Two-stage compression heat pump device

Abstract

The present invention relates to a two-stage compression heat pump device comprising an outdoor cycle in which a primary refrigerant and external air are heat-exchanged; and an indoor cycle in which a secondary refrigerant and water supplied from the outside at a high temperature are heat-exchanged, the two-stage compression heat pump device comprising: a first indoor heat exchanger which is installed on a refrigerant flow path in the indoor cycle, and in which the secondary refrigerant evaporates by heat exchange with the water being at a high temperature and is phase-changed into a gaseous phase to exist; a second indoor heat exchanger which is installed on the refrigerant flow path in the indoor cycle and in which the gaseous secondary refrigerant supplied from the first indoor heat exchanger is condensed by heat exchange with the primary refrigerant in the outdoor cycle and is phase-changed into a liquid phase to exist; and a bypass unit which is installed between the first indoor heat exchanger and the second indoor heat exchanger and supplies the secondary refrigerant of the first indoor heat exchanger to the second indoor heat exchanger by natural convection.

Description

Two-stage compression heat pump device

[0001] The present invention relates to a two-stage compression heat pump device, and more particularly, to a two-stage compression heat pump device capable of performing defrosting-related corresponding operation of an outdoor cycle by receiving evaporation heat from an indoor cycle during a defrosting operation mode of an outdoor cycle.

[0002]

[0003] In general, a heat pump device is a device that incorporates a cooling cycle and a heating cycle into the same unit, so that cooling and heating are performed simultaneously. In the summer, one unit performs cooling through the cooling cycle, and in the winter, it switches to the reverse cycle to perform heating and hot water supply.

[0004] As an example of a heat pump device, a two-stage compression heat pump device is used to evaporate the secondary refrigerant of the indoor cycle when the primary refrigerant of high temperature (50℃) provided through heat exchange between outdoor air and refrigerant in the outdoor cycle of the outdoor unit is supplied to the indoor cycle of the indoor unit. Then, the condensed primary refrigerant is reintroduced into the outdoor cycle and circulated. In the indoor cycle, the secondary refrigerant of high temperature and high pressure compressed provides high temperature (80℃) hot water to the user through heat exchange with circulating water, and the secondary refrigerant condensed through heat exchange evaporates after exchanging heat with the primary refrigerant and circulates in the indoor cycle.

[0005] However, when the outdoor temperature is low, moisture in the air passing through the outdoor heat exchanger used as an evaporator during heating operation may condense and freeze, causing frost to form on the outdoor heat exchanger, thereby reducing the heat exchange performance of the outdoor heat exchanger. Ultimately, this causes a problem that significantly reduces the heating efficiency of the heat pump device.

[0006] To solve these problems, a two-stage compression heat pump device can perform defrosting operation by supplying evaporation heat to the outdoor cycle using a hot gas bypass device located in the indoor cycle.

[0007] The defrost operation mode of a two-stage compression heat pump device does not supply the high-temperature, high-pressure secondary refrigerant discharged from the indoor compressor to the first indoor heat exchanger that functions as a condenser, but bypasses the indoor compressor using a hot gas bypass device or a switching valve and circulates the secondary refrigerant directly to the second indoor heat exchanger that functions as an evaporator.

[0008] The secondary refrigerant exchanges heat with the primary refrigerant of the outdoor cycle in the second indoor heat exchanger, and the primary refrigerant circulating to the outdoor heat exchanger of the outdoor unit absorbs the heat of evaporation and circulates through the outdoor cycle, thereby removing the frost formed on the surface of the outdoor heat exchanger.

[0009] A related prior art document is Republic of Korea Patent Publication No. 1203580.

[0010] However, the heat pump device disclosed in the prior art document had a disadvantage in that it could not provide sufficient heat from the indoor unit to the outdoor unit, and thus defrosting operation was not performed properly.

[0011] That is, according to prior art literature, when a conventional heat pump device operates in defrost mode, the high-temperature, high-pressure refrigerant discharged from the indoor compressor is bypassed and supplied to the outdoor cycle, and the second indoor heat exchanger, which was functioning as an evaporator, functions as a condenser. The condensed, subcooled liquid refrigerant is re-introduced into the indoor compressor through the accumulator without evaporation in the second indoor heat exchanger. This causes a shortage of evaporation heat at the suction end of the indoor compressor, resulting in a rapid decrease in low pressure.

[0012] This not only creates low efficiency due to the high compression ratio, but also causes the indoor compressor to go out of its reliability range, causing the indoor compressor to stop working.

