JP6169003B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus that separates oil contained in refrigerant discharged from a compressor from the refrigerant and returns the oil to the compressor.

  Conventionally, oil contained in the refrigerant discharged from the compressor is separated from the refrigerant by an oil separator, and the oil separated by the oil separator is cooled by a part of an air-cooled condenser (heat source side heat exchanger) and then compressed. An air conditioner that has been returned to the machine has been proposed (see, for example, Patent Document 1).

WO2010 / 086954

  However, in the conventional air conditioner disclosed in Patent Document 1, if the temperature of the oil returned to the compressor (oil return temperature) is too low under low outside air conditions (that is, the outside air temperature is low), There is a possibility that the flow resistance of the oil will increase due to the increase in viscosity, or the pressure difference for returning the oil to the compressor will decrease due to the decrease in the condensation pressure, and the amount of oil returned to the compressor will be insufficient. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a refrigeration apparatus that can suppress fluctuations in the oil return temperature to the compressor.

  The refrigeration apparatus according to the present invention includes a compressor that compresses refrigerant, an oil separator that separates oil contained in the refrigerant from the compressor from the refrigerant, an air-cooled condenser that condenses the refrigerant from the oil separator, and an air-cooled condenser. A first decompressor for decompressing the refrigerant, an evaporator for evaporating the refrigerant from the first decompressor, a part of the refrigerant flowing between the air-cooled condenser and the first decompressor is taken out as a bypass refrigerant, and a compressor A bypass passage for guiding the bypass refrigerant to the intermediate pressure portion, a second decompression device for decompressing the bypass refrigerant, the bypass refrigerant decompressed by the second decompression device, an air-cooled condenser, An economizer for exchanging heat with a refrigerant flowing between the pressure reducing device 1, an oil return passage for guiding oil separated by the oil separator to the compressor, an oil flowing through the oil return passage, and an air-cooled condenser Heat exchange with the exhaust hot air that passed through And a discharge hot air oil cooler that.

  The refrigeration apparatus according to the present invention includes a compressor that compresses refrigerant, an oil separator that separates oil contained in the refrigerant from the compressor from the refrigerant, an air-cooled condenser that condenses the refrigerant from the oil separator, and an air-cooled condenser A first decompressor for decompressing the refrigerant from the evaporator, an evaporator for evaporating the refrigerant from the first decompressor, a part of the refrigerant flowing between the air-cooled condenser and the first decompressor as a bypass refrigerant, A bypass flow path for guiding the bypass refrigerant to the intermediate pressure portion of the compressor, a second pressure reducing device that depressurizes the bypass refrigerant, the bypass refrigerant decompressed by the second pressure reducing device, and an air-cooled condenser. An economizer that exchanges heat with the refrigerant flowing between the first pressure reducing device, an oil return passage that guides the oil separated by the oil separator to the compressor, and an oil that flows through the oil return passage, and air cooling Flow between condenser and economizer And a refrigerant oil cooler to the heat exchange between the refrigerant.

  According to the refrigeration apparatus of the present invention, the oil flowing through the oil return passage is heat-exchanged between the exhaust hot air that has passed through the air-cooled condenser or the refrigerant that flows between the air-cooled condenser and the economizer. Fluctuation in oil return temperature to the machine can be suppressed.

It is a block diagram which shows the freezing apparatus by Embodiment 1 of this invention. FIG. 2 is a Ph diagram (pressure-enthalpy diagram) showing a refrigeration cycle operation of the refrigeration apparatus of FIG. 1. It is explanatory drawing which shows the temperature change of the oil when it passes each of the 1st and 2nd oil cooler in the oil return part of FIG.

Embodiments of the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing a refrigeration apparatus according to Embodiment 1 of the present invention. In the figure, the refrigeration apparatus 1 includes a refrigeration cycle circuit 2, a bypass unit 3, and an oil return unit 4.

  The refrigeration cycle circuit 2 includes a compressor 11, a plurality of (in this example, four) air-cooled condenser units 12, a receiver 13, a liquid open / close electromagnetic valve 14, and a first expansion valve (first decompression device). ) 15 and an evaporator (indoor cooler) 16.

