Air Conditioner

The present disclosure relates to an air conditioner.

An air conditioner is known that has: an outdoor unit including an outdoor heat exchanger functioning as a condenser; an indoor unit including a first indoor heat exchanger functioning as a cooler and a second indoor heat exchanger functioning as a reheater; and a compressor causing refrigerant to circulate through the outdoor heat exchanger, the first indoor heat exchanger, and the second indoor heat exchanger. In this air conditioner, air cooled and dehumidified by the first indoor heat exchanger is heated by the second indoor heat exchanger, so as to separately adjust the temperature and the humidity of the air blown out from the indoor unit into a space to be air-conditioned. Such an air conditioner is described for example in Japanese Patent Laying-Open No. 2002-89998 (PTL 1).

PTL 1: Japanese Patent Laying-Open No. 2002-89998

However, in the air conditioner described in the above publication, only one four-way valve is used as a refrigerant flow path switching mechanism. Thus, when a mainly cooling operation and a mainly heating operation are respectively performed for two switching states of the four-way valve, the direction of the refrigerant flowing through the indoor unit in the mainly cooling operation and that in the mainly heating operation are opposite to each other. Therefore, the indoor heat exchanger functioning as the cooler and the indoor heat exchanger functioning as the reheater in the mainly cooling operation replace each other in the mainly heating operation. As a result, in either one of the mainly cooling operation and the mainly heating operation, the air heated by the reheater is cooled by the cooler, which makes it impossible to perform sufficient dehumidification.

The present disclosure is made in view of the above problem, and an object thereof is to provide an air conditioner that enables refrigerant to flow in the same direction through a reheater and a cooler in both of a mainly cooling operation and a mainly heating operation.

An air conditioner of the present disclosure includes a refrigerant circuit and a blower. The refrigerant circuit has a compressor, a six-way valve, an outdoor heat exchanger, a reheater, a first expansion valve, and a cooler, and is configured to allow refrigerant to circulate in the refrigerant circuit. The blower is configured to blow air to the reheater and the cooler. The six-way valve is configured to be switchable between a first switching state and a second switching state. The six-way valve is configured to be switched to the first switching state to allow the refrigerant to flow through the compressor, the six-way valve, the outdoor heat exchanger, the six-way valve, the reheater, the first expansion valve, the six-way valve, and the cooler in this order in the refrigerant circuit. The six-way valve is configured to be switched to the second switching state to allow the refrigerant to flow through the compressor, the six-way valve, the reheater, the first expansion valve, the six-way valve, the outdoor heat exchanger, the six-way valve, and the cooler in this order in the refrigerant circuit. The reheater and the cooler are configured to allow the air blown by the blower to pass through the cooler and then pass through the reheater during either of the first switching state and the second switching state.

In the air conditioner of the present disclosure, a refrigerant flow path switching mechanism is configured to be switched to allow the refrigerant to flow through the reheater and the cooler in this order in the refrigerant circuit during either of the first switching state and the second switching state. Thus, in both of the mainly cooling operation and the mainly heating operation, the refrigerant can flow in the same direction through the reheater and the cooler.

Embodiments are described hereinafter with reference to the drawings. In the following, the same or corresponding parts are denoted by the same reference characters, and a description thereof is not herein repeated.

Referring to, a configuration of an air conditioneraccording to Embodiment 1 is described.

is a refrigerant circuit diagram for air conditioneraccording to Embodiment 1. As shown in, air conditionerincludes a refrigerant circuit

RC, an outdoor blower, an air passage, a blower, and a control device CD. Refrigerant circuit RC has a first pipe, a second pipe, a third pipe, a fourth pipe, a fifth pipe, a sixth pipe, a compressor, a six-way valve, an outdoor heat exchanger, a reheater, a cooler, and a first expansion valve. In refrigerant circuit RC, compressor, six-way valve, outdoor heat

exchanger, reheater, cooler, and first expansion valveare connected by first pipe, second pipe, third pipe, fourth pipe, fifth pipe, and sixth pipe.

First pipeconnects compressorand six-way valve. Second pipeconnects six-way valveand outdoor heat exchanger. Third pipeconnects outdoor heat exchangerand six-way valve. Fourth pipeconnects six-way valveand reheater. Fifth pipeconnects reheaterand six-way valvevia first expansion valve. Sixth pipeconnects six-way valveand cooler.