[0013] In addition, there was a problem in that the indoor cycle of the conventional heat pump device could not sufficiently respond to the defrosting operation of the outdoor cycle, and thus the heat pump device could not exhibit the best defrosting efficiency.

[0014] In addition, in the case of reverse cycle defrosting operation of a heat pump device, there was a problem of increasing the complexity of the cycle and the complexity of the installation structure as an additional switching valve had to be installed within the indoor cycle of the indoor unit, and increasing the power consumption of the indoor compressor used during defrosting operation.

[0015]

[0016] The purpose of the present invention is to provide a two-stage compression heat pump device capable of performing defrost-related response operation of an outdoor cycle by inducing a thermosiphon phenomenon in which gaseous refrigerant and liquid refrigerant naturally circulate during a defrost operation mode of an outdoor cycle by sequentially stacking an evaporator and a condenser upward from the ground and installing a bypass unit through which refrigerant flows between the suction end of the evaporator and the discharge end of the condenser.

[0017] The purpose of the present invention is not limited to the aforementioned purposes, and other unmentioned purposes and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0018]

[0019] In order to achieve the above-described purpose, a two-stage compression heat pump device according to the present invention is characterized in that it performs a defrosting operation of an outdoor cycle by inducing a thermosiphon phenomenon to perform refrigerant flow of an indoor cycle by natural convection, and can implement a defrosting-related response operation without a switching valve.

[0020] A two-stage compression heat pump device according to the present invention may include an outdoor cycle in which a primary refrigerant and outside air exchange heat; and an indoor cycle in which a secondary refrigerant and water supplied from outside at high temperature exchange heat.

[0021] In addition, a two-stage compression heat pump device according to the present invention is characterized by including: a first indoor heat exchanger installed on a refrigerant passage within the indoor cycle, in which the secondary refrigerant is evaporated through heat exchange with the high-temperature water and phase-changed into a gaseous phase and circulated; a second indoor heat exchanger installed on a refrigerant passage within the indoor cycle, in which the secondary refrigerant in a gaseous phase supplied from the first indoor heat exchanger is condensed through heat exchange with the primary refrigerant within the outdoor cycle and phase-changed into a liquid phase and circulated; and a bypass unit installed between the first indoor heat exchanger and the second indoor heat exchanger, and supplying the secondary refrigerant of the first indoor heat exchanger to the second indoor heat exchanger through natural convection.

[0022] The two-stage compression heat pump device according to the present invention may further include a liquid path so that the liquid secondary refrigerant in the second indoor heat exchanger moves to the first indoor heat exchanger by gravity.

[0023] According to an embodiment of the present invention, the bypass unit can be branched and connected between the suction end of the first indoor heat exchanger and the discharge end of the second indoor heat exchanger.

[0024] Accordingly, by quickly supplying the high-temperature gaseous secondary refrigerant from the first indoor heat exchanger to the second indoor heat exchanger through the bypass unit, the time required to condense the gaseous secondary refrigerant can be reduced.

[0025] In addition, the defrosting operation mode can be quickly performed by quickly exchanging heat between the high-temperature gaseous secondary refrigerant and the primary refrigerant of the outdoor cycle through the second indoor heat exchanger through the bypass unit.

[0026] According to an embodiment of the present invention, the bypass unit may be arranged on a path along which the secondary refrigerant in the gas phase supplied from the first indoor heat exchanger is supplied into the second indoor heat exchanger.

[0027] According to an embodiment of the present invention, the bypass unit may include a bypass pipe for bypassing the secondary refrigerant in a gaseous state evaporated in the first indoor heat exchanger; and a bypass valve for selectively opening and closing the bypass pipe.

[0028] According to an embodiment of the present invention, the bypass unit may be configured to operate selectively in the defrosting operation mode of the outdoor cycle.

[0029] According to an embodiment of the present invention, the first indoor heat exchanger may be located on the ground and function as a condenser, and the second indoor heat exchanger may be located above the first indoor heat exchanger and function as an evaporator.

[0030] According to an embodiment of the present invention, in the defrosting operation mode of the outdoor cycle, the indoor compressor of the indoor cycle may not operate in a stopped state.

[0031] According to an embodiment of the present invention, the second indoor heat exchanger may be arranged so that the height (H2) from the ground plus the height (H1) of the liquid refrigerant section stored in the second indoor heat exchanger is higher than the height of the first indoor heat exchanger.

[0032]

[0033] According to the two-stage compression heat pump device of the present invention having the configuration described above, there is an effect of being able to implement the defrosting operation of the outdoor cycle by performing the refrigerant flow of the indoor cycle by natural circulation by inducing the thermosiphon phenomenon.