  The bypass unit 3 includes a bypass channel 21, a second expansion valve (second decompression device) 22, and an economizer 23.

  The oil return unit 4 includes an oil separator 31, an oil return channel 32, a first oil cooler (exhaust hot air oil cooler) 33, and a second oil cooler (refrigerant oil cooler) 34. Have.

  The compressor 11, the oil separator 31, each air-cooled condenser unit 12, the receiver 13, the second oil cooler 34, the economizer 23, the liquid open / close solenoid valve 14, the first expansion valve 15, and the evaporator 16 are refrigerant pipes Are sequentially connected to form a closed circuit. Thereby, in the refrigeration apparatus 1, when the compressor 11 is driven, the refrigerant is converted into the compressor 11, the oil separator 31, each air-cooled condenser unit 12, the receiver 13, the second oil cooler 34, the economizer 23, The liquid opening / closing electromagnetic valve 14, the first expansion valve 15, and the evaporator 16 are sent in this order and returned to the compressor 11. In this example, R410A is used as the refrigerant.

  The bypass unit 3, the oil return unit 4, the compressor 11, each air-cooled condenser unit 12, and the receiver 13 are provided in a condensing unit 5 that is an outdoor unit. The liquid opening / closing solenoid valve 14, the first expansion valve 15, and the evaporator 16 are provided in a unit cooler 6 that is an indoor unit.

  The compressor 11 drives the low-stage compression unit 111, the high-stage compression unit 112 provided on the downstream side of the low-stage compression unit 111, and the low-stage compression unit 111 and the high-stage compression unit 112. A two-stage compressor having a drive motor (not shown). The compressor 11 compresses the refrigerant compressed by the low-stage compression unit 111 by the high-stage compression unit 112 after compressing the gaseous refrigerant by the low-stage compression unit 111. In this example, the rotational speed of the drive motor of the compressor 11 can be adjusted. The refrigerant compressed by the compressor 11 is sent to the oil separator 31.

  The oil separator 31 separates oil (refrigeration oil) contained in the gas refrigerant from the compressor 11 from the refrigerant. The refrigerant from which the oil has been removed by the oil separator 31 is sent to each air-cooled condenser unit 12.

  Each air-cooled condenser unit 12 includes an air-cooled condenser 121 connected in parallel to the oil separator 31 by a refrigerant pipe, and a blower (outdoor fan) 122 that sends outside air to the air-cooled condenser 121. In each air-cooled condenser unit 12, the cooling air (outside air) generated by the blower 122 passes through the air-cooled condenser 121. Each air-cooled condenser 121 exchanges heat between the refrigerant from the oil separator 31 and the cooling air generated by the blower 122 by the passage of the cooling air to the air-cooling condenser 121. Thereby, the refrigerant from the oil separator 31 is cooled and condensed, and the cooling air generated by the blower 122 is heated to become exhausted hot air. The refrigerant condensed in each air-cooled condenser 121 is sent to the receiver 13.

  The receiver 13 accumulates the liquid refrigerant output from each air-cooled condenser 121. The liquid refrigerant stored in the receiver 13 flows in the order of the second oil cooler 34, the economizer 23, and the liquid opening / closing electromagnetic valve 14, and is sent to the first expansion valve 15.

  The first expansion valve 15 depressurizes the refrigerant sent from each air-cooled condenser 121 via the second oil cooler 34, the economizer 23, and the liquid opening / closing electromagnetic valve 14. The refrigerant decompressed by the first expansion valve 15 is sent to the evaporator 16.

  The evaporator 16 exchanges heat between indoor air passing through the evaporator 16 and the refrigerant from the first expansion valve 15 by an indoor fan. Thereby, the refrigerant from the first expansion valve 15 is heated and evaporated, and the indoor air is cooled. The refrigerant evaporated in the evaporator 16 returns to the compressor 11.

