JP4341492B2 - Refrigerant cooling circuit - Google Patents

Description

  The present invention relates to a refrigerant cooling circuit that forms a refrigerant circulation path for cooling, for example, an interior of a heat insulating housing.

  2. Description of the Related Art Conventionally, for example, a refrigerant cooling circuit for cooling the inside of a refrigerator of a heat insulating housing such as a vending machine, a refrigerator, a freezer showcase / refrigerated showcase, or a beverage dispenser is known. The refrigerant cooling circuit forms a refrigerant circulation path for circulating the refrigerant mainly through the compressor, the radiator, the throttle unit, and the evaporator. As the refrigerant circulating in the refrigerant cooling circuit, a refrigerant having little influence on the global environment is used. For example, carbon dioxide is used as a refrigerant in that it has nonflammability, safety, and non-corrosion properties and has little influence on the ozone layer (see, for example, Patent Document 1).

  Further, in the refrigerant cooling circuit, the evaporator is disposed in the cooler of the heat insulating housing, and condensed water or the like is generated as drainage during the refrigerant circulation operation to the refrigerant circulation path. This drainage is led to an evaporating dish outside the refrigerator. The evaporating dish is provided with an evaporating pipe. The evaporation pipe is provided in the path between the compressor and the radiator. And the waste_water | drain guide | induced to the evaporating dish is heated and evaporated by the evaporation pipe through which a high-temperature / high-pressure carbon dioxide passes. At this time, in the evaporation pipe, carbon dioxide passing through the evaporation pipe is drained by drainage.

JP 2004-53070 A

  By the way, when carbon dioxide is used as the refrigerant in the refrigerant cooling circuit, the critical temperature of the carbon dioxide is as low as about 31 ° C., so that it is far more than when a conventional refrigerant (for example, HFC refrigerant (hydrofluorocarbon)) is used. Pressure increases. For this reason, the thing with a high viscosity is used for the refrigerating machine oil which prevents the friction in a compressor, a refrigerant | coolant leak, etc. However, in the compressor, it is difficult to completely seal the refrigerating machine oil therein, and the refrigerating machine oil is discharged from the compressor during the circulation operation of the refrigerant circulation path. That is, the refrigerating machine oil discharged from the compressor is returned to the compressor again through the radiator, the throttle unit, and the evaporator.

  However, in the conventional refrigerant cooling circuit, since the refrigeration oil stays in the evaporation pipe, it is difficult to circulate the refrigeration oil discharged from the compressor through the refrigerant circulation path and return it to the compressor. This is because the compatibility between the carbon dioxide and the refrigerating machine oil is poor and the refrigerating machine oil having a high viscosity is used as described above. Conventionally, the inner diameter of the evaporating pipe is φ4.75 mm, so that the flow rate is slow and the feeding is poor with a refrigerating machine oil having a high viscosity. Further, since the conventional evaporation pipe is formed in a spiral shape toward the side, a plurality of lower portions of the spiral shape serve as traps for retaining the refrigerating machine oil, and the refrigerating machine oil is poorly fed.

  An object of this invention is to provide the refrigerant | coolant cooling circuit which can improve the feed of refrigeration oil regarding an evaporation pipe in view of the said situation.

In order to achieve the above object, a refrigerant cooling circuit according to claim 1 of the present invention includes a compressor that compresses refrigerant, a radiator that cools refrigerant discharged from the compressor, and a supply from the radiator. a pressure reducing unit for reducing the pressure of the refrigerant, an evaporator refrigerant supplied from the pressure reducing unit is evaporated, the evaporation dish condensation water is led to the condensation in the evaporator, and the radiator and the compressor And an evaporation pipe that is stored in the evaporating dish and evaporates the condensed water led to the evaporating dish , wherein the evaporating pipe is gradually lowered from above to below. The spiral part is provided so as to be spirally swung so that the refrigerant flows from the upper side to the lower side, and is connected to the upper part of the helix and is provided straight from the lower side to the upper side. The refrigerant is discharged Characterized in that and a straight upper to.

