JP2010078309A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and compact cooling device without causing increases of circulation resistance of coolant, coolant filling quantity in a circuit, and cross-sectional area of each passage while maintaining desired cooling efficiency in the natural circulation circuit wherein natural convection of the coolant is caused by using a thermosiphon. <P>SOLUTION: A secondary cooling device 40 includes a secondary heat exchange part 42 of a cascade heat exchanger HE liquifying a gaseous phase secondary coolant, and an evaporator EP vaporizing a liquid phase secondary coolant. The secondary cooling device 40 includes a plurality of the natural circulation circuits 48 equipped with liquid piping 44 and gas piping 46 connecting the secondary heat exchange part 42 and the evaporator EP. In the evaporator EP, evaporation paths 52 of the natural circulation circuit 48 are provided in vertically separated layers. The evaporation path 52 is composed of a spiral fin tube type heat exchanger spirally wound with fins on an outer circumference of a steam generating tube carrying the secondary coolant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling device including a natural circulation circuit that naturally convects a refrigerant by using a temperature gradient between a heat exchange unit and an evaporator.

  A cooling device using a thermosiphon that naturally convects a refrigerant is employed in a storage facility such as a refrigerator or an air conditioning facility (see, for example, Patent Document 1). As shown in FIG. 20, the cooling device using the thermosyphon is a condenser 64 that condenses the vaporized refrigerant to form a liquefied refrigerant, and is disposed below the condenser 64 to evaporate the liquefied refrigerant and vaporize the refrigerant. The evaporator 66 is configured to flow down the liquefied refrigerant from the condenser 64 to the evaporator 66 through the liquid pipe 68, and the vaporized refrigerant is circulated from the evaporator 66 to the condenser 64 through the gas pipe 70. A natural circulation circuit 72 is configured.

  In the condenser 64 and the evaporator 66, the refrigerant flowing through the refrigerant paths 64a and 66a provided therein exchanges heat with other media such as outside air and water, so that the refrigerant is condensed or evaporated. . That is, since the cooling efficiency of the cooling device depends on the amount of heat exchanged between the refrigerant and the other medium, the cooling device is provided with meandering refrigerant paths 64a and 66a in the condenser 64 and the evaporator 66. Thus, the contact area (hereinafter referred to as heat exchange area) between the refrigerant paths 64a and 66a and the other medium is increased.

  Further, as the form of the evaporator 66, a refrigerant path includes a straight pipe penetrating a plurality of parallel flat fins and a bent part bent in a U shape welded to an end of the straight pipe. A so-called fin-and-tube heat exchanger in which 66a is formed in a meandering shape is employed (see, for example, Patent Document 1). This fin-and-tube heat exchanger is widely used as an air-cooled heat exchanger because it has a feature that the pipe density can be improved relatively easily. As another form of the evaporator, there is also known a spiral fin tube type heat exchanger in which fins are spirally wound around the outer periphery of an evaporation pipe through which a refrigerant flows and bent in a meandering manner.

JP 63-96463 A

  In the cooling device, when a pipe length necessary to secure a heat exchange area that can achieve a required cooling efficiency is set, the refrigerant paths 64a and 66a become longer, and the refrigerant flow resistance in the paths 64a and 66a increases. At the same time, since the lengths of the refrigerant paths 64a and 66a are made compact in order to make the refrigerant paths 64a and 66a longer, the flow resistance of the refrigerant is further increased. Further, in the method using a thermosyphon like a cooling device, since the refrigerant is naturally convected using the temperature gradient between the condenser 64 and the evaporator 66, the refrigerant is forcedly circulated by a pump or the like. In comparison, the circulating force of the refrigerant is weak, and the smooth flow of the refrigerant is greatly hindered by a slight pressure loss and flow resistance against the refrigerant. If the refrigerant does not flow smoothly in the refrigerant paths 64a and 66a, the refrigerant circulation in the natural circulation circuit 72 including the evaporator 66 is deteriorated, or the refrigerant flows backward to carry cold heat. A problem occurs in that the capacity is reduced and the object cannot be efficiently cooled. Therefore, in the cooling device, in order not to lower the cooling efficiency, the cross-sectional area of the refrigerant paths 64a and 66a is set large according to the circulation amount of the refrigerant to reduce the flow resistance of the refrigerant, thereby reducing a slight pressure loss. It is necessary to stabilize the flow state of the refrigerant that is greatly affected. However, since the pipes constituting the refrigerant paths 64a and 66a are increased in diameter, restrictions on forming the refrigerant path are increased, and the condenser 64 and the evaporator 66 are increased in size, resulting in an increase in cost. It will be connected.

  Here, the fin-and-tube heat exchanger can increase the density of the pipe, but on the other hand, since the straight pipe and the bend are welded, there are a plurality of welds in the refrigerant flow path. There is a drawback that the reliability against leakage is low. Moreover, in the fin-and-tube heat exchanger, when the interval between the flat fins is narrowed to improve the heat exchange efficiency, the flat fins are connected to all adjacent straight pipes. It was a structure in which frost easily grows on the fins between the matching straight pipes, and the gap between the pipes is blocked with frost, and the air flow is hindered.

  On the other hand, unlike the fin-and-tube heat exchanger, the spiral fin tube type heat exchanger does not require welding of pipes or pipe expansion in the manufacturing process, and the manufacturing process is large. In addition to simplification, there is an advantage that the reliability of refrigerant leakage is high because there is no pipe weld in the refrigerant flow path. In addition, the spiral fin tube type heat exchanger has a structure in which fins are wound spirally around the evaporation tube, so that even if the fin pitch of the fins is narrowed to improve heat exchange efficiency, the fins of adjacent straight pipes are mutually connected. Because it is not in contact with the fin, even if frost grows on the fin, the gap between the pipes is not easily blocked, and clogging due to frost formation is difficult to occur.

  However, since the spiral fin tube type heat exchanger bends the evaporator tube after the fins are wound, if the evaporator tube is enlarged to reduce the flow resistance of the refrigerant as described above, the minimum bending radius is reduced. And the pipe density is sparse, making it difficult to make the evaporator compact. For this reason, it is difficult to increase the pipe density of the evaporator tube to the same level as the fin-and-tube heat exchanger, and as an evaporator of a cooling device using a thermosyphon, The present situation is that a spiral fin tube type heat exchanger, which is excellent in terms of cost, reliability against refrigerant leakage, and suppression of clogging due to frost, is not employed.

  The structure for improving the cooling efficiency by the cooling device as described above and the spiral fin tube type heat exchanger can be adopted by increasing the size of the heat exchanger. However, in refrigerators in which cooling devices are used, increasing the internal volume is one of the commercial values. To ensure this, the internal heat exchanger (evaporator) can be designed compactly. It is important and it is difficult to increase the size of the heat exchanger easily. Rather, there is a need for a more compact design of the internal heat exchanger (evaporator). That is, there is a demand for a cooling device for efficiently performing heat exchange in a limited space.

  That is, the present invention has been proposed in order to suitably solve these problems inherent in the cooling device according to the prior art, and in a natural circulation circuit in which a refrigerant naturally convects using a thermosiphon, An object of the present invention is to provide an inexpensive and compact cooling device without increasing the flow resistance of the refrigerant, the refrigerant filling amount in the circuit, and the cross-sectional area of each path while maintaining the desired cooling efficiency.

In order to overcome the above-mentioned problems and achieve the intended object, the cooling device of the invention according to claim 1 of the present application includes:
A heat exchange section that condenses the vaporized refrigerant flowing through the condensation path to form a liquefied refrigerant, and a tubular evaporation that is disposed below the heat exchange section and evaporates the liquefied refrigerant flowing through the internal evaporation path to form a vaporized refrigerant. A liquefied refrigerant is allowed to flow from the condensation path of the heat exchange section to the evaporation path via the liquid pipe, and the vaporized refrigerant is circulated from the evaporation path to the condensation path of the heat exchange section via the gas pipe. In a cooling device provided with a natural circulation circuit,
A plurality of natural circulation circuits independent of each other and an evaporator constituted by a set of evaporation pipes of the plurality of natural circulation circuits are used, and carbon dioxide is used as a refrigerant circulating in each natural circulation circuit,
Each of the evaporation pipes is formed by bending in a meandering manner so that a linear portion extends in a lateral direction intersecting a flow direction of air flowing through the evaporation pipe group,
The liquid pipe is connected to a portion of the evaporation pipe downstream in the air flow direction, and the gas pipe is connected to a portion of the evaporation pipe upstream of the air flow direction,
The plurality of evaporation tubes are arranged in a layered relationship in an up-down relationship in a state of being separated from each other.

According to the first aspect of the present invention, the condensing path and the evaporating path are the liquid pipe and the gas pipe so that each natural circulation circuit forms one circuit independently of each other without branching of the path or the pipe. Connected with. Then, by providing the cooling device with the number of natural circulation circuits corresponding to the heat exchange area required in the heat exchange section and the evaporator, the necessary condensation path and evaporation path are arranged in the heat exchange section and the evaporator. The heat exchange area required for the entire circuit can be ensured. Thereby, the heat exchange area required per one condensation path and evaporation path is reduced, and the required length of each condensation path and each evaporation path can be suppressed. Since the length of each condensation path and each evaporation path is shortened, the flow resistance derived from the length of the path is reduced, and the flow resistance derived from the bent portion of the path can be reduced by reducing the number of times of meandering. It becomes. As a result, each condensing path and each evaporating path can be set with a smaller cross-sectional area than in the past, which was impossible because the flow resistance was too high in the past, and the amount of refrigerant flowing through each condensing path and each evaporating path was reduced. Can be reduced. In this way, the length and cross-sectional area of each condensing path and each evaporating path can be reduced, so that the heat exchange section and the evaporator can be made compact, and the circuit pressure can be reduced by reducing the amount of circulating refrigerant. Since the incidental facilities such as the capacity of the expansion tank that alleviates the rise are also reduced, the overall size can be reduced and the cost can be reduced. And since each natural circulation circuit is mutually independent, the drift of a refrigerant | coolant does not arise easily and a refrigerant | coolant can be smoothly convected naturally.
In addition, it is configured so that the refrigerant flows from the downstream side to the upstream side in the flow direction of the air flowing through the evaporator tube group, and by using carbon dioxide having excellent heat transfer performance as the refrigerant, the heat exchange efficiency in the evaporator is improved. A small-diameter evaporator tube with a small heat exchange area can be adopted without lowering, and the cost of the evaporator can be reduced and further downsizing can be achieved. Furthermore, the plurality of evaporator tubes function as an evaporator having high heat exchange efficiency by a configuration in which the evaporator tubes are arranged in a layered relationship in an up-down relationship in a state of being separated from each other.