  In the compressor 11, the refrigerant connection port 11 a for injecting the refrigerant into the intermediate pressure portion between the low-stage compression unit 111 and the high-stage compression unit 112, and the oil separated by the oil separator 31 are supplied. A common oil connection port 11b for returning to the low-stage compression unit 111 and the high-stage compression unit 112 of the compressor 11 is provided.

  The bypass passage 21 is connected to the refrigerant pipe at the refrigerant outlet of the economizer 23 and to the refrigerant connection port 11 a of the compressor 11. Thereby, the bypass flow path 21 takes out a part of the refrigerant that has exited from the economizer 23 as a bypass refrigerant, so that the intermediate pressure portion of the compressor 11 (that is, the low-stage compression section 111 and the high-stage compression section 112 is The bypass refrigerant.

  The second expansion valve 22 is provided in the bypass channel 21. The second expansion valve 22 depressurizes the bypass refrigerant (that is, part of the refrigerant that has flowed out from the economizer 23) that flows through the bypass flow path 21. The bypass refrigerant decompressed by the second expansion valve 22 is sent to the economizer 23.

  The economizer 23 exchanges heat between the refrigerant sent from each air-cooled condenser 121 to the first expansion valve 15 and the bypass refrigerant decompressed by the second expansion valve 22. Thereby, the refrigerant sent to the first expansion valve 15 is cooled, and the bypass refrigerant is heated. The refrigerant flowing through the bypass passage 21 is depressurized by the second expansion valve 22 and heated by the economizer 23 and then sent to the intermediate pressure portion of the compressor 11.

  The oil return channel 32 is connected to the oil separator 31 and is connected to the oil connection port 11 b of the compressor 11. As a result, the oil return flow path 32 guides the oil separated from the refrigerant by the oil separator 31 to the compressor 11.

  The first oil cooler 33 is provided in the oil return passage 32. The first oil cooler 33 exchanges heat between exhaust hot air (outside air) that has passed through any of the air-cooled condensers 121 and the oil separated from the refrigerant by the oil separator 31. As a result, the oil is cooled and the exhaust hot air is heated.

  The second oil cooler 34 exchanges heat between the refrigerant sent from the receiver 13 to the economizer 23 and the oil cooled by the first oil cooler 33. Thereby, the oil is cooled and the refrigerant is heated. The oil flowing through the oil return flow path 32 is subjected to heat exchange in the order of the first oil cooler 33 and the second oil cooler 34 and then sent to the compressor 11.

  Next, the operation | movement at the time of the cooling operation of the freezing apparatus 1 is demonstrated. FIG. 2 is a Ph diagram (pressure-enthalpy diagram) showing the refrigeration cycle operation of the refrigeration apparatus 1 of FIG. As shown in FIGS. 1 and 2, the high-temperature and high-pressure gas refrigerant (state A) output from the compressor 11 flows into the oil separator 31 and is separated from the oil by the oil separator 31. At this time, the temperature of the discharge gas refrigerant from the compressor 11 and the temperature of the oil separated from the refrigerant are both 90 ° C.

  Thereafter, the gas refrigerant from the oil separator 31 dissipates heat to the outside air in each air-cooled condenser 121 and condenses into a high-pressure liquid refrigerant (state B). Each blower 122 adjusts the amount of heat released from the air-cooled condenser 121 by adjusting the air volume to the air-cooled condenser 121 so that the refrigerant pressure becomes a set value. The condensation temperature in each air-cooled condenser 121 is adjusted to a temperature approximately 10 ° C. higher than the outside air temperature.

  Thereafter, the high-pressure liquid refrigerant condensed in each air-cooled condenser 121 flows into the receiver 13. Since the receiver 13 stores excess liquid refrigerant, the liquid refrigerant and the gas refrigerant coexist, and the refrigerant is a saturated liquid (state B).

  Thereafter, the state of the high-pressure liquid refrigerant from the receiver 13 passes through the second oil cooler 34 and becomes the state C. In this example, since the difference between the temperature of the oil in the second oil cooler 34 and the temperature of the refrigerant is small, the amount of heat exchange between the oil and the refrigerant in the second oil cooler 34 is negligible. ing.