A refrigerant cooling circuit according to a second aspect of the present invention is the refrigerant cooling circuit according to the first aspect, wherein the pressure reducing unit is an electronic expansion valve.

The refrigerant cooling circuit according to a third aspect of the present invention is characterized in that, in the first or second aspect , the immediately upper portion has a height difference of 50 mm.

The refrigerant cooling circuit according to a fourth aspect of the present invention is the refrigerant cooling circuit according to any one of the first to third aspects, wherein the compressor includes a first compressor that performs first-stage compression, and the first compressor. characterized in that a second compressor to further compress the compressed refrigerant.

A refrigerant cooling circuit according to a fifth aspect of the present invention is the refrigerant cooling circuit according to any one of the first to fourth aspects, wherein the refrigerant is carbon dioxide.

The refrigerant cooling circuit according to the present invention is accommodated in the evaporating dish, and an evaporating pipe for evaporating the condensed water led to the evaporating dish is provided by spirally turning so as to gradually become lower from the upper side to the lower side, It has a spiral part in which the refrigerant flows from the upper side to the lower side, and an upper part connected to the spiral part and discharging the refrigerant from the lower side to the upper side. For this reason, even if refrigeration oil is discharged with a refrigerant | coolant from a compressor, refrigeration oil does not stay over several places of an evaporation pipe (especially helical part). In this sense, this evaporating pipe can limit the number of refrigerating machine oil retention points (traps) to only one. In other words, the evaporation pipe can suppress the stagnation of the refrigerating machine oil even when the refrigerating machine oil is discharged from the compressor.

In particular, the evaporation pipe of the present invention is useful for a refrigerant cooling circuit in which the refrigerant cooling circuit is in a relatively high pressure state using carbon dioxide as the refrigerant .

  Exemplary embodiments of a refrigerant cooling circuit according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a schematic view showing an embodiment of a refrigerant cooling circuit according to the present invention. As shown in FIG. 1, the refrigerant cooling circuit in this embodiment mainly includes a compressor 1, a gas cooler (heat radiator) 2, an electronic expansion valve (throttle portion) 3, and an evaporator 4 to connect refrigerant. A circulating refrigerant circulation path is formed. In the present embodiment, for example, carbon dioxide is used as the refrigerant. Carbon dioxide is a refrigerant that has non-flammability, safety, and non-corrosion properties, and has little influence on the ozone layer.

  The compressor 1 compresses the carbon dioxide returned from the evaporator 4 to bring it into a high temperature and high pressure state. In the present embodiment, the compressor 1 uses the intermediate heat exchanger 10 to perform a two-stage compression operation. Specifically, in the two-stage compression operation, the compressor 1 has an intermediate heat between the first compressor 1a that performs the first-stage compression operation and the second compressor 1b that performs the second-stage compression operation. An exchanger 10 is provided. Then, after the first stage compression operation by the first compressor 1a, the intermediate heat exchanger 10 cools the carbon dioxide compressed by the first compressor 1a and returns it to the second compressor 1b. In this way, the compressor 1 performs a two-stage compression operation via the intermediate heat exchanger 10, thereby obtaining high compression efficiency with low power consumption and compressing carbon dioxide to a desired high temperature and high pressure state. It becomes possible to do. In this embodiment, carbon dioxide is compressed to about 6 MPa by the first stage compression by the first compressor 1a, and carbon dioxide is about 9 MPa (6 to 6 by the second stage compression by the second compressor 1b. To 12 MPa).

