Heat pump apparatus and method of controlling heat pump apparatus

Abstract

In a heat pump apparatus of an indirect type including a primary circuit on a heat source side and a secondary circuit on a load side, a refrigerant in the primary circuit is prevented from leaking through the secondary circuit. An air-conditioning apparatus includes a leakage detecting device that detects leakage of the refrigerant circulated through a refrigerant circuit, serving as the primary circuit, from an intermediate heat exchanger into a water circuit, serving as the secondary circuit, and a controller that closes valves arranged on both sides of the intermediate heat exchanger in the water circuit to prevent water containing the refrigerant from flowing beyond the valves when the leakage detecting device detects the leakage.

1 . A heat pump apparatus comprising:
 a first refrigerant circuit through which a refrigerant is circulated, the first refrigerant circuit including a first compressor, a first heat source heat exchanger, a first expansion mechanism, and a first intermediate heat exchanger sequentially connected in loop by pipes;   a fluid circuit through which a fluid is circulated, the fluid circuit including the first intermediate heat exchanger, a first valve, a load heat exchanger, and a second valve sequentially connected in loop by pipes;   a leakage detecting device that detects leakage of the refrigerant, circulated through the first refrigerant circuit, from the first intermediate heat exchanger into the fluid circuit; and   a controller that closes the first valve and the second valve included in the fluid circuit when the leakage detecting device detects the leakage of the refrigerant, wherein the leakage detecting device detects the leakage of refrigerant by detecting pressure within the fluid circuit.   
     
     
         2 . The heat pump apparatus of  claim 1 , further comprising:
 a first casing that accommodates the first compressor, the first heat source heat exchanger, the first expansion mechanism, the first intermediate heat exchanger, the first valve, and the second valve; and   a second casing that accommodates the load heat exchanger.   
     
     
         3 . The heat pump apparatus of  claim 1 ,
 wherein the refrigerant circulated through the first refrigerant circuit is flammable, and   wherein the fluid circulated through the fluid circuit is nonflammable.   
     
     
         4 . The heat pump apparatus of  claim 1 , wherein when the leakage detecting device detects the leakage of the refrigerant, the controller stops the first compressor. 
     
     
         5 . The heat pump apparatus of  claim 1 ,
 wherein the fluid circuit further includes a pump that circulates the fluid in such a manner that the fluid flows through the first intermediate heat exchanger, the first valve, the load heat exchanger, and the second valve in that order and the pump is connected between the second valve and the first valve in a direction in which the fluid is circulated,   wherein the first valve has an opening degree that is controlled in such a manner that the fluid circulated through the fluid circuit flows at a predetermined flow rate, and   wherein the leakage detecting device detects the leakage of the refrigerant by detecting a pressure at a point between the pump and the first valve in the fluid circuit.   
     
     
         6 . The heat pump apparatus of  claim 1 , wherein the first intermediate heat exchanger is placed in such a manner that a connection port for the pipe connected to the first compressor is disposed in upper part of the first intermediate heat exchanger and a connection port for the pipe connected to the first expansion mechanism is disposed in lower part thereof. 
     
     
         7 . The heat pump apparatus of  claim 6 ,
 wherein the first intermediate heat exchanger is a plate heat exchanger including a plurality of plates stacked on one another and a plate at one end of the stacked plates has the connection port for the pipe connected to the first compressor and the connection port for the pipe connected to the first expansion mechanism, and   wherein the first intermediate heat exchanger is inclined in such a manner that the connection port for the pipe connected to the first compressor faces obliquely upward.   
     
     
         8 . The heat pump apparatus of  claim 7 ,
 wherein the first intermediate heat exchanger is the plate heat exchanger in which the connection port for the pipe connected to the first compressor is disposed in a plate at an end of the plurality of plates another than one end at which the plate having the connection port for the pipe connected to the first expansion mechanism is disposed, and   wherein the first intermediate heat exchanger is inclined in such a manner that the connection port for the pipe connected to the first compressor faces obliquely upward and the connection port for the pipe connected to the first expansion mechanism faces obliquely downward.   
     
     
         9 . The heat pump apparatus of  claim 1 , further comprising:
 a second refrigerant circuit through which the refrigerant is circulated, the second refrigerant circuit including a second compressor, a second heat source heat exchanger, a second expansion mechanism, and a second intermediate heat exchanger sequentially connected in loop by pipes,   wherein the second intermediate heat exchanger is connected between the first intermediate heat exchanger and the first valve in the fluid circuit,   wherein the leakage detecting device detects leakage of the refrigerant circulated through the first refrigerant circuit and the refrigerant circulated through the second refrigerant circuit from the first intermediate heat exchanger into the fluid circuit.   
     
     
         10 . The heat pump apparatus of  claim 9 ,
 wherein the refrigerant circulated through the first and second refrigerant circuits is R32 or a refrigerant mixture containing R32,   wherein each of the first and second intermediate heat exchangers is a plate heat exchanger including a plurality of plates stacked on one another, and   wherein each of the first and second intermediate heat exchangers is vertically placed in such a manner that the connection ports for the pipes are positioned on an upper side and a lower side in a vertical direction, and the first and second intermediate heat exchangers are arranged side by side horizontally.   
     
     
         11 . The heat pump apparatus of  claim 9 , further comprising:
 a fan that generates airflow to deliver air which has exchanged heat with the refrigerant in one of the first and second heat source heat exchangers to the other one of the first and second heat source heat exchangers and allow the delivered air to exchange heat with the refrigerant in the other heat source heat exchanger.   
     
     
         12 . The heat pump apparatus of  claim 2 ,
 wherein the heat pump apparatus is an air-conditioning apparatus that conditions air in a room,   wherein the first casing is an outdoor unit installed outside the room, and   wherein the second casing is an indoor unit installed inside the room.   
     
     
         13 . A method of controlling a heat pump apparatus including a first refrigerant circuit through which a refrigerant is circulated and that includes a first compressor, a first heat source heat exchanger, a first expansion mechanism, and a first intermediate heat exchanger sequentially connected in loop by pipes and a fluid circuit through which a fluid is circulated and that includes the first intermediate heat exchanger, a first valve, a load heat exchanger, and a second valve sequentially connected in loop by pipes, the method comprising:
 a leakage detecting step of detecting, by a leakage detecting device, leakage of the refrigerant circulated through the first refrigerant circuit from the first intermediate heat exchanger into the fluid circuit based on pressure within the fluid circuit; and   a valve control step of closing, by a controller, the first valve and the second valve included in the fluid circuit when the leakage detecting device detects the leakage of the refrigerant.