JP2004205198A - Unified refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a unified refrigerating machine capable of sufficiently showing the refrigerating ability by appropriately combining the mixture refrigerant of nitrous oxide and HC refrigerant and a special heat exchanger for use. <P>SOLUTION: This unified refrigerating machine is formed by annularly connecting a compressor 1, a condenser 2, a pressure reducing device 8 and an evaporator 8. An air-liquid separator 3 and a heat exchanger 6 for passing the refrigerant from an air phase part of the air-liquid separator are provided in a pipe for connecting the condenser 2 to the pressure reducing device 8, and a liquid phase pipe of the air-liquid separator 3 wherein the liquid phase refrigerant flows and an outlet pipe of the evaporator 3 are connected to a return passage wherein the refrigerant returned from the heat exchanger 6 flows. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a one-way refrigeration ultra-low temperature refrigeration apparatus.
[0002]
[Prior art]
Conventionally, an ultra-low-temperature refrigeration apparatus has been used to generate an ultra-low temperature of −60 ° C. to −90 ° C. or less. This ultra-low temperature refrigeration system includes a one-way refrigeration system (a single-stage refrigeration system) and a multi-stage refrigeration system such as a binary refrigeration system including a high-temperature refrigeration circuit and a low-temperature refrigeration circuit.
[0003]
The applicant of the present invention has proposed a one-way refrigeration apparatus in which a mixture of nitrous oxide (N ₂ O) and an HC refrigerant is charged as Patent Document 1.
[0004]
[Patent Document 1]
Japanese Patent Application No. 2002-173455 [0005]
[Problems to be solved by the invention]
The one-way refrigeration system proposed by the applicant of the present invention is a refrigeration system in which a compressor, a condenser, a capillary tube, and an evaporator are connected in a circular pipe, so that part of nitrous oxide and HC refrigerant is condensed in the condenser. Refrigeration capacity could not be exhibited sufficiently.
[0006]
The present invention provides a one-way refrigeration apparatus capable of sufficiently exhibiting a refrigeration capacity by appropriately combining a mixed refrigerant of nitrous oxide and HC refrigerant and a special heat exchanger.
[0007]
[Means for Solving the Problems]
The present invention provides, in a one-way refrigeration system in which a compressor, a condenser, a decompression device, and an evaporator are connected by piping in a ring, a mixture of nitrous oxide and HC refrigerant is used as a refrigerant; A gas-liquid separator and a heat exchanger for passing uncondensed refrigerant from the gas phase of the gas-liquid separator are provided in a pipe connecting the pressure reducing device, and the heat exchange with the liquid phase of the gas-liquid separator is performed. And an outlet pipe of the evaporator through the heat exchanger and the compressor, and the refrigerant from the evaporator and the refrigerant from the auxiliary decompression device are compressed. It is configured to be sucked into the machine.
[0008]
Further, in the present invention, any of propane, ethane, ethylene, n-butane, isobutane, and n-pentane, or a mixture thereof is used as the HC refrigerant.
[0009]
In the present invention, the ratio of the HC refrigerant is set to 1 to 50% by weight.
[0010]
Further, the present invention uses an expansion valve that is closed at the time of operation stop and at the time of abnormality as the pressure reducing device.
[0011]
On the other hand, the present invention relates to a one-way refrigeration system in which a compressor, a condenser, a decompression device, and an evaporator are connected in a ring-like pipe, and a gas-liquid separator is provided in a pipe connecting the condenser and the decompression device. And a heat exchanger having a refrigerant flow passage for passing uncondensed refrigerant from the gas-phase part of the gas-liquid separator, wherein the liquid-phase pipe of the gas-liquid separator and the outlet pipe of the evaporator are connected to the heat pipe. It is connected to the refrigerant return flow path of the exchanger.
[0012]
Further, the present invention uses a mixture of nitrous oxide and HC refrigerant as the refrigerant.
