JP2007303792A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating device capable of quickly recovering a refrigerant in a refrigerant circuit at the stop of a compressor, into an expansion tank, and reducing load added to the compressor in restarting. <P>SOLUTION: This refrigerating device 1 comprises the refrigerant circuit 38 for condensing the refrigerant discharged from the compressor 20, and then evaporating the same to exert cooling effect, further comprises the expansion tank 65 connected to piping 20S at a suction side of the compressor 20 through a capillary tube 66, a check valve 67 is connected in parallel with the capillary tube 66, and the direction of the expansion tank 65 is the forward direction of the check valve. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus including a refrigerant circuit that condenses and evaporates refrigerant discharged from a compressor and exhibits a cooling action.

  Conventionally, a refrigeration apparatus using a compressor is configured by a refrigerant circuit in which a compressor, a condenser, a capillary tube (decompression apparatus), and an evaporator are connected in a ring shape. When a predetermined refrigerant is sealed in the refrigerant circuit and the compressor is operated, the high-temperature gaseous refrigerant discharged from the compressor is condensed in the condenser to be radiated and liquefied, and then in the capillary tube. It is depressurized, flows into the evaporator and evaporates, absorbs the heat of vaporization from the surroundings, cools the evaporator, and returns to the compressor.

Here, an expansion tank is connected to the suction side piping of the compressor via a decompressor, and when the compressor is stopped, the refrigerant sealed in the refrigerant circuit is stored. Thereby, the compressor operation | movement at the time of starting of a compressor is made smooth by lowering | hanging the equilibrium pressure in the refrigerant circuit at the time of a compressor stop (refer patent document 1).
JP-A-62-73046

  However, as described above, since the expansion tank is provided with a decompressor, it is difficult to quickly collect the refrigerant in the refrigerant circuit in the expansion tank when the compressor is stopped. There was a problem that it took time to achieve the equilibrium pressure. Therefore, if the compressor is restarted while the refrigerant circuit is in a high pressure state, there is a problem that the load applied to the compressor increases. Therefore, when waiting for the restart of the compressor until the equilibrium pressure is reached, the operation rate of the compressor is lowered, and the time required for the pull-down operation performed when the refrigeration apparatus is turned on becomes very long. There was a problem.

  Therefore, the present invention has been made to solve the conventional technical problem, and allows the refrigerant in the refrigerant circuit to be quickly collected in the expansion tank when the compressor is stopped, A refrigerating apparatus capable of reducing the load applied to the compressor in the present invention is provided.

  The refrigeration apparatus of the present invention is provided with a refrigerant circuit that condenses and evaporates the refrigerant discharged from the compressor and exhibits a cooling action, and is connected to a suction side pipe of the compressor via a pressure reducing device. And a check valve is connected in parallel to the pressure reducing device, and the direction of the expansion tank is the forward direction of the check valve.

  According to a second aspect of the present invention, there is provided a refrigeration apparatus comprising a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit that constitute an independent refrigerant closed circuit that condenses and evaporates the refrigerant discharged from the compressor and exhibits a cooling action. The evaporator of the high-temperature side refrigerant circuit and the condenser of the low-temperature side refrigerant circuit constitute a cascade heat exchanger, and an ultra-low temperature is obtained by the evaporator of the low-temperature side refrigerant circuit, and the compression of the low-temperature side refrigerant circuit It is provided with an expansion tank connected to the suction side pipe of the machine through a pressure reducing device, a check valve is connected in parallel to the pressure reducing device, and the direction of the expansion tank is the forward direction of the check valve. .

  The refrigeration apparatus of the invention of claim 3 includes a compressor, a condenser, an evaporator, a plurality of intermediate heat exchangers connected in series so that a return refrigerant from the evaporator flows, and a plurality of decompression devices. A kind of non-azeotropic refrigerant mixture is enclosed, and the condensed refrigerant in the refrigerant that has passed through the condenser is joined to the intermediate heat exchanger via the decompression device, and the uncondensed refrigerant in the refrigerant is cooled by the intermediate heat exchanger. Thus, the refrigerant having a lower boiling point is condensed sequentially, and the refrigerant having the lowest boiling point is caused to flow into the evaporator through the final-stage decompression device, thereby obtaining an ultra-low temperature, and the decompression device is connected to the suction side pipe of the compressor. And a check valve is connected in parallel to the pressure reducing device, and the direction of the expansion tank is the forward direction of the check valve.

  According to a fourth aspect of the present invention, there is provided a refrigeration apparatus comprising a high temperature side refrigerant circuit and a low temperature side refrigerant circuit that constitute an independent refrigerant closed circuit that condenses and evaporates the refrigerant discharged from the compressor and exhibits a cooling action. The low-temperature side refrigerant circuit has a compressor, a condenser, an evaporator, a plurality of intermediate heat exchangers connected in series so that a return refrigerant from the evaporator flows, and a plurality of decompression devices. Of the non-azeotropic refrigerant mixture, the condensed refrigerant in the refrigerant having passed through the condenser is joined to the intermediate heat exchanger via the decompression device, and the non-condensed refrigerant in the refrigerant is cooled by the intermediate heat exchanger. The refrigerant having the lower boiling point is condensed sequentially, and the refrigerant having the lowest boiling point flows into the evaporator via the decompressor in the final stage, and cascade heat is generated between the evaporator of the high temperature side refrigerant circuit and the condenser of the low temperature side refrigerant circuit. Construct an exchanger and steam in the low-temperature refrigerant circuit It is equipped with an expansion tank connected to the suction side piping of the compressor of the low-temperature side refrigerant circuit via a pressure reducing device, and connected to the pressure reducing device in parallel with a check valve. The tank direction is the forward direction of the check valve.

