JP2013178020A - Air conditioner that has cooling tower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of enhancing degree of supercooling of refrigerant than that obtained by an outdoor heat exchanger and a tower water-refrigerant heat exchanger.SOLUTION: An air conditioner includes a tower water pump 21, a main path 5, a TR (tower water-refrigerant) heat exchanger 3, a supercooler 8, a supercooling degree detection device 13 which detects degree of supercooling of the refrigerant cooled by an outdoor heat exchanger 7, the TR heat exchanger 3, and the supercooler 8, and a controller 11 which controls flow rate of the tower water pump 21 and open degree of an SC expansion valve 82 so that the degree of supercooling coincides with a predetermined target degree of supercooling.

Description

  The present invention relates to an air conditioner having a cooling tower.

  Patent Document 1 discloses an air conditioner having a cooling tower. As shown in FIG. 1 and the paragraph 0027, the air conditioner includes a tower water-refrigerant heat exchanger that exchanges heat between the tower water cooled by the cooling tower and the refrigerant. The tower water-refrigerant heat exchanger is disposed downstream of the outdoor heat exchanger and functions as a refrigerant subcooler.

JP 2006-284083 A

  The supercooling by the outdoor heat exchanger and the tower water-refrigerant heat exchanger may have insufficient cooling capacity and may not be able to cope with the cooling load. Then, this invention provides the air conditioner which can make the supercooling degree of a refrigerant | coolant larger than the supercooling degree obtained by an outdoor heat exchanger and a tower water-refrigerant heat exchanger.

  An air conditioner having a cooling tower according to the present invention is an air conditioner having a cooling tower, which connects a tower water pump that sprinkles tower water to the cooling tower, a compressor, an indoor heat exchanger, and an outdoor heat exchanger, A main path that flows, a tower water-refrigerant heat exchanger that exchanges heat between the tower water and the refrigerant, a bypass path that branches from the main path and returns the refrigerant to the compressor, and the bypass path A subcooler comprising: an expansion valve that expands the refrigerant flowing through the heat exchanger; and a heat exchanger that exchanges heat between the expanded refrigerant and the refrigerant flowing through the main path. Sometimes, an outdoor heat exchanger, a tower water-refrigerant heat exchanger, and a supercooling degree detection device that detects the degree of supercooling of the refrigerant cooled by the supercooler, A first controller for controlling the flow rate of the tower water pump and the opening of the expansion valve so as to match the degree of supercooling, and the tower water-refrigerant heat exchanger and the supercooler. Is arranged in the main path between the outdoor heat exchanger and the indoor heat exchanger, the supercooling degree is smaller than the target supercooling degree and the flow rate is smaller than a predetermined upper limit flow rate. The first control device increases the flow rate, and the first control device increases the opening degree when the supercooling degree is smaller than the target supercooling degree and the flow rate is equal to the upper limit flow rate. When the degree of supercooling is greater than the target degree of supercooling and the opening degree is greater than a predetermined lower limit opening degree, the first control device decreases the opening degree, and the degree of supercooling is the target degree of subcooling. Greater than and the opening is the lower limit opening If the two values are equal, the first controller decreases the flow rate.

  The air conditioner includes a first superheat degree detection device that detects a first superheat degree when the cooling operation is being performed, and the first superheat degree is heated by the supercooler. The degree of superheat of the refrigerant, and the first control device controls the opening degree within an opening degree range in which the first superheat degree is maintained at a predetermined lower limit superheat degree or more.

  The air conditioner includes a second superheat degree detection device that detects a second superheat degree when the cooling operation is being performed, and the second superheat degree is heated by the air heat exchanger. The degree of superheat of the refrigerant in which the refrigerant heated by the supercooler is combined with the refrigerant, and the first control device has an opening range in which the second superheat degree is maintained at a predetermined lower limit superheat degree or more. The opening is controlled.

  The air conditioner having the cooling tower according to the present invention can make the degree of supercooling of the refrigerant larger than the degree of supercooling obtained by the outdoor heat exchanger and the tower water-refrigerant heat exchanger.

FIG. 1 is a block diagram of an air conditioner. FIG. 2 is a block diagram of the air conditioner. FIG. 3 is a block diagram of the air conditioner. FIG. 4 is a block diagram of the air conditioner. FIG. 5 is a block diagram of the air conditioner. FIG. 6 is a block diagram of the air conditioner. FIG. 7 is a block diagram of the air conditioner.

