JP2008096084A - Thermosiphon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosiphon reducing a coolant amount in a circuit. <P>SOLUTION: A secondary circuit 44 of a cooling apparatus 32 is composed by connecting a secondary heat exchange part 46 condensing a secondary coolant, and an evaporator EP arranged below the heat exchange part 46 to evaporate the secondary coolant by a liquid piping 48 and a gas piping 50. In the secondary circuit 44, a natural circulation cycle is formed to send a liquid phase secondary coolant down from the secondary heat exchange part 46 to the evaporator EP via the liquid piping 48, and to communicate a gaseous phase secondary coolant from the evaporator EP to the secondary heat exchange part 46 via the gas piping 50. In an evaporation pipe 52 of the evaporator EP, an inflow end 52a is arranged higher than an outflow end 52b, and it is a downward gradient toward a circulating direction front side of the secondary coolant. A liquid sealing part formed in the secondary heat exchange part 46 acts as resistance pushing the gaseous phase secondary coolant of the evaporation pipe 52 in a circulating direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermosiphon that naturally circulates a refrigerant using a temperature gradient between a heat exchanger and an evaporator.

  There is a heat transport mechanism called a thermosiphon that forms a temperature difference in the refrigerant circuit by forming a temperature difference in the refrigerant circuit, and performs heat transfer using natural convection caused by gravity due to non-uniform density. Such a thermosiphon is used as a cooling mechanism such as a storage facility such as a refrigerator or an air conditioning facility (see, for example, Patent Document 1).

  As illustrated in FIG. 7, the cooling circuit 80 using the thermosyphon includes a condenser 82, an evaporator 84 disposed below the condenser 82, and a liquid that guides the liquefied refrigerant from the condenser 82 to the evaporator 84. The pipe 86 is constituted by a gas pipe 88 that leads the vaporized refrigerant from the evaporator 84 to the condenser 82. In the cooling circuit 80, heat is removed from the vaporized refrigerant by the forced or naturally cooled condenser 82, and the liquid refrigerant is liquefied through the liquid pipe 86 to the evaporator 84 under the action of gravity. The cooling circuit 80 vaporizes the liquefied refrigerant that has flowed into the evaporator 84 by removing heat from the ambient atmosphere of the evaporator 84. The vaporized refrigerant is phase-changed from the liquefied refrigerant in the evaporator 84 and expands in volume, so that the specific gravity decreases. Therefore, the vaporized refrigerant flows upward and is refluxed to the condenser 82 via the gas pipe 88. . In the evaporator 84, the pressure increases due to the evaporation of the liquefied refrigerant, while in the condenser 82, the pressure decreases due to the condensation of the vaporized refrigerant, so that a slight pressure difference occurs in the cooling circuit 80. That is, in the cooling circuit 80, the refrigerant is naturally circulated by two types of propulsive force, that is, the above-described difference in specific gravity of the refrigerant and the pressure difference between the evaporator 84 and the condenser 82. In the cooling circuit 80, a refrigerant circulation cycle by natural convection is constructed in one direction (circulation direction), so that the evaporator 84 exhibits a required cooling action.

  By the way, the evaporator 84 is composed of an evaporation pipe 85 having a meandering pipe line in order to increase the contact area with the surrounding atmosphere. In the evaporation pipe 85, when there is no external force acting on the vaporized refrigerant flowing upward due to the difference in specific gravity, the vaporized refrigerant is pushed out in a direction where the pressure loss is small. Here, when the vaporized refrigerant flows toward the liquid pipe 86 in the evaporation pipe 85, the liquid pipe 86 is directed in the opposite direction to the flow direction of the liquefied refrigerant that drops by gravity toward the evaporator 84, thereby inhibiting the flow of the liquefied refrigerant. Therefore, there arises a problem that the circulation rate of the refrigerant is lowered and the cooling capacity is lowered. That is, in the cooling circuit 80, in order to maintain the natural circulation of the refrigerant, it is necessary to make the circulation direction of the refrigerant coincide with the flow direction of the vaporized refrigerant in the evaporator 84.

  Therefore, as shown in FIG. 7, in the evaporator 84, the inflow end 85 a of the evaporator pipe 85 connected to the lower end of the liquid pipe 86 is arranged at the lower part of the evaporator 84, while the evaporator pipe connected to the lower end of the gas pipe 88. The outflow end 85 b of 85 is disposed at the top of the evaporator 84. In addition, by forming the pipe line of the evaporation pipe 85 so as to have an upward gradient toward the outflow end 85b as a whole, the vaporization refrigerant having a reduced specific gravity flows upward to the evaporation pipe 85. The vaporized refrigerant is guided along the gas pipe 88 and guided to the gas pipe 88. Thus, for the convenience of flowing the vaporized refrigerant using the difference in specific gravity, in the conventional evaporator 84, the outflow end 85b of the evaporation pipe 85 is positioned above the inflow end 85a, and the pipe line is circulated in the refrigerant direction. It was considered essential to form an upward slope as a whole toward the front side.