  According to the present invention, in the refrigeration apparatus provided with the refrigerant circuit that condenses and evaporates the refrigerant discharged from the compressor and exhibits the cooling action, the refrigerant is connected to the suction side piping of the compressor via the decompression device. An expansion tank is provided, a check valve is connected in parallel to the decompression device, and the direction of the expansion tank is set to the forward direction of the check valve, so that the refrigerant in the refrigerant circuit passes through the check valve when the compressor is stopped. It is possible to quickly collect in the expansion tank.

  As a result, it is possible to prevent the pressure in the refrigerant circuit from rising, and after starting the compressor, gradually return the refrigerant from the expansion tank to the refrigerant circuit via the decompression device, thereby Can be reduced.

  Therefore, by quickly collecting the refrigerant into the expansion tank when the compressor is stopped, it is possible to quickly balance the pressure in the refrigerant circuit, and when the compressor is restarted, the compressor is loaded. It is possible to smoothly restart the compressor without applying it. Thereby, the operation efficiency of the compressor can be improved, for example, the time required for the pull-down operation can be shortened, and the convenience can be improved.

  According to the invention of claim 2, the refrigerant comprises a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit that constitute an independent refrigerant closed circuit that condenses and evaporates the refrigerant discharged from the compressor and exhibits a cooling action, In the refrigeration system for obtaining an ultra-low temperature in the evaporator of the low temperature side refrigerant circuit, the cascade heat exchanger is constituted by the evaporator of the high temperature side refrigerant circuit and the condenser of the low temperature side refrigerant circuit. The simple multi-component refrigerant is provided with an expansion tank connected to the suction side pipe via a pressure reducing device, a check valve is connected in parallel to the pressure reducing device, and the direction of the expansion tank is set to the forward direction of the check valve. In the circuit, when the compressor of the low-temperature side refrigerant circuit is stopped, the refrigerant in the low-temperature side refrigerant circuit can be quickly collected into the expansion tank via the check valve.

  As a result, it is possible to prevent the pressure in the low-temperature side refrigerant circuit from rising, and after starting the compressor, the refrigerant is gradually returned from the expansion tank to the low-temperature side refrigerant circuit via the decompression device, thereby compressing the refrigerant. It becomes possible to reduce the starting load of the machine.

  Therefore, by quickly collecting the refrigerant into the expansion tank when the compressor is stopped, the pressure in the low-temperature side refrigerant circuit can be quickly balanced, and when the compressor is restarted, The compressor can be smoothly restarted without applying a load. Thereby, the operation efficiency of the compressor can be improved, for example, the time required for the pull-down operation can be shortened, and the convenience can be improved.

  According to the invention of claim 3, the compressor, the condenser, the evaporator, the plurality of intermediate heat exchangers connected in series so that the return refrigerant from the evaporator circulates, and the plurality of pressure reducing devices are provided. Of the non-azeotropic refrigerant mixture, the condensed refrigerant in the refrigerant having passed through the condenser is joined to the intermediate heat exchanger via the decompression device, and the non-condensed refrigerant in the refrigerant is cooled by the intermediate heat exchanger. In a refrigeration system that obtains ultra-low temperature by sequentially condensing a refrigerant with a lower boiling point and flowing the refrigerant with the lowest boiling point into an evaporator via a final stage decompression device, the suction side piping of the compressor is connected via a decompression device. In the simple multi-stage refrigerant circuit, the compressor of the refrigerant circuit is provided by connecting a check valve in parallel with the decompression device and connecting the check valve in the forward direction of the check valve. Check the refrigerant in the refrigerant circuit when stopping To it is possible to quickly recover the expansion tank.

  As a result, it is possible to prevent the pressure in the refrigerant circuit from rising, and after starting the compressor, gradually return the refrigerant from the expansion tank to the refrigerant circuit via the decompression device, thereby Can be reduced.

  Therefore, by quickly collecting the refrigerant into the expansion tank when the compressor is stopped, it is possible to quickly balance the pressure in the refrigerant circuit, and when the compressor is restarted, the compressor is loaded. It is possible to smoothly restart the compressor without applying it. Thereby, the operation efficiency of the compressor can be improved, for example, the time required for the pull-down operation can be shortened, and the convenience can be improved.

  According to the invention of claim 4, it comprises a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit constituting an independent refrigerant closed circuit that condenses and evaporates the refrigerant discharged from the compressor and exhibits a cooling action, The low-temperature side refrigerant circuit has a compressor, a condenser, an evaporator, a plurality of intermediate heat exchangers connected in series so that a return refrigerant from the evaporator flows, and a plurality of decompression devices. A non-azeotropic refrigerant mixture is enclosed, and the condensed refrigerant in the refrigerant that has passed through the condenser is joined to the intermediate heat exchanger via the decompression device, and the uncondensed refrigerant in the refrigerant is cooled by the intermediate heat exchanger, The refrigerant with lower boiling point is condensed sequentially, and the refrigerant with the lowest boiling point flows into the evaporator through the decompressor at the final stage, and cascade heat exchange is performed between the evaporator of the high temperature side refrigerant circuit and the condenser of the low temperature side refrigerant circuit. Low temperature refrigerant circuit evaporator In the refrigeration system for obtaining ultra-low temperature, an expansion tank connected to the suction side piping of the compressor of the low-temperature side refrigerant circuit via a pressure reducing device, a check valve connected in parallel to the pressure reducing device, and the direction of the expansion tank In the forward direction of the check valve, the refrigerant in the low-temperature side refrigerant circuit is quickly collected in the expansion tank via the check valve when the compressor of the low-temperature side refrigerant circuit is stopped in the multi-stage multi-stage refrigerant circuit. It becomes possible.