(Configuration of the first embodiment)
The air conditioner according to the first embodiment will be described with reference to FIG.

  FIG. 1 is a block diagram of an air conditioner. The air conditioner includes a refrigerant circuit 1, a tower water circuit 2, and a tower water-refrigerant heat exchanger (TR heat exchanger) 3. The refrigerant circuit 1 is a heat pump that circulates refrigerant. The tower water circuit 2 includes a cooling tower 4 that cools the tower water, and the tower water circulates in the tower water circuit 2. The TR heat exchanger 3 performs heat exchange between the tower water and the refrigerant.

  The refrigerant circuit 1 includes a main path 5, a compressor 6, an outdoor heat exchanger 7, a supercooler 8, a main expansion valve 9, an indoor heat exchanger 10, a controller 11, and an operating device 12.

  The compressor 6 causes the refrigerant to flow through the main path 5. The refrigerant flows through the compressor 6, the outdoor heat exchanger 7, the supercooler 8, the TR heat exchanger 3, the main expansion valve 9, and the indoor heat exchanger 10 in this order along the main path 5, and again the compressor 6 Return to.

  The outdoor heat exchanger 7 is disposed outdoors, and performs heat exchange between the outside air and the refrigerant.

  The subcooler 8 branches from the main path 5 and returns the refrigerant to the compressor 6, the SC expansion valve 82 that expands the refrigerant flowing in the bypass path 81, the expanded refrigerant and the refrigerant flowing in the main path 5 SC heat exchanger 83 that performs heat exchange with the other. The subcooler 8 cools the refrigerant flowing through the main path 5 by expanding the refrigerant flowing through the bypass path 81. That is, the supercooler 8 cools the remaining refrigerant sent to the evaporator by using a part of the refrigerant sent from the condenser to the evaporator.

  The bypass path 81 branches from the main path 5 at the branch point 5a, and merges with the main path 5 at the merge point 5b.

  The indoor heat exchanger 10 is arrange | positioned indoors and heat-exchanges between indoor air and a refrigerant | coolant. The main expansion valve 9 is disposed between the TR heat exchanger 3 and the indoor heat exchanger 10 and expands the refrigerant flowing through the indoor heat exchanger 10.

  The tower water circuit 2 includes a main path 20, a tower water pump 21, a sprinkler 22, a filler 23, and a water tank 24. The TR heat exchanger 4 is disposed on the main path 20 and is located between the tower water pump 21 and the water sprinkler 22. The cooling tower 4 includes a water sprinkler 22, a filler 23, and a water tank 24.

  The controller 11 controls the compressor 6, the fan of the outdoor heat exchanger 7, the SC expansion valve 82 of the supercooler 8, the main expansion valve 9, the fan of the indoor heat exchanger 10, and the tower water pump 21.

  The operating device 12 inputs a command for operating the air conditioner to the controller 11 based on an operation by the user.

  The air conditioner includes a supercooling degree detection device 13, a first superheating degree detection device 14, and a second superheating degree detection device 15.

  The supercooling degree detection device 13 detects the supercooling degree of the refrigerant cooled by the outdoor heat exchanger 7, the TR heat exchanger 3, and the supercooler 8 when the cooling operation is being performed. Specifically, the supercooling degree detection device 13 detects the supercooling degree of the refrigerant in the main path 5 between the TR heat exchanger 3 and the main expansion valve 9. The supercooling degree detection device 13 includes a first temperature sensor 31, a first pressure sensor 41, and an SC calculator (controller 11). The first temperature sensor 31 detects the temperature of the refrigerant in the main path 5 between the TR heat exchanger 3 and the main expansion valve 9. Hereinafter, the first temperature T <b> 1 is the temperature of the refrigerant detected by the first temperature sensor 31. The first pressure sensor 41 detects the pressure of the refrigerant in the main path 5 between the TR heat exchanger 3 and the main expansion valve 9. Hereinafter, the first pressure P <b> 1 is the refrigerant pressure detected by the first pressure sensor 41. The SC calculation unit is configured using the function of the controller 11. The SC calculation unit (controller 11) calculates a saturated liquid temperature TL corresponding to the first pressure P1 based on the saturated liquid line of the refrigerant. Furthermore, the SC calculation unit (controller 11) calculates a degree of supercooling that is a temperature difference between the first temperature T1 and the saturated liquid temperature TL.