In a first switching state, refrigerant circuit RC is configured to allow refrigerant to flow through compressor, first pipe, six-way valve, second pipe, outdoor heat exchanger, third pipe, six-way valve, fourth pipe, reheater, fifth pipe, first expansion valve, fifth pipe, six-way valve, sixth pipe, and coolerin this order.

In a second switching state, refrigerant circuit RC is configured to allow the refrigerant to flow through compressor, first pipe, six-way valve, fourth pipe, reheater, fifth pipe, first expansion valve, fifth pipe, six-way valve, third pipe, outdoor heat exchanger, second pipe, six-way valve, sixth pipe, and coolerin this order.

Refrigerant circuit RC is configured to cause the refrigerant to circulate. The refrigerant is a refrigerant mixture. The refrigerant mixture is a mixture of two or more types of refrigerants. The refrigerant may be a single refrigerant.

Air conditionerincludes an outdoor unitand an indoor unit. Outdoor unitand indoor unitare connected by second pipeand third pipe. Outdoor unithas outdoor heat exchangerand outdoor blower. Outdoor heat exchangerand outdoor blowerare housed in outdoor unit. Indoor unithas compressor, six-way valve, reheater, cooler, first expansion valve, air passage, blower, and control device CD. Compressor, six-way valve, reheater, cooler, first expansion valve, blower, and control device CD are housed in indoor unit. Indoor unitis provided with air passage.

Compressoris configured to compress the refrigerant. Compressoris configured to compress the sucked refrigerant and discharge the resultant refrigerant. Compressoris configured to have a variable capacity, for example. Compressoris configured to have the capacity that is changed by adjustment of the rotational speed of compressorbased on an instruction from control device CD, for example. Six-way valveis configured to be switchable between the first switching state and the second switching state. Six-way valveis configured to be switched between the first switching state and the second switching state, based on an instruction from control device CD, for example. Six-way valveis configured to be switched to the first switching state to allow the refrigerant to flow through compressor, six-way valve, outdoor heat exchanger, six-way valve, reheater, first expansion valve, six-way valve, and coolerin this order in refrigerant circuit RC. In a mainly cooling operation, six-way valveis in the first switching state.

Six-way valveis configured to be switched to the second switching state to allow the refrigerant to flow through compressor, six-way valve, reheater, first expansion valve, six-way valve, outdoor heat exchanger, six-way valve, and coolerin this order in refrigerant circuit RC. In a mainly heating operation, six-way valveis in the second switching state.

Six connection ports (a first connection port Pto a sixth connection port P) of six-way valveare connected to first pipe, second pipe, third pipe, fourth pipe, fifth pipe, and sixth pipe, respectively. First connection port Pis connected to second pipe. Second connection port Pis connected to sixth pipe. Third connection port Pis connected to fifth pipe. Fourth connection port Pis connected to third pipe. Fifth connection port Pis connected to fourth pipe. Sixth connection port Pis connected to first pipe.

In the first switching state of six-way valve, refrigerant circuit RC is configured to extend through compressor, first pipe, six-way valve, second pipe, outdoor heat exchanger, third pipe, six-way valve, fourth pipe, reheater, first expansion valve, fifth pipe, six-way valve, sixth pipe, and cooler, and return to compressor. In the first switching state of six-way valve, sixth connection port Pis connected to first connection port P, third connection port Pis connected to second connection port P, and fifth connection port Pis connected to fourth connection port P.

In the second switching state of six-way valve, refrigerant circuit RC is configured to extend through compressor, first pipe, six-way valve, fourth pipe, reheater, first expansion valve, fifth pipe, six-way valve, third pipe, outdoor heat exchanger, second pipe, six-way valve, sixth pipe, and cooler, and return to compressor. In the second switching state of six-way valve, second connection port Pis connected to first connection port P. Fourth connection port Pis connected to third connection port P. Sixth connection port Pis connected to fifth connection port P.