In order to overcome the above-mentioned problems and achieve the intended purpose, the cooling device of the invention according to claim 2 of the present application includes:
A heat exchange section that condenses the vaporized refrigerant flowing through the condensation path to form a liquefied refrigerant, and a tubular evaporation that is disposed below the heat exchange section and evaporates the liquefied refrigerant flowing through the internal evaporation path to form a vaporized refrigerant. A liquefied refrigerant is allowed to flow from the condensation path of the heat exchange section to the evaporation path via the liquid pipe, and the vaporized refrigerant is circulated from the evaporation path to the condensation path of the heat exchange section via the gas pipe. In a cooling device provided with a natural circulation circuit,
The natural circulation circuit includes an evaporator constituted by a set of a plurality of evaporation tubes, and the same number of condensation paths as the plurality of evaporation tubes, and uses carbon dioxide as a refrigerant circulating in the natural circulation circuit,
The liquid pipe connected to the outflow end of the condensing path is connected to the evaporation pipe connected to the gas pipe connected to the inflow end of the condensing path and to the evaporating pipe connected to the outflow end of the evaporation pipe. Connect the pipe to a condensation path that is connected to the condensation pipe connected to the liquid pipe connected to the inflow end of the evaporation pipe to form one natural circulation circuit as a whole,
Each of the evaporation pipes is formed by bending in a meandering manner so that a linear portion extends in a lateral direction intersecting a flow direction of air flowing through the evaporation pipe group,
The liquid pipe is connected to a portion of the evaporation pipe downstream in the air flow direction, and the gas pipe is connected to a portion of the evaporation pipe upstream of the air flow direction,
The plurality of evaporation tubes are arranged in a layered relationship in an up-down relationship in a state of being separated from each other.

According to the second aspect of the present invention, the condensing path and the evaporation path are connected by the liquid pipe and the gas pipe so as to constitute one natural circulation circuit as a whole without branching the path or the pipe. That is, the number of condensation paths and evaporation paths corresponding to the heat exchange areas required in the heat exchange unit and the evaporator can be appropriately arranged. Thereby, the heat exchange area required per one condensation path and evaporation path is reduced, and the required length of each condensation path and each evaporation path can be suppressed. Since the length of each condensation path and each evaporation path is shortened, the flow resistance derived from the length of the path is reduced, and the flow resistance derived from the bent portion of the path can be reduced by reducing the number of times of meandering. It becomes. As a result, each condensing path and each evaporating path can be set with a smaller cross-sectional area than in the past, which was impossible because the flow resistance was too high in the past, and the amount of refrigerant flowing through each condensing path and each evaporating path was reduced. Can be reduced. In this way, the length and cross-sectional area of each condensing path and each evaporating path can be reduced, so that the heat exchange section and the evaporator can be made compact, and the circuit pressure can be reduced by reducing the amount of circulating refrigerant. Since the incidental facilities such as the capacity of the expansion tank that alleviates the rise are also reduced, the overall size can be reduced and the cost can be reduced. In addition, even if a plurality of condensation paths and a plurality of evaporation paths are provided, the entire circuit is one natural circulation circuit without any branching of the paths and pipes. The refrigerant circulates in a well-balanced manner, so that the refrigerant does not drift, and the refrigerant can be smoothly convected naturally.
In addition, it is configured so that the refrigerant flows from the downstream side to the upstream side in the flow direction of the air flowing through the evaporator tube group constituting the evaporator, and by using carbon dioxide having excellent heat transfer performance as the refrigerant, Therefore, it is possible to employ a small-diameter evaporator tube having a small heat exchange area without lowering the heat exchange efficiency, thereby reducing the cost of the evaporator and making it more compact. Furthermore, the plurality of evaporator tubes function as an evaporator having high heat exchange efficiency by a configuration in which the evaporator tubes are arranged in a layered relationship in an up-down relationship in a state of being separated from each other.

The gist of the invention of claim 3 is that the inflow end to which the liquid pipe of the evaporation path is connected is located below the outflow end to which the gas pipe is connected.
According to the invention which concerns on Claim 3, the circulation of the refrigerant | coolant which evaporates with an evaporator can be performed rapidly by positioning the inflow end of an evaporation path below the outflow end.

In the invention according to claim 4, each of the evaporation pipes is formed in a step shape in the flow direction of the air flowing through the evaporation pipe group by the step portion in which the linear portion is arranged so that at least a part thereof overlaps vertically. The gist of the plurality of evaporating tubes formed in a staircase shape is that they are arranged in a layered manner so that each step is in a vertical relationship.
According to the invention of claim 4, the heat exchange length in each of the evaporation tubes is set on the same plane by forming the evaporation tubes in a stepped manner by the stepped portion in which the linear portion is arranged so that at least a part thereof overlaps vertically. Therefore, the cost can be reduced by forming an evaporator having the same capacity with a small number of evaporator tubes.

In the invention according to claim 5, a heat transfer promoting member is disposed around the outer periphery of the evaporation tube, and the heat transfer promoting members of adjacent straight portions of the evaporation tube bent in a meandering manner are separated from each other. Configured to
The gist of the plurality of evaporation tubes is that they are arranged in a layered relationship in an up-and-down relationship with the heat transfer promoting members spaced apart from each other.
According to the invention which concerns on Claim 5, while adopting a spiral fin tube type heat exchanger, the cost of an evaporator can be reduced, the reliability with respect to a refrigerant | coolant leakage can be improved, and also heat exchange Generation of clogging due to frost can be suppressed while improving efficiency. In addition, although it is difficult to raise the pipe density as a concern for the spiral fin tube type heat exchanger, the excellent heat transfer performance of carbon dioxide used as a refrigerant is a pipe formed with a low pipe density. In order to compensate the heat transfer performance on the refrigerant side of the group, it can function properly as an evaporator.

The gist of the invention according to claim 6 is that the natural circulation circuit is thermally connected to the mechanical compression primary circuit for forcibly circulating the refrigerant through the heat exchange section.
According to the invention of claim 6, by using the natural circulation circuit as the secondary side in the equipment constituting the so-called secondary loop refrigeration circuit, the entire equipment can be made compact and inexpensive without impairing the desired cooling efficiency. It can be configured.

  According to the cooling device of the present invention, while maintaining a desired cooling efficiency, it is inexpensive and compact without causing an increase in the flow resistance of the refrigerant, the refrigerant filling amount in the circuit, and the cross-sectional area of each path. Can do.

It is side sectional drawing which shows the refrigerator provided with the cooling device which concerns on suitable Example 1 of this invention as a secondary circuit of cooling equipment. It is a schematic circuit diagram which shows the principal part of the cooling equipment provided with the cooling device of Example 1 as a secondary circuit. FIG. 3 is a front view of a principal part showing an evaporation path according to the first embodiment. 2 is a plan view showing an evaporation path according to Embodiment 1. FIG. 1 is a schematic side view showing an evaporator according to Embodiment 1. FIG. It is a schematic circuit diagram which shows the principal part of the cooling equipment provided with the cooling device which concerns on suitable Example 2 of this invention as a secondary circuit. It is a schematic side view which shows the evaporator which concerns on the example of a change. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the example of a change which provided the heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the modification which does not provide a heat-transfer promotion member. It is a schematic perspective view which shows the evaporation pipe which concerns on the modification which does not provide a heat-transfer promotion member. It is a schematic side view which shows the evaporator which concerns on another modification. It is the schematic which shows the natural circulation circuit of the cooling device which concerns on a prior art.

  In recent years, in facilities equipped with a cooling device such as a refrigerator or a freezer, the use of CFC as a refrigerant is restricted from the viewpoint of preventing global warming. In particular, large facilities such as commercial refrigeration equipment use a large amount of chlorofluorocarbon, so there is a great demand for reducing the amount of chlorofluorocarbon or non-fluorocarbon. Therefore, a secondary loop refrigeration circuit, which is an advantageous circuit configuration for promoting non-fluorocarbons, has attracted attention. The secondary loop refrigeration circuit is a cascade heat exchanger that combines two independent circuits, a mechanical compression primary circuit that forcibly circulates the refrigerant and a secondary circuit that naturally convects the refrigerant using a thermosiphon. A heat medium other than chlorofluorocarbon can be used as a refrigerant to be circulated through each circuit. However, the conventional secondary loop type refrigeration circuit has the disadvantages that the entire apparatus is enlarged and requires a large installation area and costs are increased as compared with a mechanical compression type refrigeration circuit using chlorofluorocarbon as a refrigerant. Therefore, it is not competitive in terms of size and price compared to conventional chlorofluorocarbon equipment, which hinders the promotion of non-fluorocarbons. Therefore, the inventor has invented the cooling device according to the present invention having a compact and inexpensive configuration without impairing the desired cooling efficiency. For example, by applying the cooling device according to the present invention to a secondary loop refrigeration circuit, designing a facility equipped with a secondary loop refrigeration circuit at the same size and cost as a conventional chlorofluorocarbon facility. And the above-mentioned drawbacks are eliminated, and the competitiveness in the market can be acquired. That is, the cooling device according to the present invention has an effective technical position in promoting the spread of non-fluorocarbon technology using a secondary loop refrigeration circuit, which is regarded as important from the viewpoint of preventing global warming. Yes. As described above, the cooling device according to the present invention can be applied to the secondary loop refrigeration circuit to eliminate the large-scale and expensive disadvantages of the conventional secondary loop refrigeration circuit and can be widely spread. It is a very meaningful invention that can be a technology.