  The high-pressure liquid refrigerant that has passed through the second oil cooler 34 passes through the economizer 23. At this time, the high-pressure liquid refrigerant exchanges heat with the bypass refrigerant that has been decompressed by the second expansion valve 22 to become a low-temperature intermediate-pressure two-phase refrigerant (state G) to increase the degree of supercooling ( State D), flows into the unit cooler 6.

  The high-pressure liquid refrigerant that has flowed into the unit cooler 6 passes through the liquid open / close solenoid valve 14, is decompressed by the first expansion valve 15, becomes a low-pressure two-phase refrigerant (state E), and then flows into the evaporator 16.

  The low-pressure two-phase refrigerant that has flowed into the evaporator 16 exchanges heat with room air (to be cooled) in the evaporator 16 to evaporate into a low-pressure gas refrigerant (state F). Thereby, the indoor air which is a cooling object is cooled to preset temperature. Further, the degree of superheat of the refrigerant coming out of the evaporator 16 is adjusted by the first expansion valve 15.

  The refrigerant evaporated in the evaporator 16 to become low-pressure gas is sucked into the low-stage side compression unit 111 of the compressor 11 and then compressed by the low-stage side compression unit 111 to obtain an intermediate-pressure gas refrigerant (state I). Become. On the other hand, the bypass refrigerant that has been depressurized by the second expansion valve 22 to become an intermediate pressure two-phase refrigerant is subjected to heat exchange by the economizer 23 (state H) and then sucked into the intermediate pressure portion of the compressor 11. In the compressor 11, the intermediate-pressure gas refrigerant (state J) generated by the merge of the refrigerant compressed by the low-stage side compression unit 111 and the bypass refrigerant is compressed by the high-stage side compression unit 112, and is a high-temperature and high-pressure gas refrigerant. (State A) and discharged again to the oil separator 31. The refrigerant temperature coming out of the compressor 11 is adjusted by the second expansion valve 22.

  Next, operation control of the refrigeration apparatus 1 will be described. In this example, consider a case where the unit cooler 6 is installed in a freezer warehouse and the target adjustment temperature of the space in the freezer warehouse is set to -35 ° C. In this case, the rotation speed of the compressor 11 is adjusted so that the evaporation temperature in the evaporator 16 becomes −40 ° C.

  Moreover, the rotation speed of each air blower 122 is adjusted so that the condensation temperature in each air-cooled condenser 121 is 10 ° C. higher than the outside air temperature as described above. However, if the pressure in the oil separator 31 (high pressure side pressure) is too low, the pressure difference for returning oil to the compressor 11 (that is, the pressure difference between the oil separator 31 and the compressor 11) is increased. Since the amount of oil returned from the oil separator 31 to the compressor 11 may be insufficient, the oil separator 31 to the compressor 11 may be used under low outside air conditions where the outside air temperature is 10 ° C. or lower. In order to avoid the shortage of the oil return amount, the rotation speed of each blower 122 is adjusted so that the condensation temperature in each air-cooled condenser 121 does not fall below 30 ° C.

  Furthermore, the opening degree of the first expansion valve 15 is adjusted so that the degree of superheat of the refrigerant (state F) at the outlet of the evaporator 16 is about 10 ° C. Further, the opening degree of the second expansion valve 22 is adjusted so that the temperature of the gas refrigerant (state A) (discharge gas temperature) at the outlet of the compressor 11 is 90 ° C. In this example, since the evaporation temperature in the evaporator 16 is an extremely low temperature of −40 ° C., the state of the bypass refrigerant injected into the compressor 11 is two-phase including liquid refrigerant at the refrigerant connection port 11a. It is in a state (state H).

  Next, the temperature change of the oil in the oil return part 4 is demonstrated. FIG. 3 is an explanatory view showing the temperature change of the oil when passing through each of the first and second oil coolers 33 and 34 in the oil return section 4 of FIG. 1, and FIG. The figure which shows the temperature change of the oil on conditions, FIG.3 (b) is a figure which shows the temperature change of the oil on low external air conditions.