Outdoor heat exchangeris configured to exchange heat between the refrigerant flowing inside outdoor heat exchangerand air flowing outside outdoor heat exchanger. Outdoor heat exchangeris configured to function as a condenser that condenses the refrigerant in the mainly cooling operation. Outdoor heat exchangeris configured to function as an evaporator that evaporates the refrigerant in the mainly heating operation. Outdoor heat exchangeris, for example, a fin-and-tube heat exchanger having a plurality of fins and a heat transfer tube extending through the plurality of fins.

Control device CD is configured to control each device and the like of air conditionerby performing arithmetic operation/issuing an instruction, for example. Control device CD is electrically connected to compressor, six-way valve, first expansion valve, blower, and the like, and configured to control their operations.

Reheateris configured to exchange heat between the refrigerant flowing inside reheaterand air flowing outside reheater. Reheateris configured to function as a condenser that condenses the refrigerant in the mainly cooling operation and the mainly heating operation. Reheateris, for example, a fin-and-tube heat exchanger having a plurality of fins and a heat transfer tube extending through the plurality of fins.

Cooleris configured to exchange heat between the refrigerant flowing inside coolerand air flowing outside cooler. Cooleris configured to function as an evaporator that evaporates the refrigerant in the mainly cooling operation and the mainly heating operation. Cooleris, for example, a fin-and-tube heat exchanger having a plurality of fins and a heat transfer tube extending through the plurality of fins.

First expansion valveis configured to expand and thereby reduce the pressure of the refrigerant condensed by the condenser. In the mainly cooling operation and the mainly heating operation, first expansion valveis configured to reduce the pressure of the refrigerant condensed by reheater. First expansion valveis, for example, an electromagnetic expansion valve. First expansion valveis configured to cause the amount of reduction of the pressure to be changed by adjustment of the degree of opening of first expansion valvebased on an instruction from control device CD, for example.

Air passageis provided in a housing of indoor unit. Reheaterand coolerare disposed in air passage. Bloweris configured to blow air to reheaterand cooler. Reheaterand coolerare disposed side by side in the direction of flow of the air blown by blower. Reheateris disposed on the leeward side of cooleralong the flow of the air blown by blower. In air passage, cooleris disposed upstream of reheater.

Reheaterand coolershare air passageand blower. Reheaterand coolerare configured to allow the air blown by blowerto pass through coolerand then pass through reheaterduring either of the first switching state and the second switching state. During operation of blower, reheaterand coolerare configured to allow the air to pass through coolerand then pass through reheater, regardless of whether six-way valveis in the first switching state or the second switching state.

Reheaterand coolermay be configured to allow the refrigerant to flow in the direction opposite to the direction in which the air flows. Both of reheaterand coolerhave a heat transfer tube flow path configuration in which the air and the refrigerant flow in respective directions opposite to each other. Each of reheaterand coolerhas a heat transfer tube on the windward side and a heat transfer tube on the leeward side. The heat transfer tube on the windward side is connected to the heat transfer tube on the leeward side. In the mainly cooling operation and the mainly heating operation, the refrigerant flows from the heat transfer tube on the leeward side to the heat transfer tube on the windward side. In both of the mainly cooling operation and the mainly heating operation, the direction in which the refrigerant flows inside the heat transfer tubes of reheaterand cooleris opposite to the direction in which the air flows outside the heat transfer tubes.

Next, operations of air conditioneraccording to Embodiment 1 are described.

First, referring to, the mainly cooling operation of air conditioneraccording to Embodiment 1 is described. The mainly cooling operation is an operation in which the amount by which the air is cooled by cooleris larger than the amount by which the air is heated by reheaterand outdoor heat exchangerfunctions as a condenser, so that surplus heat is dissipated into outside air by this air conditioner acting as a heat pump. In the mainly cooling operation, the air after passing through reheaterhas a lower temperature and a smaller moisture content than those of the air before passing through cooler.

For the mainly cooling operation, six-way valveis switched to the first switching state as indicated by the solid line in. A vapor refrigerant compressed by compressorto have a high temperature and a high pressure flows into first pipe, passes through six-way valve, and flows into outdoor heat exchangerthrough second pipe. Outdoor heat exchangerfunctions as a condenser. The high-temperature and high-pressure vapor refrigerant dissipates heat into outdoor air introduced into outdoor heat exchangerby outdoor blower. Thus, the high-temperature and high-pressure vapor refrigerant is condensed into a high-temperature and high-pressure gas-liquid two-phase refrigerant.