  As a result, it is possible to prevent the pressure in the low-temperature side refrigerant circuit from rising, and after starting the compressor, the refrigerant is gradually returned from the expansion tank to the low-temperature side refrigerant circuit via the decompression device, thereby compressing the refrigerant. It becomes possible to reduce the starting load of the machine.

  Therefore, by quickly collecting the refrigerant into the expansion tank when the compressor is stopped, the pressure in the low-temperature side refrigerant circuit can be quickly balanced, and when the compressor is restarted, The compressor can be smoothly restarted without applying a load. Thereby, the operation efficiency of the compressor can be improved, for example, the time required for the pull-down operation can be shortened, and the convenience can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a perspective view of a refrigeration apparatus 1 to which the present invention is applied, FIG. 2 is a front view of the refrigeration apparatus 1, FIG. 3 is a plan view of the refrigeration apparatus 1, and FIG. FIG. 5 is a perspective view of the refrigeration apparatus 1 with the top panel 5 opened. The refrigeration apparatus 1 of the present embodiment is suitable for ultra-low temperature storage of, for example, a living tissue or specimen that performs long-term low-temperature storage, and is located on the side of the heat-insulating box 2 that opens to the upper surface. And the main body is comprised by the machine room 3 in which the compressor 10 grade | etc., Is installed in the inside.

  The heat insulating box 2 is composed of a steel plate outer box 6 having an open upper surface, an inner box 7 made of metal such as aluminum having good thermal conductivity, and a synthetic resin that connects between the upper ends of these boxes 6 and 7. And a heat insulating material 9 made of polyurethane resin filled in the space surrounded by the outer box 6, the inner box 7 and the breaker 8 by an in-situ foaming method. The inside is a storage chamber 4 whose upper surface is open.

  In this embodiment, in order to set the target storage chamber 4 internal temperature (hereinafter referred to as the internal temperature) to −150 ° C. or lower, for example, the heat insulating box 2 that partitions the internal storage room 4 from the outside air is A large heat insulation capacity is required as compared with a low temperature in which the internal temperature is set to around 0 ° C. Therefore, in order to ensure the heat insulation capability only by the above-described heat insulating material 9 made of polyurethane resin, it must be formed extremely thick, and the limited amount of the main body allows a sufficient amount of storage in the storage chamber 4. There is a problem that cannot be secured.

  Therefore, the heat insulation box 2 in the present embodiment is a glass wool vacuum heat insulation on each inner wall surface of the side wall 6C located on the side opposite to the side where the front wall 6A, the rear wall 6B and the machine room 3 are provided. After the panel 12 is disposed and temporarily fixed with a double-sided adhesive tape, a heat insulating material 9 is filled between these boxes 6 and 7 by an in-situ foaming method.

  This vacuum heat insulation panel 12 stores glass wool having heat insulation in a container formed of a multilayer film made of aluminum, synthetic resin or the like that does not have air permeability. Thereafter, the air in the container is discharged by a predetermined evacuation means, and the opening of the container is joined by thermal welding. Therefore, this vacuum heat insulation panel 12 can acquire the same heat insulation effect by making the thickness dimension of the heat insulating material 9 thinner than before due to the heat insulation performance.

  On the other hand, an evaporator (evaporation pipe) 62 constituting a refrigerant circuit of a cooling device R, which will be described in detail later, is attached to the peripheral surface of the inner box 7 on the heat insulating material 9 side in a heat exchange manner.

  And the upper surface of the breaker 8 of the heat insulation box 2 comprised as mentioned above is shape | molded in step shape as FIG.2 and FIG.4 shows, and the heat insulation door 13 has one end through the packing which is not shown there. In this embodiment, the pivot members 14 and 14 are provided so as to be rotatable about the rear end. In addition, the upper opening of the storage chamber 4 is provided with an inner lid 15 made of a heat insulating material so as to be freely opened and closed. In addition, a pressing portion configured to protrude downward is formed on the lower surface of the heat insulating door 13, whereby the pressing portion of the heat insulating door 13 presses the inner lid 15, thereby the upper surface of the storage chamber 4. The opening is closed so as to be freely opened and closed. Further, a handle portion 16 is provided at the other end of the heat insulating door 13, that is, the front end in this embodiment, and the heat insulating door 13 is opened and closed by operating the handle portion 16.

  On the other hand, on the side of the heat insulation box 2, a machine room 3 is provided by a side panel 3B that constitutes a side surface opposite to the side on which the front panel 3A, a rear panel (not shown) and the heat insulation box 2 are provided. . The machine room 3 in the present embodiment is provided with a partition plate 17 that divides the interior vertically. Below the partition plate 17, the compressors 10, 20, etc. constituting the cooling device R as described above are accommodated and installed. The front panel 3 </ b> A and the side panel 3 </ b> B located below the partition plate 17 have ventilation holes. A slit 3C is formed.

  Above the partition plate 17 is an upper machine chamber 18 having an upper surface opened. In the upper opening of the upper machine chamber 18, the top panel 5 is provided so as to be pivotable around one end, in this embodiment, the rear end, so that the inside of the upper machine chamber 18 can be opened and closed freely. Is done. The panel provided in front of the upper machine room 18 is an operation panel 21 for operating the refrigeration apparatus 1.