[0013]
In the present invention, any one of propane, ethane, ethylene, n-butane, isobutane, and n-pentane, or a mixture thereof is used as the HC refrigerant.
[0014]
Finally, in the present invention, the connection position between the liquid-phase pipe of the gas-liquid separator and the return flow path of the heat exchanger is more than the connection position of the outlet pipe of the evaporator and the return flow path of the heat exchanger. It is provided on the downstream side.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIG.
[0016]
FIG. 1 shows a normal refrigeration apparatus (one-way refrigeration apparatus). The refrigerating apparatus includes nitrous oxide (N ₂ O, boiling point −88.5 ° C.) and HC refrigerant (propane (R290, boiling point −42.1 ° C.)) or butane (R600, boiling point −0.5 ° C.). C) is enclosed, for example, in an amount of 1 to 50% by weight.
[0017]
The refrigerating apparatus includes a compressor 1, a condenser 2, a gas-liquid separator 3, a dehydrator 4, a capillary tube (auxiliary decompression device) 5, a heat exchanger 6, a dehydrator 7, a capillary tube (decompression device) 8, It comprises an evaporator 9 and an expansion tank 10.
[0018]
That is, as described in the claims, in a one-way refrigeration system in which the compressor 1, the condenser 2, the capillary tube (decompression device) 8, and the evaporator 9 are connected in a circular pipe, nitrous oxide and A mixture of the HC refrigerant and the refrigerant is used as a refrigerant, and a gas-liquid separator 3 and an uncondensed refrigerant from a gas phase portion of the gas-liquid separator 3 pass through a pipe connecting the condenser 2 and the pressure reducing device 8. A heat exchanger 6 is provided to connect the liquid phase portion of the gas-liquid separator 3 to the heat exchanger via a capillary tube (auxiliary decompression device) 5 and to connect an outlet pipe of the evaporator 9 to the heat exchange. The refrigerant is connected to the compressor 1 via a compressor, and the refrigerant from the evaporator 9 and the refrigerant from the auxiliary pressure reducing device 5 are sucked into the compressor 1.
[0019]
Since the nitrous oxide and the HC refrigerant constituting the refrigerant have different boiling points, they are separated by the gas-liquid separator 3 using the difference in the boiling points and the phase change accompanying the passage through the condenser 2. Although this separation is not actually complete, for the sake of simplicity, it will be described as being roughly separated into nitrous oxide having a low boiling point and being difficult to be liquefied and an HC refrigerant having a higher boiling point and being easily liquefied. .
[0020]
In this refrigerating apparatus, since the gas-liquid separator 3 is provided, the HC refrigerant having a boiling point higher than that of nitrous oxide is mainly condensed in the dehydrator 4, the capillary tube 5, and the heat exchanger 6 through the liquid phase portion. Returns to the compressor 1 through the refrigerant return flow path through which the refrigerant passes (ie, does not pass through the evaporator 9 which has the lowest temperature and has a residual problem due to viscous resistance). Nitrous oxide having a low boiling point passes through the gas phase of the gas-liquid separator 3, through which a non-condensed refrigerant (that is, gas refrigerant) in the heat exchanger 9 passes, a dehydrator 7, a capillary tube 8, The refrigerant returns to the compressor 1 via a refrigerant return flow path through which the condensed refrigerant in the evaporator 9 and the heat exchanger 6 passes. As described above, a small amount of the HC refrigerant passing through the gaseous phase part that could not be separated by the gaseous phase separator 3 also circulates through the evaporator 9, and this small amount of the HC refrigerant has high compatibility with the refrigerating machine oil. Therefore, it is excellent in transportability when mixed with nitrous oxide, and has an action as an oil carrier, so that it has circulation as a refrigerant and can prevent oil residue in the evaporator 9.
[0021]
As described above, in the present application, since the HC refrigerant is mixed with the nitrous oxide, the gas refrigerant in the compressor 1, the condenser 2, and the evaporator 9 has lower flammability than the HC refrigerant alone.
