KR20110022182A - Heat pump system having heat exchanger for increasing the temperature of water entering heat pump from heat source - Google Patents

Abstract

PURPOSE: A heat pump system with a heat exchanger for increasing the temperature of circulating water is provided to improve heating performance by the increment of the temperature of circulating water and the evaporation temperature in an evaporator. CONSTITUTION: A heat pump system(10) comprises an underground heat exchanger(210), a solenoid valve(310), a pump(110), a load heat exchanger(220), a heat exchanger(240) for increasing the temperature of circulating water, a heat source heat exchanger(250), an internal heat exchanger(230), an expansion device(400), a first four-way valve(320), and a second four-way valve(330). The underground heat exchanger exchanges the heat between circulating water and ground heat. The solenoid valve changes the flow direction of the circulating water. The pump transfers the circulating water to the solenoid valve. The load heat exchanger exchanges the heat between refrigerant and water circulating an indoor air conditioner(500). The heat exchanger for increasing the temperature of circulating water exchanges heat between the refrigerant and the circulating water. The heat-exchanger in a heat source exchanges the refrigerant and the circulating water. The internal heat exchanger exchanges heat between high temperature refrigerant and low-temperature refrigerant. The expansion device expands the refrigerant.

Description

Heat pump system having heat exchanger for increasing the temperature of water entering heat pump from heat source}

The present invention relates to a heat pump system capable of both heating and cooling, and more particularly, in a heat pump system using carbon dioxide as a working refrigerant and using geothermal heat as a heat source, before sending the circulating water from the underground heat exchanger outlet to the heat source side heat exchanger. The present invention relates to a heat pump system which improves heating performance by increasing the temperature of circulating water and the evaporation temperature of an evaporator by performing heat exchange in a heat exchanger for increasing the temperature of a refrigerant at a load side heat exchanger and a circulating water temperature.

Freon-based refrigerants, which have been widely used in various fields including refrigeration and air conditioning, are known to leak ozone layer by chlorine contained in these substances. The country has made international efforts to develop substances to replace CFC refrigerants and to protect the ozone layer. Finally, international environmental regulations such as the use of ozone-depleting substances and the suppression of carbon dioxide emissions were realized in accordance with the Montreal Protocol (1987) and the Kyoto Protocol (1997). On February 16, 2005, the Kyoto Protocol came into effect. Therefore, as a countermeasure, it is necessary to develop a refrigeration and air conditioning industrial technology using an alternative refrigerant of the freon refrigerant.

Meanwhile, countries around the world are striving to secure stable energy sources that can meet the requirements of reducing carbon dioxide emissions, preparing for high oil prices, and sustainable energy. In order to achieve the goal of supplying renewable energy, which accounts for 2.2% of total energy use as of 2006, up to 5% in 2011, the Korean government has also incurred 5% of the total construction cost for buildings of 3,000 m2 or more that are newly constructed by public institutions. Since June 2004, the Act on the Promotion of New Energy and Renewable Energy Development and Use, which requires mandatory investment in renewable energy facilities, has been enacted. In addition, from March 15, 2009, it will be expanded to buildings that are being renovated.

Among the systems using renewable energy, geothermal source system has the advantages of low initial investment cost and small scale use compared to other alternative energy such as solar and wind power, and the life of underground heat exchange system is 50 years. In addition, because it uses less energy than the existing air-conditioning system, it uses higher temperature than air heat source in winter, low temperature in summer and little temperature change during the year as heat sink and heat source. This is a high efficiency system with little change in performance of heating and cooling.

Ground source heat pump (Ground Source Heat Pump) is a system using a geothermal heat of a constant temperature (15 ℃) within 10 ~ 300m underground, the fields of use are air-conditioning, hot water production, drying, greenhouses. In case of using geothermal source, high cost is required for initial installation due to underground heat exchanger installation, but efforts are being made to reduce operation, maintenance and repair cost through effective design. According to the 2007 New Renewable Energy Statistics of the Korea Energy Management Corporation, since the first geothermal system was introduced in Korea in 2000, it has grown more than 200% every year. As of 2006, the heat pump system using geothermal sources has reached about 15,100 RT. Recently, a high efficiency geothermal heat hybrid hybrid heating and cooling system using H410 series refrigerant R410a and inverter linear control technology has been developed.