[0034] The present invention has the effect of removing frost from the outdoor heat exchanger by transferring the vapor refrigerant of the first indoor heat exchanger to the second indoor heat exchanger during the defrosting operation mode of the outdoor cycle by installing a bypass unit connecting the suction end of the first indoor heat exchanger and the discharge end of the second indoor heat exchanger in a two-stage compression heat pump device.

[0035] The present invention can obtain the effect of reverse cycle defrosting without a switching valve of a conventional two-stage compression heat pump device, and can improve the complexity of the indoor cycle and save parts by eliminating the installation of a switching valve.

[0036] By minimizing the operation of the indoor compressor, the defrosting efficiency can be improved while reducing power consumption.

[0037]

[0038] FIG. 1 is a schematic diagram showing a two-stage compression heat pump device according to an embodiment of the present invention.

[0039] FIG. 2 is a cycle diagram showing the flow of refrigerant when a two-stage compression heat pump device according to an embodiment of the present invention performs a hot water supply mode.

[0040] FIG. 3 is a drawing showing the flow of refrigerant in a condenser and evaporator related to a two-stage compression heat pump device according to an embodiment of the present invention.

[0041] FIG. 4 is a cycle diagram showing the flow of refrigerant when a two-stage compression heat pump device according to an embodiment of the present invention is in a defrosting operation mode.

[0042] FIG. 5 is a drawing showing the arrangement of the first indoor heat exchanger and the second indoor heat exchanger of a two-stage compression heat pump device according to an embodiment of the present invention.

[0043]

[0044] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention will be able to easily propose other embodiments within the scope of the same spirit by adding, deleting, modifying, or adding components, etc., but these will also be considered to be within the scope of the present invention.

[0045] When assigning reference numerals to components in each drawing, it should be noted that identical components are assigned the same numerals whenever possible, even if they appear on different drawings. Furthermore, when describing embodiments of the present invention, if a detailed description of a related known configuration or function is deemed to hinder understanding of the embodiments of the present invention, the detailed description will be omitted.

[0046] Additionally, terms such as first, second, A, B, (a), (b), etc. may be used to describe components of embodiments of the present invention. These terms are only intended to distinguish the components from other components, and the nature, order, or sequence of the components are not limited by the terms. When it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

[0047] FIG. 1 is a schematic diagram showing a two-stage compression heat pump device according to an embodiment of the present invention, and FIG. 2 is a cycle diagram showing the flow of refrigerant when the two-stage compression heat pump device according to an embodiment of the present invention performs a hot water supply mode.

[0048] As shown in FIGS. 1 and 2, a two-stage compression heat pump device according to an embodiment of the present invention includes an outdoor cycle (1) installed in an outdoor unit (10) and an indoor cycle (2) installed in an indoor unit (20) that produces hot water through heat exchange with the outdoor cycle (1).

[0049] According to an embodiment of the present invention, a fluid may be fluidly connected to the outdoor unit (10) and indoor unit (20) of a two-stage compression heat pump device. For example, the working fluid may include outdoor air, a refrigerant, and circulating water. Here, the refrigerant as the working fluid may flow to circulate through the refrigerant paths of the outdoor cycle (1) and the indoor cycle (2).

[0050] For example, the refrigerant flowing in the outdoor cycle (1) can be classified as a primary refrigerant, and the refrigerant flowing in the indoor cycle (2) can be classified as a secondary refrigerant.

[0051] Primary and secondary refrigerants can be understood as refrigerants with different condensing and evaporating temperatures. That is, the primary refrigerant can be composed of, for example, R410A, which has lower condensing and evaporating temperatures and is relatively efficient in low-temperature regions. The secondary refrigerant can be composed of, for example, R134a, which has higher condensing and evaporating temperatures than the primary refrigerant and is relatively efficient in high-temperature regions.

[0052] A two-stage compression heat pump device according to an embodiment of the present invention includes an outdoor unit (10) disposed in an outdoor space and exchanging heat with outdoor air, and an indoor unit (20) disposed in an indoor space and having an indoor cycle (2) that produces hot water through heat exchange with a refrigerant.

[0053] Specifically, a two-stage compression heat pump device may include an outdoor cycle (1) in which a primary refrigerant exchanges heat with air and can evaporate a secondary refrigerant, and an indoor cycle (2) in which the secondary refrigerant evaporated by the outdoor cycle (1) exchanges heat with water through a refrigerant circulation path (21a) to heat water. As an example, a two-stage compression heat pump device may utilize air and water as heat sources.