  Next, the cooling device according to the present invention will be described below with reference to the accompanying drawings by way of preferred embodiments. In the embodiment, a large refrigerator that can be used for business use such as a store and can store a large amount of articles such as vegetables and meat is taken as an example, and the cooling device according to the present invention is used as a cooling facility for the refrigerator on the secondary side. A case where a so-called secondary loop refrigeration circuit used in this circuit is employed will be described.

  As shown in FIG. 1, the refrigerator 10 is provided with a box body (heat insulation box body) 12 having a heat insulation structure in which a storage chamber 14 is defined, and an outer wall formed by a metal panel 18 provided above the box body 12. Cabinet 16. The box body 12 has an opening 12a that opens to the front side and serves as an entry / exit port for communicating with the storage chamber 14, and the opening 12a can be opened and closed to the front of the box body 12 by a hinge (not shown). The heat insulating door 22 supported by

  Inside the cabinet 16 is a machine room 20 in which a part of the cooling equipment 32 for cooling the storage room 14 and a control electrical box (not shown) for controlling the cooling equipment 32 are arranged. Made. At the bottom of the machine room 20, a base plate 24 that is placed on the top plate 12 b of the box 12 and serves as a common substrate for the devices disposed in the machine room 20 is installed. The metal panel 18 forming the outer wall of the cabinet 16 is provided with air circulation holes (not shown) communicating with the machine room 20 at appropriate locations, and the atmosphere in the machine room 20 and the outside air are communicated through the air circulation holes. And are to be replaced.

  In the upper part of the storage chamber 14, a cooling duct 26 is disposed at a predetermined distance from the lower surface of the top plate 12b in the box 12, and the cooling duct 26 and a notch formed in the top plate 12b of the box 12 are provided. A cooling chamber 28 is defined between the base plate 24 facing the storage chamber 14 via 12c. The cooling chamber 28 communicates with the storage chamber 14 via a suction port 26 a formed on the front side of the bottom of the cooling duct 26 and a cold air outlet 26 b formed on the rear side. A blower fan 30 is disposed at the suction port 26a. By driving the blower fan 30, the air in the storage chamber 14 is taken into the cooling chamber 28 from the suction port 26a, and the cool air in the cooling chamber 28 is drawn from the cool air outlet 26b. It is sent to the storage chamber 14. The notch 12c of the top plate 12b is hermetically closed by the base plate 24, and the storage chamber 14 (cooling chamber 28) and the machine room 20 are separated from each other by the base plate 24 and become independent spaces. (See FIG. 1).

  FIG. 2 is a schematic circuit diagram illustrating a cooling facility 32 including a secondary cooling device (cooling device) 40 according to the first embodiment as a secondary circuit. As shown in FIG. 2, the cooling facility 32 cascades a mechanical compression primary cooling device (primary circuit) 34 that forcibly circulates a refrigerant and a secondary cooling device 40 that includes a thermosiphon that naturally convects the refrigerant. A secondary loop refrigeration circuit that is thermally connected (cascade connected) so as to exchange heat via the heat exchanger HE is employed. The cascade heat exchanger HE is installed in the machine room 20 and formed in a separate system from the primary heat exchange unit 36 that constitutes the primary cooling device 34 and the primary heat exchange unit 36, and constitutes the secondary cooling device 40. A secondary heat exchanging section (heat exchanging section) 42. That is, the primary cooling device 34 and the secondary cooling device 40 are each formed with a circuit in which independent refrigerant circulates, and the secondary refrigerant (refrigerant) circulating through the secondary cooling device 40 has low viscosity and heat transfer. Highly safe carbon dioxide, which has high rate characteristics and is not toxic, flammable or corrosive, is employed. On the other hand, as the primary refrigerant circulating in the primary cooling device 34, an HC refrigerant such as butane or propane having excellent characteristics as a refrigerant such as heat of evaporation or saturation pressure, ammonia, or the like is employed. In isobutane and propane are used. That is, the cooling facility 32 does not need to use chlorofluorocarbon as a refrigerant. In addition, as the cascade heat exchanger HE, for example, a plate type, a double pipe type and the developed type thereof or the like are adopted.

  The primary cooling device 34 includes a compressor CM that compresses the gas phase primary refrigerant, a condenser CD that liquefies the compressed primary refrigerant, an expansion valve EV that reduces the pressure of the liquid primary refrigerant, and a liquid primary refrigerant. A primary heat exchanging portion 36 of the vaporizing cascade heat exchanger HE is connected by a refrigerant pipe 38 (see FIG. 2). The compressor CM and the condenser CD are commonly arranged on the base plate 24 in the machine room 20, and a condenser fan FM for forcibly cooling the condenser CD is also provided on the base plate 24 so as to face the condenser CD. It is arranged. In the primary cooling device 34, the compression of the primary refrigerant by the compressor CM forces the primary refrigerant in the order of the compressor CM, the condenser CD, the expansion valve EV, the primary heat exchange unit 36 of the cascade heat exchanger HE, and the compressor CM. Circulated and required cooling is performed in the primary heat exchange section 36 under the action of each device (see FIG. 2).

  The secondary cooling device 40 is a set of a secondary heat exchange unit 42 of a cascade heat exchanger HE that liquefies a gas phase secondary refrigerant (vaporized refrigerant) and a pipe that vaporizes the liquid phase secondary refrigerant (liquefied refrigerant). The evaporator EP comprised is comprised, and the secondary heat exchange part 42 and the evaporator EP respond | correspond in the one-to-one relationship (refer FIG. 2). Further, the secondary cooling device 40 includes a liquid pipe 44 and a gas pipe 46 that connect the secondary heat exchange unit 42 and the evaporator EP, and gravity is passed from the secondary heat exchange unit 42 to the evaporator EP via the liquid pipe 44. A natural circulation circuit 48 is provided that supplies the liquid phase secondary refrigerant under the action of the above and recirculates the gas phase secondary refrigerant from the evaporator EP to the secondary heat exchange section 42 via the gas pipe 46. In the secondary cooling device 40 of the first embodiment, a plurality of independent natural circulation circuits 48 (in the illustrated example, three circuits but two or more) may be constructed in parallel. The secondary heat exchange unit 42 is disposed in the machine room 20, while the evaporator EP is disposed in a cooling chamber 28 (inside the box body 12) located below the machine room 20. The evaporator EP is disposed below the secondary heat exchange unit 42 with the plate 24 interposed therebetween.

  The secondary heat exchanging section 42 is provided with a plurality of condensing paths 50 (three in the first embodiment) in parallel. The evaporator EP is provided with a plurality of evaporation paths 52 (three in the first embodiment) in parallel. In FIG. 2, the condensation path 50 is represented by a straight path from the inflow end 50 a connecting to the gas pipe 46 to the outflow end 50 b connecting to the liquid pipe 44, and from the inflow end 52 a connecting the evaporation path 52 to the liquid pipe 44. Although the straight path is shown to the outflow end 52b connected to the gas pipe 46, the condensing path 50 may be meandered or formed in a straight line. However, as will be described later, the evaporation path 52 is bent so as to meander. Here, in the secondary cooling device 40, the same number of the plurality of condensation paths 50, the plurality of evaporation paths 52, the plurality of liquid pipes 44, and the plurality of gas pipes 46 are provided. In each natural circulation circuit 48, the liquid pipe 44 is piped through the base plate 24 by connecting the upper end (starting end) to the outflow end 50 b of the condensing path 50 in the secondary heat exchange section 42, and to the cooling chamber 28 side. The lower end (end) located is connected to the inflow end 52a of the evaporation path 52 in the evaporator EP. In each natural circulation circuit 48, the gas pipe 46 is piped through the base plate 24 with the lower end (starting end) located on the cooling chamber 28 side connected to the outflow end 52b of the evaporation path 52 in the evaporator EP. The upper end (termination) located on the chamber 20 side is connected to the inflow end 50 a of the condensation path 50 in the secondary heat exchange section 42. Reference numeral 54 denotes a refrigerant charge port provided to fill each natural circulation circuit 48 with a refrigerant.

  In the secondary cooling device 40, in each natural circulation circuit 48, a temperature gradient is formed between the secondary heat exchanger 42 and the evaporator EP that are cooled by heat exchange with the primary heat exchanger 36 that is forcibly cooled. Thus, a refrigerant circulation cycle is formed in which the secondary refrigerant naturally convects through the secondary heat exchange unit 42, the liquid pipe 44, the evaporator EP, and the gas pipe 46 and returns to the secondary heat exchange unit 42 again.

  As shown in FIG. 3, the evaporation path 52 includes a spiral fin tube type heat exchanger 55 in which fins (heat transfer promotion members) 58 are spirally wound around the outer periphery of an evaporation pipe 56 through which a secondary refrigerant flows. Then, the evaporation pipe 56 is formed by bending it into a meandering shape composed of a straight portion 56a and a bent portion 56b (see FIG. 4). Further, the interval between the adjacent linear portions 56a and 56a is set to a dimension such that the fins 58 and 58 disposed in the respective linear portions 56a and 56a are not in contact with each other so that the fins 58 and 58 are separated from each other. Composed. The evaporation pipe 56 is bent so that all the straight portions 56a and the bent portions 56b are positioned on one plane (hereinafter referred to as an installation plane), and the installation plane is at a predetermined angle with respect to the horizontal plane. (See FIG. 5). The liquid pipe 44 is connected to the straight line portion 56a located on the inclined lower end side, and the gas pipe 46 is connected to the straight line portion 56a located on the inclined upper end side, so that the inflow in the evaporation path 52 (evaporation pipe 56). The end 52a is positioned below the outflow end 52b. Further, as shown in FIG. 4, each linear portion 56 a extends in a transverse direction intersecting with the air flow flowing through the evaporator EP (evaporation pipe 56 group) generated when the blower fan 30 is driven. At the same time, the upper inclined side of the installation plane is set on the upstream side in the air flow direction, and the lower end side of the inclination is set on the downstream side in the air flow direction (see FIG. 5). That is, the plurality of straight portions 56a constituting the evaporation pipe 56 are arranged so as to sequentially shift from the downstream side in the flow direction of the air flowing through the evaporator EP to the upstream side. Therefore, the liquid refrigerant (refrigerant) that has flowed into the evaporation pipe 56 from the liquid pipe 44 has bent portions 56b sequentially from the straight line portion 56a on the most downstream side in the air flow direction to the straight line portion 56a on the upstream side, as shown in FIG. Inflow is repeated, and finally flows out from the straight portion 56a on the most upstream side in the air flow direction to the gas pipe 46.