On the other hand, HFC-based pure refrigerants having zero ozone depletion index, or mixed refrigerants combining them as environmentally-friendly alternative refrigerants to replace the freon-based refrigerants are considered as alternative refrigerants, but they also do not solve the global warming problem. I can't. Carbon dioxide, on the other hand, has many advantages as a refrigerant, i.e. its effect on ozone depletion and global warming is very small, non-flammable, compatible with refrigeration oils and equipment materials, highly stable and non-toxic. Due to their characteristics, they are attracting attention again as candidates for replacing freon refrigerants. In addition, the carbon dioxide refrigerant has an advantage of obtaining hot water of high temperature (60 to 90 ° C.) due to thermodynamic characteristics. Therefore, a geothermal heat pump using carbon dioxide is a very promising system in terms of environment and use of a stable energy source.

Since carbon dioxide has a critical pressure of 7.38 MPa and a critical temperature of 31.1 ° C., the heat dissipation process at a high temperature heat source occurs above a critical point (supercritical high pressure) in a cooling / heating system using carbon dioxide, and the evaporation process at a low temperature heat source is a critical point. This happens below. In other words, in the radiator (load side heat exchanger) in which the heat release process occurs, unlike the condenser of the existing system, there is no phase change process, and the heat release occurs as the temperature of the high pressure single phase refrigerant is continuously reduced while passing through the radiator. Such a radiator is operated as a heat exchanger for producing hot water (or air) required for heating during a heating operation and for producing hot water for hot water operation. However, when looking at the temperature of the used water flowing into the radiator from the load side, since the temperature during the heating operation (40 ℃) is much higher than the temperature during the hot water operation (9 ~ 22 ℃), the heat energy available during the heating operation is less The disadvantage is that the thermal performance is not good.

Therefore, in the heat pump system using carbon dioxide as a working refrigerant and using geothermal heat as a heat source, the heat exchanger exchanges heat with the refrigerant at the load side heat exchanger outlet before circulating water from the underground heat exchanger outlet to the evaporator (heat source side heat exchanger). We propose a new heat pump system that can improve heating performance by increasing water temperature and evaporation temperature in the evaporator.

The heat pump system according to the present invention comprises: an underground heat exchanger buried underground so that circulating water exchanges heat with geothermal heat; A direction switching valve connected to an inlet and an outlet of the underground heat exchanger, respectively, to change a direction in which the circulating water flows; A pump for pumping circulating water to the directional valve; A compressor for compressing and discharging the refrigerant; A load side heat exchanger configured to perform heat exchange between the refrigerant and water circulating in the indoor air conditioner; A heat exchanger for increasing a circulating water temperature in which heat exchange between the refrigerant and the circulating water is performed; A heat source side heat exchanger configured to perform heat exchange between the refrigerant and the circulating water; An internal heat exchanger configured to exchange heat between the high temperature refrigerant and the low temperature refrigerant; An expansion device for expanding the refrigerant; A first four-way valve connected to the compressor, the load side heat exchanger, the heat source side heat exchanger, and the internal heat exchanger, respectively; And a second four-way valve connected to each of the heat exchanger for increasing the circulating water temperature, the internal heat exchanger, the heat source side heat exchanger, and the expansion device.