[0054] In a two-stage compression heat pump device, the primary refrigerant can exchange heat with outdoor air in the outdoor heat exchanger (15) of the outdoor unit (10), and the secondary refrigerant can exchange heat with circulating water supplied from the outside in the first indoor heat exchanger (21) of the indoor unit (20).

[0055] As described above, the refrigerant circulated in the outdoor cycle (1) of the outdoor unit (10) will be referred to as the primary refrigerant, and the refrigerant circulated in the indoor cycle (2) of the indoor unit (20) will be referred to as the secondary refrigerant.

[0056]

[0057] [Outdoor unit configuration]

[0058] The outdoor unit (10) includes an outdoor accumulator (11), an outdoor compressor (12) that compresses refrigerant, a switching valve (13) that switches the refrigerant path (100), an outdoor expansion valve (14) that expands and decompresses the primary refrigerant, and an outdoor heat exchanger (15) in which the primary refrigerant and outside air exchange heat.

[0059] Additionally, the outdoor unit (10) includes a refrigerant passage (100) through which a primary refrigerant flows and which is connected to each main component. The primary refrigerant circulating in the outdoor unit (10) flows through the refrigerant passage (100) and can exchange heat with the secondary refrigerant circulating in the indoor unit (20).

[0060] The refrigerant passage (100) includes a first refrigerant passage (110) connecting the outlet of the outdoor compressor (12) and the switching valve (13), a second refrigerant passage (120) connecting the switching valve (13) and the first connecting pipe (210) of the indoor unit (20), a third refrigerant passage (130) connecting the suction end of the outdoor compressor (12) and the discharge end of the outdoor accumulator (11), a fourth refrigerant passage (140) connecting the switching valve (13) and the outdoor heat exchanger (15), and a fifth refrigerant passage (150) connecting the outdoor heat exchanger (15) and the second connecting pipe (220) of the indoor unit (20).

[0061] Specifically, the outdoor accumulator (11) can supply low-temperature, low-pressure gaseous refrigerant to the outdoor compressor (12).

[0062] The outdoor compressor (12) is a device that compresses low-temperature, low-pressure gaseous refrigerant introduced from the outdoor accumulator (11) into high-temperature, high-pressure refrigerant. For example, the outdoor compressor (12) may be equipped with a constant-speed compressor that rotates at a constant speed and compresses to a constant capacity, or an inverter compressor that can adjust the compression capacity by varying the rotation speed according to the load.

[0063] In this way, the primary refrigerant compressed by the outdoor compressor (12) can be introduced into the second indoor heat exchanger (22) and the outdoor heat exchanger (15) through the switching valve (13) depending on the cooling and heating operation mode of the heat pump device.

[0064] The switching valve (13) may be placed at the discharge end of the outdoor compressor (12). The switching valve (13) is connected to the first refrigerant passage (110), the second refrigerant passage (120), and the fourth refrigerant passage (140), respectively. Therefore, the switching valve (13) can switch the refrigerant passage (200) depending on the operating mode. The switching valve (13) may be referred to as a four-way valve.

[0065] The outdoor expansion valve (14) is an expansion valve that expands and depressurizes the condensed primary refrigerant. The outdoor expansion valve (14) is installed on the fifth refrigerant passage (150) and may be installed adjacent to the outdoor heat exchanger (15).

[0066] The outdoor expansion valve (14) decompresses the primary refrigerant flowing through the second indoor heat exchanger (22) of the indoor cycle (2) to the outdoor heat exchanger (15) according to the cooling and heating operation mode of the heat pump device. The primary refrigerant expanded and decompressed by the outdoor expansion valve (14) exchanges heat with air in the outdoor heat exchanger (15).

[0067] The outdoor expansion valve (14) may be an electronic expansion valve such as an EEV whose opening degree can be adjusted.

[0068] The outdoor heat exchanger (15) can function as an evaporator for evaporating the primary refrigerant expanded and depressurized in the outdoor expansion valve (14). The outdoor heat exchanger (15) can be connected between the fourth refrigerant passage (140) and the fifth refrigerant passage (150). That is, the outdoor heat exchanger (15) can be connected to the suction end of the fourth refrigerant passage (140) and to the discharge end of the fifth refrigerant passage (150).

[0069] In addition, the outdoor heat exchanger (15) is installed between the outdoor expansion valve (14) and the outdoor compressor (12), and during cooling operation, the primary refrigerant supplied from the outdoor compressor (12) can be condensed through heat exchange with outdoor air. In addition, during heating operation, the outdoor heat exchanger (15) can evaporate the primary refrigerant that has exchanged heat with the secondary refrigerant supplied from the indoor cycle (2). In this way, the outdoor heat exchanger (15) can be referred to as a condenser or an evaporator.