  Under high outside air conditions (for example, conditions where the outside air temperature is 35 ° C.), as shown in FIG. 3A, the rotational speed of the blower 122 is set so that the condensation temperature in each air-cooled condenser 121 is about 45 ° C. Adjusted. At this time, the temperature of the exhaust hot air that has passed through the air-cooled condenser 121 is about 42 ° C. The 90 ° C. oil from the oil separator 31 exchanges heat with 42 ° C. exhaust hot air in the first oil cooler 33 and is cooled to 56 ° C. That is, in the first oil cooler 33, the exhaust hot air that has passed through the air-cooled condenser 121 serves as an oil cooling heat source. Thereafter, the oil cooled to 56 ° C. by the first oil cooler 33 is heat-exchanged with the liquid refrigerant at 45 ° C. (high pressure saturation temperature) in the second oil cooler 34 and cooled to 48 ° C. . That is, in the second oil cooler 34, the high-pressure saturated liquid refrigerant output from the air-cooled condenser 121 serves as an oil cooling heat source. Thereafter, the oil cooled by the second oil cooler 34 is returned to the compressor 11.

  Under a low outside air condition (for example, a condition where the outside air temperature is 0 ° C.), as shown in FIG. 3B, the rotation of each blower 122 is decelerated so that the condensation temperature in each air-cooled condenser 121 does not decrease too much. And the condensation temperature is adjusted to about 30 ° C. At this time, since the speed of the outside air passing through the air-cooled condenser 121 is decreased, the temperature of the exhaust hot air that has passed through the air-cooled condenser 121 becomes approximately 27 ° C., which is a temperature that is considerably close to the condensation temperature. The 90 ° C. oil from the oil separator 31 exchanges heat with 27 ° C. exhaust hot air in the first oil cooler 33 and is cooled to 46 ° C. Thereafter, the oil cooled to 46 ° C. by the first oil cooler 33 is cooled to 35 ° C. by heat exchange with the liquid refrigerant of 30 ° C. (high pressure saturation temperature) in the second oil cooler 34. And returned to the compressor 11.

  In such a refrigeration apparatus 1, the first oil cooler 33 that cools the oil separated from the refrigerant by the oil separator 31 by the exhaust hot air that has passed through the air-cooled condenser 121 is provided. Even under two conditions with a large difference, the temperature difference of the exhaust hot air can be reduced by the outside air passing through the air-cooled condenser 121, and the temperature of the oil returned from the oil separator 31 to the compressor 11. Can be brought close to the condensation temperature in the air-cooled condenser 121. Thereby, even if the outside air temperature fluctuates greatly, fluctuations in the oil return temperature to the compressor 11 can be suppressed, and a malfunction caused by the oil return temperature becoming too low (that is, the amount of oil returned to the compressor 11). Deficiency) can be prevented.

  Further, since the second oil cooler 34 for cooling the oil separated from the refrigerant by the oil separator 31 with the high-pressure saturated liquid refrigerant from the air-cooled condenser 121 is provided, Even under two conditions where there is a large difference, the temperature of the oil returned from the oil separator 31 to the compressor 11 can be brought close to the condensation temperature in the air-cooled condenser 121. Thereby, even if the outside air temperature fluctuates greatly, fluctuations in the oil return temperature to the compressor 11 can be suppressed, and a malfunction caused by the oil return temperature becoming too low (that is, the amount of oil returned to the compressor 11). Deficiency) can be prevented. Moreover, the fluctuation | variation of the oil return temperature to the compressor 11 can further be suppressed by using each of the 1st and 2nd oil coolers 33 and 34 together.

  Further, since the oil cooled by the first oil cooler 33 and the second oil cooler 34 is returned to the compressor 11, it is injected into the intermediate pressure portion of the compressor 11 for adjusting the temperature of the discharge gas refrigerant. The injection amount of the bypass refrigerant can be reduced by the amount of heat exchange in the first and second oil coolers 33 and 34. Thereby, the compression power of the compressor 11 can be reduced.