  A measurement hole 19 is formed in the side surface of the upper machine chamber 18 on the heat insulation box 2 side. The measurement hole 19 penetrates the outer box 6, the heat insulating material 9, and the inner box 7 constituting the heat insulating box 2 so as to communicate with the storage chamber 4 formed in the heat insulating box 2 provided adjacently. Formed. The measurement hole 19 can insert a temperature sensor into the storage chamber 4 from the outside, and the wiring drawn from the temperature sensor is connected to an external recording apparatus main body through the measurement hole 19. Then, the measurement hole 19 is closed with a plug 19A made of a special material that can be deformed in a sponge-like manner and has a heat insulating property. When the temperature sensor is not attached, the measurement hole 19 is adiabatically closed by the plug 19A.

  Thus, when using a device that measures, records, etc. the temperature in the storage chamber 4, the top panel 5 provided in the machine room 3 is opened and the heat insulating box 2 located in the upper machine room 18. The measurement instrument can be inserted into the storage chamber 4 through the measurement hole 19 formed on the side surface. Therefore, the work of installing the measuring device in the storage chamber 4 cooled to a predetermined ultra-low temperature becomes easy.

  In particular, unlike the measurement hole provided in the conventional refrigeration apparatus, the measurement hole 19 in the present embodiment is formed on the side surface of the heat insulating box 2 on the machine room 18 side. Even when it is installed adjacent to a wall or other equipment in the installation environment, it is not necessary to have a space necessary for using the measurement hole 19 exceptionally. As a result, the area required for installing the refrigeration apparatus 1 can be reduced, which is suitable for layout of a laboratory or the like.

  Moreover, the measurement hole 19 is formed in the wall surface of the heat insulation box 2 on the side adjacent to the machine room 3, so that the heat insulation box is configured to face the side other than the machine room 3, that is, the outside. The vacuum heat insulation panel 12 as described above can be disposed on the front and rear walls and side surfaces of the body 2 without affecting the position where the measurement hole 19 is formed. Thereby, the amount of cold heat leakage in the storage chamber 4 can be reduced, and wasteful use of cooling energy can be suppressed.

  Therefore, even when the interior of the storage chamber 4 is set to an ultra-low temperature such as −150 ° C. or less as in this embodiment, the heat insulation performance of the heat insulation box 2 itself can be improved, and the size of the heat insulation wall can be improved. It is possible to reduce the size, and it is possible to increase the accommodation volume in the storage chamber 4 even with the same external dimensions as the conventional one. Or even if it is the same storage volume as before, it is possible to reduce the outer dimensions, and this also makes it possible to reduce the area required for installing the refrigeration apparatus 1.

  Furthermore, since the measurement hole 19 in the present embodiment can be concealed by the top panel 5 that can open and close the upper surface opening of the upper machine room 18, the measurement hole 19 may be configured not to be exposed to the appearance. It is possible to improve the appearance. Further, by opening the top panel 5, it becomes possible to easily operate the measurement hole 19, and workability can be improved. Moreover, by removing the partition plate 17, it becomes easy to operate the equipment constituting the other cooling device R installed below the partition plate 17, and the maintenance work can be improved. The top panel 5 can be used as a working side stand by closing the inside of the machine room 18 except when operating the measurement hole 19. Thus, it is suitable for delivery work of articles such as samples into the storage chamber 4.

  In the present embodiment, the measurement hole 19 is concealed by the top panel 5 that closes the upper surface opening of the upper machine chamber 18, but is not limited to this, and in the vicinity of the measurement hole 19, A lid member or the like for concealing the measurement hole 19 may be provided.

  Next, the refrigerant circuit of the refrigeration apparatus 1 of the present embodiment will be described with reference to FIG. The refrigerant circuit of the refrigeration apparatus 1 in the present embodiment is a multi-stage multi-stage refrigerant circuit, which includes a high-temperature side refrigerant circuit 25 as an independent first refrigerant circuit and a low-temperature side refrigerant circuit 38 as a second refrigerant circuit. The original two-stage refrigerant circuit is used.

  The compressor 10 constituting the high temperature side refrigerant circuit 25 is a reciprocating electric compressor using a one-phase or three-phase AC power source, and a discharge side pipe 10 </ b> D of the compressor 10 is connected to an auxiliary condenser 26. . The auxiliary condenser 26 is connected to a frame pipe 27 for heating the opening edge of the storage chamber 4 to prevent dew condensation. The frame pipe 27 is connected to the oil cooler 29 of the compressor 10 and then connected to the condenser 28. The refrigerant pipe exiting the condenser 28 is connected to the oil cooler 30 of the compressor 20 constituting the low-temperature side refrigerant circuit 38, and then connected to the condenser 31, and the refrigerant pipe exiting the condenser 31 is In addition, a dryer 32 and a capillary tube 33 as a decompression device are connected to an evaporator 34 as an evaporator part constituting the evaporator via a tube. An accumulator 35 serving as a refrigerant reservoir is connected to the outlet side refrigerant pipe of the evaporator 34, and the refrigerant pipe exiting the accumulator 35 is connected to the suction side pipe 10 </ b> S of the compressor 10. In addition, the auxiliary condenser 26 and the condensers 28 and 31 in the present embodiment are configured as an integral condenser and are cooled by the condenser blower 36.

The high temperature side refrigerant circuit 25 is filled with a refrigerant composed of R407D and n-pentane as a non-azeotropic refrigerant having different boiling points. R407D is composed of R32 (difluoromethane: CH ₂ F ₂ ), R125 (pentafluoroethane: CHF ₂ CF ₃ ), and R134a (1,1,1,2-tetrafluoroethane: CH ₂ FCF ₃ ). The composition of R32 is 15% by weight, R125 is 15% by weight, and R134a is 70% by weight. The boiling point of each refrigerant is −321.8 ° C. for R32, −48.57 ° C. for R125, and −26.16 ° C. for R134a. The boiling point of n-pentane is + 36.1 ° C.