When operated in a heating cycle, the circulating water is circulated from the underground heat exchanger to the underground heat exchanger via the pump, the divert valve, the circulating water temperature rising heat exchanger, the heat source side heat exchanger, and the divert valve. And the refrigerant is supplied from the compressor to the first four-way valve, the load side heat exchanger, the circulating water temperature rising heat exchanger, the second four-way valve, the internal heat exchanger, the expansion device, and the second four-way valve. Circulated to the compressor via a heat source side heat exchanger, the first four-way valve and the internal heat exchanger,

When operating in a cooling cycle, the circulating water is circulated from the underground heat exchanger to the underground heat exchanger through the pump, the divert valve, the heat source side heat exchanger, the circulating water temperature rising heat exchanger, and the divert valve. The refrigerant is supplied from the compressor to the first four-way valve, the heat source side heat exchanger, the second four-way valve, the internal heat exchanger, the expansion device, the second four-way valve, and the heat exchanger for increasing the circulating water temperature. The load-side heat exchanger, the first four-way valve and the internal heat exchanger is circulated to the compressor.

In particular, the refrigerant in the present invention is characterized in that the carbon dioxide.

And a hot water supply heat exchanger for heating the water supplied from the outside between the compressor and the first four-way valve may be further included.

In this case, a three-way valve is disposed at the front end of the hot water supply heat exchanger, and the three-way valve is connected to the compressor, and a bypass line connected to the hot water supply heat exchanger and the first four-way valve, respectively.

On the other hand, in the embodiment of the present invention, the expansion device is preferably an electronic expansion valve (EEV).

The present invention relates to a heat pump system using carbon dioxide as a working refrigerant and using geothermal heat as a heat source, wherein the temperature of the circulating water is exchanged with the refrigerant at the outlet of the load side heat exchanger before the circulating water at the outlet of the underground heat exchanger is sent to the heat source side heat exchanger. The heating performance can be improved by increasing the evaporation temperature in the evaporator.

In particular, the heat pump system according to the present invention can increase the temperature of the circulating water flowing into the heat pump system from the underground heat exchanger to a maximum of 11.5 ℃ by the application of a heat exchanger for increasing the temperature of the circulating water, the heating COP is 2.84 40% performance improvement can be obtained.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the heat pump system according to the present invention. In describing one embodiment of the present invention, descriptions of well-known configurations that will be obvious to those skilled in the art will be omitted so as not to obscure the subject matter of the present invention. In addition, when referring to the drawings it should be considered that the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of description.

Meanwhile, terms to be described below are terms defined in consideration of functions or shapes in the present invention, which may vary according to the intention or custom of a user or an operator. Therefore, the definitions of these terms should be interpreted based on the contents throughout the specification.

1 is a schematic diagram showing a case in which the heat pump system is operated in a heating cycle according to an embodiment of the present invention, Figure 2 is a schematic diagram showing a case in which the heat pump system of Figure 1 is operated in a cooling cycle.

First, the configuration of the heat pump system 10 according to the present invention will be described.

The present invention includes several heat exchangers as follows. That is, a geothermal heat exchanger (GHX) 210 buried underground so that the circulating water exchanges heat with geothermal heat, and a load-side heat exchanger in which heat exchange is performed between the refrigerant and water, which is a heat transfer fluid circulating in the indoor air conditioner 500. Internal heat eXchanger (IDHX) 220, an internal heat exchanger (IHX) 230 in which heat exchange between a high temperature refrigerant and a low temperature refrigerant is performed, and a temperature of circulating water in which heat exchange between a refrigerant and a circulating water is performed Heat eXchanger for increasing the temperature of Water entering heat pump from heat source (WHX) 240 and an OutDoor Heat eXchanger (ODHX) 250 in which heat exchange between the refrigerant and the circulating water is performed. It is.

