrigerant piping that forms the inflow portion to the load cooler or the refrigerant piping that forms the outflow portion from the load cooler, and the other refrigerant piping to the one of the refrigerant piping that forms the inflow portion to the heat accumulator or the refrigerant piping that forms the outflow portion from the heat accumulator. and a bypass pipe, by which heat stored in the heat accumulator during the cooling operation of the load cooler is utilized to send refrigerant gas from the heat accumulator to the load cooler via the first bypass piping, while returning refrigerant liquid produced as a result of defrosting the load cooler from the load cooler to the heat accumulator via the second bypass piping, thereby forming a loop-type thermosiphon.

According to the refrigeration system having the above-mentioned configuration, during cooling operation, the refrigerant gas evaporated by cooling the load cooler is compressed by the compressor and dissipates heat in the heat accumulator, thereby storing heat, and the refrigerant gas or refrigerant liquid is condensed or supercooled in the condenser, and the refrigerant liquid is received in the receiver and passes through the expansion valve to form a cooling circuit that cools the load cooler again, thereby cooling the load cooler.
On the other hand, during the defrost operation of the load cooler, by utilizing the heat stored in the heat accumulator during the cooling operation of the load cooler, refrigerant gas is sent from the heat accumulator to the load cooler via the first bypass piping, and refrigerant liquid resulting from defrosting the load cooler is returned from the load cooler to the heat accumulator via the second bypass piping, thereby forming a loop-type thermosiphon by natural circulation between the heat accumulator on the hot side located below and the load cooler on the cold side located above, which makes it possible to defrost with the compressor stopped and to achieve defrosting while achieving energy savings without the problem of small heat transport limits that arise with the conventional wick type or thermosiphon type.
However, in such a refrigeration system, a one-fluid structure is adopted in which the refrigerant is shared between the cooling system and the defrost system. Therefore, when one air cooler is provided for one refrigerator, the piping system for the refrigerant can be simplified. However, when multiple air coolers are provided for one refrigerator, it is difficult to adjust the amount of refrigerant held in the part separated by an automatic valve to the defrost system, which complicates the system and, in some cases, causes technical problems that may impair reliability.

On the other hand, the refrigeration system proposed in Patent Document 2 is a refrigeration system in which a load cooler, a compressor, a heat accumulator, a condenser, a receiver, and an expansion valve are connected in this order by refrigerant piping to form a cooling circuit through which a cooling refrigerant flows, and further includes a defrost circuit that circulates between the load cooler and the heat accumulator and is independent of the cooling circuit. The defrost circuit has a defrosting heat medium flowing inside, and includes a heat absorption section in the heat accumulator that absorbs heat from the heat storage agent, and in the load cooler, The cooling circuit has a heat dissipation section in the heat storage device that dissipates heat to the heat storage agent, and a cooling section in the load cooler that cools the load fluid, so that the load fluid is cooled by the cooling section through the cooling circuit and heat is dissipated to the heat storage agent through the heat dissipation section, while the heat absorption section absorbs heat from the heat storage agent through the defrost circuit, thereby defrosting the load cooler through the defrost section.

According to the refrigeration system having the above-mentioned configuration, the load cooler, compressor, heat accumulator, condenser, receiver, and expansion valve are connected in this order by refrigerant piping, and a defrost circuit independent of the cooling circuit is provided in the cooling circuit through which the cooling refrigerant flows and circulates between the load cooler and the heat accumulator via a heat exchanger. This simplifies the system, improving reliability, and making it possible to accommodate a variety of operating modes for cooling operation and defrost operation, while enabling defrosting without affecting the type of cooling refrigerant or the temperature and pressure conditions.
However, according to such a refrigeration device, a two-fluid structure is adopted in which the refrigerant is separate for the cooling system and the defrost system, and thus the problems caused by the one-fluid structure in Patent Document 1 can be eliminated. However, because of the two-fluid structure, there are technical problems in that the air cooler structure becomes larger and more complicated, and in some cases, reliability is impaired.
Patent No. 5842310 Patent No. 6229955

In view of the above technical problems, the present invention aims to solve both the technical problems of Patent Document 1 and the technical problems of Patent Document 2 at once.
In other words, the object of the present invention is to provide a refrigeration system and a defrosting method for a load cooler that can improve defrost performance while ensuring reliability by reducing the size of the load cooler structure and the complexity of the defrost control.

In order to achieve the above object, the refrigeration device of the present invention comprises:
In a refrigeration system, a load cooler, a compressor, a heat accumulator, a condenser or gas cooler, a liquid receiver, and an expansion valve are connected in this order by refrigerant piping to form a cooling circuit through which a cooling refrigerant flows,
Further, a defrost circuit for defrosting the load cooler is provided,
The defrost circuit has a heat exchanger that exchanges heat between the cooling refrigerant of the cooling circuit and the defrost heat medium of the defrost circuit, and a defrost circuit is provided that circulates heat between the load cooler and the heat accumulator via the heat exchanger.
The defrost circuit has a heat absorption section in the heat storage device that absorbs heat from the heat storage agent via a defrost heat medium, and a defrost section in the load cooler that dissipates heat by using a cooling refrigerant in the cooling circuit,
The cooling circuit has a heat dissipation section that dissipates heat to a heat storage agent in the heat storage device, and a cooling section that cools a load fluid in the load cooler,
The heat storage device is disposed at a level below the heat exchanger;
The heat exchanger is provided below the load cooler and above the heat storage device,
The cooling refrigerant of the cooling circuit forms a first loop-type thermosiphon circulation path between the heat exchanger and the load cooler, and the defrost heat medium of the defrost circuit forms a second loop-type thermosiphon circulation path between the heat exchanger and the heat accumulator,
the refrigerant piping includes a refrigerant forward path through which a refrigerant liquid or a gas-liquid mixed refrigerant flows from the receiver toward the load cooler via the expansion valve, and a refrigerant return path through which a refrigerant gas flows from the load cooler toward the compressor,
the load cooler has a heat transfer tube that communicates with the refrigerant outflow path and the refrigerant return path,
the first loop-type thermosiphon circulation path includes a first defrost refrigerant pipe that connects the refrigerant return line side of the heat transfer tube to the heat exchanger, and a second defrost refrigerant pipe that connects the heat exchanger to the refrigerant outward line side of the heat transfer tube, one of the first defrost refrigerant pipe and the second defrost refrigerant pipe is provided with an on-off valve, and the other is provided with a check valve that allows refrigerant to flow only in one direction;
As a result, the load fluid is cooled by the cooling section through the cooling circuit and heat is dissipated to the heat storage agent through the heat dissipation section, while heat is absorbed from the heat storage agent by the heat absorption section through the defrost circuit, thereby defrosting the load cooler via the defrost section through heat exchange between the cooling refrigerant and the defrost heat medium in the heat exchanger.