In the evaporator 84, since the inflow end 85a of the evaporation pipe 85 is an inclined lower end in the pipe line, the liquefied refrigerant that has arrived through the liquid pipe 86 is concentrated on the inflow end 85a side. Further, the evaporation pipe 85 does not naturally diffuse to the outflow end 85b side of the evaporation pipe 85, and the refrigerant is moved to the outflow end 85b side by the pushing force generated by the head formed in the liquid pipe 86 as the refrigerant amount increases. Is gradually satisfied. For example, if the amount of refrigerant in the cooling circuit 80 is small, the liquefied refrigerant evaporates (drys out) only on the inflow end 85a side of the evaporation pipe 85, so the range (heat transfer area) in which the ambient atmosphere and the liquefied refrigerant exchange heat is reduced. Narrow and the evaporator 84 cannot exhibit sufficient cooling capacity (see FIG. 8A). Therefore, in the evaporator 84, the refrigerant amount of the cooling circuit 80 is set so that the liquefied refrigerant is filled from the inflow end 85a side to the outflow end 85b side of the evaporation pipe 85, and the liquefied refrigerant is evaporated also in the vicinity of the outflow end 85b. Thus, a heat transfer area is ensured over the entire evaporation pipe 85 (see FIG. 8B). Note that the amount of refrigerant in the case of FIG. 8B is appropriate, but even when the amount of refrigerant exceeds the appropriate amount and is excessively charged (see FIG. 8C), the refrigerant pipe 85 is filled. Since the wetness of the liquefied refrigerant is increased and the thermal conductivity is improved, the evaporator 84 apparently exhibits the required cooling capacity.
JP 2004-85151 A

  In the evaporator 84 described above, in order to secure a heat transfer area, it is necessary to fill the entire liquefied refrigerant from the inflow end 85a side to the outflow end 85b side of the evaporation pipe 85, and a large amount of refrigerant circulates in the cooling circuit 80. There is an inconvenience. As the amount of refrigerant circulating in the cooling circuit 80 increases, the pressure of the cooling circuit 80 when the apparatus is stopped increases, so that the pressure resistance performance required for the cooling circuit 80 increases, leading to an increase in the weight of the equipment. , Which led to an increase in cost. It is also conceivable to increase the internal volume of the circuit 80 by adding a large expansion tank to the cooling circuit 80, etc., to cope with the pressure increase, but this leads to an increase in the size of the equipment, which also contributes to an increase in cost. It becomes.

  That is, the present invention has been proposed in order to suitably solve these problems inherent in the thermosyphon according to the related art, and provides a thermosiphon that can reduce the amount of refrigerant in the circuit. With the goal.

In order to overcome the above-mentioned problems and achieve the intended object, the thermosiphon of the invention according to claim 1 of the present application is
A heat exchange part that condenses the vaporized refrigerant to be a liquefied refrigerant and an evaporator that is disposed below the heat exchange part and that evaporates the liquefied refrigerant to be a vaporized refrigerant are connected by a liquid pipe and a gas pipe. In the thermosiphon that forms a natural circulation cycle in which the refrigerant flows from the heat exchanger to the evaporator via the liquid pipe and the vaporized refrigerant flows from the evaporator to the heat exchanger via the gas pipe.
The refrigerant path extending to the evaporator has an inflow end connected to the lower end of the liquid pipe at the upper part of the evaporator and an outflow end connected to the lower end of the gas pipe at the lower part of the evaporator. Placed in
The heat exchange section or the liquid pipe is provided with a resistance section that provides a flow resistance against the vaporized refrigerant that flows backward from the evaporator.
According to the first aspect of the present invention, the refrigerant path extending to the evaporator has the inflow end provided above the evaporator and the outflow end provided below the evaporator so that the inflow end is above the outflow end. In this state, a drop is provided toward the front side in the circulation direction of the refrigerant. That is, the liquefied refrigerant that has flowed into the refrigerant path is guided to the outflow end side along the path under the action of gravity due to the head and diffuses naturally, so that a wide heat transfer area can be secured. Thus, since the heat transfer area can be secured without filling the refrigerant path with the liquefied refrigerant, the amount of refrigerant in the circuit can be reduced.

The gist of the invention according to claim 2 is that the refrigerant path is formed to have a downward gradient from the inflow end toward the outflow end.
According to the invention which concerns on Claim 2, the spreading | diffusion effect | action of a liquefied refrigerant | coolant can be improved more by making a refrigerant | coolant path | route as a whole downward gradient toward the circulation direction front of a refrigerant | coolant.

According to a third aspect of the present invention, the heat exchanging portion is configured by arranging a plurality of plates extending in the vertical direction so as to face each other in parallel, and at a lower portion of the refrigerant flow path formed between the plates, The gist of the invention is that a portion sealed with a liquefied refrigerant is provided, and the sealed portion serves as the resistance portion.
According to the invention which concerns on Claim 3, the structure of a resistance part can be simplified by utilizing as a resistance the liquid sealing effect which arises between the plates which a heat exchanger opposes.

  According to the thermosyphon of the present invention, the liquefied refrigerant that has flowed into the refrigerant path from the inflow end is guided to the outflow end side along the path under the action of gravity due to a head provided toward the front side in the refrigerant circulation direction. Since it diffuses naturally, a wide heat transfer area can be secured, and the amount of refrigerant required can be reduced.

  Next, a thermosyphon 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 thermosiphon according to the present invention is used as a cooling device 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, a refrigerator 10 according to an embodiment includes a box 12 having a heat insulating structure that internally defines a storage room (closed space) 14, and is provided above the box 12. And a cabinet 16 configured as described above. In the box 12, an opening portion 12 a that opens to the front side and serves as an entry / exit port for goods is opened in communication with the storage chamber 14. Further, a heat insulating door 22 is rotatably disposed at a front portion of the box body 12 by a hinge (not shown), and by opening the heat insulating door 22, an article can be taken into and out of the storage chamber 14 through the opening 12a. In addition, the storage chamber 14 can be sealed by closing the heat insulating door 22.

  Inside the cabinet 16 is a machine room (open space) 20 in which a part of a cooling device 32 for cooling the storage chamber 14 and a control electrical box C for controlling the cooling device 32 are arranged. (See FIG. 2). At the bottom of the machine room 20, a base plate (partition wall) 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).