A characteristic part of the present invention is that the internal heat exchanger 230 and the heat exchanger 240 for increasing the circulating water temperature are included. The internal heat exchanger 230 expands the low temperature refrigerant at the heat source side heat exchanger 250 (evaporator in the heating cycle) and the high temperature refrigerant at the outlet of the load side heat exchanger 220 (heat radiator in the heating cycle). By increasing the supercooling of the refrigerant at the inlet to reduce irreversible losses in the expansion device, by ensuring the superheat at the inlet of the compressor 100 to prevent the refrigerant flowing into the inlet of the compressor 100 to become a liquid phase In addition, by reducing the dryness of the inlet of the evaporator increases the cooling capacity per unit refrigerant flow rate, and serves to reduce the performance degradation due to the change in the state of the radiator outlet, such as reducing the discharge pressure and the temperature rise at the radiator outlet.

In general, the application of the internal heat exchanger 230 in the heating cycle can maintain a high discharge pressure and temperature, so that the heating capacity is slightly increased, but at the same time, the required power of the compressor 100 increases, so that the heating performance of the internal heat exchanger 230 is increased. Similar performance is achieved regardless of the application. However, the application of the high-efficiency internal heat exchanger 230 more than necessary may increase the volume of the compressor 100 by rapidly increasing the temperature at the inlet of the compressor 100 when a condition such that the refrigerant temperature at the radiator outlet is much higher than the standard operating condition occurs. The efficiency can be reduced, and thus the flow rate of the refrigerant discharged can be reduced, so that the performance can be drastically reduced. In some cases, an increase in the refrigerant temperature at the inlet of the compressor 100 may be described as "a rise in the refrigerant temperature at the compressor outlet → an increase in the refrigerant temperature at the radiator outlet → an increase in the refrigerant temperature at the compressor inlet → a refrigerant temperature at the compressor outlet. The vicious cycle of "rising of" may be repeated, and the heat pump system 10 may be abnormally operated. Therefore, the internal heat exchanger 230 must be designed to maintain a predetermined temperature or less at the inlet of the compressor 100.

On the other hand, when the high-pressure side pressure of the heat pump system 10 is maintained in the heat exchanger 240 for increasing the circulating water temperature of the present invention, the increase in the evaporation temperature may bring about a reduction in the compression work, thereby improving heating performance. It is conceived from the point that there is. In the present invention, considering that the outlet temperature of the refrigerant in the load-side heat exchanger 220 (heat radiator) is 45 ℃, it was configured to use this thermal energy. That is, before the circulating water at the outlet of the underground heat exchanger 210 (the standard temperature of the circulating water is 5 ° C. in the heating cycle) is transferred to the heat source side heat exchanger 250 (evaporator), the refrigerant at the outlet of the load side heat exchanger 220 is exchanged with each other. In order to increase the temperature of the circulating water and the evaporation temperature in the evaporator, a heat exchanger 240 for increasing the circulating water temperature is disposed between the load side heat exchanger 220 and the internal heat exchanger 230.

In addition, the heat pump system 10 of the present invention has a plurality of valves for controlling the fluid (circulating water and refrigerant) to flow in the forward or reverse direction required for the configuration of the cycle so that the heat pump system can be operated as well as the heating cycle. do. There are three valves in total, and the direction switching valve 310 is connected to the inlet and the outlet of the underground heat exchanger 210 so as to change the direction in which the circulating water flows, and the first four-way valve 320 is a compressor. The high temperature and high pressure refrigerant, which is connected to the 100, the load side heat exchanger 220, the heat source side heat exchanger 250, and the internal heat exchanger 230, and is pumped from the compressor 100, is the load side heat exchanger 220 or the heat source side. The second four-way valve 330 is controlled to flow to the heat exchanger 250, the second four-way valve 330 is a heat exchanger 240, internal heat exchanger 230, heat source side heat exchanger 250 and expansion device 400 for increasing the temperature of the circulating water Connected to each other to control the flow of the refrigerant constituting the heating or cooling cycle.

Here, the expansion device 400 is a known component that rapidly expands the volume of the refrigerant to lower the temperature of the refrigerant. The refrigerant passing through the expansion device 400 is a heat source side heat exchanger 250 in the case of a heating cycle. , In the case of the cooling cycle flows to the heat exchanger 240 for increasing the temperature of the circulating water. In a preferred embodiment of the present invention, the expansion device 400 is an electronic expansion valve (EEV).

