Refrigeration cycle device

Abstract

A refrigeration cycle device (1) comprises: a refrigerant circuit (110); an outdoor fan (14); an indoor fan (25); a heater (24); and a control device (60). The refrigerant circuit (110) includes: a compressor (11) and a condenser (13) which are provided outdoors; and a reheat heat exchanger (21), an expansion valve (22), and an evaporator (23) which are provided indoors. The refrigerant circuit is configured such that the refrigerant is circulated in the the given during the cooling operation. The outdoor fan (14) sends air to the condenser (13). The evaporator (23), the reheat heat exchanger (21), and the heater (24) are disposed side by side such that air blown by the indoor fan (25) reaches the foregoing in the given order. During the cooling operation, the control device (60) operates the heater (24) if the indoor temperature is lower than a target value and the rotational speed of the outdoor fan (14) is lower than a threshold.

Description

Refrigeration Cycle Equipment

[0001] The present disclosure relates to a refrigeration cycle device.

[0002] Japanese Patent Application Laid-Open Publication No. 2004-132573 (Patent Document 1) discloses an air conditioner capable of reheating cooled and dehumidified air (hereinafter also referred to as "cooling reheat dehumidification operation"). This air conditioner includes a refrigerant circulation circuit and an indoor fan that blows air into the room. The refrigerant circulation circuit includes a compressor and an outdoor heat exchanger disposed outdoors, and a first indoor heat exchanger, an indoor expansion valve, and a second indoor heat exchanger disposed indoors, and is configured so that the refrigerant circulates in this order during cooling reheat dehumidification operation. The second indoor heat exchanger and the first indoor heat exchanger are arranged side by side so that the air blown by the indoor fan hits them in this order. During cooling reheat dehumidification operation, the outdoor heat exchanger and the first indoor heat exchanger function as condensers, and the second indoor heat exchanger functions as an evaporator. Therefore, the air (room air) blown by the indoor fan is first cooled and dehumidified by the second indoor heat exchanger, and then heated by the first indoor heat exchanger, thereby enabling cooling reheat dehumidification operation in which the cooled and dehumidified air is reheated.

[0003] Japanese Patent Application Laid-Open No. 2004-132573

[0004] In the air conditioner disclosed in Japanese Patent Laid-Open Publication No. 2004-132573 (Patent Document 1), during cooling and reheating dehumidification operation, the indoor air cooled and dehumidified by the second indoor heat exchanger is heated by the first indoor heat exchanger. In this configuration, depending on the operating conditions of the air conditioner, it is possible that the amount of heating provided by the first indoor heat exchanger may be insufficient, resulting in insufficient reheating of the indoor air. One possible solution to this problem is to install a heater downstream of the first indoor heat exchanger in the airflow direction and heat the indoor air with the heater. However, because operating the heater requires additional power, unnecessary operation of the heater may result in a decrease in energy efficiency.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to enable sufficient reheating during cooling reheat dehumidification operation without compromising energy saving performance.

[0006] A refrigeration cycle device according to the present disclosure includes a refrigerant circuit including a compressor and a first condenser disposed outdoors, a second condenser, an expansion valve, and an evaporator disposed indoors, in which a refrigerant circulates in this order during cooling operation, a first fan that blows air to the first condenser, a second fan that blows air into the indoors, a heater disposed indoors, and a control device. The evaporator, second condenser, and heater are arranged in order so that the air blown by the second fan hits them in this order. The control device activates the heater during cooling operation when the indoor temperature is lower than a target value and the rotation speed of the first fan is lower than a threshold value.

[0007] According to the present disclosure, sufficient reheating can be performed during cooling reheat dehumidification operation without deteriorating energy saving performance.

[0008] It is a diagram showing an example of the overall configuration of a refrigeration cycle device. It is a flowchart showing an example of a processing procedure performed by a control device during a cooling reheat dehumidification operation.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments described below, when numbers, quantities, etc. are mentioned, the scope of the present disclosure is not necessarily limited to those numbers, quantities, etc., unless otherwise specified. The same reference numerals will be used for the same or equivalent parts, and overlapping descriptions may not be repeated.