[0070] Additionally, an outdoor fan (16) that forms air flow is installed on one side of the outdoor heat exchanger (15).

[0071] An outdoor fan (16) is installed to circulate outdoor air to the outdoor heat exchanger (15).

[0072] In particular, the outdoor fan (16) rotates when the outdoor compressor (12) is driven to form a flow of outdoor air toward the outdoor heat exchanger (15) to enable fast and efficient heat exchange. By driving the outdoor fan (16), heat exchange can be smoothly performed between the outdoor air flowing into the outdoor heat exchanger (15) and the primary refrigerant.

[0073] In addition, it includes a control valve (17) that controls the flow of refrigerant between the outdoor unit (10) and the indoor unit (20). The control valve (17) includes a first control valve (17b) arranged in the second refrigerant passage (120) and a second control valve (17a) arranged in the fifth refrigerant passage (150).

[0074] The first connecting pipe (210) may include an inlet pipe that guides the primary refrigerant that has passed through the outdoor compressor (12) to the second connecting pipe (220). The second connecting pipe (220) includes a discharge pipe that guides the primary refrigerant that has passed through the first connecting pipe (210) to the outdoor heat exchanger (15).

[0075] Strainers (211, 221) are installed in the first connecting pipe (210) and the second connecting pipe (220). The strainers (211, 221) may be provided to filter out waste or foreign substances in the primary refrigerant flowing in the outdoor cycle. As an example, the strainers (211, 221) may be formed of a metal mesh. The strainers (211, 221) may include a first strainer (211) installed in the first connecting pipe (210) and a second strainer (221) installed in the second connecting pipe (220).

[0076] The first refrigerant can be phase-changed while continuously circulating through the outdoor accumulator (11) of the outdoor cycle (1) -> outdoor compressor (12) -> changeover valve (13) -> second indoor heat exchanger (22) -> outdoor expansion valve (14) -> outdoor heat exchanger (15) -> outdoor accumulator (11).

[0077]

[0078] [Indoor unit configuration]

[0079] The indoor unit (20) can be connected to the outdoor unit (10). The indoor unit (20) exchanges heat between the secondary refrigerant and the circulating water supplied from the outside, and can cool or heat the indoor space or supply hot water to the indoor space.

[0080] The indoor unit (20) includes a first indoor heat exchanger (21), a second indoor heat exchanger (22), an indoor accumulator (23), an indoor compressor (24), an oil separator (25), a first indoor expansion valve (26), a second indoor expansion valve (27), and a bypass unit (300).

[0081] The first indoor heat exchanger (21) can exchange heat between the circulating water supplied from the water supply unit that supplies water and the secondary refrigerant circulating in the indoor unit (20).

[0082] The indoor accumulator (23) can be placed at the suction end of the indoor compressor (24) as a gas-liquid separator. The indoor accumulator (23) can separate gaseous refrigerant and liquid refrigerant from the refrigerant supplied to the indoor compressor (24) and supply the separated gaseous refrigerant to the indoor compressor (24). Therefore, the indoor accumulator (23) can prevent a decrease in efficiency due to liquid infiltration of the indoor compressor (24).

[0083] The indoor compressor (24), like the outdoor compressor (12), can compress and discharge high-temperature, high-pressure gaseous refrigerant introduced from the indoor accumulator (23).

[0084] A temperature sensor (28) that measures the air temperature of the indoor space of the indoor unit (20) may be attached to the indoor compressor (24).

[0085] Meanwhile, the refrigerant passage (100) may include a sixth refrigerant passage (160) connecting the indoor accumulator (23) and the indoor compressor (24). In addition, the refrigerant passage (100) may include a seventh refrigerant passage (170) connecting the indoor compressor (24) and the oil separator (25) so that the refrigerant discharged from the indoor compressor (24) is supplied to the oil separator (25).

[0086] The indoor compressor (24) is installed between the sixth refrigerant passage (160) and the seventh refrigerant passage (170). The indoor compressor (24) can be understood to have the same configuration and function as the outdoor compressor (12), except that the installation location is different.

[0087] The oil separator (25) can recover some of the high-temperature, high-pressure gaseous refrigerant discharged from the indoor compressor (24) to the indoor compressor (24). The oil separator (25) can be installed between the discharge end of the indoor compressor (24) and the suction end of the first indoor heat exchanger (21).

[0088] The oil separator (25) supplies some of the secondary refrigerant discharged from the indoor compressor (24) to the hot gas bypass device bypass unit (30300) and the first indoor heat exchanger (21), and recovers the remaining refrigerant to the indoor compressor (24).