In the refrigeration system having the above configuration, the load cooler, compressor, heat accumulator, condenser or gas cooler, receiver, and expansion valve are connected in this order by refrigerant piping, and a defrost circuit is provided for a cooling circuit through which a cooling refrigerant flows, which circulates between the load cooler and the heat accumulator via a heat exchanger, and the defrost circuit is provided with a heat exchanger for exchanging heat between the cooling refrigerant of the cooling circuit and the defrost heat medium of the defrost circuit, the heat exchanger being located below the load cooler and above the heat accumulator, and the cooling refrigerant of the cooling circuit forms a first loop thermosiphon type circulation path between the heat exchanger and the load cooler, and the defrost heat medium of the defrost circuit forms a second loop thermosiphon type circulation path between the heat exchanger and the heat accumulator. a refrigerant pipe for forming a circulation path, the refrigerant pipe having a refrigerant outgoing path through which a refrigerant liquid or a gas-liquid mixed refrigerant flows from the receiver to the load cooler via an expansion valve, and a refrigerant return path through which a refrigerant gas flows from the load cooler to the compressor, the load cooler having a heat transfer tube connecting the refrigerant outgoing path and the refrigerant return path, the loop type thermosiphon type first circulation path having a defrost refrigerant first pipe line connected to the refrigerant return path side of the heat transfer tube and going to the heat exchanger, and a defrost refrigerant second pipe line connected to the heat exchanger on the refrigerant outgoing path side of the heat transfer tube, the defrost refrigerant first pipe line having an opening/closing valve, and the defrost refrigerant second pipe line having a check valve that allows only a flow from the heat exchanger to the refrigerant outgoing path,
The second loop-type thermosiphon circulation path allows the defrosting heat medium heated in the heat storage device to flow toward the heat exchanger, where it dissipates heat to the cooling refrigerant. The first loop-type thermosiphon circulation path allows the heated cooling refrigerant to flow through the second defrosting refrigerant pipe toward the refrigerant outward path side of the heat transfer tube of the load cooler, where it performs defrosting from the inside of the heat transfer tube. The cooling refrigerant that has dissipated heat flows from the refrigerant return path side of the heat transfer tube toward the heat exchanger through the first defrosting refrigerant pipe, whereby a circulating flow is formed. By repeating this process, the defrosting circuit can have, in the heat storage device, a heat absorption section that absorbs heat from the heat storage agent via the defrosting heat medium, and in the load cooler, a defrost section that dissipates heat by utilizing the cooling refrigerant of the cooling circuit, whereby the defrosting performance can be improved while ensuring reliability by reducing the size of the load cooler structure and the complexity of the defrost control.

It is also preferable that the heat dissipating portion dissipates heat to the heat storage material in the heat storage device by an external heat source.
Furthermore, the load cooler may be provided in a plurality of units, at least some of which may be installed at different levels;
The defrost circuit is provided with a defrost heat medium forward path through which a defrost heat medium gas heated by the heat accumulator flows from the heat accumulator toward the heat exchanger, and a defrost heat medium return path through which a defrost heat medium liquid cooled by the heat exchanger flows from the heat exchanger toward the heat accumulator,
Furthermore, it is preferable to provide a receiver for the defrosting heat medium in the defrosting heat medium return path so that the liquid level of the defrosting heat medium is lower than the lowermost heat exchanger and higher than the heat accumulator.

Furthermore, it is preferable to provide a bypass pipe which bypasses the defrost heat medium forward path and the portion of the defrost heat medium return path at a level above the receiver.
In addition, the heat accumulator may be provided with a circulation path between another exhaust heat source and the heat accumulator so that other exhaust heat can be utilized in addition to or independently of the heat dissipated by the cooling circuit.
The heat storage agent is preferably a phase change material.

Further, each of the load coolers has a casing provided with a cooling air inlet opening and a cooling air outlet opening arranged opposite each other, and provided with an airflow passage therein extending from the cooling air inlet opening to the cooling air outlet opening;
The heat transfer tube is disposed in the casing so as to cross the air flow along the ventilation flow path, and an air-cooling refrigerant flows through the heat transfer tube during a cooling operation, and the air-cooling refrigerant is used for defrosting during a defrost operation.
In the heat transfer tube, one end opening and the other end opening are connected to an air-cooling refrigerant inlet opening and an air-cooling refrigerant outlet opening, respectively, which are provided in the casing;
an inlet-side refrigerant branch pipe and an outlet-side refrigerant branch pipe are connected to the air-cooling refrigerant inlet opening and the air-cooling refrigerant outlet opening, respectively;
In order to enable internal heating defrosting of the heat transfer tube within the casing, it is preferable that the inlet side refrigerant branch pipe is connected in communication with the second defrost refrigerant pipeline, and the outlet side refrigerant branch pipe is connected in communication with the first defrost refrigerant pipeline and the defrost refrigerant return line.
Furthermore, it is preferable to provide a drain pan arranged below the casing for receiving liquid generated during defrosting, and a heat transfer tube for the drain pan connected to the defrost refrigerant inlet path and routed so as to heat the drain pan.

In order to achieve the above object, the defrosting method for a load cooler of the present invention comprises the steps of:
A method for defrosting a load cooler, comprising: a load cooler, a compressor, a heat accumulator, a condenser or gas cooler, a liquid receiver, and an expansion valve connected in this order by refrigerant piping; a cooling circuit through which a cooling refrigerant flows stores heat through a heat accumulator and cools the load cooler; and a defrost circuit which circulates heat between the load cooler and the heat accumulator via a heat exchanger dissipates heat through the heat accumulator and defrosts the load cooler,
The heat storage unit is installed at a lower level than the heat exchanger installed at the lowest level;
a heat exchanger for exchanging heat between the cooling refrigerant of the cooling circuit and the defrost heat medium of the defrost circuit is provided below the load cooler and above the heat accumulator;
The cooling refrigerant of the cooling circuit forms a first loop-type thermosiphon circulation path between the heat exchanger and the load cooler, and the defrost heat medium of the defrost circuit forms a second loop-type thermosiphon circulation path between the heat exchanger and the heat accumulator,
a step of storing heat in the heat accumulator by performing a cooling operation on the load cooler using the cooling circuit;
The defrosting heat medium stored in the heat storage step is circulated between the heat exchanger and the heat storage device via a second loop-type thermosiphon type circulation path, while the cooling refrigerant of the cooling circuit is circulated between the heat exchanger and the load cooler via a first loop-type thermosiphon type circulation path, thereby performing a defrost operation of the load cooler using the cooling refrigerant heated by the defrosting heat medium.

In addition, the load cooler is provided in a plurality of units, at least some of which are installed at different levels,
The defrost circuit is provided with a defrost heat medium forward path through which a defrost heat medium gas heated by the heat accumulator flows from the heat accumulator toward the heat exchanger, and a defrost heat medium return path through which a defrost heat medium liquid cooled by the heat exchanger flows from the heat exchanger toward the heat accumulator,
Furthermore, it is preferable to provide a receiver for the defrosting heat medium in the defrosting heat medium return path so that the liquid level of the defrosting heat medium is lower than the lowermost heat exchanger and higher than the heat accumulator.
Furthermore, the defrost operation step may include a step of storing heat in a heat storage device by performing a cooling operation on any one of the plurality of load coolers, while simultaneously performing a defrost operation on any one of the remaining plurality of load coolers.
Furthermore, the defrost operation step preferably includes a step of stopping the cooling operation of all of the plurality of load coolers and, in parallel therewith, performing a defrost operation on all or any of the plurality of load coolers.

In addition, in the loop-type thermosiphon first circulation path, the first defrost refrigerant line is a defrost refrigerant forward line through which the defrost refrigerant flows from the refrigerant return line side of the heat transfer tube to the heat exchanger, and the second defrost refrigerant line is a defrost refrigerant return line through which the defrost refrigerant flows from the heat exchanger to the refrigerant forward line side of the heat transfer tube, and the defrost refrigerant forward line may be provided with an on-off valve, and the defrost refrigerant return line may be provided with a check valve that allows only flow from the heat exchanger to the refrigerant forward line.