 Other configurations include a pump 110 for pumping circulating water to the directional valve 310 and a compressor 100 for compressing and discharging the refrigerant at high temperature and high pressure. Particularly, in the preferred embodiment of the present invention, the refrigerant is carbon dioxide. to be. In addition, the heat pump system 10 according to the present invention, the oil separator 510 for separating the oil contained in the refrigerant from the compressor 100, the refrigerant tank 520 for storing the refrigerant, and the refrigerant flows back or liquid In case of being absorbed, the compressor 100 may include an accumulator 530 that temporarily stores a mixture of oil and refrigerant to prevent the compressor 100 from being damaged.

Meanwhile, the present invention may further include a hot water supply heat exchanger 260 for heating water supplied from the outside between the compressor 100 and the first four-way valve 320. In this case, a three-way valve 340 is disposed in front of the hot water heat exchanger 260, and the bypass 100 connected to the compressor 100, the hot water heat exchanger 260, and the first four-way valve 320 is disposed on the three-way valve 340. If each of the lines 350 are connected, it is possible to improve the thermal efficiency by blocking the supply of high-temperature, high-pressure refrigerant flowing to the hot water heat exchanger 260 as necessary to prevent unnecessary heat transfer.

A case in which the heat pump system 10 of the present invention having the above configuration is operated with a heating cycle will be described with reference to FIG. 1.

When the heat pump system 10 is operated by a heating cycle, the circulating water is transferred from the underground heat exchanger 210 to the pump 110, the diverter valve 310, and the heat exchanger 240 for increasing the circulating water temperature. ), And is circulated to the underground heat exchanger 210 through the heat source side heat exchanger 250 and the direction switching valve 310,

The refrigerant is supplied from the compressor 100 to the first four-way valve 320, the load side heat exchanger 220, the circulating water temperature raising heat exchanger 240, the second four-way valve 330, and the internal heat exchanger. The compressor 230, the expansion device 400, the second four-way valve 330, the heat source side heat exchanger 250, the first four-way valve 320, and the internal heat exchanger 230. Circulated to 100.

In the case of using water as the circulating water and carbon dioxide as the refrigerant, the heat exchange that occurs when passing through each heat exchanger, the compressor 100, and the expansion device 400 is performed using a continuous equation, an energy balance equation, a state equation, and the like. To simplify the calculation and make some assumptions and interpret them briefly, the temperature of the fluid in each step is

Assuming that the underground temperature is constant at 15 ° C., the circulating water entering the underground heat exchanger 210 at 2 ° C. is heated to 7 ° C. under geothermal heat. The circulating water at 7 ° C. is heated to 9 ° C. by heat exchange with a 41 ° C. refrigerant from the load side heat exchanger 220 while passing through the heat exchanger 240 for increasing the circulating water temperature, and the circulating water at 9 ° C. is heated at the heat source side heat exchanger. At 250, the heat is deprived of the low temperature refrigerant of -4 ° C. through the expansion device 400 and cooled to 2 ° C., and then enters the underground heat exchanger 210.

On the other hand, when looking at the temperature of the refrigerant in each step, the refrigerant discharged at a high temperature and high pressure of 100 ℃ from the compressor 100 is heat exchanged with the indoor air conditioner 500 (that is, the heater) while passing through the load-side heat exchanger 220 41 ℃ The temperature drops to. The refrigerant at 41 ° C. exchanges heat with the circulating water at 7 ° C. in the heat exchanger 240 for increasing the temperature of the circulating water and descends to 38 ° C., and the refrigerant passes through the internal heat exchanger 230 and is at the heat source side heat exchanger 250. Heats down with -1 ° C low temperature refrigerant and goes further down to 32 ° C. The refrigerant at 32 ° C. is rapidly cooled to −2 ° C. while passing through the expansion device 400, and then heated to −1 ° C. by circulating water at 9 ° C. in the heat source side heat exchanger 250. As described above, the refrigerant at −1 ° C. rises to 20 ° C. by the high temperature refrigerant at 38 ° C. in the internal heat exchanger 230, and then enters the compressor 100.