[0089] The oil separator (25) may further include an oil return pipe (25a) for returning oil to the indoor compressor (24), and a check valve (not shown) disposed in the oil return pipe (25a) to ensure that the refrigerant is supplied to the indoor compressor (24) without backflow.

[0090] Additionally, the refrigerant passage (100) may include an eighth refrigerant passage (180) connecting the oil separator (25) and the first indoor heat exchanger (21).

[0091] An oil separator (25) is installed between the seventh refrigerant passage (170) and the eighth refrigerant passage (180).

[0092] Meanwhile, the refrigerant passage (100) may include a ninth refrigerant passage (190) installed to be connected between the first indoor heat exchanger (21) and the second indoor heat exchanger (22). In addition, the refrigerant passage (100) may include a tenth refrigerant passage (200) connected between the second indoor heat exchanger (22) and the indoor accumulator (23).

[0093] The first indoor heat exchanger (21) is provided with a refrigerant circulation path (21a) through which high-temperature, high-pressure secondary refrigerant discharged from the indoor compressor (24) passes and is condensed, and a circulating water path (21b) through which circulating water supplied from the water supply unit is heated and passes. In other words, the first indoor heat exchanger (21) can function as a condenser that condenses the compressed secondary refrigerant discharged from the indoor compressor (24).

[0094] Accordingly, the secondary refrigerant discharged from the indoor compressor (24) can heat the circulating water supplied from the water supply unit to the first indoor heat exchanger (21) by exchanging heat with the circulating water. In this case, the first indoor heat exchanger (21) may be a water-refrigerant heat exchanger. When the first indoor heat exchanger (21) is a water-refrigerant heat exchanger, a water pipe may be further included in the first indoor heat exchanger (21). The heat pump device may function as a water heater that supplies hot water to a hot water demander connected to the water pipe, and may function as a chiller that supplies cold water to a cold water demander connected to the water pipe. The water pipe may be referred to as a circulating water path (21b).

[0095] The refrigerant circulation path (21a) through which the secondary refrigerant of the first indoor heat exchanger (21) flows is connected to the ninth refrigerant path (190), and the first indoor expansion valve (26) is installed on the ninth refrigerant path (190).

[0096] An inlet pipe (21c) that guides circulating water from a cold water demand source or a hot water demand source to the circulating water flow path (21b) of the first indoor heat exchanger (21) can be connected.

[0097] A pump (not shown) that pumps circulating water to circulate between a cold water demand source and a hot water demand source and a circulating water path may be installed in the water inlet pipe (21c). In addition, a relief valve (21d) that relieves pressure when the water pressure in the water inlet pipe (21c) is high may be connected to the water inlet pipe (21c).

[0098] In addition, a water outlet pipe (21e) that guides the circulating water passing through the circulating water path (21b) to a cold water demand source or a hot water demand source can be connected to the circulating water path (21b) of the first indoor heat exchanger (21).

[0099] The first indoor expansion valve (26) is an expansion valve that expands the secondary refrigerant that passes through the first indoor heat exchanger (21) and flows toward the second indoor heat exchanger (22). The first indoor expansion valve (26) can be installed between the first indoor heat exchanger (21) and the second indoor heat exchanger (22) via the ninth refrigerant passage (190).

[0100] The first indoor expansion valve (26) is connected on one side to the refrigerant circulation path (21a) of the first indoor heat exchanger (21) through the ninth refrigerant path (190), and on the other side to the evaporation path (22b) of the second indoor heat exchanger (22).

[0101] The first indoor expansion valve (26) may be an electronic expansion valve such as EEV whose opening degree can be adjusted.

[0102] The second indoor heat exchanger (22) can be connected to the refrigerant circulation path (21a) of the first indoor heat exchanger (21) via the ninth refrigerant path (190). The second indoor heat exchanger (22) can exchange heat between the primary refrigerant provided from the outdoor cycle (1) of the outdoor unit (10) and the secondary refrigerant provided from the indoor cycle (2) of the indoor unit (20).

[0103] A second indoor heat exchanger (22) according to an embodiment of the present invention includes a condensation path (22a) through which the primary refrigerant of the outdoor cycle (1) passes and condenses, and an evaporation path (22b) through which the secondary refrigerant of the indoor cycle (2) passes and evaporates.

[0104] As shown in Fig. 2, the two-stage compression heat pump device circulates along a normal route in which the secondary refrigerant is compressed in the indoor compressor (24), condensed in the first indoor heat exchanger (21), expanded and decompressed in the first indoor expansion valve (26), evaporated in the evaporation path (22b) of the second indoor heat exchanger (22), and then returned to the indoor compressor (24) via the indoor accumulator (23).