  As shown in FIG. 5, the respective evaporation pipes 56 are arranged in layers in a parallel relationship with the arrangement plane of the evaporation pipes 56 spaced apart in the vertical direction. Further, the fins 58, 58 of the evaporation pipes 56, 56 positioned above and below are set so as to be separated from each other. In the first embodiment, the refrigerant inflow end 52a and the outflow end 52b of each evaporation path 52 are arranged in a positional relationship in which they are aligned in the vertical direction.

[Operation of Example 1]
Next, the effect | action of the cooling equipment 32 provided with the secondary cooling device 40 which concerns on Example 1 is demonstrated. In the cooling facility 32, when the cooling operation is started, circulation of the refrigerant is started in each of the primary cooling device 34 and the secondary cooling device 40. First, the primary cooling device 34 will be described. The compressor CM and the condenser fan FM are driven, the gas-phase primary refrigerant is compressed by the compressor CM, and this primary refrigerant is supplied to the condenser CD through the refrigerant pipe 38. Then, the liquid phase is obtained by condensing and liquefying by forced cooling by the condenser fan FM. The liquid phase primary refrigerant is decompressed by the expansion valve EV, and in the primary heat exchanging part 36 of the cascade heat exchanger HE, it takes heat from the secondary refrigerant flowing through the secondary heat exchanging part 42 (endothermic) and expands and vaporizes all at once. . Thus, the primary cooling device 34 functions to forcibly cool the secondary heat exchange unit 42 by the primary heat exchange unit 36 in the cascade heat exchanger HE. Then, the gas phase primary refrigerant evaporated in the primary heat exchange unit 36 repeats the forced circulation cycle that returns to the compressor CM through the refrigerant pipe 38.

  In the secondary cooling device 40, the secondary heat exchanging section 42 is cooled by the primary heat exchanging section 36, so that in the natural circulation circuit 48, air is circulated through each condensation path 50 of the secondary heat exchanging section 42. The phase secondary refrigerant dissipates heat and condenses, and the specific gravity increases as the state changes from the gas phase to the liquid phase. Therefore, the liquid phase secondary refrigerant flows along the respective condensation paths 50 of the secondary heat exchange unit 42 under the action of gravity. The next refrigerant flows down. In the secondary cooling device 40, the secondary heat exchange unit 42 is disposed in the machine room 20, while the evaporator EP is disposed in the cooling chamber 28 located below the machine room 20, thereby the secondary heat exchange unit 42. And an evaporator EP are provided with a head. That is, in each natural circulation circuit 48, the liquid phase secondary refrigerant is directed to the evaporator EP configured by a set of a plurality of evaporation pipes 56 through the liquid pipe 44 connected to the lower part of the secondary heat exchange unit 42. Can flow naturally under the action of gravity. In the process of flowing through the respective evaporation paths 52 of the evaporator EP, the liquid secondary refrigerant evaporates by taking heat from the ambient atmosphere of the evaporator EP constituted by the collection of the evaporation pipes 56 and moves to the gas phase. The gas phase secondary refrigerant is refluxed from the evaporator EP to the secondary heat exchanging section 42 via the gas pipe 46, and the secondary cooling device 40 does not use power from a pump, a motor, or the like in each natural circulation circuit 48. The cycle in which the secondary refrigerant naturally circulates with a simple configuration is repeated.

  The air in the storage chamber 14 sucked into the cooling chamber 28 from the suction port 26a by the blower fan 30 is blown to the cooled evaporator EP, thereby exchanging heat with the evaporator EP configured by a set of the evaporation pipes 56. Air becomes cold. The storage chamber 14 is cooled by sending the cool air from the cooling chamber 28 to the storage chamber 14 via the cool air outlet 26b. The cold air circulates inside the storage chamber 14 and repeats a cycle of returning to the cooling chamber 28 again through the suction port 26a. In this case, in the evaporation path 52 in each natural circulation circuit 48, the straight portion 56a connected to the liquid pipe 44 is located on the most downstream side in the air flow direction, and the straight portion 56a connected to the gas pipe 46 flows in the air flow. Since the high-temperature air and the refrigerant exchange heat at the outflow end 52b side and vaporize, the circulation of the secondary refrigerant is promoted, and the heat in the evaporator EP is obtained. Exchange is performed efficiently. In addition, by using carbon dioxide having excellent heat transfer performance as the secondary refrigerant, more efficient heat exchange is achieved in the evaporator EP configured by the collection of the evaporator tubes 56. That is, it is configured such that the refrigerant flows from the downstream side to the upstream side in the flow direction of the air flowing through the evaporator EP, and the heat in the evaporator EP is obtained by using carbon dioxide having excellent heat transfer performance as the secondary refrigerant. Exchange efficiency can be improved. Therefore, even if a small diameter small heat exchange area is adopted as the evaporation pipe 56 of the heat exchanger 55, it is possible to suppress the heat exchange efficiency in the evaporator EP from being lowered. The evaporator EP itself can be made compact. Even if the pipe density decreases due to the adoption of the spiral fin tube type heat exchanger 55, the excellent heat transfer performance of carbon dioxide used as the secondary refrigerant compensates for the decrease in heat transfer performance due to the decrease in pipe density. It can function properly as an evaporator EP. Further, since the refrigerant outflow end 52b in the evaporation path 52 faces a position higher than the inflow end 52a, the vaporized secondary refrigerant can be circulated quickly.

  In the secondary cooling device 40, the condensing path 50 and the evaporating path 52 are connected to the liquid pipe 44 and the evaporating path 52 so that each natural circulation circuit 48 forms one circuit independently of each other without any branching of the path or piping. They are connected by a gas pipe 46. Thus, since each natural circulation circuit 48 is independent from each other, secondary refrigerant is unevenly distributed between the condensation paths 50 and 50 and between the evaporation paths 52 and 52 or between the condensation path 50 and the evaporation path 52. Can be suppressed, and the amount of secondary refrigerant flowing through each condensation path 50 and each evaporation path 52 can be matched.

  Further, the secondary refrigerant circulating in each natural circulation circuit 48 may be unevenly distributed in either the condensation path 50 or the evaporation path 52 due to external factors such as fluctuations in the outside air temperature acting on the secondary cooling device 40. However, since the natural circulation circuits 48 are configured as thermosyphons independent of each other, the balance of the secondary refrigerant is naturally set so that the amount of the secondary refrigerant in each condensation path 50 and each evaporation path 52 matches. Adjusted. Therefore, in each condensation path 50 and each evaporation path 52, the secondary refrigerant is hardly unevenly distributed, and even if the secondary refrigerant is unevenly distributed, the amount of the secondary refrigerant flowing through the condensation path 50 and the evaporation path 52 is reduced. Since the adjusting force acts so as to match, it is not necessary to provide adjusting means such as a valve in order to adjust the balance of the secondary refrigerant, and the configuration of the secondary cooling device 40 can be simplified. In addition, since the secondary refrigerant smoothly convects naturally in the natural circulation circuit 48, the cooling efficiency in the evaporator EP constituted by the collection of the evaporation pipes 56 can be improved. Then, by providing the secondary cooling device 40 with the number of natural circulation circuits 48 corresponding to the heat exchange area required in the secondary heat exchange section 42 and the evaporator EP, the required condensation path 50 and evaporation path 52 are provided. Can be disposed in the secondary heat exchange section 42 and the evaporator EP, and the heat exchange area required for the entire apparatus is secured.

  In the secondary cooling device 40, a plurality of condensing paths 50 and evaporating paths 52 can be arranged in the secondary heat exchanging section 42 and the evaporator EP, respectively. That is, the heat exchange area required for each condensation path 50 and evaporation path 52 is reduced, and the length of each condensation path 50 and each evaporation path 52 can be shortened. Thereby, in each condensation path 50 and each evaporation path 52, the number of times of meandering in order to earn a required pipe length can be reduced, and the bent portion that becomes a distribution resistance can be reduced. Therefore, the condensation path 50 and the evaporation path 52 are reduced. The pressure loss of the secondary refrigerant that circulates can be reduced. In addition, each natural circulation circuit 48 is configured by a single refrigerant path without branching the liquid pipe 44, the gas pipe 46, the condensation path 50, and the evaporation path 52, and therefore pressure caused by a branching portion such as a pipe. There is no loss. Further, in each natural circulation circuit 48, the head difference of the secondary refrigerant required for natural convection between the condensation path 50 and the evaporation path 52 can be reduced, so that there is a requirement between the condensation path 50 and the evaporation path 52. Thus, the drop between the secondary heat exchanger 42 and the evaporator EP can be narrowed, and the secondary cooling device 40 can be made compact. Further, in each natural circulation circuit 48, since the pressure loss of the secondary refrigerant is small, the same amount of the secondary refrigerant is placed in the circuit even when the liquid pipe 44 and the gas pipe 46 are selected to have a smaller pipe diameter than the conventional one. Therefore, it is possible to reduce the amount of secondary refrigerant to be filled in the entire circuit.

  Thus, since the length and cross-sectional area of each condensation path 50 and each evaporation path 52 can be reduced, the secondary heat exchange unit 42 and the evaporator EP can be made compact, and the amount of circulating refrigerant is reduced. As a result, incidental facilities such as the capacity of an expansion tank (not shown) that alleviates the pressure increase in the natural circulation circuit 48 are also reduced, so that the secondary cooling device 40 as a whole can be made compact and the cost can be reduced. Become. Further, by reducing the diameter of the pipes such as the liquid pipe 44, the gas pipe 46, and the evaporation pipe 56, it is possible to reduce the wall thickness necessary for ensuring pressure resistance performance in these pipes 44, 46, and 56. . That is, not only the diameter of each pipe 44, 46, 56 is reduced, but also synergistic with the decrease in the thickness of each pipe 44, 46, 56, the pipe weight can be further reduced, and the cost can be reduced. Further reduction can be achieved. Further, by reducing the size of the evaporator EP disposed in the cooling chamber 28 in the storage chamber 14, the installation space required for disposing the evaporator EP is reduced (miniaturization of the cooling chamber 28). On the other hand, the internal volume that can store articles in the storage chamber 14 can be increased, and the commercial value of the refrigerator can be improved.

