Heat pump system

Abstract

A heat pump system includes a refrigerant circuit, an inlet temperature sensor measuring a heat exchanger inlet temperature of an aqueous medium in a usage-side heat exchanger of the refrigerant circuit, an outlet temperature sensor measuring a heat exchanger outlet temperature of the aqueous medium in the usage-side heat exchanger, a variable-capacity circulating pump circulating the aqueous medium inside a hot-water circuit of a loop, and a controller. The controller controls refrigerant-side circulation rate in the refrigerant circuit to bring a temperature of the aqueous medium at the outlet of the usage-side heat exchanger to a targeted first target temperature, and operating capacity of the circulating pump to bring a medium temperature differential of the aqueous medium between the outlet and the inlet of the usage-side heat exchanger to a targeted second target temperature differential.

1 . A heat pump system comprising:
 a refrigerant circuit including a compressor, a usage-side heat exchanger arranged to carry out heat exchange between a refrigerant and an aqueous medium, an expansion valve, and a heat-source-side heat exchanger are connected in a loop;   an inlet temperature sensor arranged to measure a heat exchanger inlet temperature of the aqueous medium in the usage-side heat exchanger;   an outlet temperature sensor arranged to measure a heat exchanger outlet temperature of the aqueous medium in the usage-side heat exchanger;   a variable-capacity circulating pump arranged to circulate the aqueous medium inside a hot-water circuit of the loop; and   a controller configured to control
 refrigerant-side circulation rate in the refrigerant circuit to bring a temperature of the aqueous medium at the outlet of the usage-side heat exchanger to a targeted first target temperature, and 
 operating capacity of the circulating pump to bring a medium temperature differential of the aqueous medium between the outlet and the inlet of the usage-side heat exchanger to a targeted second target temperature differential. 
   
     
     
         2 . The heat pump system as recited in  claim 1 , wherein
 the controller is further configured to control operating capacity of the circulating pump by carrying out PI control such that the medium temperature differential at a current point in time is brought into approximation with the second target temperature differential.   
     
     
         3 . The heat pump system as recited in  claim 1 , wherein
 air-warming of a target space is carried out using hot water produced by condensing the refrigerant in the usage-side heat exchanger.   
     
     
         4 . The heat pump system as recited in  claim 3 , wherein the controller is further configured to carry out
 a control in which operating capacity of the circulating pump is decreased in a case where the medium temperature differential is smaller than the second target temperature differential and the temperature of the aqueous medium at the outlet of the usage-side heat exchanger is equal to or greater than the first target temperature, and   a control in which operating capacity of the circulating pump is increased in a case where the medium temperature differential is greater than the second target temperature differential.   
     
     
         5 . The heat pump system as recited in  claim 4 , further comprising:
 an air-temperature-setting element configured to set an air temperature of a target space for which air-warming is to be carried out; and   an air-temperature-detecting element configured to detect the air temperature of the target space,   in a case where an air temperature differential between a detected air temperature detected by the air-temperature-detecting element and a set air temperature set by the air-temperature-setting element is greater than a predetermined third target temperature differential, the controller being further configured to change the second target temperature differential in the direction of a smaller medium temperature differential.   
     
     
         6 . The heat pump system as recited in  claim 2 , wherein air-warming of a target space is carried out using hot water produced by condensing the refrigerant in the usage-side heat exchanger. 
     
     
         7 . The heat pump system as recited in  claim 6 , wherein the controller is further configured to carry out
 a control in which operating capacity of the circulating pump is decreased in a case where the medium temperature differential is smaller than the second target temperature differential and the temperature of the aqueous medium at the outlet of the usage-side heat exchanger is equal to or greater than the first target temperature, and   a control in which operating capacity of the circulating pump is increased in a case where the medium temperature differential is greater than the second target temperature differential.   
     
     
         8 . The heat pump system as recited in  claim 7 , further comprising:
 an air-temperature-setting element configured to set an air temperature of a target space for which air-warming is to be carried out; and   an air-temperature-detecting element configured to detect the air temperature of the target space,   in a case where an air temperature differential between a detected air temperature detected by the air-temperature-detecting element and a set air temperature set by the air-temperature-setting element is greater than a predetermined third target temperature differential, the controller being further configured to change the second target temperature differential in the direction of a smaller medium temperature differential.