  As shown in FIG. 3, the cooling device 32 includes two circuits, a primary circuit 34 of a mechanical compression type that forcibly circulates a refrigerant, and a secondary circuit 44 that includes a thermosiphon that naturally convects the refrigerant. A secondary loop refrigeration circuit that is connected so as to exchange heat (cascade connection) is adopted. The heat exchanger HE is formed in a separate system from the primary heat exchange unit 36 constituting the primary circuit 34 and the primary heat exchange unit 36, and the secondary heat exchange unit (heat exchange unit) constituting the secondary circuit 44. 46, and the heat exchanger HE is disposed on the base plate 24 at the rear side of the machine room 20 (see FIG. 2). That is, an independent refrigerant circulation path is formed in each of the primary circuit 34 and the secondary circuit 44, and the secondary refrigerant (refrigerant) circulating in the secondary circuit 44 has toxicity, flammability, and corrosivity. Highly safe carbon dioxide is adopted. On the other hand, as the primary refrigerant circulating in the primary circuit 34, CH-type refrigerants such as methane and propane or ammonia, which have excellent characteristics as refrigerants such as heat of evaporation and saturation pressure, are employed. Is used.

  The primary circuit 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 vaporizes the liquid primary refrigerant. The heat exchanger HE is connected to a primary heat exchanging portion 36 by a refrigerant pipe 38 (see FIG. 3). 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. Here, the condenser CD is disposed on the front side of the machine room 20 in the vicinity of the metal panel (front panel) 18 that forms the front surface of the cabinet 16, and the condenser fan FM is disposed on the rear side of the condenser CD. . The compressor CM is disposed on the rear side of the condenser fan FM (see FIG. 2). Thus, in the machine room 20, the condenser CD, the condenser fan FM, and the compressor CM are arranged in a straight line along the flow direction of the air generated by the condenser fan FM in the machine room 20. . That is, outside air is taken into the machine room 20 from the air circulation hole opened in the front panel 18 by driving the condenser fan FM, and this outside air is circulated from the front side to the rear side of the machine room 20 to cause the condenser CD and the compressor. It is designed to exchange heat with CM. In the primary circuit 34, the primary refrigerant is forcibly circulated in the order of the compressor CM, the condenser CD, the expansion valve EV, the primary heat exchange unit 36 of the heat exchanger HE, and the compressor CM by the compression of the primary refrigerant by the compressor CM. The required cooling is performed in the primary heat exchange section 36 under the action of each device (see FIG. 3). The control electrical box C described above is disposed on the base plate 24 at a position that does not obstruct the air flow by the condenser fan FM in the machine room 20 (side of the machine room 20 in the embodiment). .

  The secondary circuit 44 includes a secondary heat exchange unit 46 of the 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). (See FIG. 3). Further, the secondary circuit 44 is a liquid pipe that guides the liquid phase secondary refrigerant from the secondary heat exchange section 46 to the evaporator EP under the action of gravity as a pipe connecting the secondary heat exchange section 46 and the evaporator EP. 48 and a gas pipe 50 that guides the gas phase secondary refrigerant from the evaporator EP to the secondary heat exchange unit 46. As described above, the secondary heat exchanging portion 46 of the secondary circuit 44 is disposed in the machine room 20, while the evaporator EP is disposed in the cooling chamber 28 located below the machine room 20. The evaporator EP is disposed below the secondary heat exchange unit 46 with the plate 24 interposed therebetween. Here, the evaporator EP is fixed to the lower surface of the base plate 24 and can be handled integrally with the base plate 24. The cooling duct 26 positioned below the evaporator EP also functions as a dew receiving tray that receives defrosted water or the like dripping from the evaporator EP.

  The liquid pipe 48 is connected to the lower part of the secondary heat exchanging portion 46 at the upper end and is piped through the base plate 24, and the lower end facing the cooling chamber 28 is connected to the evaporator EP. The gas pipe 50 has an upper end connected to the upper part of the secondary heat exchange unit 46 and is piped through the base plate 24, and a lower end facing the cooling chamber 28 is connected to the evaporator EP. In the secondary circuit 44, a temperature gradient is formed between the secondary heat exchange unit 46 cooled by heat exchange with the primary heat exchange unit 36 that is forcibly cooled and the evaporator EP, and the secondary refrigerant is A refrigerant circulation cycle is formed in which the secondary heat exchange unit 46, the liquid pipe 48, the evaporator EP, and the gas pipe 50 are naturally circulated and returned to the secondary heat exchange unit 46 again. In addition, the penetration site | part of the base plate 24 in the liquid piping 48 and the gas piping 50 is airtightly sealed with the seal | sticker etc. FIG.

  Since the secondary circuit 44 employs carbon dioxide that does not liquefy at room temperature as the secondary refrigerant, the secondary circuit 44 includes an expansion tank 54 for suppressing an increase in the pressure of the secondary refrigerant when the cooling device 32 is stopped (see FIG. 3). The expansion tank 54 is connected in the middle of the gas pipe 50, and a certain amount of secondary refrigerant is stored in the expansion tank 54 in addition to the secondary refrigerant involved in heat transfer in the evaporator EP. In addition, the expansion tank 54 is disposed on the base plate 24 along with the condenser CD and the condenser fan FM in the front-rear direction on the rear side of the compressor CM in the machine room 20. That is, the expansion tank 54 is located on the front side in the flow direction of the air generated by the condenser fan FM, and is located in the flow path of exhaust heat from the condenser CD and the compressor CM (see FIG. 2).