Here, the cost reduction by reducing the diameter of the pipes such as the liquid pipe 44, the gas pipe 46, and the evaporation pipe 56 will be specifically described.
For example, the wall thickness t of the pipe having the pressure resistance performance P is obtained by the following equation. Here, σ is the allowable stress of the material, and D is the outer diameter of the pipe.
t = PD / 2 (σ + P) (B)
The pipe weight M of the length L is calculated | required with the following formula | equation. C is the specific gravity of the material, and D _i is the inner diameter of the pipe.
M = πLC (D ² −D _i ² ₎ / 4 (b)
Further, since it can be expressed as D _i = D−2t, substituting this into the expression (b) yields the following expression.
M = πLC (Dt−t ²⁾ (C)
Then, by substituting (A) into (C), the following equation is derived.
M = (1-P / 2 (σ + P)) × πLCPD 2/2 (σ + P) ... ( d)
The expression (d) indicates the weight of the pipe having the pressure resistance performance P. In the expression (D), if conditions other than D are unchanged, the conditions of π, L, C, P, and σ can be treated as constants. Therefore, the weight of the pipe having the pressure resistance performance P (the outer diameter D of the pipe) can be expressed by the following expression.
M = {(1−P / 2 (σ + P)) × πLCP / 2 (σ + P)} × D ² (e)
Since the value in {} in the expression (e) is a constant as described above, it can be expressed as M = AD ² .
Then, the pipe weight MD ₁ of the pipe outside diameter D ₁ having a pressure resistance P is AD ₁ ^2, pipe weight MD ₂ of the outer diameter D ₂ pipe having a pressure resistance P is AD ₂ ^2.
Furthermore, the ratio of the pipe weight MD ₁ and the pipe weight MD ₂ is expressed as follows.
MD ₂ / MD ₁ = D ₂ ² / D ₁ ² (f)

The description will be made by applying specific numbers to the formula (f). In a general cooling device, the outer diameter of the evaporation tube is often set to 9.52 mm. On the other hand, if it is a cooling device of Example 1, although it changes with conditions, an evaporation pipe with an outer diameter of 6.35 mm can be used. When these conditions are applied to the above equation (f), the following is obtained.
MD _φ 6.35 / MD _φ 9.52 = (6.35) ² /(9.52) ² = 0.44
Moreover, in the cooling device of Example 1, when an evaporation tube having an outer diameter of 4.76 mm is used, the following is obtained.
MD _φ 4.76 / MD _φ 9.52 = (4.76) ² /(9.52) ² = 0.25
That is, the weight ratio of the pipe can be said to be a ratio of the material price of the pipe. Therefore, according to the secondary cooling device 40 of the first embodiment, the pipe is greatly reduced in diameter as compared with the conventional cooling device. Clearly, significant cost savings can be achieved.

  As described above, by providing a plurality of natural circulation circuits 48, the diameter of the pipe through which the refrigerant flows can be reduced. Therefore, a spiral in which fins 58 are spirally wound around the outer periphery of the evaporation pipe 56 as the evaporation path 52. Even if the fin tube type heat exchanger 55 is employed, the enlargement of the evaporator EP can be suppressed. That is, by reducing the minimum bending radius of the evaporation pipe 56, the dimensions can be made compact, and the pipe density equivalent to that of the fin-and-tube heat exchanger can be obtained. And in a spiral fin tube type heat exchanger, it is not necessary to perform welding of pipes or pipe expansion of pipes in the manufacturing process, and the manufacturing process can be greatly simplified and the manufacturing cost can be kept low. Further, the spiral fin tube type heat exchanger 55 has a seamless structure in which the U-bend portion is not welded to the straight pipe like the fin and tube type heat exchanger. Reliability is improved. That is, since it becomes possible to reduce the pipe diameter in each natural circulation circuit 48, the evaporation pipe 56 has a compact configuration in which the minimum bending radius of the evaporation pipe 56 is reduced, and to the same extent as a fin-and-tube heat exchanger. It is possible to employ a heat exchanger 55 having a configuration in which the adjacent straight portions of the fins 58 are not in contact with each other as in the spiral fin tube type in which the piping density of 56 is increased.

  As described above, the spiral fin tube type heat exchanger 55 is less likely to be clogged due to frost formation than the fin and tube type heat exchanger. The frequency of performing the defrosting operation by the frosting means can be reduced. Thereby, the temperature rise in the storage chamber 14 resulting from frequent defrosting operation can be suppressed. In addition, since the spiral fin tube type heat exchanger 55 constituting the evaporation paths 52 of the plurality of natural circulation circuits 48 is arranged in parallel layers spaced apart from each other as shown in FIG. Can be made thin to reduce the proportion of the cooling chamber 28, thereby saving space. In addition, since the fins 58 and 58 of the heat exchangers 55 and 55 arranged in layers above and below are separated from each other, clogging due to frost formation between the heat exchangers 55 and 55 hardly occurs.

  In the cooling facility 32, the primary cooling device 34 and the secondary cooling device 40 are connected by a cascade heat exchanger HE, and in the cascade heat exchanger HE, the primary refrigerant of the primary cooling device 34 and the secondary cooling device 40 are connected to each other. The secondary refrigerant exchanges heat under the action of evaporation and condensation. That is, since it has a very high heat transfer coefficient compared to heat exchange using only sensible heat, the heat transfer area between the primary cooling device 34 and the secondary cooling device 40 can be reduced. In addition, since both the primary refrigerant and the secondary refrigerant transport heat by latent heat, a large amount of heat can be transmitted with a relatively small amount, so that the amount of heat exchange in the cascade heat exchanger HE is not reduced. The heat volumes of the primary cooling device 34 and the secondary cooling device 40 can be reduced. Therefore, both the primary refrigerant amount of the primary cooling device 34 and the secondary refrigerant amount of the secondary cooling device 40 can be reduced, and the cost of the cooling equipment 32 can be reduced by reducing costs and downsizing the primary cooling device 34 and the secondary cooling device 40. Space can be achieved.

  Since the amount of the primary refrigerant required for the primary cooling device 34 is small, it can be set to the upper limit amount of the refrigerant defined by the method cooling or the like, and there is a range of options for the type of refrigerant used as the primary refrigerant. spread. The machine room 20 is an open space in which air can be exchanged for the purpose of air-cooling the condenser CD and the compressor CM. Since the primary cooling device 34 is disposed in the machine room 20, even if the primary refrigerant leaks out, there is no possibility of staying in the machine room 20. Further, since the machine room 20 is airtightly separated from the storage room 14 which is a closed space by the base plate 24, the leaked primary refrigerant does not flow into the storage room 14, and the articles stored in the storage room 14 Corrosive gases such as ammonia and hydrogen sulfide derived from the above do not flow into the machine room 20. In addition, by configuring the cooling facility 32 with a secondary loop refrigeration circuit including the primary cooling device 34 and the secondary cooling device 40, it is possible to select carbon dioxide having excellent safety as the secondary refrigerant. . In other words, in the secondary cooling device 40, the evaporator EP faces the storage chamber 14 (cooling chamber 28), but even if the secondary refrigerant leaks into the storage chamber 14, for example, safety for the user can be ensured.

  The primary cooling device 34 and the secondary cooling device 40 are thermally connected by the primary heat exchange unit 36 and the secondary heat exchange unit 42 of the cascade heat exchanger HE, but are independent of each other as a refrigerant circulation path. ing. When the cooling facility 32 is stopped (compressor CM: stopped), the high-temperature liquid-phase primary refrigerant flows from the condenser CD into the primary heat exchange unit 36 into the primary cooling device 34. As a result, the temperature of the cascade heat exchanger HE is increased, but the secondary cooling device 40 is independent. Therefore, the evaporator EP is not heated, and the storage chamber 14 when the cooling facility 32 is stopped is not used. The temperature rise becomes gradual. That is, by cooling the storage chamber 14 to a required set temperature by the cooling facility 32, it is possible to lengthen the time until the cooling facility 32 is driven again after the cooling facility 32 is stopped. Therefore, since the operating rate of the cooling facility 32 is reduced, the power consumption is reduced.

  Thus, by applying the secondary cooling device 40 of the first embodiment to the cooling facility 32 composed of the secondary loop type refrigeration circuit, the cooling facility is equivalent in size and cost to the conventional cooling facility using chlorofluorocarbon. 32 can be designed, and compared with a mechanical compression type refrigeration circuit using chlorofluorocarbon as a refrigerant, the entire apparatus is enlarged and requires a large installation area, and disadvantages associated with an increase in cost are eliminated in the market. Can be competitive. In other words, the secondary cooling device 40 according to the first embodiment is effective in positioning the non-fluorocarbon technology using the secondary loop refrigeration circuit, which is regarded as important from the viewpoint of preventing global warming. have.

  FIG. 6 is a schematic circuit diagram illustrating a cooling facility 32 including a secondary cooling device (cooling device) 60 according to the second embodiment as a circuit on the secondary side. The cooling facility 32 of the second embodiment is installed in the refrigerator 10 described in the first embodiment.

  As shown in FIG. 6, the cooling facility 32 according to the second embodiment includes a mechanical compression type primary cooling device (primary side circuit) 34 that forcibly circulates a refrigerant and a secondary cooling device that includes a thermosiphon that naturally convects the refrigerant. A secondary loop refrigeration circuit in which the (cooling device) 60 is thermally connected (cascade connection) so as to exchange heat with the cascade heat exchanger HE is employed. Since the configuration of the primary cooling device 34 is the same as that of the first embodiment, detailed description thereof is omitted, and the same members are denoted by the same reference numerals. For the secondary cooling device 60, the same members as those in the first embodiment are denoted by the same reference numerals.