  Moreover, when the oil return temperature to the compressor 11 becomes extremely low, the discharge gas temperature of the compressor 11 is sufficiently cooled only by the oil return, and the amount of bypass refrigerant injected into the intermediate pressure portion of the compressor 11 is reduced. By reducing, the economizer 23 may not function sufficiently. In the present embodiment, it is possible to prevent the oil return temperature to the compressor 11 from becoming extremely low, and thus it is possible to avoid such deterioration of the performance of the economizer 23.

  Moreover, since the rotation speed of the compressor 11 can be adjusted, the evaporation temperature in the evaporator 16 can be adjusted by adjusting the rotation speed of the compressor 11, and the temperature setting of the space to be cooled can be easily adjusted. can do.

  Further, the condensation temperature in the air-cooled condenser 121 is adjusted by adjusting the amount of air sent to the air-cooled condenser 121 by the blower 122, and the superheat degree of the refrigerant coming out of the evaporator 16 is adjusted by the first expansion valve 15, and compression Since the temperature of the refrigerant discharged from the machine 11 is adjusted by the second expansion valve 22, it is possible to ensure a pressure difference for returning the oil from the oil separator 31 to the compressor 11 even if the outside air temperature fluctuates greatly. It is possible to avoid the shortage of the amount of oil returned to the compressor 11 more reliably.

  In the above example, in the first oil cooler 33, heat exchange is performed between the exhaust hot air that has passed through one of the plurality of air-cooled condensers 121 and the oil. The heat exchange between the exhaust hot air that has passed through the condenser 121 and the oil may be performed by the first oil cooler 33.

  In the above example, the oil separated from the refrigerant by the oil separator 31 is cooled by each of the first oil cooler 33 and the second oil cooler 34. The oil separated from the refrigerant in the vessel 31 may be cooled only by the first oil cooler 33 or may be cooled only by the second oil cooler 34.

  DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus, 11 Compressor, 15 1st expansion valve (1st decompression device), 16 Evaporator, 21 Bypass flow path, 22 2nd expansion valve (2nd expansion valve), 23 Economizer, 31 Oil Separator, 32 oil return flow path, 33 first oil cooler (exhaust hot air oil cooler), 34 second oil cooler (refrigerant oil cooler), 121 air-cooled condenser, 122 blower.

Claims (3)

A compressor for compressing the refrigerant,
An oil separator for separating the oil contained in the refrigerant from the compressor from the refrigerant;
An air-cooled condenser that condenses the refrigerant from the oil separator;
A first decompression device for decompressing the refrigerant from the air-cooled condenser;
An evaporator for evaporating the refrigerant from the first pressure reducing device;
A bypass flow path that takes out a part of the refrigerant flowing between the air-cooled condenser and the first pressure reducing device as a bypass refrigerant and guides the bypass refrigerant to an intermediate pressure portion of the compressor;
A second decompression device that is provided in the bypass flow path and decompresses the bypass refrigerant;
An economizer for exchanging heat between the bypass refrigerant decompressed by the second decompression device and the refrigerant flowing between the air-cooled condenser and the first decompression device;
An oil return passage for guiding the oil separated by the oil separator to the compressor ;
An exhaust hot air oil cooler that cools oil by exchanging heat between the oil flowing through the oil return passage and the exhaust hot air that has passed through the air-cooled condenser , and
A refrigeration apparatus comprising a refrigerant oil cooler that cools oil by exchanging heat between the oil flowing through the oil return passage and the refrigerant flowing between the air-cooled condenser and the economizer . The refrigerating apparatus according to claim 1 , wherein the rotation speed of the compressor is adjustable. The condensation temperature in the air-cooled condenser is adjusted by adjusting the amount of air sent to the air-cooled condenser by a blower,
The degree of superheat of the refrigerant coming out of the evaporator is adjusted by the first pressure reducing device,
The refrigerant | coolant apparatus of Claim 1 or Claim 2 with which the refrigerant | coolant temperature which comes out of the said compressor is adjusted with the said 2nd decompression device.

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