  An oil separator 11 is connected to the compressor 1. The oil separator 11 is for returning the refrigeration oil discharged from the compressor 1 from the high pressure side to the low pressure side of the refrigerant circulation path. The high pressure side of the refrigerant circulation path is from the outlet side of the compressor 1 to the inlet side of the electronic expansion valve 3 through the gas cooler 2. The low pressure side of the refrigerant circulation path is from the outlet side of the electronic expansion valve 3 to the inlet side of the compressor 1 through the evaporator 4. The refrigerating machine oil prevents friction and refrigerant leakage in the compressor 1, but it is difficult to completely seal the refrigerating machine oil inside the compressor 1. In particular, the compressor 1 compresses carbon dioxide to a high pressure as described above, and this pressure is much higher than when a conventional refrigerant (for example, HFC refrigerant (hydrofluorocarbon)) is used. The amount of refrigeration oil discharged from the machine 1 increases. Therefore, in the present embodiment, in the compressor 1, the oil separator 11 is connected between the outlet side of the second compressor 1b and the inlet side of the first compressor 1a, and discharged from the second compressor 1b. The refrigerating machine oil thus returned is returned to the first compressor 1a. In this embodiment, since the pressure of carbon dioxide is high, a refrigerating machine oil having a viscosity index of approximately 100 (40 ° C., 0 Wt%) is employed for the purpose of preventing friction and refrigerant leakage inside the compressor 1 as much as possible. It is.

  The compressor 1 includes a reciprocating compressor, a rotary compressor, a scroll compressor, or an inverter compressor that can adjust the compression capacity thereof. And what is necessary is just to apply suitably the compressor corresponding to the object which arrange | positions a refrigerant | coolant cooling circuit, an environment, or the cost of a refrigerant | coolant cooling circuit.

  The gas cooler 2 is for liquefying carbon dioxide by releasing heat from high-temperature and high-pressure carbon dioxide supplied from the compressor 1. The gas cooler 2 in the present embodiment uses a fin tube type composed of, for example, a copper tube and an aluminum fin. The gas cooler 2 is provided with a fan 21. The fan 21 is for blowing the gas cooler 2 and is driven by a fan motor 22.

  The electronic expansion valve 3 is for reducing the pressure of carbon dioxide supplied from the gas cooler 2 and controlling the evaporation temperature and flow rate.

  The evaporator 4 is for cooling the ambient temperature by absorbing ambient heat when the liquid carbon dioxide supplied from the electronic expansion valve 3 evaporates. The evaporator 4 in the present embodiment uses a fin tube type composed of, for example, a copper tube and an aluminum fin. The evaporator 4 is provided with a fan 41. The fan 41 is for blowing the evaporator 4 and is driven by a fan motor 42.

  The evaporator 4 is arrange | positioned inside the refrigerator of the heat insulation housing | casing in a vending machine, a refrigerator, a freezer showcase, a refrigerated showcase, or a drink dispenser etc., for example. In particular, in this embodiment, for example, in an automatic vending machine, in order to cool a plurality of (three rooms in the embodiment) refrigerators (product storage units) independently, the evaporators 4 (4a, 4a, 4b, 4c) are arranged respectively. That is, the evaporators 4a, 4b, and 4c are connected to respective paths branched from the electronic expansion valve 3 in three directions. Further, electromagnetic valves 12a, 12b, and 12c are provided on the inlet sides of the evaporators 4a, 4b, and 4c in the respective paths. And carbon dioxide from the electronic expansion valve 3 is supplied to each evaporator 4a, 4b, 4c by selectively open | releasing each solenoid valve 12a, 12b, 12c. Further, the paths on the outlet side of the evaporators 4a, 4b, and 4c are gathered together and connected to the first compressor 1a of the compressor 1. The solenoid valves 12a, 12b, and 12c in the present embodiment are configured so that the valve body is seated by utilizing a pressure difference between the inlet side and the outlet side (for example, the inlet side is high pressure and the output side is low pressure) and spring elastic force. A configuration is adopted in which the valve body is separated from the valve seat and opened when the electromagnetic coil portion is energized from this state to assist in contact with the valve.

  The decompression means 13a is connected to each of the evaporators 4a, 4b, and 4c from the electronic expansion valve 3 and between each of the solenoid valves 12a, 12b, and 12c and each of the evaporators 4a, 4b, and 4c. , 13b, 13c are provided. The decompression means 13a, 13b, and 13c act as throttles that provide pressure resistance in the path between the electromagnetic valves 12a, 12b, and 12c and the evaporators 4a, 4b, and 4c. The decompression means 13a, 13b, and 13c in the present embodiment are formed as orifices provided in the respective paths. The decompression means 13a, 13b, and 13c are not limited to orifices as long as they function as a throttle that provides pressure resistance in the path.