[0105]

[0106] [Thermosiphon system configuration]

[0107] The present invention can be applied to a two-stage compression heat pump device having an outdoor cycle (1) and an indoor cycle (2) to operate a refrigerant circulation type thermosiphon system in a defrost operation mode.

[0108] FIG. 3 is a diagram showing the flow of refrigerant in a condenser and evaporator related to defrosting of a two-stage compression heat pump device according to an embodiment of the present invention, and FIG. 4 is a cycle diagram showing the flow of refrigerant when the two-stage compression heat pump device according to an embodiment of the present invention performs a defrosting operation mode.

[0109] Referring to FIG. 4, in the defrosting operation mode of the two-stage compression heat pump device according to the present invention, the indoor cycle (2) can be configured so that the first indoor heat exchanger (21) functions as an evaporator and the second indoor heat exchanger (22) functions as a condenser.

[0110] The two-stage compression heat pump device according to the present invention applies a thermosiphon system.

[0111] The thermosyphon system includes a first indoor heat exchanger (21) in which a secondary refrigerant flows along a refrigerant circulation path (21a) to exchange heat with high-temperature circulating water supplied from a hot water supply unit (30) and circulated along a circulating water path (21b). In other words, unlike a two-stage compression heat pump device that performs a hot water supply mode, the hot water supply unit (30) in the defrosting operation mode is adapted to supply high-temperature water to the circulating water path (21b).

[0112] The bypass unit (300) of the thermosiphon system according to the present invention does not operate in the general hot water supply mode, but is selectively operated only in the defrost operation mode.

[0113] In order to perform defrosting operation in a two-stage compression heat pump device using such a thermosiphon system, a bypass unit (300) is required.

[0114] The bypass unit (300) can be branched and connected between the eighth refrigerant passage (180) connected to the suction end of the first indoor heat exchanger (21) and the tenth refrigerant passage (200) connected to the discharge end of the second indoor heat exchanger (22).

[0115] In addition, the second indoor heat exchanger (22) is included, which performs a defrosting operation of the outdoor cycle (1) by transferring the evaporation heat to the outdoor cycle (1) of the outdoor unit (10) while the secondary refrigerant, which has increased in temperature by heat exchange with the high-temperature circulating water passing through the condensation path (22a) through the bypass unit (300) in the first indoor heat exchanger (21), passes through the evaporation path (22b).

[0116] As illustrated in FIG. 3, either the first indoor heat exchanger (21) or the second indoor heat exchanger (22) may be stacked on top of the other. As an example, the second indoor heat exchanger (22) may be configured to be stacked on top of the first indoor heat exchanger (21).

[0117] On the other hand, the first indoor heat exchanger (21) is located on the ground, and a refrigerant circulation path (21a) is arranged to enable evaporation of the secondary refrigerant that exchanges heat with the circulating water by absorbing heat from the high-temperature circulating water supplied from the hot water supply unit (30). The first indoor heat exchanger (21) performs an evaporator function. That is, the secondary refrigerant in a liquid state vaporizes by absorbing heat corresponding to the latent heat from the circulating water.

[0118] The second indoor heat exchanger (22) is located above the first indoor heat exchanger (21), and changes the secondary refrigerant into a liquid phase by lowering the temperature of the secondary refrigerant through heat exchange with the outdoor cycle (1). The second indoor heat exchanger (22) performs a condenser function. The secondary refrigerant that has undergone a phase change in the second indoor heat exchanger (22) flows in a liquid state through the ninth refrigerant passage (190) to the first indoor heat exchanger (21) located below.

[0119] Meanwhile, the bypass unit (300) is equipped with a bypass pipe (310) that induces a secondary refrigerant in a gaseous state to bypass, and a bypass valve (320) that selectively opens and closes the bypass pipe (310). The bypass pipe (310) is installed so that the secondary refrigerant in a gaseous state can bypass the suction end of the first indoor heat exchanger (21) in order to minimize the loss of high-temperature refrigerant.

[0120] Referring to the attached drawing, the thermosyphon system serves to supply some of the secondary refrigerant vaporized by the evaporation process from the first indoor heat exchanger (21) to the second indoor heat exchanger (22) through the bypass unit (300). Here, the bypass unit (300) can promote natural circulation of the secondary refrigerant by supplying the secondary refrigerant, which is vaporized from the first indoor heat exchanger (21) and moves to the second indoor heat exchanger (22) in the upper side by natural convection, through the bypass pipe (310) into the second indoor heat exchanger (22).