  The first superheat degree detection device 14 detects the superheat degree (first superheat degree) of the refrigerant heated by the supercooler 8 when the cooling operation is being executed. Specifically, the 1st superheat degree detection apparatus 14 detects the superheat degree of a refrigerant | coolant in the main path | route 5 between the supercooler 8 (SC heat exchanger 83) and the confluence | merging location 5b. The first superheat degree detection device 14 includes a second temperature sensor 32, a second pressure sensor 42, and a first SH calculation unit (controller 11). The second temperature sensor 32 detects the temperature of the refrigerant in the main path 5 between the supercooler 8 and the junction 5b. Hereinafter, the second temperature T2 is the temperature of the refrigerant detected by the second temperature sensor 32. The second pressure sensor 42 detects the pressure of the refrigerant in the main path 5 between the junction 5 b and the compressor 6. Hereinafter, the second pressure P <b> 2 is the refrigerant pressure detected by the second pressure sensor 42. Here, when the cooling operation is being performed, the pressure of the refrigerant is equal to the second pressure in the entire main path 5 from the subcooler 8 and the indoor heat exchanger 10 to the compressor 6. That is, the second pressure P2 is equal to the refrigerant pressure in the main path 5 between the supercooler 8 and the junction 5b. The first SH calculation unit is configured using the function of the controller 11. The first SH calculation unit (controller 11) calculates a saturated vapor temperature TV corresponding to the second pressure P2 based on the saturated vapor line of the refrigerant. Further, the first SH calculation unit (controller 11) calculates a degree of superheat (first degree of superheat) that is a temperature difference between the second temperature T2 and the saturated steam temperature TV.

  When the cooling operation is being executed, the second superheat degree detection device 15 combines the refrigerant heated by the indoor heat exchanger 10 with the refrigerant heated by the supercooler 8 (second superheat degree). Degree). Specifically, the second superheat degree detection device 15 detects the superheat degree of the refrigerant in the main path 5 between the junction 5 b and the compressor 6. The second superheat degree detection device 15 includes a third temperature sensor 33, a second pressure sensor 42, and a second SH calculation unit (controller 11). The third temperature sensor 33 detects the temperature of the refrigerant in the main path 5 between the junction 5 b and the compressor 6. Hereinafter, the third temperature T3 is the temperature of the refrigerant detected by the third temperature sensor 33. The second pressure sensor 42 is shared by the first superheat degree detection device 14 and the second superheat degree detection device 15. The second pressure P <b> 2 is also equal to the refrigerant pressure in the main path 5 between the junction 5 b and the compressor 6. The second SH calculation unit is configured using the function of the controller 11. The second SH calculation unit (controller 11) calculates a saturated vapor temperature TV corresponding to the second pressure P2 based on the saturated vapor line of the refrigerant. Further, the first SH calculation unit (controller 11) calculates a superheat degree (second superheat degree) that is a temperature difference between the third temperature T3 and the saturated steam temperature TV.

  In order to maintain the air conditioning performance, it is necessary to prevent the gas refrigerant from being mixed with the liquid refrigerant toward the main expansion valve 9 and to prevent the liquid refrigerant from being mixed with the gas refrigerant returning to the compressor 6. Simply, if the degree of supercooling of the refrigerant is a positive value, it is estimated that the liquid refrigerant is not mixed with gas refrigerant, and if the degree of superheat of the refrigerant is a positive value, the gas refrigerant is not mixed with liquid refrigerant. Presumed. In order to ensure certainty, a predetermined lower limit supercooling degree is set for the supercooling degree, and a predetermined lower limit superheating degree is set for the superheating degree. On the other hand, excessively increasing the degree of supercooling and the degree of superheat decreases the air conditioning capacity per power consumption. For this reason, a predetermined target supercooling degree is set for the supercooling degree, and the air conditioner is operated so that the supercooling degree is maintained at the target supercooling degree. The degree of superheat varies depending on the degree of supercooling. For this reason, control of a supercooling degree is restrict | limited so that a superheat degree may be maintained more than a minimum superheat degree.

  Hereinafter, the degree of supercooling refers to the degree of supercooling detected by the degree of supercooling detection device 13, the first degree of superheating refers to the degree of superheat detected by the first degree of superheat detection device 14, and the second degree of superheat is The superheat degree detected by the second superheat degree detection device 15 is indicated. Moreover, a mere superheat degree points out both the 1st superheat degree and the 2nd superheat degree.