  The high-temperature gaseous refrigerant discharged from the compressor 10 is condensed in the auxiliary condenser 26, the frame pipe 27, the oil cooler 29, the condenser 28, the oil cooler 30 of the compressor 20 in the low-temperature side refrigerant circuit 38, and the condenser 31. Then, the moisture contained in the dryer 32 is removed, and the pressure is reduced in the capillary tube 33 and flows into the evaporator 34 one after another to evaporate the refrigerants R32, R125, and R134a. It absorbs and cools the evaporator 34, and returns to the compressor 10 through the accumulator 35 as a refrigerant liquid reservoir.

  At this time, the capacity of the compressor 10 is 1.5 HP, for example, and the final temperature reached by the evaporator 34 during operation is −27 ° C. to −35 ° C. Under such a low temperature, the boiling point of n-pentane in the refrigerant is + 36.1 ° C., so that it does not evaporate in the evaporator 34 and remains in a liquid state, and therefore hardly contributes to cooling. The function of returning the mixed moisture that could not be absorbed by the dryer 32 to the compressor 10 while being dissolved therein and the evaporation of the liquid refrigerant in the compressor 10 reduce the temperature of the compressor 10. Play a function.

  On the other hand, in the low-temperature side refrigerant circuit 38, the compressor 20 is a reciprocating electric compressor that uses a one-phase or three-phase alternating current power supply like the compressor 10, and the discharge-side piping 20D of the compressor 20 includes The oil separator 40 is connected through a radiator 39 composed of a wire capacitor. The oil separator 40 is connected to an oil return pipe 41 that returns to the compressor 20. The refrigerant pipe connected to the outlet side of the oil separator 40 is connected to a condensing pipe 42 as a high-pressure side pipe inserted into the evaporator 34. The condensing pipe 42 and the evaporator 34 constitute a cascade heat exchanger 43.

  The discharge pipe connected to the outlet side of the condensing pipe 42 is connected to the first gas-liquid separator 46 via the dryer 44. The gas-phase refrigerant separated by the gas-liquid separator 46 passes through the first intermediate heat exchanger 48 via the gas-phase pipe 47 and flows into the second gas-liquid separator 49. The liquid-phase refrigerant separated by the first gas-liquid separator 46 flows into the first intermediate heat exchanger 48 via the liquid-phase pipe 50, the dryer 51, and the capillary tube 52 serving as a decompression device. Cooling is achieved by evaporating the phase refrigerant.

  The liquid-phase refrigerant separated by the second gas-liquid separator 49 flows through the liquid-phase piping 53 through the dryer 54 and then through the capillary tube 55 as a decompression device to the second intermediate heat exchanger 56. The gas-phase refrigerant separated by the second gas-liquid separator 54 passes through the second intermediate heat exchanger 56 via the gas-phase pipe 57, and the third and fourth intermediate heat exchangers 58, The liquid is cooled and liquefied while passing through 59, and flows into a capillary tube 61 as a pressure reducing device through a pipe 68 through a dryer 60. The capillary tube 61 is connected to an evaporation pipe 62 as an evaporator, and the evaporation pipe 62 is further connected to a fourth intermediate heat exchanger 59 via a return pipe 69.

  The fourth intermediate heat exchanger 59 is connected to the third, second, and first intermediate heat exchangers 58, 56, and 48 one after another, and then connected to the suction side pipe 20 </ b> S of the compressor 20. Further, an expansion tank 65 for storing refrigerant when the compressor 20 is stopped is connected to the suction side pipe 20S via a capillary tube 66 as a decompression device, and the direction of the expansion tank 65 is forward to the capillary tube 66. The check valve 67 is connected in parallel.

The low temperature side refrigerant circuit 38 is filled with a non-azeotropic refrigerant mixture including R245fa, R600, R404A, R508, R14, R50, and R740 as seven types of mixed refrigerants having different boiling points. R245fa is 1,1,1, -3,3-pentafluoropropane (CF ₃ CH ₂ CHF ₂ ), and R600 is butane (CH ₃ CH ₂ CH ₂ CH ₃ ). The boiling point of R245fa is + 15.3 ° C., and the boiling point of R600 is −0.5 ° C. Therefore, by mixing these at a predetermined ratio, it can be used as a substitute for R21 having a boiling point of + 8.9 ° C., which has been conventionally used.

  Since R600 is a flammable substance, it is mixed with the nonflammable R245fa at a predetermined ratio, in this embodiment, at a ratio of R245fa / R600: 70/30, so that it is sealed in the refrigerant circuit 38 as nonflammable. And In this embodiment, R245fa is set to 70% by weight based on the total weight of R245fa and R600, but if it is more than that, it becomes nonflammable, so it may be more than that.

R404A includes R125 (pentafluoroethane: CHF ₂ CF ₃ ), R143a (1,1,1-trifluoroethane: CH ₃ CF ₃ ), and R134a (1,1,1,2-tetrafluoroethane: CH ₂ FCF ₃ ), and the composition is 44% by weight of R125, 52% by weight of R143a, and 4% by weight of R134a. The mixed refrigerant has a boiling point of −46.48 ° C. Therefore, it can be used as a substitute for R22 having a boiling point of −40.8 ° C. which has been conventionally used.

R508 is composed of R23 (trifluoromethane: CHF ₃ ) and R116 (hexafluoroethane: CF ₃ CF ₃ ), and the composition thereof is 39% by weight for R23 and 61% by weight for R116. The mixed refrigerant has a boiling point of −88.64 ° C.