Furthermore, in the loop-type thermosiphon first circulation path, the first defrost refrigerant line is a defrost refrigerant return line through which the defrost refrigerant flows from the heat exchanger to the refrigerant return line side of the heat transfer tube, and the second defrost refrigerant line is a defrost refrigerant outward line through which the defrost refrigerant flows from the refrigerant outward line side of the heat transfer tube to the heat exchanger, and the defrost refrigerant outward line may be provided with an opening/closing valve, and the defrost refrigerant return line may be provided with a check valve that allows only flow from the heat exchanger to the refrigerant return line.

The first embodiment of the refrigeration device according to the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the refrigeration device 10 has a load cooler 12, a compressor 14, a heat storage device 16, a condenser 18, a receiver 17, and an expansion valve 151 connected in this order by refrigerant piping to form a cooling circuit 70 through which a cooling refrigerant flows, and also has a defrost circuit 72 that circulates heat between the load cooler 12 and the heat storage device 16 via a heat exchanger 200. The defrost circuit 72 has a heat absorption section 74 through which a defrosting heat medium flows and absorbs heat from the heat storage agent in the heat storage device 16, and a defrost section 76 that dissipates heat in the load cooler 12 using the cooling refrigerant (described later).

The cooling circuit 70 has a heat dissipation section 78 that dissipates heat to the heat storage agent in the heat storage device 16 , and a cooling section 80 that cools the load fluid in the load cooler 12 .
As a result, the load fluid is cooled by the cooling section 80 through the cooling circuit 70 and heat is dissipated to the heat storage agent through the heat dissipation section 78, while the load cooler 12 is defrosted through the defrost section 76 by absorbing heat from the heat storage agent through the defrost circuit 72 by the heat absorption section 74.

In the defrost circuit 72, the heat storage device 16 is installed at a lower level than the load coolers 12, and a defrost heat medium forward path 82 through which the defrost heat medium heated by the heat dissipation section 78 flows from the heat storage device 16 toward the heat exchanger 200, and a defrost heat medium return path 84 through which the defrost heat medium cooled by the defrost section 76 flows from the heat exchanger 200 toward the heat storage device 16 are provided. The defrost heat medium return path 84 is provided with a check valve 143, which prevents the defrost heat medium from flowing into the heat exchanger 200 during cooling operation when some of the load coolers 12 are performing cooling operation and other load coolers 12 connected in parallel are performing defrost operation, as will be described later.
The defrost circuit 72 has a heat exchanger 200 that exchanges heat between the cooling refrigerant of the cooling circuit 70 and the defrost heat medium of the defrost circuit 72, and the heat exchanger 200 is arranged below the load cooler 12 and above the heat storage device 16.
The cooling refrigerant in the cooling circuit 70 constitutes a first loop thermosiphon circulation path between the heat exchanger 200 and the load cooler 12, and the defrost heat medium in the defrost circuit 72 constitutes a second loop thermosiphon circulation path between the heat exchanger 200 and the heat accumulator 16. Both the first loop thermosiphon circulation path and the second loop thermosiphon circulation path are conventionally known loop thermosiphons, with a high temperature part at the bottom and a low temperature part at the top, forming a circulation path that circulates between the high temperature part and the low temperature part, with the medium heated in the high temperature part flowing toward the low temperature part and the medium cooled at a low temperature flowing toward the high temperature part, and this is repeated, so that the medium functions as a heat transporter in a natural circulation manner.
The loop-type thermosiphon first circulation path has a defrost refrigerant outflow path 204 that is connected to the heat transfer tube on the refrigerant return path 153 side and leads to the heat exchanger 200, and a defrost refrigerant return path 202 that is connected to the heat transfer tube on the refrigerant outflow path 155 side, the defrost refrigerant outflow path 204 is provided with an on-off valve 208, and the defrost refrigerant return path 202 is provided with a check valve 206 that allows only a flow from the heat exchanger 200 to the refrigerant outflow path 155,
The second loop-type thermosiphon circulation path allows the defrosting heat medium heated in the heat storage device 16 to flow toward the heat exchanger 200, where it dissipates heat to the cooling refrigerant. The first loop-type thermosiphon circulation path allows the heated cooling refrigerant to flow toward the refrigerant outward path 155 of the heat transfer tube of the load cooler 12 through the defrosting refrigerant return path 202, where defrosting is performed from inside the heat transfer tube. The cooling refrigerant that has dissipated heat flows from the refrigerant return path 153 side of the heat transfer tube toward the heat exchanger 200 through the defrosting refrigerant outward path 204, whereby a circulating flow is formed. By repeating this process, the defrosting circuit 72 can form a heat absorption section in the heat storage device 16 that absorbs heat from the heat storage agent through the defrosting heat medium, and a defrost section in the load cooler 12 that dissipates heat by utilizing the cooling refrigerant of the cooling circuit 70.

On the other hand, the cooling circuit 70 has cooling outward paths 155A, B that connect the water-cooled condensing unit 81 and the load cooler 12, cooling return paths 153A, B that connect the load cooler 12 and the water-cooled condensing unit 81, a heat storage outward path 147A that connects the water-cooled condensing unit 81 and the heat storage device 16, and a heat storage return path 147B that connects the heat storage device 16 and the water-cooled condensing unit 81.
As a result, by utilizing the heat stored in the heat storage device 16 during the cooling operation of the load cooler 12, a defrosting heat medium is circulated between the heat storage device 16 and the heat exchanger 200 via the loop-type thermosiphon type second circulation path, and thermal energy is supplied from the heat exchanger 200 to the load cooler 12 via the loop-type thermosiphon type first circulation path using the cooling refrigerant of the cooling circuit 70, and the load cooler 12 is defrosted using the defrosting thermal energy.
The relative installation level difference H of the heat accumulator 16 with respect to the heat exchanger 200 (more precisely, the liquid level of the defrost heat transfer liquid in the receiver 20, which will be described later) may be determined appropriately from the viewpoint of forming a loop-type thermosiphon. The heat storage material of the heat accumulator 16 may be a latent heat storage material or a sensible heat storage material. For example, a paraffin-based latent heat storage material is an example, and a sensible heat storage material is water.
The water-cooled condensing unit 81 is provided with a cooling water return pipe 145A and a cooling water supply pipe 145B, which are used for condensing the refrigerant by the condenser 18.

A plurality of load coolers 12 (four in FIG. 1 ) are provided and are connected in parallel to the cooling circuit 70 via an inlet side refrigerant branch pipe 86 and an outlet side refrigerant pipe 92, and are connected in parallel to the defrost circuit 72 via a refrigerant forward path 202 and a refrigerant return path 204.
As shown in FIG. 1, of the four load coolers 12, load coolers 12A and 12B are installed, for example, on the second floor of a building, and load coolers 12C and 12D are installed, for example, on the first floor of a building, with load coolers 12A and 12B installed at a higher level than load coolers 12C and 12D, and load coolers 12A and 12B are installed at the same level, and load coolers 12C and 12D are installed at the same level.
As described below, each defrost heat medium pipe (the defrost heat medium forward path 82 and the defrost heat medium return path 84) is provided with a switching valve from the viewpoint of switching between the normal operation mode and the defrost operation mode.
More specifically, the defrost heat medium outflow path 82 is provided with switching valves 300 and 302 for switching between the defrost heat medium for heat exchangers 200A and 200B and the defrost heat medium for heat exchangers 200C and D, switching valves 210A and 210B are provided for switching between the defrost heat medium for heat exchanger 200A and the defrost heat medium for heat exchanger 200B, switching valves 210C and 210D are provided for switching between the defrost heat medium for heat exchanger 200C and the defrost heat medium for heat exchanger 200D, and the defrost heat medium return path 84 is provided with a switching valve 312 upstream of the heat accumulator 16.