[0022]
Since nitrous oxide has a lower boiling point than HC refrigerant, nitrous oxide is mainly supplied from the gas phase of the gas-liquid separator 3 to the refrigerant flow passage of the heat exchanger 6. This nitrous oxide is cooled (condensed) by passing through the refrigerant flow passage by heat exchange between the refrigerant flowing through the refrigerant flow passage and the refrigerant return passage in the heat exchanger 6, and is liquefied at the outlet side. For this reason, a liquid refrigerant containing a small amount of HC refrigerant but rich in nitrous oxide flows into the evaporator 9, evaporates here, and in the heat exchanger 6 as compared with the case where nitrous oxide alone is used. A refrigerant having a lower temperature is obtained by the heat exchange. Further, since the refrigerant separated into the gaseous phase and the liquid phase exchanges heat without being mixed in the heat exchanger 6, not only does the temperature of the refrigerant flowing into the evaporator 9 decrease, but also the evaporation without passing through the heat exchanger 6. The refrigeration capacity can be increased due to the circulation of the refrigerant at a lower temperature as compared with the circuit that flows into the vessel 9. Since the HC refrigerant (flammable refrigerant) is suppressed to 50% by weight or less, the combustion capacity of the HC refrigerant can be sufficiently canceled by the non-flammable and extinguishing nitrous oxide. Even if a leak occurs, the mixed refrigerant hardly burns and leaks, so that the safety as the refrigerant can be ensured.
[0023]
In particular, it is a well-known fact that the ability of vaporizing (absorbing heat = cooling) action by a refrigerant having a high boiling point (that is, refrigeration capacity) is larger than that of a refrigerant having a low boiling point, but a refrigerant having a different boiling point is mixed. In such a case, setting the mixing ratio of the HC refrigerant having a high boiling point to more than 50% by weight is the only one that can exhibit its refrigeration capacity without regret. In the present invention, by setting the upper limit of the mixing ratio to 50% by weight, the refrigeration capacity of the refrigerant can be sufficiently exhibited in view of the nonflammability.
[0024]
As described above, as the HC refrigerant to be filled, in addition to propane and butane, isobutane (R600a, boiling point: -11.7 ° C), ethane (boiling point: 88.5 ° C), and ethylene (boiling point: 103.57) ° C), n-butane (boiling point -0.55 ° C), n-pentane (boiling point 36.2 ° C), a mixture thereof, or the like may be used. Even in this case, it is the same that the mixing ratio of the HC refrigerant must be within 50% by weight in view of the fire extinguishing action of nitrous oxide. If the amount exceeds 50% by weight, the combustion capacity is not immediately restored and a danger is not caused. Of course, the weight ratio differs depending on the selection of the HC refrigerant to be mixed. However, the total amount of the HC refrigerant may be 50% by weight.
[0025]
Although the expansion tank 10 is used in this embodiment, for example, when the stop pressure of the compressor 1 is small, the tank 10 is not essential.
[0026]
Further, according to the present application, assuming that a refrigerant leak occurs, taking into account the fact that the HC refrigerant is flammable, a gas sealing measure is taken around the heat exchanger 6 and the gas-liquid separator 3. Is good. For example, it is good to take measures such as covering with a metal container.
[0027]
Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 2, the same parts as those in FIG.
[0028]
2, the expansion valve 12 is used as a pressure reducing device. In this embodiment, the refrigerant from the heat exchanger 6 is supplied to the evaporator 9 via the accumulator 11 and the expansion valve 12.
[0029]
The expansion valve 12 is closed when the operation is stopped and when an abnormality occurs. This is because, as described above, according to this refrigeration apparatus, even if a refrigerant leak occurs, in the refrigerant circuit (especially near the evaporator) after the gas-liquid separator, the refrigerant in which nitrous oxide is rich is circulated. Although the flammability is low because of this, HC refrigerant that has not been completely separated by the gas-liquid separator may leak out over time. For this reason, the mechanical or electronic expansion valve 12 is arranged in front of the evaporator 9, and the valve 12 is forcibly closed at the time of operation stop or abnormality, thereby preventing the refrigerant from flowing into the evaporator 9.
