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.

Description

TECHNICAL FIELD[0001]The present invention relates to a heat pump system for circulating an aqueous medium.BACKGROUND ART[0002]Hydronic heating devices of a heat pump type like that disclosed in Patent Citation 1 (Japanese Laid-open Patent Application 2003-314838) are known in the prior art. This hydronic heating device is provided with an outdoor unit of a heat pump type; a water / refrigerant heat exchanger for bringing about heat exchange between a refrigerant and water; an air-warming floor panel or air-warming heat exchanger connected to the water / refrigerant heat exchanger by a hot-water tube; and a circulating pump for circulating hot water through the hot-water tube.SUMMARY OF THE INVENTION[0003]However, a problem with such conventional hydronic heating devices of a heat pump type is that in a case of a decrease in load on the air-warming floor panel or air-warming heat exchanger which warms the room, the outlet / inlet temperature differential of the water / refrigerant heat exch...

AI Technical Summary

Benefits of technology

[0004]An object of the present invention is to provide a heat pump system that can adapt to changes in operating load and provide comfortable air conditioning.

[0006]Specifically, in this heat pump system, as a first control, the refrigerant-side circulation rate in the refrigerant circuit is controlled to bring the temperature of the aqueous medium at the outlet of the usage-side heat exchanger to a targeted first target temperature, controlling the water temperature at the outlet side of the usage-side heat exchanger to maintain it at a predetermined temperature. Also, as a second control, the operating capacity of the circulating pump is controlled to bring the 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, controlling the outlet / inlet temperature differential to a predetermined temperature differential. In so doing, excessive temperature fluctuations of the aqueous medium can be reliably prevented, even in cases of decreased load on the usage-side heat exchanger.

[0008]According to the aspect described above, because temperature control can take place so as to bring the medium temperature differential at a current point in time into approximation with the second target temperature differential and eliminate deviation therebetween through PI control, excessive temperature rise of the aqueous medium can be reliably prevented.

[0010]According to the aspect described above, by using hot water produced by condensing the refrigerant in the usage-side heat exchanger for air-warming of a target space, an excessive rise in the temperature of the aqueous medium can be reliably prevented, even in cases of decreased load on the usage-side heat exchanger in association with higher room temperature in the target space.

[0012]According to the aspect described above, control is carried out to decrease the operating capacity of the pump in a case where the medium temperature differential is smaller than the second target temperature differential, and moreover 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, while control is carried out to increase the operating capacity of the pump in a case where the medium temperature differential is greater than the second target temperature differential; whereby 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, it can be decided that the load on the usage-side heat exchanger has decreased, and excessive temperature rise of the aqueous medium can be reliably prevented.

[0014]According to the aspect described above, because in a case where an air temperature differential between a detected air temperature detected by the air-temperature-detecting means and a set air temperature set by the air-temperature-setting means is greater than a predetermined third target temperature differential, the second target temperature differential is modified in the direction of a smaller medium temperature differential, flow rate control of the aqueous medium can take place in coordination with room temperature, and excessive temperature rise of the aqueous medium can be more reliably prevented, even in cases of decreased load on the usage-side heat exchanger.

Problems solved by technology

However, a problem with such conventional hydronic heating devices of a heat pump type is that in a case of a decrease in load on the air-warming floor panel or air-warming heat exchanger which warms the room, the outlet / inlet temperature differential of the water / refrigerant heat exchanger becomes smaller, resulting in an excessive temperature rise of the water being supplied to the air-warming floor panel or air-warming heat exchanger, possibly leading to auto-shutoff or poor energy efficiency of the unit, as well as to diminished comfort.

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