[0010] 1 is a diagram schematically illustrating an example of the overall configuration of a refrigeration cycle apparatus 1 according to this embodiment. The refrigeration cycle apparatus 1 includes an outdoor unit 10, an indoor unit 20, and a control device 60.

[0011] The outdoor unit 10 includes a compressor 11, a condenser (first condenser) 13, and an outdoor fan (first fan) 14. The indoor unit 20 includes a reheat heat exchanger (second condenser) 21, an expansion valve 22, an evaporator 23, a heater 24, an indoor fan (second fan) 25, and a room temperature sensor 26.

[0012] The compressor 11 and condenser 13 provided in the outdoor unit 10 and the reheat heat exchanger 21, expansion valve 22, and evaporator 23 provided in the indoor unit 20 are connected by refrigerant piping 30 to form a refrigerant circuit 110. The refrigerant circuit 110 is configured so that during indoor cooling operation (when the compressor 11 is operating), the refrigerant circulates through the compressor 11, condenser 13, reheat heat exchanger 21, expansion valve 22, and evaporator 23 in this order.

[0013] The compressor 11 draws in and compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The compressor 11 discharges the refrigerant at a flow rate that corresponds to the frequency (rotation speed). The frequency (rotation speed) of the compressor 11 is controlled by the control device 60.

[0014] The condenser 13 is a heat exchanger having a flow path through which the refrigerant flows. In the condenser 13, the refrigerant flowing inside the flow path is cooled by heat exchange with the air outside the flow path. Part or all of the high-pressure gas refrigerant discharged from the compressor 11 is condensed by heat exchange in the condenser 13.

[0015] The outdoor fan 14 is provided in a position close to the condenser 13 and sends air to the condenser 13. The air sent by the outdoor fan 14 promotes heat exchange in the condenser 13.

[0016] The reheat heat exchanger 21 is a heat exchanger having a flow path through which a refrigerant flows. In the reheat heat exchanger 21, the refrigerant flowing inside the flow path is cooled by heat exchange with the air outside the flow path. The refrigerant cooled in the condenser 13 is further cooled by heat exchange in the reheat heat exchanger 21. That is, in the refrigerant circuit 110 according to this embodiment, the condenser 13 functions as a first condenser, and the reheat heat exchanger 21 functions as a second condenser that further cools and condenses the gas refrigerant that was not condensed in the condenser 13. The air around the reheat heat exchanger 21 is warmed by absorbing the heat of the refrigerant flowing through the reheat heat exchanger 21.

[0017] The expansion valve 22 is a pressure reducing device that reduces the pressure of the high-pressure refrigerant. As the expansion valve 22, for example, an electronically controlled expansion valve having a valve element whose opening degree can be adjusted can be used.

[0018] The evaporator 23 is a heat exchanger having a flow path through which the refrigerant flows. In the evaporator 23, heat exchange occurs between the refrigerant flowing inside the flow path and the air outside the flow path. The refrigerant decompressed by the expansion valve 22 evaporates into gas refrigerant through heat exchange in the evaporator 23. The air around the evaporator 23 is cooled and dehumidified through heat exchange with the refrigerant flowing through the evaporator 23. The gas refrigerant discharged from the evaporator 23 is drawn into the compressor 11.

[0019] The indoor fan 25 is provided near the evaporator 23 and blows air into the room. The indoor fan 25 is controlled to start and stop by the control device 60.

[0020] The heater 24 is provided near the reheat heat exchanger 21 and heats the surrounding air. The activation and deactivation of the heater 24 is controlled by the control device 60.

[0021] The evaporator 23, reheat heat exchanger 21, and heater 24 are arranged in this order so that they are exposed to the air blown by the indoor fan 25. Specifically, the reheat heat exchanger 21 is arranged downstream of the evaporator 23 in the direction of the air blown by the indoor fan 25. The heater 24 is arranged downstream of the reheat heat exchanger 21 in the direction of the air blown by the indoor fan 25.