A receiver 20 equipped with a liquid level gauge 149 is provided at a level between heat exchangers 200A and 200B and heat exchangers 200C and 200D of the defrost heat medium return path 84, and as will be explained later, during defrost operation of the load cooler 12, the defrost heat medium defrosts the load cooler 12 as a defrost heat medium gas and becomes a defrost heat medium liquid. Since the liquid level of the defrost heat medium liquid in each of the defrost heat medium forward path 82 and the defrost heat medium return path 84 can fluctuate depending on the state of the heat storage device 16 and/or the load cooler 12, the receiver 20 is provided to prevent such liquid level fluctuations from impeding the stability of the defrost operation. The level of the receiver 20 is lower than the heat exchangers 200A and 200B, but should be as close as possible to the level of the heat exchangers 200A and 200B, in order to ensure a level difference with the heat storage tank 16 and achieve natural circulation using a loop-type thermosiphon, as will be described later.

The load cooler 12 is installed within a storage facility, such as a freezer, a refrigerated warehouse, a shipping room, or the like, to cool the interior of the storage facility.
As shown in Fig. 2, each of the load coolers 12 is a unit cooler fixed to the interior ceiling with, for example, a hanging bolt and nut via a hanging bracket 117, and has a casing 102 provided with a cooling air inlet opening (not shown) and a cooling air outlet opening (not shown) arranged opposite each other, and provided with an air flow path 100 inside from the cooling air inlet opening to the cooling air outlet opening. A blower 101 is provided on a pair of opposing side surfaces of the casing 102. Numeral 103 denotes a terminal box to which the terminals of the blower 101 are wired.
Within the casing 102, heat transfer tubes 104, through which an air-cooling refrigerant flows, are arranged parallel to each other and are arranged so as to cross the air flow along the ventilation flow path 100. As will be described later, each heat transfer tube 104 is formed by connecting a U-shaped tube section 130 arranged outside each of the opposing partition plates 120 of the casing 102 to a straight tube section 128 extending between the opposing partition plates 120.

The heat transfer tube 104 is connected to the cooling outward path 155 downstream of the expansion valve 151 (see Figure 1) via the diverter 141 and the inlet side refrigerant branch pipe 86 that branches from the diverter 141, while it is connected to the cooling return path 153 via the outlet side refrigerant pipe 92 (see Figure 1).

As shown in FIG. 3 , each of the opposing partition plates 120 of the casing 102 is provided with a number of through holes 122, and the heat transfer tube 104 has a cooling straight pipe section 128 extending between the opposing partition plates 120 inside the casing 102, and a cooling U-shaped pipe section 130 (omitted in FIG. 3 ) outside the casing 102 that connects the cooling straight pipe sections 128 to each other via the through holes 122.
The refrigerant in the cooling piping is collected in a diverter 141 on one of the partition plates 120, from which it branches out by inlet side refrigerant branch pipes 86 (six branches in the figure), and each branch pipe is composed of a cooling U-shaped bend pipe 130 provided in one of the opposing partition plates 120, a cooling straight pipe section 128 extending between the opposing partition plates 120, and a cooling U-shaped bend pipe 130 provided in the other of the opposing partition plates 120, and the cooling U-shaped bend pipes 130 are provided so as to connect, in a discontinuous manner as necessary, to the through holes aligned in the vertical and horizontal directions provided in each partition plate 120, and each branch pipe is collected in a header 105 on one of the partition plates 120, and from there connected to a cooling return line 153.
On the other hand, the defrost heat transfer gas from the heat exchanger 200 via the refrigerant return path 202A is connected to the cooling outward path 155 downstream of the flow divider 141 (it can also be on the upstream side as shown by the dotted line in Figure 3), flows through the cooling straight pipe section 128 within the casing 102, and performs defrosting, and the cooled defrost heat transfer liquid is connected to the refrigerant outward path 204A via the header 105 on one side of the partition plate 120, and returns to the heat exchanger 200.

2, plate-shaped fins 132 for the heat transfer tubes 104 are further provided inside the casing 102, and each of the plate-shaped fins 132 has a number of through holes 122 at the same positions as the partition plate 120. A plurality of the plate-shaped fins 132 are provided parallel to each other so as to be perpendicular to the ventilation channel 100.
In this case, the plate-like fins 132 that serve to increase the heat transfer area of the heat transfer tubes 104 are used to support the heat transfer tubes 104 .
Each straight tube section 128 of the heat transfer tube 104 is fixed to the plate-shaped fins 132 in a manner that penetrates the through holes 122, so that the refrigerant flowing inside the heat transfer tube 104 and heated by the heat exchanger 200 defrosts the heat transfer tube 104 and the plate-shaped fins 132 that support it from the inside in the form of heat radiation or heat conduction.

The cooling refrigerant temperature is, for example, -10°C, and the air is cooled from room temperature to -5°C, while the cooling refrigerant temperature that is heated in the heat exchanger 200 and used for defrosting is 20°C, and the frost that has formed inside the air cooler is defrosted (described later).

As shown in FIG. 3, a drain pan 134 is disposed below the casing 102 to receive the liquid generated during defrosting, and a branch pipe 136 is provided that branches off from the refrigerant forward path 202 connected to the heat transfer pipe 104. A defrosting heat transfer pipe 135 is connected to the branch pipe 136 and routed downwardly so as to contact the bottom surface 137 of the drain pan 134. The entire bottom surface 137 of the drain pan 134 is heated in a thermally conductive manner through the defrosting heat transfer pipe 135, enabling defrosting. The defrosting heat transfer pipe 135 is connected to the defrosting heat medium return path 84.

From the viewpoints of heat transferability and cost, the material of the cooling refrigerant pipes 104 is preferably copper pipes, although aluminum pipes or stainless steel pipes may be used in some cases. The material of the plate-shaped fins 132 is preferably aluminum in order to prioritize heat transferability, although copper or stainless steel may be used in some cases. The casing is, for example, a galvanized steel plate, and the drain pan is SUS.
As a modified example, as shown in FIG. 3B, on the other partition plate 120 side, defrost heat transfer gas may flow into the header 105, and on one partition plate 120 side, the cooled heat transfer liquid used for defrosting may flow out via the inlet side refrigerant branch pipe 86.

The operation of the refrigeration system 10 having the above configuration will be described below with reference to Figs. 4 to 8, along with an explanation of the operating method of the refrigeration system 10.
The operation mode of the refrigeration system 10 is divided into a normal cooling operation mode (heat storage stage) (FIG. 4) and a defrost operation mode (FIG. 6).
A case will be described in which the normal cooling operation mode (heat storage stage) is performed for all of the load coolers 12A to 12D, and then the defrost operation mode is performed for only the load cooler 12A located at the upper level.