  Control of the degree of supercooling and the degree of superheat in the cooling operation will be described. The controller (first control device) 11 controls the flow rate of the tower water pump 21 and the opening of the SC expansion valve 82 so that the degree of supercooling matches the target degree of supercooling.

  As will be described below, the flow rate of the tower water pump 21 and the opening of the SC expansion valve 82 correspond to the degree of supercooling, the first degree of superheat, and the second degree of superheat. The flow rate of the tower water pump 21 corresponds to the amount of heat taken from the tower water in the cooling tower 4, and corresponds to the amount of heat taken from the refrigerant in the TR heat exchanger 3. For this reason, when the flow rate of the tower water pump 21 increases, the amount of heat taken away from the refrigerant in the TR heat exchanger 3 increases. The opening of the SC expansion valve 82 corresponds to the flow rate of the refrigerant flowing through the bypass path 81, and corresponds to the amount of heat taken away from the refrigerant flowing through the main path 5 in the subcooler 8. For this reason, when the opening degree of the SC expansion valve 82 increases, the amount of heat taken from the refrigerant in the supercooler 8 increases. Here, the amount of heat is taken from the refrigerant flowing in the main path 5 in the subcooler 8, and the amount of heat is given to the refrigerant flowing in the bypass path 81 in the subcooler 8. When the amount of heat of the refrigerant changes, the degree of supercooling, the first degree of superheating, and the second degree of superheating change.

  In the control of the degree of supercooling, the cooling of the cooling tower 4 by the TR heat exchanger 3 is executed with priority over the cooling by the supercooler 8. The use of the cooling tower 4 increases the air conditioning capacity per power consumption as compared to the use of the supercooler 8. Moreover, utilization of the supercooler 8 brings about a decrease in the first superheat degree and the second superheat degree. For this reason, when there is a margin in the capacity of the cooling tower 4, it is more efficient to use the cooling tower 4 than to use the supercooler 8.

The controller 11 controls the flow rate of the tower water pump 21 and the opening of the SC expansion valve 82 based on the following conditions.
(A) When the degree of supercooling is smaller than the target degree of supercooling and the flow rate is smaller than a predetermined upper limit flow rate, the controller 11 increases the flow rate.
(B) When the supercooling degree is smaller than the target supercooling degree and the flow rate is equal to the upper limit flow rate, the controller 11 increases the opening degree.
(C) When the degree of supercooling is larger than the target degree of supercooling and the opening degree is larger than the predetermined lower limit opening degree, the controller 11 decreases the opening degree.
(D) When the degree of supercooling is larger than the target degree of supercooling and the opening degree is equal to the lower limit opening degree, the controller 11 decreases the flow rate.

  The control of the degree of supercooling is changed according to the magnitude of the degree of superheat so as to reliably prevent the liquid refrigerant from flowing into the compressor 6. The opening degree of the SC expansion valve 82 is controlled so as to suppress a decrease in the degree of superheat. Here, the opening degree of the main expansion valve 9 is kept constant. On the other hand, the opening degree of the SC expansion valve 82 is changed within a predetermined opening degree range in accordance with the change in the degree of supercooling. Hereinafter, the upper limit opening indicates the upper limit of the opening range. The lower limit of the opening range indicates that the opening is 0, that is, the SC expansion valve 82 is closed. When the opening degree of the SC expansion valve 82 is the upper limit opening degree, the air conditioner is set so that the degree of superheat of the refrigerant returning from the indoor heat exchanger 10 to the compressor 6 along the main path 5 is larger than the first degree of superheat. Is designed. For this reason, when the opening degree of the SC expansion valve 82 is at the upper limit opening degree, the second superheat degree that is the superheat degree of the refrigerant after the merge is larger than the first superheat degree. For this reason, when the second superheat degree is equal to or greater than the predetermined lower limit superheat degree, the first superheat degree is always equal to or greater than the lower limit superheat degree.

  Since control is preferably performed in a state where there is a margin, the degree of supercooling is basically limited based on the monitoring of the first degree of superheat. When the cooling capacity of the refrigerant is insufficient, the degree of supercooling is limited based on the monitoring of the second degree of superheat. Specifically, when the cooling capacity is insufficient, the cooling tower 4 is stopped. The case where the operation of the cooling tower 4 is stopped when the cooling operation is executed is, for example, the case where the cooling tower 4 is out of order.