[0030]
A third embodiment of the present invention will be described with reference to FIG. In FIG. 3, the same portions as those in FIG.
[0031]
FIG. 3 shows the connection position A between the liquid-phase pipe of the gas-liquid separator 3 and the return flow path of the heat exchanger 6 in the heat exchanger 6, the outlet pipe of the evaporator 9 and the return flow path of the heat exchanger 6 This is an example in which it is provided on the downstream side in the return flow path (upstream side in the refrigerant flow path) with respect to the connection position B. This is because the temperature of the refrigerant flowing through the liquid-phase pipe of the gas-liquid separator 3 (specifically, the outlet side of the capillary tube serving as the auxiliary pressure reducing device) is about −30 ° C., whereas the refrigerant flowing through the outlet pipe of the evaporator 9 is This is a consideration due to the fact that the cooling capacity of the latter is higher because the temperature is as low as about −85 ° C. That is, the connection position A with the liquid phase pipe of the gas-liquid separator 3 is located upstream (downstream in the return flow path) with respect to the refrigerant flow passage of the heat exchanger 6 through which the refrigerant having a temperature of about + 40 ° C. flows. By arranging, the refrigerant having a high temperature flowing through the refrigerant flow passage is primarily cooled, the gas refrigerant is condensed as much as possible, and the refrigerant flowing through the outlet pipe of the low-temperature evaporator 9 flowing into the downstream connection position B is cooled by the refrigerant. By performing the next cooling, even if an uncondensed portion of the refrigerant remains in the refrigerant flow passage, the refrigerant can be condensed by lower-temperature heat exchange (that is, two-stage cooling can be performed). Can be reduced more efficiently. In addition, since the capillary tube 5 as an auxiliary decompression device is arranged in the liquid phase tube, the refrigerant flowing into the heat exchanger 6 is narrowed down, while being condensed as much as possible to lower the refrigerant temperature.
[0032]
【The invention's effect】
In the present invention, the mixed refrigerant is separated into a gas phase and a liquid phase by a gas-liquid separator, and the separated liquid phase refrigerant and the gas phase refrigerant are heat-exchanged by a heat exchanger. With this configuration, the amount of refrigerant condensed into the decompression device can be increased and the temperature of the refrigerant can be reduced as compared with the case where the refrigerant is circulated from the condenser directly to the decompression device. Therefore, the circulation of the uncondensed refrigerant can be suppressed, and a decrease in the refrigerating capacity of the refrigerator can be prevented.
[0033]
Further, as described in claim 2, as the HC refrigerant, any of propane, ethane, ethylene, n-butane, isobutane, and n-pentane, or a mixture thereof is used. Since it is inexpensive and easily available, a one-way refrigeration apparatus can be provided at low cost.
[0034]
Further, since the ratio of the HC refrigerant is set to 1 to 50% by weight, the refrigerating capacity can be increased as compared with the case where only nitrous oxide is used, and the amount of the refrigerant can be reduced. Even if one leak occurs, the refrigerant after passing through the gas-liquid separator is hardly burnable in a state in which nitrous oxide is rich, so that danger due to combustion can be suppressed.
[0035]
Furthermore, since the expansion valve that is closed when the operation is stopped or abnormally is used as the pressure reducing device as in the invention according to claim 4, it is possible to minimize the possibility that the refrigerant leaks from the evaporator when the operation is stopped or abnormally. Can be.
[0036]
On the other hand, according to the fifth aspect of the present invention, in a one-way refrigeration system in which a compressor, a condenser, a decompression device, and an evaporator are connected in a circular pipe, a gas connecting a condenser and a decompression device is connected to a pipe. A liquid separator and a heat exchanger having a refrigerant flow passage through which uncondensed refrigerant flows from the gas phase of the gas-liquid separator are provided, and heat exchange is performed between the liquid-phase pipe of the gas-liquid separator and the outlet pipe of the evaporator. Connected to the refrigerant return flow path of the heat exchanger, the refrigerant separated into the gaseous phase and the liquid phase is heat-exchanged without being mixed in the heat exchanger, and the temperature of the refrigerant flowing into the evaporator can be lowered, thereby evaporating. The refrigeration capacity of the vessel is improved.