First, as shown in FIG. 5, in the normal cooling operation mode (heat storage stage), compressor 14 is operated with switching valves 300, 302, 312, 208A, 208B, 208C, 208D, 322A, 322B, 322C, 322D, 210A, 210B, 210C, and 210D, of which 322A, 322B, and 322D are opened, and the rest are closed.
The refrigerant flows from the load cooler 12 through the outlet side refrigerant pipe 92 and the cooling return path 153A into the compressor 14, where it is compressed, and then flows from the compressor 14 through the heat storage forward path 147A into the heat accumulator 16, where the refrigerant dissipates heat and is stored in the heat accumulator 16, and then flows from the heat accumulator 16 through the heat storage return path 147B into the condenser 18, where it is condensed or supercooled, and then flows from the condenser 18 through the cooling forward path 155A into the expansion valve 151, where the opening of the expansion valve 151 is adjusted to adjust the degree of superheat of the refrigerant, and then returns from the expansion valve 151 through the diverter 141 to the load cooler 12, thereby forming a cooling circuit.

As described above, the refrigerant flows as shown by the arrows in Figure 5, and is in a gas state from the load cooler 12 via the compressor 14 to the heat accumulator 16, and in particular, is in a low-pressure gas state between the load cooler 12 and the compressor 14, is in a high-pressure gas state between the compressor 14 and the heat accumulator 16, and is in a liquid or wet vapor state from the heat accumulator 16 to the load cooler 12 via the expansion valve 151.

Next, as shown in FIG. 6, when the defrost operation mode is performed only for the load cooler 12A, the compressor 14 is stopped, and the changeover valves 300, 312, 208A, 322B, 322C, 322D and 210A are opened, and the others are closed.
As a result, the heat stored in the heat storage device 16 is transported to the load cooler 12 via the heat exchanger 200 through a loop-type thermosiphon type second circulation path formed by a defrost heat medium forward path 82 and a defrost heat medium return path 84 that connect the heat storage device 16 and the heat exchanger 200, and a loop-type thermosiphon type first circulation path formed by a refrigerant forward path 202 and a refrigerant return path 204 that connect the load cooler 12 and the heat exchanger 200.

More specifically, the defrost heat medium that has evaporated (absorbed heat) due to the heat stored in the heat storage device 16 flows through the defrost heat medium forward path 82 to the heat exchanger 200, where it exchanges heat (heats) with the refrigerant that has been defrosted in the load cooler 12 and flows through the refrigerant return path 204 to the heat exchanger 200, and the heated defrost heat medium returns to the heat storage device 16 through the defrost heat medium return path 84, while the heated refrigerant flows through the refrigerant forward path 202 to the load cooler 12. By repeating this natural circulation, two loop-type thermosiphons are formed and defrosting is performed for the load cooler 12A.
The heat is transferred in the form of thermal conduction through the heat transfer tube 104 to the plate-shaped fins 132 and further to the other heat transfer tubes 104 via the plate-shaped fins 132, and also in the form of thermal radiation through the heat transfer tube 104 to the plate-shaped fins 132 and the outer peripheral surfaces 160 of the other heat transfer tubes 104.
When the defrosting of the load cooler 12 is completed by this defrost operation, the operation mode returns to the normal cooling operation mode, and heat storage is resumed in preparation for the next defrost operation.

The timing of switching between the normal cooling operation mode (Figure 5) and the defrost operation mode (Figure 6) of some of the load coolers 12A to D may be manually switched as appropriate depending on the frost formation condition in the load cooler 12, or if the load on the load cooler 12 is relatively constant and the frost progresses relatively regularly, a timer may be set in advance to automatically switch, or the temperature of the heat transfer tube 104 of the load cooler 12 may be detected and set based on the detected temperature.

As shown in FIG. 4, during cooling operation, among the switching valves 300, 302, 312, 208A, 208B, 208C, 208D, 322A, 322B, 322C, 322D, 210A, 210B, 210C, and 210D, 322A, 322B, and 322D are opened, and the others are closed. When only the load cooler 12A is to be defrosted, the switching valves 300, 312, and 208A are closed. , 322B, 322C, 322D, and 210A are opened, and the others are closed. When only the load cooler 12B is to be defrosted, the changeover valves 300, 312, 208B, 322A, 322C, 322D, and 210B are opened, and the others are closed. When only the load cooler 12C is to be defrosted, the changeover valves 302, 312, 208C, 322A, 322B, 322D, and 210C are opened, and the others are closed. The rest are closed, and when only the load cooler 12C is to be defrosted, the changeover valves 302, 312, 208C, 322A, 322B, 322D, and 210C are opened, and the rest are closed, and when only the load cooler 12D is to be defrosted, the changeover valves 302, 312, 208D, 322A, 322B, 322C, and 210D are opened, and the rest are closed, and the load coolers 12A and When defrosting only load cooler 12B, switching valves 300, 312, 208A, 208B, 322C, 322D, 210A, and 210B are opened and the others are closed. When defrosting only load cooler 12C and load cooler 12D, switching valves 302, 312, 208C, 208D, 322A, 322B, 210C, and 210D are opened and the others are closed (see Figure 7).

As an example of a variation of the operating method, in this embodiment, all four air coolers are operated in cooling mode while storing heat, and then the load cooler 12A located at the upper level is operated in defrost mode. However, this is not limited to this, and as long as the amount of heat storage required for the defrost mode is ensured, any of the four air coolers may be operated in cooling mode while storing heat, while the remaining air cooler is operated in parallel in defrost mode, in other words, a catch-up operation may be performed.

Specifically, as shown in FIG. 8, switching valves 302, 312, 208C, 208D, 322A, 322B, 210C, and 210D are opened, and the others are closed, so that the load coolers 12A and 12B are cooled by the cooling circuit 70 while storing heat in the heat storage device 16, while the load coolers 12C and 12D are defrosted by the defrost circuit 72.
In addition, by operating the switching valve, cooling may be performed by the cooling circuit 70 for only one of the load coolers 12A and 12B, while defrosting may be performed by the defrost circuit 72 for only one of the load coolers 12C and 12D. In this case, the other of the load coolers 12A and 12B is in a stopped state, but the other of the load coolers 12C and 12D may be in a cooling operation or in a stopped state.

According to the refrigeration system having the above configuration, the refrigeration system 10 having the above configuration, during cooling operation, the refrigerant gas that has evaporated by cooling the load cooler 12 is compressed by the compressor 14 and dissipates heat in the heat accumulator 16, resulting in heat storage, and the refrigerant gas or refrigerant liquid is condensed or supercooled in the condenser 18, and the refrigerant liquid is received by the receiver 17, passes through the expansion valve 151, and cools the load cooler 12 again by forming a cooling circuit.

