Heat pump and method for operating heat pump

Abstract

A heat pump may include a compressor configured to compress a refrigerant; an accumulator configured to supply the refrigerant to the compressor; a receiver connected to the accumulator; a fluid-refrigerant heat exchanger configured to exchange heat between a fluid, such as water, and the refrigerant; an outdoor heat exchanger configured to exchange heat between outdoor air and the refrigerant; a 4-way valve configured to guide the refrigerant, discharged from the compressor, to flow into the fluid-refrigerant heat exchanger or the outdoor heat exchanger; at least one expansion valve disposed between the fluid-refrigerant heat exchanger and the outdoor heat exchanger; a first valve disposed between the fluid-refrigerant heat exchanger and the receiver; a second valve disposed between the compressor and the receiver; and a third valve disposed between the receiver and the accumulator.

What is claimed is: 
     
         1 . A heat pump, comprising:
 a compressor configured to compress a refrigerant;   an accumulator configured to supply the refrigerant to the compressor;   a receiver connected to the accumulator;   a fluid-refrigerant heat exchanger configured to exchange heat between a fluid and the refrigerant;   an outdoor heat exchanger configured to exchange heat between outdoor air and the refrigerant;   a 4-way valve configured to guide the refrigerant, discharged from the compressor, to flow into the fluid-refrigerant heat exchanger or the outdoor heat exchanger;   at least one expansion valve disposed between the fluid-refrigerant heat exchanger and the outdoor heat exchanger;   a first valve disposed between the fluid-refrigerant heat exchanger and the receiver;   a second valve disposed between the compressor and the receiver; and   a third valve disposed between the receiver and the accumulator.   
     
     
         2 . The heat pump of  claim 1 , wherein during a heating operation, in response to the first valve and the third valve being opened, a portion of a refrigerant having passed through the fluid-refrigerant heat exchanger flows to the receiver, and in response to the second valve and the third valve being opened, a refrigerant stored in the receiver flows to the accumulator. 
     
     
         3 . The heat pump of  claim 2 , further comprising a controller configured to control opening and closing of the first to third valves based on a refrigerant amount during operation. 
     
     
         4 . The heat pump of  claim 3 , wherein:
 during the heating operation, in response to a subcooling degree being higher than an upper-limit reference value, the controller is configured to control the first valve and the third valve to be opened; and   during the heating operation, in response to the subcooling degree being lower than a lower-limit reference value, the controller is configured to control the second valve and the third valve to be opened.   
     
     
         5 . The heat pump of  claim 3 , wherein during the heating operation, the controller is configured to control the 4-way valve to guide the refrigerant, discharged from the compressor, to flow into the fluid-refrigerant heat exchanger. 
     
     
         6 . The heat pump of  claim 1 , further comprising a capillary tube disposed between the third valve and the accumulator. 
     
     
         7 . The heat pump of  claim 1 , further comprising a fourth valve disposed between the outdoor heat exchanger and the receiver. 
     
     
         8 . The heat pump of  claim 7 , wherein during a cooling operation, in response to the fourth valve and the third valve being opened, a portion of a refrigerant having passed through the outdoor heat exchanger flows to the receiver, and in response to the second valve and the third valve being opened, a refrigerant stored in the receiver flows to the accumulator. 
     
     
         9 . The heat pump of  claim 8 , further comprising a controller configured to control opening and closing of the first to fourth valves based on a refrigerant amount during operation. 
     
     
         10 . The heat pump of  claim 9 , wherein:
 during a heating operation, in response to a subcooling degree being higher than an upper-limit reference value, the controller is configured to control the first valve and the third valve to be opened and the second valve and the fourth valve to be closed, and   during the heating operation, in response to the subcooling degree being lower than a lower-limit reference value, the controller is configured to control the second valve and the third valve to be opened and the first valve and the fourth valve to be closed.   
     