R14 is tetrafluoromethane (carbon tetrafluoride: CF ₄ ), R50 is methane (CH ₄ ), and R740 is argon (Ar). As for these boiling points, R14 is −127.9 ° C., R50 is −161.5 ° C., and R740 is −185.86 ° C. In addition, although R50 has a danger of causing an explosion when combined with oxygen, mixing with R14 eliminates the danger of an explosion. Therefore, even if a mixed refrigerant leakage accident occurs, no explosion occurs.

  These refrigerants as described above are once mixed with R245fa and R600 and R14 and R50 in advance to be incombustible state, then mixed with R245fa and R600, R404A, R508A, R14 and R50. The mixed refrigerant and R740 are mixed in advance and sealed in the refrigerant circuit. Alternatively, they are sealed in the order of R245fa and R600, then R404A, R5080A, R14 and R50, and finally R740 in descending order of boiling point. The composition of each refrigerant is, for example, 10.3% by weight of a mixed refrigerant of R245fa and R600, 28% by weight of R404A, 29.2% by weight of R508A, 26.4% by weight of a mixed refrigerant of R14 and R50, and R740. It shall be 5.1% by weight.

  In this embodiment, 4% by weight of n-pentane (in the range of 0.5 to 2% by weight with respect to the total weight of the non-azeotropic refrigerant) may be added to R404A.

  Next, the circulation of the refrigerant on the low temperature side will be described. The high-temperature and high-pressure gaseous mixed refrigerant discharged from the compressor 20 flows into the radiator 39 through the discharge-side pipe 20D and is radiated there, and the oil having a high boiling point in the mixed refrigerant and good oil compatibility. A part of n-pentane or R600 as a carrier refrigerant condenses.

  The mixed refrigerant that has passed through the radiator 39 flows into the oil separator 40, and most of the lubricating oil of the compressor 20 mixed with the refrigerant and a part of the refrigerant condensed and liquefied by the radiator 39 (n-pentane). , A part of R600) is returned to the compressor 20 by the oil return pipe 41. Thereby, a low-boiling-point refrigerant with higher purity flows through the refrigerant circuit 38 subsequent to the cascade heat exchanger 43, and it is possible to efficiently obtain an ultra-low temperature. Thereby, even if it is the compressors 10 and 20 of the same capability, it becomes possible to cool the inside of the storage chamber 4 which is a to-be-cooled object of larger capacity to a predetermined ultra-low temperature, and the entire refrigeration apparatus 1 is enlarged. It is possible to increase the storage capacity without doing so.

  Here, in this embodiment, since the refrigerant flowing into the oil separator 40 is once cooled by the radiator 39, the temperature of the refrigerant entering the cascade heat exchanger 43 can be lowered. Specifically, in the present embodiment, it is possible to reduce the refrigerant temperature flowing into the cascade heat exchanger 43 from about + 65 ° C. to about + 45 ° C. in the present embodiment.

  Therefore, in the cascade heat exchanger 43, it is possible to reduce the load applied to the compressor of the high temperature side refrigerant circuit 25 for cooling the refrigerant in the low temperature side refrigerant circuit 35. In addition, since the refrigerant in the low temperature side refrigerant circuit 35 can be effectively cooled, the load applied to the compressor 20 constituting the low temperature side refrigerant circuit 35 can be reduced. Thereby, it becomes possible to improve the operation efficiency of the entire refrigeration apparatus 1.

  Other mixed refrigerants themselves are cooled to about −40 ° C. to −30 ° C. from the evaporator 34 by the cascade heat exchanger 43, and some of the refrigerants having a high boiling point in the mixed refrigerant (one of R245fa, R600, R404A, and R508). Part). The mixed refrigerant that has exited the condensing pipe 42 of the cascade heat exchanger 43 flows into the first gas-liquid separator 46 through the dryer 44. At this time, R14, R50, and R740 in the mixed refrigerant are not condensed yet because they have a very low boiling point, and are in a gas state, and only a part of R245fa, R600, R404A, and R508 is condensed and liquefied. , R50 and R740 are separated into the gas phase piping 47, and R245fa, R600, R404A and R508A are separated into the liquid phase piping 50.

  The refrigerant mixture that has flowed into the gas phase piping 47 is condensed by exchanging heat with the first intermediate heat exchanger 48, and then reaches the second gas-liquid separator 49. Here, the low-temperature refrigerant returning from the evaporation pipe 62 flows into the first intermediate heat exchanger 48, and the liquid refrigerant flowing into the liquid-phase pipe 50 is decompressed by the capillary tube 52 through the dryer 51. Thereafter, it flows into the first intermediate heat exchanger 48 and evaporates there, thereby contributing to cooling. As a result, a part of uncondensed R14, R50, R740, and R508 is cooled, resulting in the first intermediate heat. The intermediate temperature of the exchanger 48 is about −60 ° C. Accordingly, R508 in the mixed refrigerant that has passed through the gas-phase pipe 47 is completely condensed and liquefied, and is divided into the second gas-liquid separator 49. R14, R50, and R740 are still in a gas state because of their lower boiling points.

  In the second intermediate heat exchanger 56, R508 separated by the second gas-liquid separator 49 is dehydrated by the dryer 54 and decompressed by the capillary tube 55, and then the second intermediate heat exchanger 56. R14, R50, and R740 in the gas-phase pipe 57 are cooled together with the low-temperature refrigerant returning to the evaporation pipe 62 and condensing R14 having the highest evaporation temperature. As a result, the intermediate temperature of the second intermediate heat exchanger 56 is about −90 ° C.