The high-temperature and high-pressure gas-liquid two-phase refrigerant flows into third pipe, passes through six-way valve, and flows into reheaterthrough fourth pipe. Reheaterfunctions as a condenser. The high-temperature and high-pressure gas-liquid two-phase refrigerant dissipates heat into the air introduced into reheaterby blower. Thus, the high-temperature and high-pressure gas-liquid two-phase refrigerant is condensed into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows into first expansion valve.

The high-pressure liquid refrigerant is expanded and reduced in pressure by first expansion valveinto a low-temperature and low-pressure gas-liquid two-phase refrigerant. The low-temperature and low-pressure gas-liquid two-phase refrigerant flows into fifth pipe, passes through six-way valve, and flows into coolerthrough sixth pipe. Coolerfunctions as an evaporator. By absorbing heat from the air introduced into coolerby blower, the low-temperature and low-pressure gas-liquid two-phase refrigerant evaporates into a low-pressure vapor refrigerant. The low-pressure vapor refrigerant is thereafter sucked into compressor. In the mainly cooling operation, the refrigerant thereafter circulates in refrigerant circuit RC through the same process.

Reheaterand coolershare air passageand blower. The air introduced into air passageby blowerfirst passes through coolerto be cooled and dehumidified. Accordingly, the temperature of the air lowers and the moisture content of the air decreases. The air having passed through cooleris guided by air passageto pass through reheaterso that the air is heated. Thus, the temperature of the air rises. Generally, reheaterdoes not humidify the air, and therefore, the moisture content of the air remains the same before and after passing through reheater. The air having passed through reheateris guided by air passageto be blown out into a space to be air-conditioned.

The air is cooled and dehumidified by cooler, and thereafter heated by reheateras required, and therefore, the amount by which the air is dehumidified and the temperature of the air can be adjusted separately. Accordingly, the air having a temperature and a humidity that are set by a user can be supplied into the space to be air-conditioned.

Next, referring to, the mainly heating operation of air conditioneraccording to Embodiment 1 is described. The mainly heating operation is an operation in which the amount by which the air is heated by reheateris larger than the amount by which the air is cooled by coolerand outdoor heat exchangerfunctions as an evaporator, so that surplus cold is dissipated into the outside air by this air conditioner acting as a heat pump. In the mainly heating operation, the air after passing through reheaterhas a higher temperature and a smaller moisture content than those of the air before passing through cooler.

For the mainly heating operation, six-way valveis switched to the second switching state as indicated by the solid line in. A vapor refrigerant compressed by compressorto have a high temperature and a high pressure flows into first pipe, passes through six-way valve, and flows into reheaterthrough fourth pipe. Reheaterfunctions as a condenser. The high-temperature and high-pressure vapor refrigerant dissipates heat into the air introduced into reheaterby blower. Thus, the high-temperature and high-pressure vapor refrigerant is condensed into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows into first expansion valve.

The high-pressure liquid refrigerant is expanded and reduced in pressure by first expansion valveinto a low-temperature and low-pressure gas-liquid two-phase refrigerant. The low-temperature and low-pressure gas-liquid two-phase refrigerant flows into fifth pipe, passes through six-way valve, and flows into outdoor heat exchangerthrough third pipe. Outdoor heat exchangerfunctions as an evaporator. By absorbing heat from the outdoor air introduced into outdoor heat exchangerby outdoor blower, a part of the low-temperature and low-pressure gas-liquid two-phase refrigerant evaporates. The low-temperature and low-pressure gas-liquid two-phase refrigerant thereafter flows into six-way valvethrough second pipe, and flows into coolerthrough sixth pipe.

Coolerfunctions as an evaporator. By absorbing heat from the air introduced into coolerby blower, the low-temperature and low-pressure gas-liquid two-phase refrigerant evaporates into a low-pressure vapor refrigerant. The low-pressure vapor refrigerant is sucked into compressor. In the mainly heating operation, the refrigerant thereafter circulates in refrigerant circuit RC through the same process.