  The secondary cooling device 60 includes a secondary heat exchange unit 42 of the cascade heat exchanger HE that liquefies the gas phase secondary refrigerant (vaporized refrigerant), and an evaporator EP that vaporizes the liquid phase secondary refrigerant (liquefied refrigerant). The secondary heat exchange section 42 and the evaporator EP correspond to each other in a one-to-one relationship (see FIG. 6). The secondary cooling device 60 also includes a liquid pipe 44 and a gas pipe 46 that connect the secondary heat exchange unit 42 and the evaporator EP, and the gravity is transferred from the secondary heat exchange unit 42 to the evaporator EP via the liquid pipe 44. A natural circulation circuit 62 is provided that supplies the liquid phase secondary refrigerant under the action of the above and recirculates the gas phase secondary refrigerant from the evaporator EP to the secondary heat exchange section 42 via the gas pipe 46. The secondary heat exchange unit 42 is disposed in the machine room 20, while the evaporator EP is disposed in the cooling chamber 28 located below the machine room 20, and performs secondary heat exchange with the base plate 24 interposed therebetween. The evaporator EP is disposed below the part 42. Reference numeral 54 denotes a refrigerant charge port provided for charging the natural circulation circuit 62 with the refrigerant. In the secondary cooling device 60 of the second embodiment, since the natural circulation circuit 62 is single, One set of incidental facilities such as a charge port 54, a safety valve, and an expansion tank (both not shown) are sufficient.

  The secondary heat exchanging section 42 is provided with a plurality of condensing paths 50 (in the case of distinction, α, β, γ... Are added to the reference numeral 50) in parallel (three in the second embodiment). ing. Further, the evaporator EP is provided with a plurality of evaporation paths 52 in parallel (three in the second embodiment, and α, β, γ,... Are added to the reference numeral 52 when particularly distinguished). Yes. In FIG. 6, the condensation path 50 is represented by a straight path from the inflow end 50 a connecting to the gas pipe 46 to the outflow end 50 b connecting to the liquid pipe 44, and from the inflow end 52 a connecting the evaporation path 52 to the liquid pipe 44. Although the straight path is shown to the outflow end 52b connected to the gas pipe 46, the condensing path 47 may be meandered or formed in a straight line.

  Here, in the secondary cooling device 60, a plurality of condensation paths 50, a plurality of evaporation paths 52, a plurality of liquid pipes 44 (α, β, γ. These gas pipes 46 (in particular, α, β, γ... Are added to the reference numeral 46 when distinguished) are set to the same number. The liquid pipe 44 is piped through the base plate 24 by connecting the upper end (starting end) to the outflow end 50b of the condensation path 50 in the secondary heat exchanging section 42, and the lower end (end) located on the cooling chamber 28 side. It is connected to the inflow end 52a of the evaporation path 52 in the evaporator EP. The gas pipe 46 is connected to the outflow end 52b of the evaporation path 52 in the evaporator EP at the lower end (starting end) located on the cooling chamber 28 side and is piped through the base plate 24, and is located on the machine room 20 side. The upper end (termination) is connected to the inflow end 50a of the condensation path 50 in the secondary heat exchange section 42.

  In the secondary cooling device 60, the liquid pipe 44 connected to the outflow end 50b of the condensation path 50 is different from the evaporation path 52 connected to the gas pipe 46 connected to the inflow end 50a of the condensation path 50. 52 is configured to connect. Further, in the secondary cooling device 60, the gas pipe 46 connected to the outflow end 52 b of the evaporation path 52 is different from the condensation path 50 connected to the liquid pipe 44 connected to the inflow end 52 a of the evaporation path 52. 50, a plurality of condensation paths 50, a plurality of evaporation paths 52, a plurality of liquid pipes 44, and a plurality of gas pipes 46 constitute a single natural circulation circuit 62 as a whole. In the secondary cooling device 60, a temperature gradient is formed between the secondary heat exchange unit 42 cooled by heat exchange with the primary heat exchange unit 36 that is forcibly cooled and the evaporator EP, and the secondary refrigerant However, a refrigerant circulation cycle is formed in which the secondary heat exchange section 42, the liquid pipe 44, the evaporator EP, and the gas pipe 46 are naturally convected and returned to the secondary heat exchange section 42 again.

  The natural circulation circuit 62 configured in the secondary cooling device 60 will be described more specifically with reference to FIG. In the secondary cooling device 60 of the second embodiment, the secondary heat exchange unit 42 is provided with three condensation paths 50α, 50β, 50γ as refrigerant paths, and the evaporator EP has three evaporation paths 52α, 52β as refrigerant paths. , 52γ. The starting end of the first liquid pipe 44α is connected to the outflow end 50b of the first condensing path 50α, the end of the first liquid pipe 44α is connected to the inflow end 52a of the first evaporation path 52α, and the first condensing path 50α. Is supplied to the first evaporation path 52α through the first liquid pipe 44α. The outflow end 52b of the first evaporation path 52α is connected to the start end of the first gas pipe 46α, the end of the first gas pipe 46α is connected to the inflow end 50a of the second condensation path 50β, and the first evaporation path 52α. To the second condensing path 50β through the first gas pipe 46α. The outflow end 50b of the second condensing path 50β is connected to the start end of the second liquid pipe 44β, the end of the second liquid pipe 44β is connected to the inflow end 52a of the second evaporation path 52β, and the second condensing path 50β. Is supplied to the second evaporation path 52β through the second liquid pipe 44β. The start end of the second gas pipe 46β is connected to the outflow end 52b of the second evaporation path 52β, the end of the second gas pipe 46β is connected to the inflow end 50a of the third condensation path 50γ, and the second evaporation path 52β The secondary vaporized refrigerant is returned to the third condensing path 50γ through the second gas pipe 46β. The outflow end 50b of the third condensing path 50γ is connected to the starting end of the third liquid pipe 44γ, the end of the third liquid pipe 44γ is connected to the inflow end 52a of the third evaporation path 52γ, and the third condensing path 50γ. To the third evaporation path 52γ through the third liquid pipe 44γ. The start end of the third gas pipe 46γ is connected to the outflow end 52b of the third evaporation path 52γ, the end of the third gas pipe 46γ is connected to the inflow end 50a of the first condensation path 50α, and the third evaporation path 52γ. The secondary vaporized refrigerant is returned to the first condensation path 50α through the third gas pipe 46γ, and the secondary refrigerant makes a round in the natural circulation circuit 62.

  Each evaporation path 52 in the secondary cooling device 60 of the second embodiment is configured by a spiral fin tube type heat exchanger 55 shown in FIGS. 3 to 5 as in the first embodiment.

[Operation of Example 2]
Next, the effect | action of the cooling equipment 32 provided with the secondary cooling device 60 which concerns on Example 2 is demonstrated. In the cooling facility 32, when the cooling operation is started, circulation of the refrigerant is started in each of the primary cooling device 34 and the secondary cooling device 60. In addition, since the effect | action of the primary cooling device 34 has been demonstrated in paragraph [0032], it abbreviate | omits.

  In the secondary cooling device 60, since the secondary heat exchange unit 42 is cooled by the primary heat exchange unit 36, the gas phase secondary refrigerant dissipates heat in the course of flowing through each condensation path 50 of the secondary heat exchange unit 42. Then, the specific gravity increases by condensing and changing the state from the gas phase to the liquid phase, so that the liquid phase secondary refrigerant flows down along the respective condensation paths 50 of the secondary heat exchange unit 42 under the action of gravity. In the secondary cooling device 60, the secondary heat exchange unit 42 is disposed in the machine room 20, while the evaporator EP is disposed in the cooling chamber 28 located below the machine room 20, thereby the secondary heat exchange unit 42. And an evaporator EP are provided with a head. That is, the liquid phase secondary refrigerant is allowed to flow naturally under the action of gravity through the liquid pipe 44 connected to the lower portion of the secondary heat exchange unit 42 toward the evaporator EP formed by the collection of the evaporation pipes 56. be able to. In the process of flowing through the respective evaporation paths 52 of the evaporator EP, the liquid secondary refrigerant evaporates by taking heat from the ambient atmosphere of the evaporator EP constituted by the collection of the evaporation pipes 56 and moves to the gas phase. The gas phase secondary refrigerant is refluxed from the evaporator EP to the secondary heat exchanging unit 42 via the gas pipe 46, and the secondary cooling device 60 can perform secondary operation with a simple configuration without using power of a pump, a motor, or the like. The cycle in which the refrigerant naturally circulates is repeated.

  In the natural circulation circuit 62 configured in the secondary cooling device 60, one condensing path 50 and one condensing path 50 are connected by alternately connecting a plurality of condensing paths 50 and the same number of condensing paths 50. One thermosiphon that allows the secondary refrigerant to flow alternately to the evaporation path 52 is formed. That is, according to the natural circulation circuit 62, the plurality of condensation paths 50 and the plurality of evaporation paths 52 are provided in one circuit without branching the liquid pipe 44, the gas pipe 46, the condensation path 50, and the evaporation path 52. be able to. As described above, since the natural circulation circuit 62 is constituted by one refrigerant path as a whole, the secondary is between the condensation paths 50 and 50 and between the evaporation paths 52 and 52 or between the condensation path 50 and the evaporation path 52. The uneven distribution of the refrigerant can be suppressed, and the amount of the secondary refrigerant flowing through each condensation path 50 and each evaporation path 52 can be matched.