  The evaporator EP has an evaporation pipe (refrigerant path) 52 having meandering pipe lines, and an inflow end 52a of the evaporation pipe 52 connected to the lower end of the liquid pipe 48 is disposed at the upper part of the evaporator EP. The outflow end 52b of the evaporation pipe 52 connected to the lower end of the gas pipe 50 is disposed at the lower part of the evaporator EP (see FIG. 3). The evaporator EP is configured such that the inflow end 52a of the evaporation pipe 52 is positioned above the outflow end 52b. The pipe of the evaporation pipe 52 extends between the upper and lower positions of the inflow end 52a and the outflow end 52b, and the liquid secondary refrigerant that has flowed into the evaporation pipe 52 is subjected to gravity along the pipe. It is guided to diffuse to the outflow end 52b side. More specifically, the evaporating pipe 52 is formed in a meandering shape in which the inclined straight part is folded in a distorted state in an up-and-down relationship, and the bent part is laterally spaced, and this pipe line is formed at the inflow end. It is comprised so that it may become a downward slope as it goes to the outflow end 52b side from 52a side.

  As shown in FIG. 4, a so-called plate heat exchanger is employed as the heat exchanger HE. In the heat exchanger HE, a plurality of plates 60 extending in the vertical direction are arranged to face each other in parallel at a predetermined interval, and a plurality of flow paths 60a and 60b through which a refrigerant flows are provided between the opposed plates 60 and 60. Formed in parallel. A primary inflow path 64 connected to a refrigerant pipe 38 communicating with the expansion valve EV in the primary circuit 34 is provided in the lower part of the heat exchanger HE, and the compressor CM in the primary circuit 34 is provided in the upper part of the heat exchanger HE. A primary outflow path 66 connected to the communicating refrigerant pipe 38 is provided. Further, a secondary inflow path 68 connected to the gas pipe 50 of the secondary circuit 44 is provided at the upper part of the heat exchanger HE, and connected to the liquid pipe 48 of the secondary circuit 44 at the lower part of the heat exchanger HE. Secondary outflow passage 70 is provided.

  In the heat exchanger HE, the primary inflow path 64 is opened every other flow path 60a parallel in the lateral direction, and the primary outflow path 66 is formed into a flow path 60a in which the primary inflow path 64 is opened. A corresponding opening is formed. And every other flow path 60a with which the primary inflow path 64 and the primary outflow path 66 communicate, the primary heat exchange part 36 is comprised, and each primary heat exchange part 36 is comprised under the negative pressure action of compressor CM. The primary refrigerant flows through the flow path 60a from below to above. On the other hand, the secondary inflow path 68 and the secondary outflow path 70 open to the flow paths 60b arranged alternately with the flow paths 60a in which the primary inflow path 64 and the primary outflow path 66 described above are opened. (See Figure 4). The secondary heat exchange section 46 is constituted by every other flow path 60b communicating with the secondary inflow path 68 and the secondary outflow path 70, and each flow path 60b constituting the secondary heat exchange section 46 under the action of gravity. The secondary refrigerant is circulated from above to below. That is, the heat exchanger HE is configured so that the primary refrigerant and the secondary refrigerant are alternately circulated through the parallel flow paths 60a and 60b, and the primary refrigerant and the secondary refrigerant are heat-exchanged via the respective plates 60. . The heat exchanger HE is covered with a heat insulating material 58 to promote heat exchange between the primary refrigerant flowing through the primary heat exchange unit 36 and the secondary refrigerant flowing through the secondary heat exchange unit 46. (See FIG. 4).

  In the secondary heat exchange section 46, the flow path 60b between the opposing plates 60, 60 is set to a narrow relationship of about 1 mm, for example, and the adhesive force or surface tension of the liquid phase secondary refrigerant acts. Thus, a so-called liquid seal is formed in which the lower part of the flow path 60b on the secondary circuit 44 side is closed with the liquid phase secondary refrigerant (see FIG. 4). In the embodiment, the liquid seal portion 62 generated in each flow path 60b of the secondary heat exchanging portion 46 serves as a resistance portion with respect to the gas phase secondary refrigerant.

  In the secondary circuit 44, the amount of the liquid phase secondary refrigerant that has flowed from the inflow end 52a of the evaporation pipe 52 in the evaporator EP can reach the vicinity of the outflow end 52b of the evaporation pipe 52 by being guided by the pipeline. The amount of the secondary refrigerant is defined so that the saturated liquid phase secondary refrigerant evaporates even in the vicinity of the outflow end 52b (see FIG. 5). The secondary refrigerant amount is appropriately set in consideration of the required cooling capacity, the capacity of the secondary circuit 44, the circulation speed of the secondary refrigerant, or other factors.