  The gas phase pipe 57 passing through the second intermediate heat exchanger 56 passes through the fourth intermediate heat exchanger 59 via the third intermediate heat exchanger 58. Here, the refrigerant immediately after leaving the evaporator 62 is fed back to the fourth intermediate heat exchanger 59, and according to experiments, the intermediate temperature of the fourth intermediate heat exchanger 59 is about -130 ° C. Reach low temperature.

  Therefore, in the fourth intermediate heat exchanger 59, a part of R50 and R740 in the gas-phase pipe 57 is condensed, and a part of the liquefied R14, R50 and R740 is removed by the dryer 60, and the capillary After being depressurized by the tube 61, it flows into the evaporation pipe 62, where it evaporates and cools the surroundings. According to experiments, at this time, the temperature of the evaporation pipe 62 became an extremely low temperature of −160.3 ° C. to −157.3 ° C.

  In this way, by using the difference in the evaporation temperature of each refrigerant in the low-temperature side refrigerant circuit 38, the intermediate heat exchangers 48, 56, 58, 59 condense the refrigerant still in a gas phase state one after another, An extremely low temperature of −150 ° C. or lower can be achieved in the evaporation pipe 42. Therefore, the said evaporation pipe 62 is comprised by heat-exchanged along the heat insulating material 9 side of the inner box 6, and the inside of the storage chamber 4 of the freezing apparatus 1 has the internal temperature of -152 degrees C or less. It can be realized.

  The refrigerant exiting the evaporation pipe 62 flows in sequence into the fourth intermediate heat exchanger 59, the third intermediate heat exchanger 58, the second intermediate heat exchanger 56, and the first intermediate heat exchanger 48, It merges with the refrigerant evaporated in each heat exchanger and returns to the compressor 20 from the suction pipe 20S.

  Most of the oil discharged from the compressor 20 after being mixed with the refrigerant is separated by the oil separator 40 and returned to the compressor 20. However, the oil is discharged from the oil separator 40 together with the refrigerant in the form of a mist. What has been removed is returned to the compressor 20 in a state of being dissolved in R600 having high compatibility with oil. Thereby, poor lubrication and locking of the compressor 20 can be prevented. Moreover, since R600 returns to the compressor 20 in a liquid state and is evaporated in the compressor 20, the discharge temperature of the compressor 20 can be reduced.

  The compressor 20 constituting the low-temperature side refrigerant circuit 38 as described above is ON / OFF controlled by a control device (not shown) based on the internal temperature in the storage chamber 4. In this case, when the operation of the compressor 20 is stopped by the control device, the mixed refrigerant in the low-temperature side refrigerant circuit 38 enters the expansion tank 65 via the check valve 67 whose forward direction is the direction of the expansion tank 65. Collected.

  Therefore, the refrigerant in the refrigerant circuit 38 is recirculated through the check valve 67 more rapidly than when the refrigerant is collected in the expansion tank 65 through the capillary tube 66 when the compressor 20 is stopped. It becomes possible to collect in 65.

  As a result, it is possible to prevent the pressure in the refrigerant circuit 38 from rising, and when the compressor 20 is activated by the control device, the refrigerant circuit 38 gradually enters the refrigerant circuit 38 from the expansion tank 65 via the capillary tube 66. It becomes possible to reduce the starting load of the compressor 20 by returning the refrigerant to the initial position.

  Therefore, by quickly collecting the refrigerant into the expansion tank 65 when the compressor 20 is stopped, the pressure in the refrigerant circuit 38 can be quickly balanced, and the compressor 20 is compressed when the compressor 20 is restarted. The compressor 20 can be smoothly restarted without imposing a load on the machine 20. Thereby, the operation efficiency of the compressor 20 can be improved by significantly reducing the time required for the inside of the refrigerant circuit 38 to reach the equilibrium pressure when the compressor is started. For example, the time required for the pull-down operation is reduced. It is possible to improve convenience.

  In this embodiment, the refrigerant circuit constituting the refrigeration apparatus 1 condenses the refrigerant discharged from the compressor 10 or 20, respectively, and then evaporates it to constitute an independent refrigerant closed circuit that exhibits a cooling action. The refrigerant circuit 25 includes a refrigerant circuit 25 and a low-temperature refrigerant circuit 38. The low-temperature refrigerant circuit 38 is connected in series so that the compressor 20, the condensation pipe 42, the evaporation pipe 62, and the return refrigerant from the evaporation pipe 62 circulate. A plurality of, specifically, four intermediate heat exchangers 48, 56, 58, 59 and a plurality of, more specifically, three capillary tubes 42, 55, 61. The boiling mixed refrigerant is enclosed, and the condensed refrigerant in the refrigerant passing through the condensation pipe 42 is joined to each intermediate heat exchanger via each capillary tube, and the uncondensed refrigerant in the refrigerant is cooled by the intermediate heat exchanger. ,order The refrigerant having a lower boiling point is condensed, and the refrigerant having the lowest boiling point is caused to flow into the evaporation pipe 62 via the capillary tube 61 in the final stage, and the evaporator 34 of the high temperature side refrigerant circuit 25 and the condensation pipe 42 of the low temperature side refrigerant circuit 38. The cascade heat exchanger 43 is configured as a two-stage multi-stage refrigeration apparatus 1 that obtains an ultra-low temperature with the evaporation pipe 42 of the low-temperature side refrigerant circuit 38, but the present invention is limited to this. is not.