Like the mainly cooling operation, the air introduced into air passageby bloweris cooled and dehumidified by cooler, thereafter heated by reheater, and blown out into the space to be air-conditioned. Therefore, the amount by which the air is dehumidified and the temperature of the air can be adjusted separately. Accordingly, the air having a temperature and a humidity that are set by the user can be supplied into the space to be air-conditioned.

Next, functions and effects of air conditioneraccording to Embodiment 1 are described.

In the air conditioner according to Embodiment 1, six-way valveis configured to be switched to allow the refrigerant to flow through reheaterand coolerin this order in refrigerant circuit RC during either of the first switching state and the second switching state. Six-way valveis switched to the first switching state for the mainly cooling operation, and switched to the second switching state for the mainly heating operation. Thus, in both of the mainly cooling operation and the mainly heating operation, the refrigerant can flow in the same direction through reheaterand cooler. Therefore, in either of the mainly cooling operation and the mainly heating operation, the air cooled and dehumidified by coolercan be heated by reheater. Accordingly, the air having a temperature and a humidity that are set by the user can be supplied into the space to be air-conditioned.

Further, reheaterand coolerare configured to allow the air blown by blowerto pass through coolerand then pass through reheaterduring either of the first switching state and the second switching state. Thus, in both of the mainly cooling operation and the mainly heating operation, the air can be reheated after being cooled and dehumidified. Therefore, in both of the mainly cooling operation and the mainly heating operation, sufficient dehumidification can be performed.

In particular, sufficient dehumidification can be performed in the mainly heating operation, and therefore, the mainly heating operation can be utilized for drying and dehumidifying the space to be air-conditioned. Accordingly, air conditioneraccording to Embodiment 1 can also be used for drying foods and raw materials.

Further, in the mainly cooling operation, the refrigerant having passed through outdoor heat exchangerflows through reheater. In the mainly heating operation, the refrigerant having passed through outdoor heat exchangerflows through cooler. Therefore, the amount of heat exchange of the refrigerant is easily adjusted by adjusting the effective heat transfer area of outdoor heat exchanger. Further, the amount of heat exchange of the refrigerant is easily adjusted by adjusting the rotational speed of outdoor blower. Since the refrigerant having the amount of heat (internal energy) adjusted in outdoor heat exchangercan be supplied to reheateror cooler, the amount of heat exchange in reheateror coolercan be adjusted continuously. Accordingly, it is possible to achieve operation of air conditionerin which the blow-out temperature of indoor unitis stable.

In the air conditioner according to Embodiment 1, in the first switching state, refrigerant circuit RC is configured to allow the refrigerant to flow through compressor, first pipe, six-way valve, second pipe, outdoor heat exchanger, third pipe, six-way valve, fourth pipe, reheater, fifth pipe, first expansion valve, fifth pipe, six-way valve, sixth pipe, and coolerin this order. In the second switching state, refrigerant circuit RC is configured to allow the refrigerant to flow through compressor, first pipe, six-way valve, fourth pipe, reheater, fifth pipe, first expansion valve, fifth pipe, six-way valve, third pipe, outdoor heat exchanger, second pipe, six-way valve, sixth pipe, and coolerin this order. Accordingly, the refrigerant can flow through reheaterand coolerin this order in refrigerant circuit RC during either of the first switching state and the second switching state.

In air conditioneraccording to Embodiment 1, the refrigerant is a refrigerant mixture. The refrigerant mixture that is a mixture of two or more types of refrigerants is generally non-azeotropic, and therefore, the temperature is not constant in gas-liquid phase transition. Accordingly, when phase transition of the refrigerant mixture occurs, a temperature gradient is generated in a heat exchanger. This requires optimum design of the heat exchanger. In air conditioneraccording to Embodiment 1, reheaterand coolercan be designed dedicatedly to function as a reheater and a cooler respectively, so that high-performance air conditionercan be achieved even when the refrigerant mixture is used.

In air conditioneraccording to Embodiment 1, reheaterand coolerare configured to allow the refrigerant to flow in the direction opposite to the direction in which the air flows. Accordingly, the temperature gradient of the refrigerant mixture in the heat exchanger can be utilized to reduce the difference in heat exchange temperature between the air and the refrigerant. Therefore, a high-performance operation of air conditionercan be achieved.