(Effects of Example)
Next, the operation of the thermosiphon according to the embodiment will be described. In the cooling device 32, when the cooling operation is started, circulation of the refrigerant is started in each of the primary circuit 34 and the secondary circuit 44. First, the primary circuit 34 will be described. The compressor CD 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. The liquid phase is obtained by condensing and liquefying by forced cooling by the condenser fan FM. The liquid primary refrigerant is depressurized by the expansion means EV, and in the primary heat exchanging section 36 of the heat exchanger HE, it takes heat from the secondary refrigerant flowing through the secondary heat exchanging section 46 (heat absorption) and expands and vaporizes all at once. Thus, the primary circuit 34 functions so as to forcibly cool the secondary heat exchange unit 46 by the primary heat exchange unit 36 in the 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 circuit 44, since the secondary heat exchange unit 46 is cooled by the primary heat exchange unit 36, the secondary heat exchange unit 46 radiates and condenses the gas phase secondary refrigerant, and the liquid phase from the gas phase Since the specific gravity increases due to the state change, the liquid phase secondary refrigerant flows down along the flow paths 60b of the secondary heat exchange section 46 under the action of gravity. In the secondary circuit 44, the secondary heat exchange unit 46 is arranged in the machine room 20, while the evaporator EP is arranged in the cooling chamber 28 located below the machine room 20, so that the secondary heat exchange unit 46 and A head is provided with the evaporator EP. That is, the liquid phase secondary refrigerant can be naturally flowed under the action of gravity toward the evaporator EP via the liquid pipe 48 connected to the lower portion of the secondary heat exchange section 46. The liquid secondary refrigerant evaporates by taking heat from the ambient atmosphere of the evaporator EP in the process of flowing through the evaporation pipe 52 of the evaporator EP and moves to the gas phase. The gas phase secondary refrigerant is refluxed from the evaporator EP to the secondary heat exchange unit 46 via the gas pipe 50, and the secondary circuit 44 has a simple configuration without using power from a pump, a motor, or the like. A cycle in which natural circulation occurs is repeated.

  By blowing the air in the storage chamber 14 sucked into the cooling chamber 28 from the suction port 26a by the blower fan 30 onto the cooled evaporator EP, the air heat-exchanged with the evaporator EP becomes cold air. 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 40. 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.

  Here, the behavior of the secondary refrigerant in the evaporator EP will be further described. The evaporation pipe 52 extending to the evaporator EP has an inflow end 52a at the upper part of the evaporator EP and an outflow end 52b at the lower part of the evaporator EP so that the inflow end 52a is positioned above the outflow end 52b. Thus, a drop is provided between the inflow end 52a and the outflow end 52b. In addition, the evaporation pipe 52 has a meandering shape in which the linear portion is folded up and down between the outflow end 52b and the inflow end 52a, and is inclined downward from the inflow end 52a toward the outflow end 52b. A pipe line is formed. That is, since the evaporation pipe 52 as a whole has a downward slope toward the front side in the circulation direction of the secondary refrigerant in the secondary circuit, the liquid-phase secondary refrigerant flowing into the evaporation pipe 52 from the inflow end 52a Under the action, it can be evaporated while being guided along the pipe line toward the outflow end 52b. Therefore, in the evaporator EP, the liquid secondary refrigerant stays in the vicinity of the inflow end 52a of the evaporation pipe 52 and does not preferentially evaporate in the vicinity of the inflow end 52a, but the secondary refrigerant flows out along the pipe line. Since it diffuses naturally on the side of 52b, a wide heat transfer area can be secured.

  When the flow rate of the liquid phase secondary refrigerant flowing through the evaporation pipe 52 is low, the secondary refrigerant flows in a state of being concentrated on the bottom of the evaporation pipe 52 (see FIG. 6A). In this case, since the secondary refrigerant flowing through the evaporation pipe 52 is only in contact with the inner bottom portion of the evaporation pipe 52, there is a drawback that the heat transfer area is reduced. However, since the pipe line in the evaporation pipe 52 of the embodiment is inclined to the front side in the circulation direction of the secondary refrigerant, the flow rate of the secondary refrigerant is slow in the vicinity of the inflow end 52a of the evaporation pipe 52, so that it is concentrated on the pipe bottom. Although the flow in the state appears preferentially, the flow rate of the secondary refrigerant gradually increases toward the outflow end 52b. As a result, an annular flow in which the liquid phase secondary refrigerant circulates in an annular shape over the entire inner surface of the evaporation tube 52 appears preferentially in the evaporation tube 52 (see FIG. 6B). Accordingly, since the liquid phase secondary refrigerant contacts the entire circumference of the evaporation pipe 52, it is possible to secure a wider heat transfer area. Furthermore, since the evaporation pipe 52 is inclined, water dripped from the evaporation pipe 52 such as defrosted water can be concentrated and dropped at the outflow end 52b.

  In the evaporator EP, the secondary phase of the secondary circuit 44 is such that the liquid phase secondary refrigerant reaches the vicinity of the outflow end 52b of the evaporation pipe 52 and the saturated liquid phase secondary refrigerant evaporates also in the vicinity of the outflow end 52b. The next refrigerant amount is defined (see FIG. 5). At this time, in the evaporator EP, the liquid phase secondary refrigerant naturally flows down along the pipe line of the evaporation pipe 52. Therefore, even if the liquid phase secondary refrigerant does not fill the evaporation pipe 52, the secondary refrigerant is removed from the evaporation pipe. 52 near the outflow end. That is, the amount of secondary refrigerant required in the secondary circuit 44 can be reduced.