  That is, for example, each of the high-temperature side refrigerant circuit includes a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit that constitute an independent refrigerant closed circuit that condenses and evaporates the refrigerant discharged from the compressor and exhibits a cooling action. A cascade heat exchanger is constituted by the evaporator and the condenser of the low-temperature side refrigerant circuit, and the same effect is obtained even in a simple multiple (two-way) type refrigeration apparatus that obtains ultra-low temperature in the evaporator of the low-temperature side refrigerant circuit Can be obtained.

  Similarly, a compressor, a condenser, an evaporator, a plurality of intermediate heat exchangers connected in series so that a return refrigerant from the evaporator circulates, and a plurality of decompression devices are provided, and a plurality of types of non-azeotropic components are provided. The mixed refrigerant is enclosed, and the condensed refrigerant in the refrigerant that has passed through the condenser is joined to the intermediate heat exchanger via the decompression device, and the uncondensed refrigerant in the refrigerant is cooled by the intermediate heat exchanger, thereby sequentially lowering The same effect can be obtained even in a simple multi-stage refrigeration apparatus that obtains an ultra-low temperature by condensing the boiling-point refrigerant and allowing the lowest-boiling point refrigerant to flow into the evaporator via the final-stage decompression device.

  Furthermore, the same effect can be obtained even in a refrigerant circuit that exhibits a cooling action by condensing and evaporating the refrigerant discharged from the compressor.

It is a perspective view of the freezing apparatus to which this invention is applied. It is a front view of the freezing apparatus of FIG. It is a top view of the freezing apparatus of FIG. It is the side view of the state which saw through the storage chamber of the freezing apparatus of FIG. It is a perspective view of the freezing apparatus in the state where the top panel is opened. FIG. 2 is a refrigerant circuit diagram of the refrigeration apparatus in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus 2 Heat insulation box 3 Machine room 4 Storage room 6 Outer box 7 Inner box 9 Heat insulating material 10 High temperature side compressor 11 Vacuum heat insulation panel 13 Heat insulation door 20 Low temperature side compressor 25 High temperature side refrigerant circuit 26 Auxiliary condenser 27 Frame Pipe 28, 31 Condenser 29, 30 Oil cooler 32, 44, 51, 54, 60 Dryer 33, 52, 55, 61 Capillary tube 34 Evaporator 35 Accumulator 36 Condenser blower 38 Low temperature side refrigerant circuit 39 Radiator 40 Oil Separator 41 Oil return pipe 42 Condensation pipe 43 Cascade heat exchanger 46 First gas-liquid separator 48 First intermediate heat exchanger 49 Second gas-liquid separator 56 Second intermediate heat exchanger 58 Third Intermediate heat exchanger 59 Fourth intermediate heat exchanger 62 Evaporation pipe

Claims (4)

In the refrigeration apparatus provided with the refrigerant circuit that condenses the refrigerant discharged from the compressor and then evaporates it to exert a cooling action.
An expansion tank connected to a pipe on the suction side of the compressor via a decompression device, a check valve connected in parallel to the decompression device, and the direction of the expansion tank was set as the forward direction of the check valve A refrigeration apparatus characterized by that. A high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit constituting independent refrigerant closed circuits that condense and evaporate the refrigerant discharged from the compressor and exhibit a cooling action, respectively, and an evaporator of the high-temperature side refrigerant circuit; In the refrigeration apparatus that forms a cascade heat exchanger with the condenser of the low-temperature side refrigerant circuit and obtains an ultra-low temperature in the evaporator of the low-temperature side refrigerant circuit,
An expansion tank connected to a suction side pipe of a compressor of the low-temperature side refrigerant circuit via a decompression device; a check valve is connected in parallel to the decompression device; and the direction of the expansion tank is the check valve A refrigeration apparatus characterized by having a forward direction. A compressor, a condenser, an evaporator, a plurality of intermediate heat exchangers connected in series so that a return refrigerant from the evaporator flows, and a plurality of decompression devices are provided, and a plurality of types of non-azeotropic refrigerant mixtures are enclosed. The condensing refrigerant in the refrigerant that has passed through the condenser is joined to the intermediate heat exchanger via the decompression device, and the intermediate heat exchanger cools the uncondensed refrigerant in the refrigerant, thereby sequentially lowering the boiling point. In the refrigerating apparatus for obtaining an ultra-low temperature by condensing the refrigerant of the above, and flowing the refrigerant having the lowest boiling point into the evaporator through the decompression device in the final stage,
An expansion tank connected to a pipe on the suction side of the compressor via a decompression device, a check valve connected in parallel to the decompression device, and the direction of the expansion tank was set as the forward direction of the check valve A refrigeration apparatus characterized by that. Each of the refrigerant discharged from the compressor is provided with a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit constituting an independent refrigerant closed circuit that evaporates and evaporates to exhibit a cooling action. A plurality of intermediate heat exchangers and a plurality of decompression devices connected in series so that the return refrigerant from the evaporator circulates, and a plurality of non-azeotropic refrigerant mixtures are enclosed. The condensing refrigerant in the refrigerant that has passed through the condenser is joined to the intermediate heat exchanger via the decompression device, and the intermediate heat exchanger cools the uncondensed refrigerant in the refrigerant, thereby sequentially lowering the boiling point. The refrigerant having the lowest boiling point is caused to flow into the evaporator via the decompression device in the final stage, and cascade heat exchange is performed between the evaporator of the high temperature side refrigerant circuit and the condenser of the low temperature side refrigerant circuit. The low temperature side In the refrigeration system to obtain a cryogenic in the evaporator of the medium circuits,
An expansion tank connected to a suction side pipe of a compressor of the low-temperature side refrigerant circuit via a decompression device; a check valve is connected in parallel to the decompression device; and the direction of the expansion tank is the check valve A refrigeration apparatus characterized by having a forward direction.

Images