In particular, a defrost circuit 72 is provided for a cooling circuit 70 in which a load cooler 12, a compressor 14, a heat accumulator 16, a condenser 18, a receiver 17, and an expansion valve 151 are connected in this order by refrigerant piping, and a cooling refrigerant flows therein. The defrost circuit 72 is provided with a heat exchanger 200 for exchanging heat between the cooling refrigerant of the cooling circuit 70 and the defrost heat medium of the defrost circuit 72, the heat exchanger 200 being disposed below the load cooler 12 and above the heat accumulator 16. The cooling refrigerant of the cooling circuit 70 forms a first loop-type thermosiphon circulation path between the heat exchanger 200 and the load cooler 12, and the defrost heat medium of the defrost circuit 72 forms a second loop-type thermosiphon circulation path between the heat exchanger 200 and the heat accumulator 16. The medium piping has a refrigerant forward path 155 through which a refrigerant liquid or a gas-liquid mixed refrigerant flows from the receiver 17 to the load cooler 12 via an expansion valve 151, and a refrigerant return path 153 through which a refrigerant gas flows from the load cooler 12 to the compressor 14. The load cooler 12 has a heat transfer tube 104 that communicates and connects the refrigerant forward path 155 and the refrigerant return path 153. The loop-type thermosiphon type first circulation path is a refrigerant return path of the heat transfer tube. 153 side and directed toward the heat exchanger 200, and a defrost refrigerant return path 202 which is connected from the heat exchanger 200 to the refrigerant forward path 155 side of the heat transfer tube, the defrost refrigerant forward path 204 is provided with an on-off valve 208, and the defrost refrigerant return path 202 is provided with a check valve 206 which allows only a flow from the heat exchanger 200 toward the refrigerant forward path 155,
The defrosting heat medium heated in the heat accumulator 16 flows through the loop-type thermosiphon second circulation path to the heat exchanger 200, where it dissipates heat to the cooling refrigerant. The heated cooling refrigerant flows through the defrosting refrigerant return path 202 to the refrigerant forward path 155 side of the heat transfer tube of the load cooler 12, where defrosting is performed from inside the heat transfer tube. The cooling refrigerant that has dissipated heat flows through the defrosting refrigerant return path 153 side of the heat transfer tube to the defrosting refrigerant forward path 204. 3 to the heat exchanger 200, forming a circulation flow. By repeating this, the defrost circuit 72 can have a heat absorption section in the heat storage device 16 that absorbs heat from the heat storage agent via the defrost heat medium, and a defrost section in the load cooler 12 that dissipates heat by utilizing the cooling refrigerant in the cooling circuit 70. This makes it possible to improve the defrost performance while ensuring reliability by reducing the size of the load cooler 12 structure and the complexity of the defrost control.

According to the above-mentioned defrosting method for the load cooler 12, the load cooler 12 is configured by connecting multiple load coolers 12, compressors 14, heat storage devices 16, condensers 18, receivers 17, and expansion valves 151 in parallel in this order with refrigerant piping, and the cooling circuit through which the cooling refrigerant flows stores heat through the heat storage device 16 and cools the load cooler 12, while the defrosting circuit in which the defrosting heat medium circulates heat between each of the multiple load coolers 12 and the heat storage device 16 releases heat through the heat storage device 16 and defrosts the load cooler 12. In this defrosting method for the load cooler 12, the load cooler 12 is defrosted by performing a cooling operation on one of the multiple load coolers 12 to store heat in the heat storage device 16, and performing a defrosting operation on one of the multiple load coolers 12.

In this case, the defrost operation stage may include a stage in which one of the multiple load coolers 12 is cooled to store heat in the heat storage 16 while simultaneously performing a defrost operation on one of the remaining multiple load coolers 12, or the defrost operation stage may include a stage in which the cooling operation of all of the multiple load coolers 12 is stopped while simultaneously performing a defrost operation on one of the multiple load coolers 12, making it possible to defrost without affecting the type of cooling refrigerant or temperature and pressure conditions while being able to accommodate a variety of operating modes for cooling and defrost operations.

As a variant, during the cooling operation, there may be a step of bypassing the heat accumulator 16 after the heat accumulation step has ended.
More specifically, since the refrigerant gas discharged from the compressor 14 flows to the condenser 18 via the heat storage device 16, pressure loss in the heat storage device 16 is unavoidable. In order to eliminate such pressure loss, a heat storage device bypass pipe may be provided connecting the heat storage forward path 147A and the heat storage return path 147B, and the heat storage device 16 may be bypassed via the heat storage device bypass pipe (not shown).
In particular, in the normal cooling operation, after sufficient heat has been stored in the heat accumulator 16, the heat accumulator 16 may be bypassed via the heat accumulator bypass pipe, so that only the cooling operation can be performed.

A second embodiment of the refrigeration device according to the present invention will be described in detail below with reference to the drawings.
In the following description, the same components as those in the first embodiment are given the same reference numerals and the description thereof will be omitted, and the characteristic parts of this embodiment will be described in detail below.
The second embodiment of the present invention is characterized in that the receiver 20 is installed in the defrost heat medium return line 84 at a different installation level, thereby expanding the versatility of the defrost operation.
More specifically, in the first embodiment, the receiver 20 installed in the defrost heat medium return path 84 is at a level between the heat exchangers 200A and 200B and the heat exchangers 200C and 200D as shown in FIG. 1, but in this embodiment, as shown in FIG. 9, it is installed at a level between the heat exchangers 200C and 200D, which are located at the lowest level, and the heat accumulator 16. As a result, while in the first embodiment it was difficult to perform defrost operation on all four load coolers 12A to 12D simultaneously during defrost operation, in this embodiment, it is possible to perform defrost operation on all four load coolers 12A to 12D simultaneously.

The level difference H between the liquid level of the defrost heat medium in the receiver 20 and the heat accumulator 16 may be determined from this viewpoint, and is preferably immediately below the heat exchanger 200C and the heat exchanger 200D.
The cooling operation is similar to that of the first embodiment, and the defrost operation is similar to that of the first embodiment in that natural circulation is achieved by the loop-type thermosiphon.
Regarding the mode of the defrost operation, the method may have a step of storing heat in a heat accumulator by performing a cooling operation of any of the multiple load coolers, and a step of performing a defrost operation on all or any of the multiple load coolers, and the defrost operation step may have a step of storing heat in the heat accumulator by performing a cooling operation of any of the multiple load coolers while simultaneously performing a defrost operation on any of the remaining multiple load coolers, and the defrost operation step may have a step of stopping the cooling operation of all of the multiple load coolers while simultaneously performing a defrost operation on all or any of the multiple load coolers.

More specifically, as shown in FIG. 9, after heat is stored in the heat accumulator by the cooling operation of the load coolers 12A to 12D, the compressor 14 is stopped and all of the switching valves 300, 302, 312, 208A, 208B, 208C, 208D, 322A, 322B, 322C, 322D, 210A, 210B, 210C, and 210D are opened to perform a defrost operation for all of the load coolers 12A to 12D. After storing heat in the heat accumulator by the cooling operation of the load coolers 12A to 12D, the load coolers 12C and 12D located at the lower level may be defrosted while the load coolers 12A and 12B located at the upper level are cooled, or the load coolers 12A and 12B located at the upper level may be defrosted while the load coolers 12C and 12D located at the lower level are cooled, so that so-called chase operation may be performed. Alternatively, after storing heat in the heat accumulator by the cooling operation of the load coolers 12A to 12D, the compressor 14 may be stopped, and only the load coolers that require defrosting among the load coolers 12A to 12D may be selected and defrosted.
In this case, when performing defrost operation for all of the load coolers 12A to 12D, in order to ensure that the defrost operation of the upper level load coolers 12A and 12B is performed, the flow path resistance can be reduced by making the diameter of the defrost heat transfer medium inlet path to the load coolers 12A and 12B larger than the diameter of the defrost heat transfer medium inlet path to the load coolers 12C and 12D.
As described above, this embodiment expands the variety of cases in which the defrost operation is performed using the loop thermosiphon, compared to the first embodiment.