The controller 11 limits the control of the degree of supercooling according to the operating state of the cooling tower 4 and the degree of superheat.
(D) When the operation of the cooling tower 4 is executed, the controller 11 controls the opening degree within the opening degree range in which the first superheat degree is maintained at the lower limit superheat degree or more.
(E) When the operation of the cooling tower 4 is stopped, the controller 11 controls the opening degree within the opening degree range in which the second superheat degree is maintained to be equal to or higher than the lower limit superheat degree.

(Configuration of Second Embodiment)
With reference to FIG. 2, an air conditioner according to the second embodiment will be described. FIG. 2 is a block diagram of the air conditioner. The air conditioner according to the second embodiment limits the control of the degree of supercooling according to only the magnitude of the first degree of superheating. For this reason, the air conditioner according to the second embodiment does not include the second superheat degree detection device 15. Other points are the same between the first embodiment and the second embodiment.

(F) The controller 11 controls the opening degree within an opening degree range in which the first superheat degree is maintained at the lower limit superheat degree or more.

(Configuration of Third Embodiment)
With reference to FIG. 3, the air conditioner which concerns on 3rd Embodiment is demonstrated. FIG. 3 is a block diagram of the air conditioner. The air conditioner according to the third embodiment limits the control of the degree of supercooling according to only the magnitude of the second degree of superheating. For this reason, the air conditioner according to the third embodiment does not include the first superheat degree detection device 14. Other points are the same between the first embodiment and the third embodiment.

(G) The controller 11 controls the opening degree within an opening degree range in which the second superheat degree is maintained at the lower limit superheat degree or more.

(Configuration of Fourth Embodiment)
With reference to FIG. 4, the air conditioner which concerns on 4th Embodiment is demonstrated. FIG. 4 is a block diagram of the air conditioner. The air conditioner according to the fourth embodiment does not limit the control of the degree of supercooling based on the degree of superheat. For this reason, the air conditioner according to the fourth embodiment does not include the first superheat degree detection device 14 and the second superheat degree detection device 15. Other points are the same between the first embodiment and the fourth embodiment.

  In the fourth embodiment, the opening range is set in advance so that the degree of superheat does not become less than the lower limit superheat degree. That is, the upper limit opening degree in the fourth embodiment is smaller than the upper limit opening degree in the first to third embodiments.

(Configuration of Fifth Embodiment)
With reference to FIG. 5, the air conditioner which concerns on 5th Embodiment is demonstrated. FIG. 5 is a block diagram of the air conditioner. In the air conditioner according to the fifth embodiment, the TR heat exchanger 3 is disposed inside the water tank 24 of the cooling tower 4. On the other hand, in the air conditioner according to the first embodiment, the TR heat exchanger 3 is disposed outside the water tank 24. Other points are the same between the first embodiment and the fifth embodiment.

(Effect of this embodiment)
The air conditioner which concerns on this embodiment has the following effect by the above-mentioned structure.

(1) The air conditioner according to the first to fifth embodiments includes a tower water pump 21, a main path 5, a TR heat exchanger (tower water-refrigerant heat exchanger) 3, a supercooler 8, and a supercooling degree detection device 13. And a controller (first control device) 11. The controller 11 performs control of the degree of supercooling according to the conditions (a)-(d).

  The refrigerant is cooled by the outdoor heat exchanger 7, the TR heat exchanger 3, and the supercooler 11. For this reason, the air conditioner according to the first to fifth embodiments can make the degree of supercooling of the refrigerant larger than the degree of supercooling obtained by the outdoor heat exchanger 7 and the TR heat exchanger 3.

  The control of the degree of supercooling gives priority to the cooling by the TR heat exchanger 3 of the cooling tower 4 over the cooling by the supercooler 8. For this reason, the air conditioner according to the first to fifth embodiments can efficiently cool the refrigerant in the air conditioning capacity per power consumption.

(2) The air conditioner according to the first, second, and fifth embodiments includes a first superheat degree detection device, and the controller 11 has an opening degree range in which the first superheat degree is maintained at or above a predetermined lower limit superheat degree. The opening is controlled within.