  For example, when the amount of the secondary refrigerant is extremely small, the liquid phase secondary refrigerant evaporates before reaching the vicinity of the outflow end 52b of the evaporation pipe 52, so that the cooling action cannot be obtained as the entire evaporator EP, and is required. The cooling ability cannot be demonstrated. Further, when the amount of the secondary refrigerant is excessive, the liquid phase secondary refrigerant is filled in the entire evaporation pipe 52 and a head is generated in the gas pipe 50 that obstructs the circulation of the gas phase secondary refrigerant. Stays in the evaporation pipe 52. At this time, in the evaporation pipe 52, the head formed in the gas pipe 50 is suddenly pushed up by the phase in which the circulation of the gas phase secondary refrigerant is delayed by the head of the gas pipe 50 and the increase in the internal pressure in the evaporation pipe 52, The phase where the circulation of the gas phase secondary refrigerant is temporarily resumed is repeated. In the phase where the circulation of the gas phase secondary refrigerant is stagnant, a larger amount of the gas phase secondary refrigerant stays in the evaporation pipe 52 than in the phase where the circulation of the gas phase secondary refrigerant is normally performed. Since the heat transfer area by the liquid phase secondary refrigerant having a high conductivity is reduced, the cooling capacity of the evaporator EP is lowered. As described above, the decrease in the cooling capacity that occurs when the secondary refrigerant in the evaporator EP is excessive is due to a decrease in the refrigerant circulation amount by the head of the gas pipe 50 and an increase in the gas phase secondary refrigerant that stays in the evaporation pipe 52. The main cause is the decrease in thermal conductivity. That is, the evaporator EP cannot obtain the required cooling capacity even if the amount of the secondary refrigerant is small or large, and it is important to fill the secondary refrigerant with an appropriate amount. According to the configuration of the evaporator EP according to the embodiment, the appropriate amount of the secondary refrigerant is the lowest part of the liquid phase secondary refrigerant that evaporates while flowing down the evaporation pipe 52 (near the outflow end 52b of the evaporation pipe 52). ), And can be easily obtained.

  In the evaporation pipe 52 of the evaporator EP, the gas phase secondary refrigerant obtained by evaporating the liquid phase secondary refrigerant decreases in specific gravity due to volume expansion, and thus flows upward. Since the evaporating pipe 52 is higher on the inflow end 52a side than the outflow end 52b side, the vapor phase secondary refrigerant tends to flow backward to the inflow end 52a side. However, since the liquid sealing portion 62 made of the liquid phase secondary refrigerant is formed below each flow path 60a in the secondary heat exchanging portion 46, the gas phase secondary refrigerant whose flow has been hindered stays in the evaporation pipe 52. The internal pressure inside the evaporation pipe 52 is increased. As the internal pressure in the evaporation pipe 52 rises, an internal force acts so that the refrigerant in the evaporation pipe 52 is pushed out toward the outflow end 52b, which is the only pressure release portion. That is, since the gas phase secondary refrigerant is pushed out from the evaporator EP toward the gas pipe 50, it can be naturally circulated in the normal circulation direction in the secondary circuit 44 against the pipe shape of the evaporation pipe 52. it can. Here, in the liquid sealing part 62, the liquid phase secondary refrigerant that condenses and flows down above the liquid sealing part 62 sequentially forms the liquid sealing part 62, while preventing the circulation of the gas phase secondary refrigerant. The liquid phase secondary refrigerant that has formed the sealing portion 62 flows down under the action of gravity. Therefore, the liquid sealing portion 62 does not hinder the flow of the liquid phase secondary refrigerant.

  In the secondary heat exchange section 46, the gas phase secondary refrigerant is condensed by heat exchange with the primary heat exchange section 36, and the volume is reduced to reduce the pressure inside the secondary heat exchange section 46. The suction force toward the secondary heat exchange unit 46 is acting on the gas pipe 50. As described above, the evaporation pipe 52 is not configured to be entirely filled with the liquid phase secondary refrigerant, and the outflow end 52b of the evaporation pipe 52 and the gas pipe 50 are not sealed with the liquid phase secondary refrigerant and are opened. Therefore, the suction force applied to the gas pipe 50 can also be applied to the evaporation pipe 52. Therefore, the gas phase secondary refrigerant can be recirculated to the secondary heat exchange unit 46 by effectively utilizing the suction force by the secondary heat exchange unit 46.

  In the initial stage of operation in the cooling device 32, the liquid seal portion 62 may not be formed in the secondary heat exchange portion 46. In this case, since no external force is applied in the circulation direction to the vapor phase secondary refrigerant evaporated in the evaporator EP, the vapor phase secondary refrigerant flows back to the lower portion of the secondary heat exchange section 46 via the liquid pipe 48. It is also possible to do. Here, since the secondary heat exchange unit 46 has already been cooled by the primary heat exchange unit 36, the gas phase secondary refrigerant that has arrived at the lower part of the secondary heat exchange unit 46 via the liquid pipe 48 has the secondary heat. The liquid is immediately liquefied at the lower part of each flow path 60b in the exchange part 46. Then, the liquid seal portion 62 is located below the flow path 60b in the secondary heat exchange section 46 by the liquid phase secondary refrigerant and the liquid phase secondary refrigerant that has been liquefied and flowed down in the secondary heat exchange section 46 due to normal circulation. Formed. The liquid seal portion 62 prevents the reverse flow of the gas-phase secondary refrigerant and an external force acts on the gas-phase secondary refrigerant in the circulation direction, so that the gas-phase secondary refrigerant is in the normal circulation direction in the secondary circuit 44. It is circulated to.

  According to the secondary circuit 44, the liquid-phase secondary refrigerant is configured to naturally flow down the evaporating pipe 52 to the front side in the circulation direction under the action of gravity, so that a wide heat transfer area can be secured with a small amount of secondary refrigerant. Can do. That is, since the amount of secondary refrigerant in the secondary circuit 44 can be reduced, the secondary circuit 44 itself can be downsized. Further, since the amount of the secondary refrigerant is reduced, the maximum pressure value required when the cooling device 32 is stopped for a long period of time can be kept low, so the pressure strength required for the secondary circuit 44 is set low. Therefore, the cost can be reduced and the degree of design freedom can be improved. In particular, when a secondary refrigerant that evaporates at room temperature, such as carbon dioxide in the embodiment, the maximum value of the internal pressure in the secondary circuit 44 can be kept low. Further, the capacity of the expansion tank 54 can be reduced, and the expansion tank 54 can be downsized, the space in the machine room 20 can be effectively used, and the cost can be reduced. Furthermore, even if it is an existing facility, if a plate-type heat exchanger is used as the heat exchanger HE, only the evaporator EP according to the embodiment is used, and the amount of secondary refrigerant charged by the evaporator EP of the embodiment It is possible to enjoy the above-described excellent effects such as the reduction of the above. In addition, since the maximum pressure value of the secondary refrigerant can be suppressed as described above, even when a pressure relief valve (not shown) is provided in the gas pipe 50, the set value of the pressure relief valve can be lowered.