Although the embodiment of the present invention has been described in detail above, those skilled in the art can make various modifications and changes without departing from the scope of the present invention.
For example, the loop-type thermosiphon first circulation path has a defrost refrigerant outward path in which the defrost refrigerant flows from the refrigerant return path side of the heat transfer tube to the heat exchanger, and a defrost refrigerant return path in which the defrost refrigerant flows from the heat exchanger to the refrigerant outward path side of the heat transfer tube, and has been described as being provided with an on-off valve in the defrost refrigerant outward path and a check valve that allows only flow from the heat exchanger to the refrigerant outward path in the defrost refrigerant return path, but is not limited thereto, and it is also possible to reverse the flow of the defrost refrigerant, i.e., The type thermosiphon first circulation path has a defrost refrigerant return path, in which the defrost refrigerant flows from the heat exchanger to the refrigerant return path side of the heat transfer tube, and a defrost refrigerant outward path, in which the defrost refrigerant flows from the refrigerant outward path side of the heat transfer tube to the heat exchanger, and the defrost refrigerant outward path may be provided with an on-off valve, and the defrost refrigerant return path may be provided with a check valve that only allows flow from the heat exchanger to the refrigerant return path, and in either case, it is preferable that there be a counterflow to the defrost heat medium in the heat exchanger.
For example, as long as sufficient heat is stored in the heat storage device 16, defrost operation may be performed individually only for the load coolers 12 that require defrosting. In this case, if there are multiple load coolers 12 that require defrosting, a so-called catch-up operation may be performed in which heat is stored while cooling operation is being performed and defrost operation is performed at the same time.
For example, in this embodiment, the heat storage device 16 has been described, but the present invention is not limited to this, and as long as heat can be stored from the refrigerant, a heat storage tank may be used. Furthermore, instead of storing heat using a refrigerant, heat may be stored using an external heat source, such as exhaust heat.

For example, in the first and second embodiments, when there are multiple load coolers 12, the receiver 20 is installed in the defrost heat medium return path 84, but this is not limited to this. When multiple load coolers 12 are all installed at the same level and the load fluctuations on the load cooler 12 side or the heat storage tank 16 side are not large, stable natural circulation is possible using the loop thermosiphon, so the receiver 20 may be omitted.
For example, in this embodiment, the first loop-type thermosiphon circulation path between the heat exchanger 200 and the load cooler 12 has been described as running clockwise as viewed in the drawing (FIG. 1), i.e., from the heat exchanger 200 to the load cooler 12 through the refrigerant forward path 202, and from the load cooler 12 back to the heat exchanger 200 through the refrigerant return path 204. However, this is not limited to this, and as long as the refrigerant for the cooling circuit 70 can be diverted through the first loop-type thermosiphon circulation path, it may also run counterclockwise. In this case, the check valve 206 provided in the refrigerant forward path 202 may be reversed.

For example, in this embodiment, the first loop-type thermosiphon circulation path between the heat exchanger 200 and the load cooler 12 is described as being clockwise as viewed in the drawing (Fig. 1), i.e., from the heat exchanger 200 to the load cooler 12 through the refrigerant forward path 202, and from the load cooler 12 back to the heat exchanger 200 through the refrigerant return path 204, with a check valve 206 provided in the refrigerant forward path 202 and an on-off valve 208 provided in the refrigerant return path 204, but this is not limited thereto, and an on-off valve 208 may be provided in the refrigerant forward path 202 and a check valve 206 may be provided in the refrigerant return path 204.

1 is a configuration diagram of a refrigeration device 10 according to a first embodiment of the present invention. FIG. 1 is a perspective view of an air cooler of a refrigeration device 10 according to a first embodiment of the present invention. 1 is a schematic diagram showing the periphery of an air cooler of a refrigeration device 10 according to a first embodiment of the present invention. 4 is a table showing opening and closing states of a switching valve according to a defrost operation of the refrigeration device 10 according to the first embodiment of the present invention. 1, but showing a normal cooling operation during heat storage in the refrigeration device 10 according to the first embodiment of the present invention. FIG. FIG. 2 is a view similar to FIG. 1 , showing a defrost operation in the refrigeration device 10 according to the first embodiment of the present invention. 1 , showing a defrost operation of a modified example in the refrigeration device 10 according to the first embodiment of the present invention. FIG. 1 , but showing an operating state of a modified example of the refrigeration device 10 according to the first embodiment of the present invention. FIG. FIG. 2 is a view similar to FIG. 1, showing a refrigeration device 10 according to a second embodiment of the present invention.

H Level difference 10 Refrigeration device 12 Load cooler 14 Compressor 16 Heat accumulator 17 Receiver 18 Condenser 20 Liquid receiver 70 Cooling circuit 72 Defrost circuit 74 Heat absorption section 76 Defrost section 78 Heat dissipation section 80 Cooling section 81 Condensing unit 82 Defrost heat medium forward path 84 Defrost heat medium return path 86 Inlet side refrigerant branch pipe 90 Outlet side refrigerant pipe 92 Outlet side defrost heat medium pipe 100 Ventilation flow path 101 Blower 102 Casing 103 Terminal box 104 Heat transfer pipe 105 Refrigerant header 106 Defrost heat transfer pipe 112 Air cooling refrigerant inlet opening 113 Partition plate 117 Hanging bracket 118 Defrost heat medium outlet opening 120 Partition plate 122 Refrigerant pipe through hole 128 Cooling straight pipe section 130 Cooling U-shaped pipe section 132 Plate-shaped fin 134 Drain pan 135 Defrost heat transfer pipe 136 Branch pipe 137 Bottom surface 140 Check valve 141 Divider 143 Check valve 145A Cooling water supply pipe 145B Cooling water return pipe 147A Heat storage forward path 147B Heat storage return path 149 Level gauge 151 Expansion valve 153 Cooling return path 155 Cooling forward path 200 Heat exchanger 202 Refrigerant return path 204 Refrigerant forward path 206 Check valve 208 Adjusting valve 210 Adjusting valve 300 Switching valve 302 Switching valve 312 Switching valve 322 Switching valve

Claims (14)