The heat pump system 10 according to the present invention operates the directional valve 310 and the first and second four-way valves 320 and 330 to circulate the flow of circulating water and refrigerant to the reverse of the heating cycle to perform a cooling cycle. Can be.

When operating in a cooling cycle, the circulating water is transferred from the underground heat exchanger 210 to the pump 110, the diverter valve 310, the heat source side heat exchanger 250, and the circulating water temperature raising heat exchanger. Circulated to the underground heat exchanger 210 via the 240 and the direction switching valve 310, and the refrigerant flows from the compressor 100 to the first four-way valve 320 and the heat source side heat exchanger 250. The second four-way valve 330, the internal heat exchanger 230, the expansion device 400, the second four-way valve 330, the circulating water temperature rising heat exchanger 240, and the load side heat exchanger 220, the first four-way valve 320 and the internal heat exchanger 230 are circulated to the compressor 100.

Even for the cooling cycle, the temperature of the fluid at each stage is analyzed as follows.

Assuming that the underground temperature is also constant at 15 ° C, the circulating water entering the underground heat exchanger 210 at 28 ° C loses heat and is cooled to 25 ° C. The circulating water at 25 ° C. is heated to 30 ° C. by heat exchange with the high temperature refrigerant at 80 ° C. in the heat source side heat exchanger 250, and then the refrigerant at 4 ° C. from the expansion device 400 in the heat exchanger 240 for circulating water temperature rise. Heat exchange with and cooled to 28 ℃, the circulating water of 28 ℃ enters the underground heat exchanger (210).

On the other hand, when looking at the temperature of the refrigerant in each step, the refrigerant discharged at a high temperature and high pressure of 80 ℃ in the compressor 100 heat exchanges with the circulation water of 25 ℃ in the heat source side heat exchanger 250, the temperature is lowered to 26 ℃. The refrigerant at 26 ° C. is further dropped to 20.5 ° C. by the low temperature refrigerant at 10 ° C. in the internal heat exchanger 230, and the refrigerant is cooled to 4 ° C. in the expansion device 400, and then the heat exchanger 240 for increasing the circulating water temperature. It heats up with circulating water of 30 degreeC, and it heats up to 7 degreeC. Thereafter, the low temperature refrigerant at 7 ° C. heats up to 10 ° C. by exchanging heat with the indoor air conditioner 500 (that is, the air conditioner), and the refrigerant at 10 ° C. is subjected to the high temperature refrigerant at 26 ° C. in the internal heat exchanger 230 as described above. The temperature rises to 16 ° C. and enters the compressor 100.

As described above, since the temperature of the circulating water is increased during the operation of the heating cycle by the application of the heat exchanger 240 for increasing the circulating water temperature, the heat transfer amount in the underground heat exchanger 210 is reduced. This means that the amount of heat transfer in the underground heat exchanger 210 may increase during the operation of the cooling cycle, so it is necessary to examine the operating conditions of the cooling cycle.

In the cooling cycle of the geothermal heat pump system 10 as in the present invention, unlike the heating cycle in which the circulating water at the outlet of the underground heat exchanger 210 and the refrigerant at the inlet of the internal heat exchanger 230 form heat exchange, the heat source side heat exchanger The circulation water at the outlet 250 (heat radiator) and the refrigerant at the outlet of the internal heat exchanger 230 form heat exchange. In general, the temperature of the circulating water at the outlet of the heat source side heat exchanger 250 during the cooling cycle operation is 25 to 35 ° C., and the refrigerant at the outlet of the internal heat exchanger 230 in the heat pump system 10 using carbon dioxide as the refrigerant. The temperature is 25-30 ° C. Therefore, during the cooling cycle operation, the amount of heat obtained from the heat exchanger 240 for circulating water temperature increase is almost zero. That is, since there is almost no amount of cooling heat additionally charged by the underground heat exchanger 210 during the cooling cycle due to the application of the heat exchanger 240 for increasing the circulating water temperature, the heat transfer area of the underground heat exchanger 210 is for raising the circulating water temperature. It can be seen that irrespective of the application of the heat exchanger 240.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art to which the art belongs can make various modifications and other equivalent embodiments therefrom. I will understand. Therefore, the true technical protection scope of the present invention will be defined by the claims.