  When the first superheat degree is maintained to be equal to or higher than the lower limit superheat degree that is a positive value, the liquid refrigerant does not mix with the refrigerant that returns to the compressor 6. For this reason, the air conditioner according to the first, second, and fifth embodiments can prevent the compressor 6 from being damaged or overloaded.

(2) The air conditioner according to the first, third, and fifth embodiments includes the second superheat degree detection device, and the controller 11 has an opening degree range in which the second superheat degree is maintained at a predetermined lower limit superheat degree or more. The opening is controlled within.

  When the second superheat degree is maintained at a value equal to or higher than the lower limit superheat degree that is a positive value, the liquid refrigerant does not mix with the refrigerant that returns to the compressor 6. For this reason, the air conditioner according to the first, third, and fifth embodiments can prevent the compressor 6 from being damaged or overloaded.

(Modification)
Although the 1-5th embodiment is an air conditioner which performs only cooling operation, the air conditioner concerning the present invention is not limited to the air conditioner only for cooling. The component according to the present invention can be applied to an air conditioner capable of switching between cooling and heating. In this air conditioner, when the cooling operation is executed, the above-described supercooling degree control is executed.

  In the first to fifth embodiments, the TR heat exchanger 3 is disposed upstream of the subcooler 8 between the outdoor heat exchanger 10 and the indoor heat exchanger as seen from the refrigerant flow in the cooling operation. Yes. The TR heat exchanger and the subcooler 8 may be arranged in the main path between the outdoor heat exchanger 10 and the indoor heat exchanger. Therefore, the TR heat exchanger 3 may be disposed downstream of the supercooler 8.

(First embodiment)
With reference to FIG. 6, the air conditioner which concerns on 1st another embodiment is demonstrated. FIG. 6 is a block diagram of the air conditioner. There are the following differences between the first alternative embodiment and the first embodiment. The air conditioner according to the first alternative embodiment includes a refrigerant-refrigerant heat exchanger (RR heat exchanger) 16 instead of the supercooler 8, and includes a first superheat degree detector 14 and a second superheat degree detector. Instead of 15, a superheat detector 17 is provided. Further, the content of the control of the degree of supercooling is changed according to the change of the configuration related to the supercooling. Other points are the same between the first embodiment and the first alternative embodiment.

  In FIG. 6, the RR heat exchanger 16 performs heat exchange between the upstream liquid refrigerant and the downstream gas refrigerant. The upstream liquid refrigerant indicates the refrigerant that flows through the main path 5 between the indoor heat exchanger 7 and the TR heat exchanger 3. The downstream gas refrigerant refers to the refrigerant that flows through the main path 5 between the indoor heat exchanger 10 and the compressor 6. The temperature of the downstream gas refrigerant is lower than the temperature of the upstream liquid refrigerant. For this reason, in the RR heat exchanger 16, the amount of heat moves from the liquid refrigerant to the gas refrigerant, and the liquid refrigerant is cooled. That is, the RR heat exchanger 16 functions as a condenser and a subcooler.

  The superheat degree detection device 17 detects the superheat degree of the refrigerant heated by the RR heat exchanger 16 when the cooling operation is being executed. The superheat degree detection device 17 detects the superheat degree of the refrigerant in the main path 5 between the RR heat exchanger 16 and the compressor 6. The superheat degree detection device 17 includes an inlet temperature sensor 34, an inlet pressure sensor 44, and an SH calculation unit (controller 11). The inlet temperature sensor 34 detects the temperature of the refrigerant in the main path 5 between the RR heat exchanger 16 and the compressor 6. Hereinafter, the inlet temperature T4 is the temperature of the refrigerant detected by the inlet temperature sensor 34. The inlet pressure sensor 44 detects the pressure of the refrigerant in the main path 5 between the RR heat exchanger 16 and the compressor 6. Hereinafter, the inlet pressure P4 is the refrigerant pressure detected by the inlet pressure sensor 44. The SH calculation unit is configured using the function of the controller 11. The SH calculation unit (controller 11) calculates a saturated vapor temperature TV corresponding to the inlet pressure P4 based on the saturated vapor line of the refrigerant. Furthermore, the SH calculation unit (controller 11) calculates the degree of superheat that is the temperature difference between the inlet temperature T4 and the saturated steam temperature TV.

  The controller 11 controls the flow rate of the tower water pump 21 so that the degree of supercooling matches the target degree of supercooling.