  Note that the temperature at the periphery of the evaporator 4 decreases as the evaporator 4 absorbs the heat at the periphery. As the refrigeration cycle, it is necessary to throw away the heat of evaporation absorbed by the evaporator 4, but the inside of the heat-insulating housing provided with the evaporator 4 is considerably lower than the outside temperature, and is taken away from the low temperature part. Heat cannot be thrown away directly to the hot outside. Therefore, the compressor 1 plays the role of converting carbon dioxide supplied from the evaporator 4 into high-temperature and high-pressure steam in order to discard the evaporation heat of the evaporator 4 at a temperature higher than the outside air temperature.

  Further, when carbon dioxide is used as a refrigerant, the temperature of the gas cooler 2 may exceed the critical temperature of carbon dioxide (about 31 ° C.) in summer when the outside air temperature becomes high. In this case, the gas cooler 2 is in a supercritical pressure state in which carbon dioxide is not vaporized while being vaporized. On the other hand, it is desirable that all the carbon dioxide that has passed through the evaporator 4 is vaporized. If the carbon dioxide that has passed through the evaporator 4 is supplied to the compressor 1 while being partially liquefied, the compressor 1 may cause liquid compression and damage the cylinder.

  Therefore, an internal heat exchanger 14 is provided between the gas cooler 2 and the electronic expansion valve 3 and between the evaporator 4 and the compressor 1 (first compressor 1a). Although not clearly shown in the figure, inside the internal heat exchanger 14, a refrigerant line between the gas cooler 2 and the electronic expansion valve 3 and a refrigerant line between the evaporator 4 and the compressor 1 are They are arranged so as to have non-contact countercurrent with a distance allowing heat exchange with each other. Thereby, the carbon dioxide obtained from the gas cooler 2 becomes easy to liquefy. On the other hand, the carbon dioxide vaporized from the evaporator 4 is supplied to the compressor 1.

  Further, with respect to the evaporator 4 provided inside the cooler of the heat insulating housing, dew condensation water or the like is generated as drainage during the refrigerant circulation operation to the refrigerant circulation path. Then, the waste water is led to the evaporation means 15 located outside the cooler and provided with the compressor 1, the gas cooler 2, and the like. The evaporation means 15 is provided between the compressor 1 (second compressor 1 b) and the gas cooler 2 and in a path between the outlet side of the oil separator 11 and the inlet side of the gas cooler 2.

  As shown in FIG. 2, the evaporating means 15 has an evaporating dish 151 through which waste water is guided, an evaporating pipe 152 disposed in the evaporating dish 151, and a water-absorbing evaporating sheet (not shown) related to the evaporating pipe 152. is doing. The evaporation pipe 152 is connected to a path between the outlet side of the oil separator 11 and the inlet side of the gas cooler 2, and high-temperature and high-pressure carbon dioxide discharged from the compressor 1 passes therethrough. That is, the wastewater led to the evaporating dish 151 is heated by the evaporating pipe 152 through which high-temperature and high-pressure carbon dioxide passes, and is absorbed by the evaporating sheet and evaporates. At this time, carbon dioxide passing through the evaporation pipe 152 is precooled by drainage.

  The evaporation pipe 152 in the present embodiment has an outer diameter of φ4.76 mm and an inner diameter of φ3.16 mm. Here, in order to set the pressure on the high pressure side to approximately 7 MPa, for example, when the compression volume of the compressor 1 is 1.5 cc and the frequency of the inverter is 55 Hz, carbon dioxide is discharged at about 70 cc per second. Become. At this time, when the inner diameter of the evaporation pipe 152 is 3.16 mm, the flow rate of carbon dioxide passing through the evaporation pipe 152 is about 892 cm / second. On the other hand, when about 70 cc of carbon dioxide is discharged per second, when the inner diameter of the evaporation pipe 152 is φ4.75 mm, the flow rate of carbon dioxide passing through the evaporation pipe 152 is about 395 cm / second. Become. As described above, the evaporation pipe 152 in the present embodiment has an inner diameter of φ3.16 mm, so that the flow rate of carbon dioxide is increased compared to the conventional case.