[0022] By operating the indoor fan 25 during indoor cooling operation (while the compressor 11 is operating), the indoor air is cooled and dehumidified by the evaporator 23, and then warmed by the reheat heat exchanger 21 or heater 24, which are located downstream of the evaporator 23. That is, the refrigerant circuit 110 according to this embodiment can perform cooling reheat dehumidification operation.

[0023] The room temperature sensor 26 detects the room temperature and outputs the detection result to the control device 60 .

[0024] The control device 60 includes a CPU (Central Processing Unit) 61, a memory 62, and an input / output port (not shown) for inputting and outputting various signals. The control device 60 controls the various devices (such as the compressor 11, the expansion valve 22, the outdoor fan 14, the heater 24, and the indoor fan 25) of the refrigeration cycle apparatus 1 based on signals from various sensors (such as the room temperature sensor 26) and devices, as well as programs stored in the memory 62. Note that the control performed by the control device 60 is not limited to software processing, and can also be performed by dedicated hardware (electronic circuits).

[0025] As described above, the refrigeration cycle apparatus 1 according to this embodiment can perform a cooling reheat dehumidification operation. In the cooling reheat dehumidification operation, the indoor fan 25 is operated, and the indoor air is cooled and dehumidified by the evaporator 23, and then heated by the reheat heat exchanger 21 or the heater 24, which are disposed downstream of the evaporator 23 in the airflow direction.

[0026] During this cooling reheat dehumidification operation, if the heater 24 is operated excessively, the power consumption of the heater 24 increases and energy saving performance deteriorates, while if the heater 24 is not operated and only reheating is performed by the reheat heat exchanger 21, sufficient reheating may not be achieved depending on the operating conditions.

[0027] Therefore, the control device 60 according to this embodiment improves energy conservation by basically not operating the heater 24 and instead reheating the air using the reheat heat exchanger 21 during cooling reheat dehumidification operation (while the compressor 11 is operating), and operates the heater 24 only when sufficient reheating cannot be achieved using only the reheat heat exchanger 21. This results in excellent energy conservation and allows sufficient reheating under any operating conditions.

[0028] 2 is a flowchart showing an example of a processing procedure performed by the control device 60 during the cooling reheat dehumidification operation. The flowchart of FIG. 2 is repeatedly executed every time a predetermined condition is satisfied during the cooling reheat dehumidification operation (for example, every predetermined period).

[0029] The control device 60 determines whether the room temperature (the value detected by the room temperature sensor 26) is lower than a target value (step S10). The target value is, for example, a room temperature desired by the user and is set in advance by the user.

[0030] If the indoor temperature is higher than the target value (NO in step S10), it is assumed that a sufficient amount of reheat is secured, and therefore control device 60 ends the process without operating heater 24.

[0031] If the indoor temperature is lower than the target value (NO in step S10), it is assumed that the amount of reheating is insufficient, and therefore control device 60 performs processing to increase the amount of reheating (steps S12 to S20).

[0032] First, the control device 60 determines whether the rotation speed of the outdoor fan 14 is equal to or lower than a threshold value (step S12). The threshold value is the lower limit value for controlling the rotation speed of the outdoor fan 14 or a value close to this limit.

[0033] If the rotation speed of outdoor fan 14 is higher than the threshold value (NO in step S12), control device 60 reduces the rotation speed of outdoor fan 14 by a predetermined value (step S14) without operating heater 24. This reduces the amount of air sent from outdoor fan 14 to condenser 13, reducing the amount of heat released by the refrigerant in condenser 13, thereby increasing the amount of heat released by the refrigerant in reheat heat exchanger 21.