     
         11 . The heat pump of  claim 9 , wherein:
 during the cooling operation, in response to a subcooling degree being higher than an upper-limit reference value, the controller is configured to control the fourth valve and the third valve to be opened and the first valve and the second valve to be closed; and   during the cooling operation, in response to the subcooling degree being lower than a lower-limit reference value, the controller is configured to control the second valve and the third valve to be opened and the first valve and the fourth valve to be closed.   
     
     
         12 . The heat pump of  claim 9 , wherein:
 during the cooling operation, the controller is configured to control the 4-way valve to guide the refrigerant, discharged from the compressor, to flow into the outdoor heat exchanger; and   during the heating operation, the controller is configured to control the 4-way valve to guide the refrigerant, discharged from the compressor, to flow into the fluid-refrigerant heat exchanger.   
     
     
         13 . The heat pump of  claim 9 , wherein the controller is configured to control the first to fourth valves to be closed during a set initial stabilization period. 
     
     
         14 . The heat pump of  claim 1 , further comprising:
 a first pipe that connects the fluid-refrigerant heat exchanger and the expansion valve; and   a second pipe that is branched from the first pipe to be connected to the receiver, wherein the first valve is located in the second pipe.   
     
     
         15 . The heat pump of  claim 1 , wherein the at least one expansion valve comprises:
 a first expansion valve disposed between the fluid-refrigerant heat exchanger and the first valve; and   a second expansion valve disposed between the outdoor heat exchanger and the second valve.   
     
     
         16 . The heat pump of  claim 15 , wherein:
 during a heating operation, the first expansion valve is opened to a maximum opening degree, and the second expansion valve expands the refrigerant; and   during a cooling operation, the first expansion valve expands the refrigerant, and the second expansion valve is opened to a maximum opening degree.   
     
     
         17 . The heat pump of  claim 1 , wherein the receiver and the accumulator are integrally formed, wherein an inner space of receiver and an inner space of the accumulator communicate via a pipe, and wherein the third valve is disposed on the pipe. 
     
     
         18 . A heat pump, comprising:
 a compressor configured to compress a refrigerant;   an accumulator configured to supply the refrigerant to the compressor;   a receiver connected to the accumulator;   a fluid-refrigerant heat exchanger configured to exchange heat between a fluid and the refrigerant;   an outdoor heat exchanger configured to exchange heat between outdoor air and the refrigerant;   a 4-way valve configured to guide the refrigerant, discharged from the compressor, to flow into the fluid-refrigerant heat exchanger or the outdoor heat exchanger;   a first expansion valve and a second expansion valve disposed between the fluid-refrigerant heat exchanger and the outdoor heat exchanger;   a first valve disposed between the fluid-refrigerant heat exchanger and the receiver;   a second valve disposed between the compressor and the receiver; and   a third valve disposed between the receiver and the accumulator, wherein the first valve is disposed on a first pipe that is connected to a second pipe at a location between the first expansion valve and the second expansion valve.   
     
     
         19 . A heat pump, comprising:
 a compressor configured to compress a refrigerant;   an accumulator configured to supply the refrigerant to the compressor;   a receiver connected to the accumulator;   at least one two-way indoor unit that provides both cooling and heating, each at least one two-way indoor unit including an indoor heat exchanger;   an outdoor heat exchanger configured to exchange heat between outdoor air and the refrigerant;   a 4-way valve configured to guide the refrigerant, discharged from the compressor, to flow into the at least one two-way indoor unit or the outdoor heat exchanger;   at least one expansion valve disposed between the at least one two-way indoor unit and the outdoor heat exchanger;   a first valve disposed between the at least one two-way indoor unit and the receiver;   a second valve disposed between the compressor and the receiver; and   a third valve disposed between the receiver and the accumulator.   
     
     
         20 . The heat pump of  claim 19 , wherein:
 during a heating operation, the at least one expansion valve expands the refrigerant, and an indoor unit expansion valve disposed on an indoor unit side is opened to a maximum opening degree; and   during a cooling operation, the at least one expansion valve is opened to a maximum opening degree, and the indoor unit expansion valve on the indoor unit side expands the refrigerant.