In a refrigeration system, a load cooler, a compressor, a heat accumulator, a condenser or gas cooler, a liquid receiver, and an expansion valve are connected in this order by refrigerant piping to form a cooling circuit through which a cooling refrigerant flows,
Further, a defrost circuit for defrosting the load cooler is provided,
The defrost circuit has a heat exchanger that exchanges heat between the cooling refrigerant of the cooling circuit and the defrost heat medium of the defrost circuit, and a defrost circuit is provided that circulates heat between the load cooler and the heat accumulator via the heat exchanger.
The defrost circuit has a heat absorption section in the heat storage device that absorbs heat from the heat storage agent via a defrost heat medium, and a defrost section in the load cooler that dissipates heat by using a cooling refrigerant in the cooling circuit,
The cooling circuit has a heat dissipation section that dissipates heat to a heat storage agent in the heat storage device, and a cooling section that cools a load fluid in the load cooler,
The heat storage device is disposed at a level below the heat exchanger,
The heat exchanger is provided below the load cooler and above the heat storage device,
The cooling refrigerant of the cooling circuit forms a first loop-type thermosiphon circulation path between the heat exchanger and the load cooler, and the defrost heat medium of the defrost circuit forms a second loop-type thermosiphon circulation path between the heat exchanger and the heat accumulator,
the refrigerant piping includes a refrigerant forward path through which a refrigerant liquid or a gas-liquid mixed refrigerant flows from the receiver toward the load cooler via the expansion valve, and a refrigerant return path through which a refrigerant gas flows from the load cooler toward the compressor,
the load cooler has a heat transfer tube that communicates with the refrigerant outflow path and the refrigerant return path,
the first loop-type thermosiphon circulation path includes a first defrost refrigerant pipe that connects the refrigerant return line side of the heat transfer tube to the heat exchanger, and a second defrost refrigerant pipe that connects the heat exchanger to the refrigerant outward line side of the heat transfer tube, one of the first defrost refrigerant pipe and the second defrost refrigerant pipe is provided with an on-off valve, and the other is provided with a check valve that allows refrigerant to flow only in one direction;
As a result, the load fluid is cooled by the cooling section through the cooling circuit, and heat is dissipated to the heat storage agent through the heat dissipation section, while heat is absorbed from the heat storage agent by the heat absorption section through the defrost circuit, thereby defrosting the load cooler via the defrost section through heat exchange between the cooling refrigerant and the defrost heat medium in the heat exchanger. The refrigeration device according to claim 1, wherein the heat dissipation section dissipates heat to the heat storage material in the heat storage device using an external heat source. The load cooler is provided in a plurality of units, at least some of which are installed at different levels;
The defrost circuit is provided with a defrost heat medium forward path through which a defrost heat medium gas heated by the heat accumulator flows from the heat accumulator toward the heat exchanger, and a defrost heat medium return path through which a defrost heat medium liquid cooled by the heat exchanger flows from the heat exchanger toward the heat accumulator,
The refrigeration apparatus according to claim 1, further comprising a receiver for the defrosting heat medium in the defrosting heat medium return path so that the liquid level of the defrosting heat medium is lower than the lowest heat exchanger and higher than the heat accumulator. The refrigeration system according to claim 3, further comprising a bypass pipe that bypasses the defrost heat medium forward path and the portion of the defrost heat medium return path at a level above the receiver. The refrigeration device according to claim 1, wherein a circulation path is provided between the heat accumulator and another exhaust heat source so that the heat accumulator can utilize other exhaust heat in addition to or independently of the heat dissipated by the cooling circuit. The refrigeration device of claim 1, wherein the heat storage material is a phase change material. Each of the load coolers has a casing having a cooling air inlet opening and a cooling air outlet opening arranged opposite to each other, and an air flow passage provided therein from the cooling air inlet opening to the cooling air outlet opening;
The heat transfer tube is disposed in the casing so as to cross the air flow along the ventilation flow path, and an air-cooling refrigerant flows through the heat transfer tube during a cooling operation, and the air-cooling refrigerant is used for defrosting during a defrost operation.
In the heat transfer tube, one end opening and the other end opening are connected to an air-cooling refrigerant inlet opening and an air-cooling refrigerant outlet opening, respectively, which are provided in the casing;
an inlet-side refrigerant branch pipe and an outlet-side refrigerant branch pipe are connected to the air-cooling refrigerant inlet opening and the air-cooling refrigerant outlet opening, respectively;
4. The refrigeration apparatus according to claim 3, wherein within the casing, the inlet side refrigerant branch pipe is connected in communication with the defrost refrigerant second pipe, and the outlet side refrigerant branch pipe is connected in communication with the defrost refrigerant first pipe and a defrost refrigerant return line, so that the heat transfer tube can be defrosted in an internal heating manner. The refrigeration device according to claim 7, further comprising a drain pan disposed below the casing for receiving liquid generated during defrosting, and a heat transfer tube for the drain pan connected to the defrosting refrigerant inlet path and routed so as to heat the drain pan. A method for defrosting a load cooler, comprising: a load cooler, a compressor, a heat accumulator, a condenser or gas cooler, a liquid receiver, and an expansion valve, which are connected in this order by refrigerant piping; a cooling circuit through which a cooling refrigerant flows stores heat through a heat accumulator and cools the load cooler; and a defrost circuit that circulates heat between the load cooler and the heat accumulator dissipates heat through the heat accumulator and defrosts the load cooler,
The heat storage unit is installed at a lower level than the heat exchanger installed at the lowest level;
a heat exchanger for exchanging heat between the cooling refrigerant of the cooling circuit and the defrost heat medium of the defrost circuit is provided below the load cooler and above the heat accumulator;
The cooling refrigerant of the cooling circuit forms a first loop-type thermosiphon circulation path between the heat exchanger and the load cooler, and the defrost heat medium of the defrost circuit forms a second loop-type thermosiphon circulation path between the heat exchanger and the heat accumulator,
a step of storing heat in the heat accumulator by performing a cooling operation on the load cooler using the cooling circuit;
The defrosting heat medium stored in the heat storage step is circulated between the heat exchanger and the heat accumulator through a loop-type thermosiphon type second circulation path, while the cooling refrigerant of the cooling circuit is circulated between the heat exchanger and the load cooler through a loop-type thermosiphon type first circulation path, thereby performing a defrosting operation of the load cooler with the cooling refrigerant heated by the defrosting heat medium.
A method for defrosting a load cooler comprising the steps of: The load cooler is provided in a plurality of units, at least some of which are installed at different levels;
The defrost circuit is provided with a defrost heat medium forward path through which a defrost heat medium gas heated by the heat accumulator flows from the heat accumulator toward the heat exchanger, and a defrost heat medium return path through which a defrost heat medium liquid cooled by the heat exchanger flows from the heat exchanger toward the heat accumulator,
The defrosting method for a load cooler as described in claim 9, further comprising providing a receiver for the defrosting heat medium in the defrosting heat medium return path so that the liquid level of the defrosting heat medium is lower than the lowest heat exchanger and higher than the heat accumulator. The defrosting method for a load cooler according to claim 9, wherein the defrosting operation step includes a step of cooling one of the plurality of load coolers to store heat in a heat storage device while simultaneously performing a defrosting operation on one of the remaining plurality of load coolers. The defrosting method for a load cooler according to claim 9, wherein the defrosting operation step includes a step of defrosting all or any of the plurality of load coolers while stopping the cooling operation of all of the plurality of load coolers. The refrigeration device according to claim 1, wherein in the first loop-type thermosiphon circulation path, the first defrost refrigerant line is a defrost refrigerant forward line through which the defrost refrigerant flows from the refrigerant return line side of the heat transfer tube to the heat exchanger, and the second defrost refrigerant line is a defrost refrigerant return line through which the defrost refrigerant flows from the heat exchanger to the refrigerant forward line side of the heat transfer tube, and the defrost refrigerant forward line is provided with an on-off valve, and the defrost refrigerant return line is provided with a check valve that allows only flow from the heat exchanger to the refrigerant forward line. 2. The refrigeration apparatus according to claim 1, wherein in the first loop-type thermosiphon circulation path, the first defrost refrigerant pipe is a defrost refrigerant return path through which the defrost refrigerant flows from the heat exchanger to the refrigerant return path side of the heat transfer tube, and the second defrost refrigerant pipe is a defrost refrigerant outward path through which the defrost refrigerant flows from the refrigerant outward path side of the heat transfer tube to the heat exchanger, and the defrost refrigerant outward path is provided with an opening/closing valve, and the defrost refrigerant return path is provided with a check valve that allows only a flow from the heat exchanger to the refrigerant return path.

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