[0037]
Finally, according to claim 8 of the present invention, the connection position between the liquid phase pipe of the gas-liquid separator and the return flow path of the heat exchanger is connected to the connection between the outlet pipe of the evaporator and the return flow path of the heat exchanger. Since it is provided downstream from the position, the high-temperature gas-phase refrigerant flowing through the refrigerant flow passage in the heat exchanger is heat-exchanged with the low-temperature liquid-phase refrigerant to perform primary cooling, and the refrigerant after passing through the low-temperature evaporator continues. Since the secondary cooling can be performed, the temperature of the refrigerant passing through the refrigerant flow passage of the heat exchanger can be reduced in two stages, and as a result, the refrigeration capacity of the evaporator in which the low-temperature refrigerant circulates can be efficiently increased. Can be improved.
[Brief description of the drawings]
FIG. 1 is a refrigeration circuit diagram for explaining an embodiment of the present invention.
FIG. 2 is a refrigeration circuit diagram for explaining another embodiment of the present invention.
FIG. 3 is a heat exchanger diagram for explaining still another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Gas-liquid separator 5 Capillary tube (auxiliary decompression device)
6 heat exchanger 8 capillary tube (decompression device)
9 Evaporator 12 Expansion valve (pressure reducing device)
A Connection position B Connection position

Claims (8)

In a one-way refrigeration apparatus configured by connecting a compressor, a condenser, a decompression device, and an evaporator in an annular pipe, a mixture of nitrous oxide and HC refrigerant is used as a refrigerant, and the condenser and the decompression device are connected to each other. A gas-liquid separator and a heat exchanger for passing uncondensed refrigerant from the gas phase part of the gas-liquid separator are provided in the connecting pipe, and the liquid-phase part of the gas-liquid separator and the heat exchanger are assisted. While connecting via a decompression device, the outlet pipe of the evaporator is connected to the compressor via the heat exchanger, and the refrigerant from the evaporator and the refrigerant from the auxiliary decompression device are sucked into the compressor. A one-way refrigeration apparatus characterized in that: The one-way refrigeration system according to claim 1, wherein any one of propane, ethane, ethylene, n-butane, isobutane, and n-pentane or a mixture thereof is used as the HC refrigerant. The one-way refrigeration system according to claim 1 or 2, wherein the ratio of the HC refrigerant is 1 to 50% by weight. The one-way refrigeration system according to any one of claims 1 to 3, wherein an expansion valve that is closed when operation is stopped and when an abnormality occurs is used as the pressure reducing device. In a one-way refrigeration system in which a compressor, a condenser, a decompression device, and an evaporator are connected in a circular pipe, a gas-liquid separator and a gas-liquid separation device are provided in a pipe connecting the condenser and the decompression device. A heat exchanger for passing uncondensed refrigerant from the gas phase part of the vessel, and connecting a liquid phase pipe of the gas-liquid separator and an outlet pipe of the evaporator to a return flow path of the heat exchanger. One-way refrigeration equipment. The one-way refrigeration apparatus according to claim 5, wherein a mixture of nitrous oxide and HC refrigerant is used as the refrigerant. The one-way refrigeration system according to claim 6, wherein any one of propane, ethane, ethylene, n-butane, isobutane, and n-pentane or a mixture thereof is used as the HC refrigerant. The connection position between the liquid-phase pipe of the gas-liquid separator and the return flow path of the heat exchanger is provided downstream of the connection position between the outlet pipe of the evaporator and the return flow path of the heat exchanger. The one-way refrigeration apparatus according to claim 5, wherein

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