  Further, the secondary refrigerant circulating in the natural circulation circuit 62 may be unevenly distributed in either the condensation path 50 or the evaporation path 52 due to external factors such as fluctuations in the outside air temperature acting on the secondary cooling device 60. However, since the natural circulation circuit 62 is composed of one thermosyphon, the balance of the secondary refrigerant is naturally adjusted so that the amount of the secondary refrigerant in each condensation path 50 and each evaporation path 52 matches. The Therefore, in each condensation path 50 and each evaporation path 52, the secondary refrigerant is hardly unevenly distributed, and even if the secondary refrigerant is unevenly distributed, the amount of the secondary refrigerant flowing through the condensation path 50 and the evaporation path 52 is reduced. Since the adjusting force acts so as to match, it is not necessary to provide adjusting means such as a valve in order to adjust the balance of the secondary refrigerant, and the configuration of the secondary cooling device 60 can be simplified. Moreover, since the secondary refrigerant smoothly convects naturally in the natural circulation circuit 62, the cooling efficiency in the evaporator EP can be improved. Therefore, a plurality of condensation paths 50 and evaporation paths 52 can be provided in the secondary heat exchange section 42 and the evaporator EP, and a heat exchange area can be gained without bending or branching the condensation paths 50 and the evaporation paths 52. .

  In the secondary cooling device 60, a plurality of condensation paths 50 and evaporation paths 52 can be arranged in each of the cascade heat exchanger HE and the evaporator EP. That is, the heat exchange area required for each condensation path 50 and evaporation path 52 is reduced, and the length of each condensation path 50 and each evaporation path 52 can be shortened. Thereby, in each condensation path 50 and each evaporation path 52, the number of times of meandering in order to earn a required pipe length can be reduced, and the bent portion that becomes a distribution resistance can be reduced. Therefore, the condensation path 50 and the evaporation path 52 are reduced. The pressure loss of the secondary refrigerant that circulates can be reduced. In addition, the secondary cooling device 60 includes the natural circulation circuit 62 as a whole with one refrigerant path without branching the liquid pipe 44, the gas pipe 46, the condensation path 50, and the evaporation path 52. No pressure loss due to the branching part. In the natural circulation circuit 62, the head difference of the secondary refrigerant required for natural convection between the condensation path 50 and the evaporation path 52 can be reduced, so that the required drop between the condensation path 50 and the evaporation path 52 is required. Becomes smaller, and it is possible to narrow the upper and lower arrangement intervals between the secondary heat exchange section 42 and the evaporator EP, and the secondary cooling device 60 can be made compact. In addition, since the pressure loss of the secondary refrigerant is small in the natural circulation circuit 62, the same amount of the secondary refrigerant is put in the circuit even if the pipe diameter is smaller than the conventional pipe diameter as the liquid pipe 44 and the gas pipe 46. It is possible to circulate, and it is possible to reduce the amount of secondary refrigerant to be filled in the entire circuit.

  Thus, since the length and cross-sectional area of each condensation path 50 and each evaporation path 52 can be reduced, the secondary heat exchange unit 42 and the evaporator EP can be made compact, and the amount of circulating refrigerant is reduced. As a result, incidental facilities such as the capacity of an expansion tank (not shown) that relieve the pressure increase in the natural circulation circuit 62 are also reduced, so that the secondary cooling device 60 as a whole can be made compact and the cost can be reduced. Become. Further, by reducing the diameter of the pipes such as the liquid pipe 44, the gas pipe 46, and the evaporation pipe 56, it is possible to reduce the wall thickness necessary for ensuring pressure resistance performance in these pipes 44, 46, and 56. . That is, not only the diameter of each pipe 44, 46, 56 is reduced, but also synergistic with the decrease in the thickness of each pipe 44, 46, 56, the pipe weight can be further reduced, and the cost can be reduced. Further reduction can be achieved. Further, even the cooling facility 32 of the second embodiment exhibits the effects described in the paragraphs [0036] and [0041] to [0048].

  Since the secondary cooling device 60 of the second embodiment is composed of a single natural circulation circuit 62, the refrigerant charge port 54, a safety valve for preventing an excessive increase in pressure, an expansion tank (none of which are shown), and the like. It is only necessary to provide one incidental facility. That is, as compared with the configuration including a plurality of independent natural circulation circuits 48 as in the secondary cooling device 40 of the first embodiment, advantages such as prevention of drift of the secondary refrigerant and reduction in the pipe diameter are maintained. On the other hand, the incidental equipment becomes compact and the cost can be reduced. Moreover, since the secondary cooling device 60 of Example 2 performs only the refrigerant | coolant filling operation | work in a manufacturing process or a maintenance with respect to the single natural circulation circuit 62, workability | operativity and maintainability can be improved.

(Example of change)
The present application is not limited to the configuration of each of the embodiments described above, and other configurations can be appropriately employed.
1. In the embodiment, the case where the refrigerant inflow ends and the outflow ends in the plurality of evaporation paths are arranged in a positional relationship aligned in the vertical direction has been described. However, as shown in FIG. 52a and the outflow end 52b may be arranged so as to be biased in the air flow direction.
2. In the embodiment, the description has been given of the case where the evaporation tubes of the spiral fin tube type heat exchanger are arranged in a meandering manner on the same plane (installation plane), but the configuration in which the linear portion and the bent portion are not arranged on the same plane. It may be. For example, as shown in FIG. 19, by arranging the evaporator tubes 56 in a meandering manner on a stepped plane, the evaporator tubes 56 are stepped in the direction of the air flowing through the evaporator tube group as a whole. Form. More specifically, the evaporation pipe 56 includes an upper stage part 56A formed by meandering on a plane set on the upstream side in the flow direction of air flowing through the evaporator pipe group, and an upper stage part 56A on the downstream side. A lower step portion 56B formed by meandering on a plane set at a position that is lowered by one step, a downstream end portion in the air flow direction in the upper step portion 56A, and an upstream end portion in the air flow direction in the lower step portion 56B. The upstream end portion of the lower step portion 56B extends upstream from the downstream end portion of the upper step portion 56A, and is formed in a Z shape as a whole. The plurality of evaporation tubes 56 formed in a step shape are arranged in layers so as to separate each step up and down. In other words, the upper step portion 56A in the upper evaporation tube 56 and the upper step portion 56A in the lower evaporation tube 56 are arranged in layers in a vertically separated manner, and the lower step portion 56B in the upper evaporation tube 56 is located. And the lower step portion 56B of the evaporation pipe 56 located on the lower side are arranged in layers in a vertically spaced manner.
In this way, each evaporation pipe 56 is formed in a stepped shape (Z-shape) by the step portion 56C arranged so that the straight portions 56a and 56a overlap each other in the vertical direction, whereby the heat exchange length in each evaporation pipe 56 is evaporated. It can be made longer than the case where it is bent in a meandering manner on one plane having the same length in the flow direction of the air flowing through the tube group. That is, the evaporator EP having the same capacity can be configured with a small number of the evaporation pipes 56, and the number of parts and assembly man-hours can be reduced to reduce the manufacturing cost. Each of the evaporation pipes 56 is formed in a stepped shape that rises from the inflow end 52a side to the outflow end 52b side in the evaporation path 52, and the straight portions 56a constituting the upper step portion 56A and the lower step portion 56B are inflow ends of the refrigerant. Sequentially deviates upward from the 52a side toward the outflow end 52b (the plane on which the upper step portion 56A and the lower step portion 56B are formed is an inclined surface inclined upward from the inflow end 52a side toward the outflow end 52b side. The refrigerant that evaporates in the evaporation pipe 56 is circulated quickly.
In the modification shown in FIG. 19, a space where the evaporation pipe 56 does not exist is formed below the upper stage portion 56A of the evaporation pipe 56 located on the lower side. As shown in FIG. When the evaporator EP is disposed in the cooling chamber 28, this is a portion where the amount of air drawn into the cooling chamber 28 by the blower fan 30 is small. That is, even if a space is created by forming the evaporation pipe 56 in a stepped shape, the heat exchange by the air flowing through the cooling chamber 28 is not greatly reduced. The number of stages of the evaporation pipe 56 is not limited to two, but may be three or more, and the step part 56C that connects the upper part 56A and the lower part 56B is at least part of the straight parts 56a, 56a such as vertical. Need only be in a relationship of overlapping vertically.
3. In the embodiment, the description has been given of the case where the evaporation tubes of the spiral fin tube type heat exchanger are arranged in a meandering manner on the same plane (installation plane), but the configuration in which the linear portion and the bent portion are not arranged on the same plane. It may be. For example, the evaporator tubes are arranged in a meandering manner on a stepped (e.g., crank-shaped) plane to constitute a heat exchanger, and each stage in each heat exchanger is arranged in a layered manner with a vertical separation. May be. Note that, even in a configuration that is not arranged on the same plane, it is preferable that the linear portions are arranged so as to be displaced upward in order from the refrigerant inflow end side to the outflow end side.
4). In the embodiment, the case where a spiral fin tube type in which fins are spirally wound around the outer periphery of the evaporation tube is employed as the heat exchanger has been described. However, the present invention is not limited to this configuration. The configuration shown in FIG. 16 can be adopted.
FIG. 8 shows an increase in the axial thickness (longitudinal direction of the evaporation tube 56) of the protruding heat transfer promotion member 74 spirally wound around the outer periphery of the evaporation tube 56, and the helical pitch of the heat transfer promotion member 74. Is set narrowly.
FIG. 9 shows a case where the thickness of the heat transfer promotion member 74 in the axial direction is made smaller than that of the modified example of FIG.
FIG. 10 shows a so-called spine fin tube in which a large number of spine fins (heat transfer promoting members) 76 project in a spiral manner around the outer periphery of the evaporation tube 56.
In FIG. 11, a number of protruding heat transfer promoting members 78 are provided on the outer periphery of the evaporation tube 56 so as to draw a spiral. In addition, the helical pitch in the heat transfer promotion member 78 which concerns on the example of a change of FIG. 11, the thickness of an axial direction, etc. can be set arbitrarily.
FIG. 12 shows a plurality of plate-like heat transfer promoting members 80 arranged in parallel and spaced apart in the longitudinal direction of the evaporation pipe 56. The shape of the heat transfer promoting member 80 shown in the modified example of FIG. 12 includes a circle in FIG. 12 (a), a quadrangle in FIG. 12 (b), an octagon in FIG. 12 (c), and up, down, left and right in FIG. It may be a polygon having a protrusion and a cross shape as a whole, and various other shapes may be adopted.
In FIG. 13, the plate-like heat transfer promotion members 82 are arranged in parallel so as to be in contact with a plurality of (two or more and fewer than all the evaporation tubes) in common with a plurality of evaporation tubes 56 that are separated in the longitudinal direction of the evaporation tubes 56. Are arranged. As the shape of the heat transfer promoting member 82 shown in the modified example of FIG. 13, the rectangular shape of FIG. 13 (a), the oval shape of FIG. 13 (b), and the rectangular shape of FIG. A polygon having a protrusion may be used, and various other shapes may be employed.
FIG. 14 shows a configuration in which a plurality of annular heat transfer promoting members 84 are arranged in parallel apart from each other in the longitudinal direction of the evaporation pipe 56. The axial thickness is increased and the axial separation interval is set wide. It is a thing. The shape of the heat transfer promoting member 84 shown in the modified example of FIG. 14 may be the circular shape of FIG. 14 (a), the square shape of FIG. 14 (b), the octagonal shape of FIG. 14 (c), and other various shapes. Can be adopted.
FIG. 15 shows a configuration in which a plurality of heat transfer promoting members 86, each having a plurality of protrusions 86a projecting in a circular shape around the outer periphery of the evaporation pipe 56, are arranged in parallel spaced apart from each other in the longitudinal direction. In addition, the axial separation distance, the axial thickness, and the like of the heat transfer promotion member 86 of the modification shown in FIG. 15 can be arbitrarily set. Further, with respect to the shape of each protrusion 86a, the heat transfer promoting member 86 composed of a plurality of protrusions 86a is generally the same as the outer shape of the heat transfer promoting member 84 of the modified example shown in FIGS. 14 (b), (c) and the like. It may be the same.
FIG. 16 shows an example in which the thickness in the axial direction of the heat transfer promoting member 88 is increased and the helical pitch of the heat transfer promoting member 88 is set narrower than in the modified example of FIG. In addition, about the shape of the heat transfer promotion member 88 of the modification shown in FIG. 16, the thing of various shapes is employable similarly to the modification of FIG. Moreover, each heat-transfer promotion member 88 may be comprised from several protrusion like the example of a change of FIG.
5). In the examples, a spiral fin tube type was adopted as the heat exchanger, but by using carbon dioxide having excellent heat transfer performance as the secondary refrigerant and the arrangement of the evaporation tubes with respect to the air flow through the evaporator, Efficient heat exchange in the evaporator is achieved, so a heat exchanger consisting of only the evaporation pipe (tube body) that does not include various heat transfer promoting members on the evaporation pipe (tube body) is used. can do. And by adopting a heat exchanger consisting only of an evaporator tube (tube body) in this way, it is possible to reduce the spacing between the plurality of heat exchangers, and to make the evaporator more compact. .
In addition, as an evaporation pipe | tube which does not arrange | position a heat-transfer promotion member, the structure of FIG. 17 and FIG. 18 is employable, for example.
FIG. 17 shows a polygonal cross-sectional shape of the evaporation tube 56 to increase the surface area, and various other cross-sections such as an octagon in FIG. 17 (a) and a cross in FIG. 17 (b). Shape can be adopted.
FIG. 18 shows a structure in which a groove for promoting heat transfer is formed on the surface of the evaporation tube 56. As shown in FIGS. 18 (a) and 18 (b), the groove 90 continuous on the circumference is separated in the axial direction. As shown in FIGS. 18C to 18E, it is possible to employ a structure in which a large number of grooves 92 that are not continuous with each other are formed apart from each other in the circumferential direction and the axial direction. In addition, the shape of the groove of the modified example shown in FIG. 18 is not limited to the illustrated shape, and any shape can be adopted.
6). Absorption and other refrigeration circuits can also be employed as the primary cooling device for the cooling facility. In addition, the cooling device according to the present invention may be an air-cooling type that cools the heat exchanging portion by blowing air from a fan or the like.
7). In the cascade heat exchanger, the primary heat exchange unit and the secondary heat exchange unit may be configured separately, or a heat exchanger of another type may be used.
8). In the embodiment, the expansion valve is used as the means for reducing the pressure of the liquefied refrigerant in the primary cooling device. However, the present invention is not limited to this, and a capillary tube or other pressure reducing means may be employed.
9. In the Example, the example which uses the cooling device which concerns on this invention is given to the secondary side of the cooling equipment provided with a secondary loop type refrigerating circuit. As described above, it is possible to eliminate the disadvantages of the cooling equipment provided with the secondary loop type refrigeration circuit. Therefore, it is very useful to apply the cooling device according to the present invention to the secondary loop type refrigeration circuit. However, the cooling device according to the present invention is not limited to being applied to a secondary loop refrigeration circuit, and can be used alone as a cooling device.
10. The cooling device of the present invention can also be applied to so-called storages such as a freezer, a freezer / refrigerator, a showcase and a prefabricated store, and other air conditioning equipment.