[0034] That is, in the refrigerant circuit 110 according to this embodiment, the condenser 13 functions as a first condenser, and the reheat heat exchanger 21 functions as a second condenser. Therefore, the total amount of heat released by the refrigerant during condensation is the sum of the amount of heat released by the condenser 13 and the amount of heat released by the reheat heat exchanger 21 (the amount of heat reheated by the reheat heat exchanger 21). Therefore, a decrease in the amount of heat released by the condenser 13 increases the amount of heat released by the reheat heat exchanger 21 (the amount of heat reheated by the reheat heat exchanger 21). Taking advantage of this, the control device 60 reduces the rotation speed of the outdoor fan 14 to reduce the amount of heat released by the condenser 13, thereby increasing the amount of heat released by the reheat heat exchanger 21 (the amount of heat reheated by the reheat heat exchanger 21). This allows the amount of heat reheated to be increased without operating the heater 24.

[0035] On the other hand, if the rotation speed of the outdoor fan 14 is equal to or lower than the threshold value (YES in step S12), the amount of reheating by the reheat heat exchanger 21 is already nearly at its maximum and it is difficult to further increase the amount of reheating by the reheat heat exchanger 21, so the control device 60 activates the heater 24 (step S16). This makes it possible to increase the amount of reheating while limiting the operation of the heater 24 to the minimum necessary.

[0036] While the heater 24 is operating, the control device 60 determines whether the indoor temperature (the value detected by the room temperature sensor 26) is higher than the target value (step S18). If the indoor temperature is lower than the target value while the heater 24 is operating (NO in step S18), the control device 60 returns the process to step S16 and continues operating the heater 24.

[0037] If the indoor temperature becomes higher than the target value while heater 24 is operating (YES in step S18), control device 60 stops heater 24 (step S20). This makes it possible to ensure the necessary amount of reheat while limiting the operating time of heater 24 to the minimum necessary.

[0038] As described above, during cooling reheat dehumidification operation (while the compressor 11 is operating), the control device 60 according to this embodiment improves energy conservation by basically reheating the air using the reheat heat exchanger 21 without activating the heater 24, and activates the heater 24 only when sufficient reheating cannot be achieved using the reheat heat exchanger 21 alone. Specifically, even when the indoor temperature is lower than the target value, if the rotation speed of the outdoor fan 14 is higher than the threshold value, the control device 60 increases the amount of reheating by the reheat heat exchanger 21 by reducing the rotation speed of the outdoor fan 14 without activating the heater 24. On the other hand, if the indoor temperature is lower than the target value and the rotation speed of the outdoor fan 14 is equal to or lower than the threshold value, the control device 60 activates the heater 24 to reheat the air. This ensures the required amount of reheating while minimizing the operation time of the heater 24. As a result, sufficient reheating can be achieved during cooling reheat dehumidification operation without deteriorating energy conservation.

[0039] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0040] REFRIGERATION CYCLE DEVICE, 10 OUTDOOR UNIT, 11 COMPRESSOR, 13 CONDENSER, 14 OUTDOOR FAN, 20 INDOOR UNIT, 21 REHEAT HEAT EXCHANGER, 22 EXPANSION VALVE, 23 EVAPORATOR, 24 HEATER, 25 INDOOR FAN, 26 ROOM TEMPERATURE SENSOR, 30 REFRIGERANT PIPE, 60 CONTROL DEVICE, 62 MEMORY, 110 REFRIGERANT CIRCUITS.

Claims

1. a refrigerant circuit including a compressor and a first condenser arranged outdoors, and a second condenser, an expansion valve, and an evaporator arranged indoors, wherein the refrigerant circulates in this order during cooling operation; a first fan that sends air to the first condenser; a second fan that blows air into the room; a heater disposed in the chamber; a control device; the evaporator, the second condenser, and the heater are arranged side by side so that the air blown by the second fan hits them in this order; the control device operates the heater when the indoor temperature is lower than a target value and the rotation speed of the first fan is lower than a threshold value during the cooling operation; The control device reduces the rotation speed of the first fan without operating the heater when the indoor temperature is lower than the target value and the rotation speed of the first fan is higher than the threshold value during operation of the compressor.

2. The refrigeration cycle apparatus according to claim 1 , wherein the control device stops the heater when it is determined that the temperature inside the room is higher than the target value while the heater is operating.