The controller 11 controls the flow rate of the tower water pump 21 and the opening of the SC expansion valve 82 based on the following conditions.
(A2) When the degree of supercooling is smaller than the target degree of supercooling, the controller 11 increases the flow rate.
(D2) When the degree of supercooling is larger than the target degree of supercooling, the controller 11 decreases the flow rate.

The controller 11 limits the control of the degree of supercooling according to the magnitude of the degree of superheat. That is, priority is given to control for preventing a decrease in the degree of superheat over control for making the degree of supercooling coincide with the target degree of supercooling.
(H) The controller 11 controls the flow rate within a flow rate range in which the first superheat degree is kept equal to or higher than the lower limit superheat degree.

(Second embodiment)
With reference to FIG. 7, the air conditioner which concerns on 2nd another embodiment is demonstrated. FIG. 7 is a block diagram of the air conditioner. There are the following differences between the second alternative embodiment and the first alternative embodiment. The air conditioner according to the second alternative embodiment includes an SC indoor heat exchanger 18 instead of the RR heat exchanger 16. Other points are the same between the second alternative embodiment and the first alternative embodiment.

  In FIG. 7, the SC indoor heat exchanger 18 exchanges heat between the outside air and the refrigerant, like the indoor heat exchanger 7. The SC indoor heat exchanger 18 functions as a condenser and a subcooler.

3 TR heat exchanger (tower water-refrigerant heat exchanger) 3
4 Cooling tower 5 Main path 6 Compressor 7 Outdoor heat exchanger 8 Subcooler 10 Indoor heat exchanger 11 Controller (first control device)
DESCRIPTION OF SYMBOLS 13 Supercooling degree detection apparatus 14 1st superheat degree detection apparatus 15 2nd superheat degree detection apparatus 21 Tower water pump 81 Bypass path 82 SC expansion valve 83 SC heat exchanger

Claims (3)

In an air conditioner with a cooling tower,
A tower water pump for spraying tower water to the cooling tower;
A main path for connecting the compressor, the indoor heat exchanger, and the outdoor heat exchanger, and flowing the refrigerant;
A tower water-refrigerant heat exchanger that exchanges heat between the tower water and the refrigerant;
Heat is generated between a bypass path that branches from the main path and returns the refrigerant to the compressor, an expansion valve that expands the refrigerant that flows through the bypass path, and the expanded refrigerant and the refrigerant that flows through the main path. A subcooler comprising: a heat exchanger for exchanging;
A supercooling degree detection device for detecting the degree of supercooling of the refrigerant cooled by the outdoor heat exchanger, the tower water-refrigerant heat exchanger, and the supercooler when the cooling operation is being performed;
A first controller that controls the flow rate of the tower water pump and the opening of the expansion valve so as to match the degree of supercooling with a predetermined target degree of supercooling,
The tower water-refrigerant heat exchanger and the subcooler are disposed in the main path between the outdoor heat exchanger and the indoor heat exchanger,
When the degree of supercooling is smaller than the target degree of supercooling and the flow rate is smaller than a predetermined upper limit flow rate, the first controller increases the flow rate,
When the degree of supercooling is smaller than the target degree of supercooling and the flow rate is equal to the upper limit flow rate, the first control device increases the opening degree,
When the degree of supercooling is greater than the target degree of supercooling and the opening is greater than a predetermined lower limit opening, the first control device decreases the opening,
The air conditioner having a cooling tower, wherein the first control device decreases the flow rate when the degree of supercooling is larger than the target degree of supercooling and the opening degree is equal to the lower limit opening degree. A first superheat degree detection device that detects the first superheat degree when the cooling operation is being performed;
The first superheat degree is a superheat degree of the refrigerant heated by the supercooler,
2. The air conditioner having a cooling tower according to claim 1, wherein the first control device controls the opening degree within an opening degree range in which the first superheat degree is maintained at a predetermined lower limit superheat degree or more. A second superheat degree detection device that detects the second superheat degree when the cooling operation is being performed;
The second superheat degree is a superheat degree of the refrigerant obtained by combining the refrigerant heated by the supercooler with the refrigerant heated by the air heat exchanger,
2. The air conditioner having a cooling tower according to claim 1, wherein the first control device controls the opening degree within an opening degree range in which the second superheat degree is maintained at a predetermined lower limit superheat degree or more.

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