34 Primary cooling device (primary side circuit), 42 Secondary heat exchange part (heat exchange part), 44 Liquid piping 46 Gas piping, 48 Natural circulation circuit, 50 Condensation path, 52 Evaporation path 52a Inlet end, 52b Outlet end, 55 Heat exchanger, 56 Evaporating tube, 56a Linear portion 56C Stepped portion, 58 Fin (heat transfer promoting member), 62 Natural circulation circuit 74, 78, 80, 82, 84, 86, 88 Heat transfer promoting member 76 Spine fin ( Heat transfer promotion member), EP evaporator

Claims (6)

A heat exchange section (42) that condenses the vaporized refrigerant flowing through the condensation path (50) to form a liquefied refrigerant, and a liquefaction that is disposed below the heat exchange section (42) and flows through the internal evaporation path (52). A tubular evaporation pipe (56) that evaporates the refrigerant to be a vaporized refrigerant, and connects the liquid pipe (44) from the condensation path (50) of the heat exchange section (42) to the evaporation path (52) of the liquefied refrigerant. A cooling device provided with a natural circulation circuit (48) for flowing the vaporized refrigerant from the evaporation path (52) to the condensation path (50) of the heat exchange section (42) via the gas pipe (46). In
Each natural circulation circuit (48) includes a plurality of natural circulation circuits (48) independent of each other and an evaporator (EP) configured by a set of evaporation pipes (56) of the plurality of natural circulation circuits (48). Carbon dioxide is used as the refrigerant circulating through
Each of the evaporation pipes (56) is formed by being bent in a meandering manner so that a linear portion (56a) extends in a transverse direction intersecting a flow direction of air flowing through the evaporation pipe (56) group,
The liquid pipe (44) is connected to a part of the evaporation pipe (56) on the downstream side in the air flow direction, and the gas pipe (56) is connected to a part of the evaporation pipe (56) on the upstream side in the air flow direction. 46) is connected,
The cooling device, wherein the plurality of evaporation pipes (56) are arranged in a layered relationship in an up-down relationship in a state of being separated from each other. A heat exchange section (42) that condenses the vaporized refrigerant flowing through the condensation path (50) to form a liquefied refrigerant, and a liquefaction that is disposed below the heat exchange section (42) and flows through the internal evaporation path (52). A tubular evaporation pipe (56) that evaporates the refrigerant to be a vaporized refrigerant, and connects the liquid pipe (44) from the condensation path (50) of the heat exchange section (42) to the evaporation path (52) of the liquefied refrigerant. And a cooling device provided with a natural circulation circuit (62) for flowing the vaporized refrigerant from the evaporation path (52) to the condensation path (50) of the heat exchange section (42) via the gas pipe (46). In
The natural circulation circuit (62) includes an evaporator (EP) constituted by a set of a plurality of evaporation tubes (56), and the same number of condensation paths (50) as the plurality of evaporation tubes (56), Using carbon dioxide as a refrigerant circulating in the natural circulation circuit (62),
The liquid pipe (44) connected to the outflow end (50b) of the condensation path (50) is an evaporation pipe (46) connected to the gas pipe (46) connected to the inflow end (50a) of the condensation path (50). 56) and another evaporation pipe (56) and a gas pipe (46) connected to the outflow end (52b) of the evaporation pipe (56) is connected to the inflow end (52a) of the evaporation pipe (56). Connected to the condensing path (50) to which the liquid pipe (44) connected is connected to another condensing path (50) to constitute one natural circulation circuit (62) as a whole,
Each of the evaporation pipes (56) is formed by being bent in a meandering manner so that a linear portion (56a) extends in a transverse direction intersecting a flow direction of air flowing through the evaporation pipe (56) group,
The liquid pipe (44) is connected to a part of the evaporation pipe (56) on the downstream side in the air flow direction, and the gas pipe (56) is connected to a part of the evaporation pipe (56) on the upstream side in the air flow direction. 46) is connected,
The cooling device, wherein the plurality of evaporation pipes (56) are arranged in a layered relationship in an up-down relationship in a state of being separated from each other.   The cooling according to claim 1 or 2, wherein the inflow end (52a) to which the liquid pipe (44) of the evaporation path (52) is connected is located below the outflow end (52b) to which the gas pipe (46) is connected. apparatus.   Each of the evaporation pipes (56) is stepped in the flow direction of the air flowing through the evaporation pipe (56) group by a step portion (56C) in which the linear portion (56a) is arranged so that at least a part thereof overlaps vertically. The cooling device according to any one of claims 1 to 3, wherein the plurality of evaporation pipes (56) formed in a stepped manner are arranged in layers so that the respective stages are in a vertical relationship. A heat transfer promoting member (58, 74, 76, 78, 80, 82, 84, 86, 88) is disposed around the outer periphery of the evaporation tube (56), and the evaporation tube is bent in a meandering manner. The heat transfer promoting members (58, 74, 76, 78, 80, 82, 84, 86, 88) of the adjacent straight portions (56a) in (56) are configured to be separated from each other,
The plurality of evaporation tubes (56) are arranged in layers in a vertical relationship with the heat transfer promoting members (58, 74, 76, 78, 80, 82, 84, 86, 88) being separated from each other. The cooling device as described in any one of Claims 1-4.   The natural circulation circuit (48, 62) is thermally connected to the mechanical compression primary circuit (34) for forcedly circulating the refrigerant through the heat exchange section (42). The cooling device according to any one of 5.

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