1 is a schematic diagram showing a case in which the heat pump system is operated in a heating cycle according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a case where the heat pump system of FIG. 1 is operated with a cooling cycle. FIG.

Description of the Related Art

10: heat pump system

100: compressor 110: pump

210: underground heat exchanger 220: load side heat exchanger

230: internal heat exchanger 240: heat exchanger for circulating water temperature rise

250: heat source side heat exchanger 260: hot water supply heat exchanger

310: direction switching valve 320: first four-way valve

330: second four-way valve 340: three-way valve

350: bypass line 400: expansion device

500: indoor air conditioner 510: oil separator

520: refrigerant tank 530: accumulator

Claims (5)

An underground heat exchanger buried underground so that circulating water exchanges heat with geothermal heat; A direction switching valve connected to an inlet and an outlet of the underground heat exchanger, respectively, to change a direction in which the circulating water flows; A pump for pumping circulating water to the directional valve; A compressor for compressing and discharging the refrigerant; A load side heat exchanger configured to perform heat exchange between the refrigerant and water circulating in the indoor air conditioner; A heat exchanger for increasing a circulating water temperature in which heat exchange between the refrigerant and the circulating water is performed; A heat source side heat exchanger configured to perform heat exchange between the refrigerant and the circulating water; An internal heat exchanger configured to exchange heat between the high temperature refrigerant and the low temperature refrigerant; An expansion device for expanding the refrigerant; A first four-way valve connected to the compressor, the load side heat exchanger, the heat source side heat exchanger, and the internal heat exchanger, respectively; And a second four-way valve connected to each of the heat exchanger for increasing the circulating water temperature, the internal heat exchanger, the heat source side heat exchanger, and the expansion device. When operated in a heating cycle, the circulating water is circulated from the underground heat exchanger to the underground heat exchanger via the pump, the divert valve, the circulating water temperature rising heat exchanger, the heat source side heat exchanger, and the divert valve. And the refrigerant is supplied from the compressor to the first four-way valve, the load side heat exchanger, the circulating water temperature rising heat exchanger, the second four-way valve, the internal heat exchanger, the expansion device, and the second four-way valve. Circulated to the compressor via a heat source side heat exchanger, the first four-way valve and the internal heat exchanger, When operating in a cooling cycle, the circulating water is circulated from the underground heat exchanger to the underground heat exchanger through the pump, the divert valve, the heat source side heat exchanger, the circulating water temperature rising heat exchanger, and the divert valve. The refrigerant is supplied from the compressor to the first four-way valve, the heat source side heat exchanger, the second four-way valve, the internal heat exchanger, the expansion device, the second four-way valve, and the heat exchanger for increasing the circulating water temperature. And a heat circulating to the compressor via the load side heat exchanger, the first four-way valve and the internal heat exchanger. The method according to claim 1, And the refrigerant is carbon dioxide. The method according to claim 1, Heat pump system, characterized in that further comprising a hot water supply heat exchanger for heating the water supplied from the outside between the compressor and the first four-way valve. The method of claim 3, A three-way valve is disposed in front of the hot water heat exchanger, and the three-way valve is connected to the compressor and the bypass line connected to the hot water heat exchanger and the first four-way valve, respectively. The method according to claim 1, The expansion device is a heat pump system, characterized in that the electronic expansion valve (EEV).

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