  In the cooling device 32, the primary circuit 34 and the secondary circuit 44 are connected by a heat exchanger HE. In the heat exchanger HE, the primary refrigerant of the primary circuit 34 and the secondary refrigerant of the secondary circuit 44 are evaporated and evaporated. Heat exchange is performed under condensation. That is, since the heat transfer coefficient is very high compared to heat exchange using only sensible heat, the heat transfer area between the primary circuit 34 and the secondary circuit 44 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 in a relatively small amount, so that the amount of heat exchange in the heat exchanger HE is not reduced. It is possible to reduce the internal volume of the primary circuit 34 and the secondary circuit 44. Therefore, both the primary refrigerant amount of the primary circuit 34 and the secondary refrigerant amount of the secondary circuit 44 can be reduced, and the cost can be reduced and the space of the cooling device 32 can be saved by downsizing the primary circuit 34 and the secondary circuit 44. obtain.

  Since the amount of the primary refrigerant required for the primary circuit 34 is small, the upper limit amount of the refrigerant stipulated by laws and regulations can be avoided, and the range of options for the type of refrigerant used as the primary refrigerant is expanded. Further, the machine room 20 is an open space in which air is exchanged for the purpose of air-cooling the condenser CD and the compressor CM. Since the primary circuit 34 is disposed in the machine room 20 as described above, even if the primary refrigerant leaks, 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, since the cooling device 32 is configured by a secondary loop of the primary circuit 34 and the secondary circuit 44, the cooling capacity of the secondary circuit 44 is increased, so that the characteristics as a refrigerant such as evaporation heat and saturation pressure are inferior. However, it is possible to select carbon dioxide or the like excellent in safety as the secondary refrigerant. That is, in the secondary circuit 44, the evaporator EP faces the storage chamber 14 (cooling chamber 28), but even if a secondary refrigerant leaks into the storage chamber 14, for example, safety for the user can be ensured.

  In the cooling device 32, the compressor CM, the condenser CD, the condenser fan FM, and the heat exchanger HE of the primary circuit 34, and the evaporator EP and the expansion tank 54 of the secondary circuit 44 are shared by the base plate 24. Since it is a structure to arrange | position, the whole cooling device 32 can be handled integrally through the base plate 24. FIG. In other words, the cooling device 32 can be integrally attached to or detached from the refrigerator 10, has excellent maintainability, and can easily perform maintenance work such as repair.

  The primary circuit 34 and the secondary circuit 44 are thermally connected by the primary heat exchange unit 36 and the secondary heat exchange unit 46 of the heat exchanger HE, but are independent of each other as a refrigerant circulation path. When the cooling device 32 is stopped (compressor CM: stopped), the high-temperature liquid-phase primary refrigerant flows into the primary circuit 34 from the condenser CD into the primary circuit 34. As a result, the temperature of the heat exchanger HE is raised, but the secondary circuit 44 is independent. Therefore, the temperature of the evaporator EP is not raised, and the temperature of the storage chamber 14 rises when the cooling device 32 is stopped. Becomes moderate. That is, by cooling the storage chamber 14 to a required set temperature by the cooling device 32, it is possible to lengthen the time until the cooling device 32 is driven again after the cooling device 32 is stopped. Therefore, since the operating rate of the cooling device 32 is reduced, the power consumption is reduced.

  The expansion tank 54 is arranged in a straight line with the condenser CD, the condenser fan FM, and the compressor CD in the machine room 20, and is disposed on the front side in the air flow direction by the condenser fan FM. For this reason, since the air that has been taken into the machine room 20 from the front side of the cabinet 16 by the drive of the condenser fan FM and heat-exchanged with the condenser CD and the compressor CM is blown to the expansion tank 54, the expansion is performed. The tank 54 is heated using the exhaust heat of the primary circuit 34. Here, the amount of the secondary refrigerant staying in the expansion tank 54 is a value that changes according to the pressure and temperature, and this pressure changes because it depends on the evaporation temperature defined by the operating conditions and the like in the primary circuit 34. I can't let you. Therefore, by raising the temperature of the expansion tank 54 by the exhaust heat of the primary circuit 34, the secondary refrigerant density in the expansion tank 54 is reduced, so that the amount of the secondary refrigerant staying in the expansion tank 54 can be reduced. . If the amount of the secondary refrigerant staying in the expansion tank 54 is reduced, there is an advantage that the amount of secondary refrigerant in the secondary circuit 44 can be reduced.