  Further, as shown in FIG. 2, the evaporation pipe 152 in the present embodiment is formed of a conduction portion 152a and a staying portion 152b. The conducting portion 152a is provided in a spiral shape from above to below. The staying part 152b is provided only from the lower part to the upper part, continuing from the lower end part of the conducting part 152a. In this embodiment, the total length of the evaporation pipe 152 is approximately 2000 mm, and the staying portion 152b is provided with a height difference H of approximately 50 mm. Then, carbon dioxide passes through the conduction portion 152a from the top to the bottom, and carbon dioxide passes through the stay portion 152b from the bottom to the top.

  Hereinafter, the operation of the refrigerant cooling circuit of the present invention using carbon dioxide as the refrigerant will be described. In the following operation of the refrigerant cooling circuit, only the electromagnetic valve 12a is open, and the other electromagnetic valves 12b and 12c are closed.

  The carbon dioxide returned from the evaporator 4a in the refrigerator is sucked into the first compressor 1a via the internal heat exchanger 14 and compressed at a low pressure (compressed to about 6 MPa). The carbon dioxide discharged from the first compressor 1a is cooled through the intermediate heat exchanger 10, and then sucked into the second compressor 1b and compressed at a high pressure (compressed to about 9 MPa). At this time, the refrigerating machine oil discharged together with carbon dioxide from the second compressor 1b is returned to the inlet side of the first compressor 1a by the oil separator 11.

  Next, the carbon dioxide discharged from the second compressor 1 b is pre-cooled by the evaporation means 15 and sent to the gas cooler 2. The carbon dioxide sent to the gas cooler 2 is radiated and liquefied, and reaches the electronic expansion valve 3 via the internal heat exchanger 14.

  Next, in the electronic expansion valve 3, the carbon dioxide is depressurized and the evaporation temperature and flow rate are controlled. Thereafter, the carbon dioxide passes through the electromagnetic valve 12a in the open state and reaches the evaporator 4a through the decompression means 13a.

  Finally, the carbon dioxide supplied to the evaporator 4a absorbs heat and is vaporized as heated steam. The inside of the refrigerator provided with the evaporator 4a is cooled independently by the absorption of carbon dioxide. The carbon dioxide is sucked from the evaporator 4a through the internal heat exchanger 14 to the first compressor 1a and returned to be circulated.

  In the carbon dioxide circulation operation, refrigeration oil that cannot be returned to the compressor 1 by the oil separator 11 reaches the evaporation pipe 152 of the evaporation means 15. The refrigerating machine oil tends to stay in the evaporation pipe 152 because the viscosity index is approximately 100. However, in the evaporation means 15 in the present embodiment, the inner diameter of the evaporation pipe 152 is set to φ3.16 mm, so that the flow rate of carbon dioxide passing through the evaporation pipe 152 is increased as compared with the prior art. As a result, since the refrigerating machine oil that has reached the evaporating pipe 152 is pumped by carbon dioxide in the evaporating means 15, the refrigerating machine oil can be passed through without being retained in the evaporating pipe 152.

  Further, in the evaporation means 15 in the present embodiment, a conduction portion 152a provided in a spiral shape from above to below and a staying portion 152b provided only from the bottom to the top connected to the lower end portion of the conduction portion 152a. An evaporation pipe 152 is formed. In the evaporation pipe 152, the reached refrigerating machine oil is guided from the upper side to the lower side by the conduction part 152a and is retained in the only staying part 152b. Since the staying part 152b is provided only, the refrigerating machine oil flows by high-pressure carbon dioxide after temporarily staying in the staying part 152b. That is, the staying part 152 b is the only trap in the evaporation means 15. As a result, in the evaporating means 15, the refrigerating machine oil that has reached the evaporating pipe 152 is guided from the upper side to the lower side by the conducting part 152 a, and then once accumulated in the staying part 152 b and pumped by carbon dioxide. It is possible to pass through without staying inside.