(Change example)
The present invention is not limited to the configuration of the embodiment, and can be modified as follows.
(1) As an evaporator tube of an evaporator, a so-called fin tube having a radially extending fin on the outer periphery or a so-called spiral fin tube having a spiral extending radially on the outer periphery is employed. May be. Further, the pipes of the evaporation pipes are branched into a plurality of (two systems) systems at the inflow end, and these plurality of system branch evaporation pipes extend in a meandering manner so as to have a downward slope toward the front side in the circulation direction. It is also possible to adopt a configuration that exists and is brought together again at the outflow end.
(2) In the embodiment, the pipe of the evaporation pipe is formed so as to be inclined downward from the inflow end side to the outflow end side. However, as a whole, the liquefied refrigerant can be diffused under the action of gravity toward the outflow end side. If there is, a part inclined upward toward the outflow end side or a part extending horizontally may be provided in a part of the pipeline.
(3) Although the evaporation pipe of the embodiment is formed with a pipe line so as to extend between the upper and lower positions of the inflow end and the outflow end, it may be extended at least above the outflow end.
(4) In the embodiment, as the means for preventing the back flow of the gas phase secondary refrigerant, the liquid seal portion formed in the flow path of the secondary heat exchange portion in the plate heat exchanger is used, but is not limited thereto. In addition, a drag that provides a flow resistance against the gas phase secondary refrigerant may be provided between the liquid pipe and the vicinity of the connection with the liquid pipe in the heat exchanger. For example, as a configuration in which the liquid phase secondary refrigerant is stored in the inner bottom portion of the heat exchanger or in the middle of the liquid pipe, a head (water head) of the secondary refrigerant stored in the storage portion may be used as the resistance portion. Furthermore, a means for increasing the flow resistance in the liquid pipe, a pipe shape provided with a throttle part or a trap, or a check valve inserted in the liquid pipe can be used as the resistance part. In addition to using the resistance portions of these various modes as a single unit, the configurations of the embodiments and the modified examples may be combined to function as a resistance portion.
(5) The thermosiphon according to the embodiment can be applied to a cooling circuit such as an air conditioner.
(6) The evaporator according to the embodiment has a configuration in which the evaporation pipe extends, but may be an evaporation pipe of a type in which a refrigerant path is formed by dividing the inside of the box with a wall.

(7) In the embodiment, the storage chamber and the machine room are separated from each other by a base plate serving as a common substrate for equipment disposed in the machine room so that there is no air flow between the machine room and the storage room. However, the machine room and the storage room may be separated by a box top plate.
(8) In the embodiment, the case where the thermosiphon according to the present invention is employed as the refrigerator cooling device has been described, but the present invention can also be applied to so-called storages such as a freezer, a freezer / refrigerator, a showcase, and a prefabricated warehouse.

(9) Although the mechanical compression type refrigeration circuit is employed as the primary circuit of the cooling device in the embodiment, an absorption type and other refrigeration circuits can also be employed.
(10) Although the plate type heat exchanger provided with the 1st heat exchange part of the primary circuit and the 2nd heat exchange part of the secondary circuit was used as a heat exchanger of an example, the 1st heat exchange part and the 2nd The heat exchange unit may be configured as a separate body or may be a heat exchanger of another type.
(11) In the embodiment, the expansion valve is used as means for reducing the pressure of the liquefied refrigerant in the primary circuit. However, the present invention is not limited to this, and a capillary tube or other pressure reducing means may be employed.

It is a sectional side view which shows the refrigerator cooled by the cooling device provided with the thermosiphon which concerns on the suitable Example of this invention in the secondary circuit. It is a plane sectional view showing the machine room in the refrigerator of an example. It is a schematic circuit diagram which shows the cooling device of an Example. It is a sectional side view which shows the heat exchanger of an Example. It is a schematic diagram which shows the evaporator of an Example. It is sectional drawing of the evaporation pipe | tube of an Example, (a) shows the AA sectional view of FIG. 3, (b) shows the BB sectional view of FIG. It is a schematic circuit diagram which shows the conventional thermosiphon. It is a schematic diagram showing an evaporator in a conventional thermosyphon, where (a) shows a case where the amount of refrigerant is small, (b) shows a case where the amount of refrigerant is appropriate, and (c) shows that the amount of refrigerant is excessive. Indicates a case.

Explanation of symbols

46 Secondary heat exchange section (heat exchange section), 48 liquid pipe, 50 gas pipe, 52 evaporation pipe (refrigerant path)
52a inflow end, 52b outflow end, 60 plate, 60b flow path 62 liquid seal part (resistor part, liquid sealed part), EP evaporator

Claims (3)

A heat exchange section (46) that condenses the vaporized refrigerant to form a liquefied refrigerant, and an evaporator (EP) that is disposed below the heat exchange section (46) and vaporizes the liquefied refrigerant to form a vaporized refrigerant. The pipe (48) and the gas pipe (50) are connected, and the liquefied refrigerant flows down from the heat exchange section (46) to the evaporator (EP) through the liquid pipe (48), and the vaporized refrigerant is evaporated to the evaporator (EP). In the thermosiphon that formed a natural circulation cycle that circulates through the gas pipe (50) from the heat exchanger (46) to
In the refrigerant path (52) extending to the evaporator (EP), an inflow end (52a) connected to a lower end of the liquid pipe (48) is disposed at an upper portion of the evaporator (EP), and the gas The outflow end (52b) connected to the lower end of the pipe (50) is disposed at the lower part of the evaporator (EP),
A thermosiphon, wherein a resistance portion (62) serving as a flow resistance against the vaporized refrigerant flowing backward from the evaporator (EP) is provided in the heat exchange portion (46) or the liquid pipe (48).   The thermosiphon according to claim 1, wherein the refrigerant path (52) is formed to have a downward slope from the inflow end (52a) toward the outflow end (52b).   The heat exchanging section (46) is configured by arranging a plurality of plates (60) extending in the vertical direction to face each other in parallel, and a refrigerant flow path (between the plates (60, 60)) ( The thermosiphon according to claim 1 or 2, wherein a part (62) sealed with a liquefied refrigerant is provided at a lower part of 60b), and the part (62) sealed with liquid becomes the resistance portion.

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