  Note that, in the carbon dioxide circulation operation, the evaporators 4b and 4c provided in the path having the solenoid valves 12b and 12c in the closed state are the same as the evaporator 4a in the refrigerant circulation path in which the circulation operation is performed. The exit side is gathered. For this reason, conventionally, when only the solenoid valve 12a is in an open state, the pressure difference between the inlet side and the outlet side of the solenoid valves 12b and 12c in the closed state becomes substantially equal. However, in this embodiment, decompression means 13a, 13b, and 13c are provided in the paths between the electromagnetic valves 12a, 12b, and 12c and the evaporators 4a, 4b, and 4c, respectively. For this reason, in the path having the closed solenoid valves 12b and 12c, the decompression means 13b and 13c act as a throttle for applying pressure resistance in the path, so that the outlet side of the closed solenoid valves 12b and 12c has a low pressure. The inlet side becomes high pressure. Accordingly, a pressure difference is generated between the inlet side and the outlet side of the electromagnetic valves 12b and 12c in the closed state, and the closed state of the electromagnetic valves 12b and 12c is assisted by the pressure difference between the inlet side and the outlet side. The closed state of the electromagnetic valves 12b and 12c is maintained.

  The inner diameter φ 3.16 mm of the evaporation pipe 152 described above is particularly suitable when the pressure on the high pressure side is approximately 7 MPa and the viscosity index of the refrigerating machine oil is approximately 100, and the pressure on the high pressure side is 6 to 12 MPa. Even if the viscosity index of the refrigerating machine oil is 76 to 100, the above effect can be obtained if the inner diameter of the evaporation pipe is set in the range of φ3 to 3.16 mm.

  Further, the evaporation pipe 152 formed by the conductive portion 152a provided in a spiral shape from the upper side to the lower side and the staying portion 152b provided only from the lower side to the upper side connected to the lower end portion of the conductive portion 152a has a particularly high pressure. This is suitable when the pressure on the side is about 7 MPa and the viscosity index of the refrigerating machine oil is about 100, and when the pressure on the high pressure side is 6 to 12 MPa and the viscosity index of the refrigerating machine oil is 76 to 100. However, the above effect can be obtained.

It is the schematic which shows one Example of the refrigerant cooling circuit which concerns on this invention. It is a side view which shows an evaporation means. It is a perspective view which shows an evaporation pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 1a 1st compressor 1b 2nd compressor 2 Gas cooler (heat radiator)
21 Fan 22 Fan motor 3 Electronic expansion valve (throttle part)
4 (4a, 4b, 4c) Evaporator 41 Fan 42 Fan motor 10 Intermediate heat exchanger 11 Oil separator 12a, 12b, 12c Solenoid valve 13a, 13b, 13c Pressure reducing means 14 Internal heat exchanger 15 Evaporating means 151 Evaporating dish 152 Evaporating Pipe 152a Conducting part 152b Staying part

Claims (5)

A compressor for compressing refrigerant, said a radiator of refrigerant discharged from the compressor for cooling, the pressure reducing portion for reducing the pressure of the refrigerant supplied from the radiator, the refrigerant supplied from the pressure reducing unit evaporation The evaporator, the evaporation tray to which the condensed water condensed in the evaporator is guided, and the condensation that is provided between the compressor and the radiator and is accommodated in the evaporation tray and guided to the evaporation tray. In a refrigerant cooling circuit comprising an evaporation pipe for evaporating water ,
The evaporation pipe is
A spiral part that is spirally swiveled so as to gradually decrease from above to below, and through which the refrigerant flows from above to below,
A straight upper portion connected to the spiral portion and provided straight from the bottom to the top and from which the refrigerant is discharged from the bottom to the top;
Refrigerant cooling circuit, characterized in that it has a. The refrigerant cooling circuit according to claim 1, wherein the decompression unit is an electronic expansion valve. The refrigerant cooling circuit according to claim 1, wherein the immediately upper portion has a height difference of 50 mm. The compressor includes a first compressor for compressing the first stage, according to claim 1, characterized in that a second compressor to further compress the compressed refrigerant in the first compressor The refrigerant cooling circuit according to any one of the above. The refrigerant, the refrigerant cooling circuit according to any one of claims 1-4, characterized in that the carbon dioxide.

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