[0121] In addition, during the defrosting operation of the outdoor cycle (1), the secondary refrigerant returns to the first indoor heat exchanger (21) through the ninth refrigerant passage (190). That is, it serves as a path for the liquid secondary refrigerant from the second indoor heat exchanger (22) to move to the first indoor heat exchanger (21) by gravity. The ninth refrigerant passage (190), like other refrigerant passages, is a pipe-shaped member that interconnects the suction end of the second indoor heat exchanger (22) and the discharge end of the first indoor heat exchanger (21), and corresponds to a path for causing the gaseous secondary refrigerant that has risen to the second indoor heat exchanger (22) due to natural convection to fall and flow to the first indoor heat exchanger (221) below.

[0122] Unlike the hot water supply mode, the refrigerant cycle of this type of defrosting operation mode can be converted to a reverse cycle defrosting operation mode through reverse operation in which the refrigerant circulates from the first indoor heat exchanger (21) to the second indoor heat exchanger (22) through the bypass unit (300).

[0123] FIG. 5 is a drawing showing the arrangement of the first indoor heat exchanger (21) and the second indoor heat exchanger (22) of a two-stage compression heat pump device according to an embodiment of the present invention.

[0124] As shown in Fig. 5, the second indoor heat exchanger (22) is installed at a predetermined height above the ground, and the first indoor heat exchanger (21) is installed on the ground.

[0125] The second indoor heat exchanger (22) is used as a condenser of the indoor cycle (1) during the outdoor cycle's defrosting, and stores the secondary refrigerant, which is partially phase-changed from a gaseous refrigerant to a liquid phase through heat exchange with the outdoor cycle (1).

[0126] At this time, the second indoor heat exchanger (22) may be arranged so that the height of the second indoor heat exchanger (22) above the ground (H2) plus the height of the liquid refrigerant section (H1) stored in the second indoor heat exchanger (22) is higher than the height of the liquid + gaseous refrigerant section (H3) in which the liquid refrigerant and gaseous refrigerant of the first indoor heat exchanger (21) are stored, i.e., higher than the height of the first indoor heat exchanger (21).

[0127] Accordingly, the second indoor heat exchanger (22) can be positioned at a predetermined height higher than the first indoor heat exchanger (21) so that the liquid secondary refrigerant generated in the second indoor heat exchanger (22) flows to the first indoor heat exchanger (21) below due to the height difference between the first indoor heat exchanger (21) and the second indoor heat exchanger (22).

[0128] The heat generated from high-temperature circulating water can be utilized for defrosting of the outdoor cycle (1) through a two-stage compression heat pump device using a thermosiphon system configured in this manner.

[0129]

[0130] [Freeze operation mode]

[0131] Hereinafter, the defrosting operation mode for the outdoor cycle of the two-stage compression heat pump device according to the present invention will be described.

[0132] First, high-temperature circulating water is supplied from a hot water supply unit (30) to the circulating water path (21b) of the first indoor heat exchanger (21) of the indoor cycle (2) located on the ground and functioning as an evaporator and circulated, and secondary refrigerant is supplied to the refrigerant circulation path (21a) of the first indoor heat exchanger (21) and circulated. The secondary refrigerant undergoes heat exchange with the high-temperature circulating water and changes into a vaporized gaseous state, thereby increasing its temperature.

[0133] The vaporized high-temperature secondary refrigerant discharged from the first indoor heat exchanger (21) is supplied by natural convection to the evaporation path (22b) of the second indoor heat exchanger (22) located above the first indoor heat exchanger (21) through the bypass pipe (310) of the bypass unit (300). That is, the secondary refrigerant is supplied from the first indoor heat exchanger (21) into the second indoor heat exchanger (22) through the bypass pipe (310) of the bypass unit (300).

[0134] In the second indoor heat exchanger (22), which is located above the first indoor heat exchanger (21) and functions as a condenser, the primary refrigerant supplied to the condensation path (22a) through the outdoor cycle (1) and the secondary refrigerant supplied to the evaporation path (22b) exchange heat with each other.

[0135] The primary refrigerant absorbs heat from the high-temperature secondary refrigerant, thereby removing the frost formed on the outdoor heat exchanger (15) of the outdoor cycle (1).

[0136] In the second indoor heat exchanger (22), the high-temperature secondary refrigerant is condensed through heat exchange with the primary refrigerant. That is, when the temperature of the high-temperature secondary refrigerant decreases and a portion of the secondary refrigerant changes into a liquid phase, the liquid secondary refrigerant can fall by gravity to the first indoor heat exchanger (21) located below the second indoor heat exchanger (22) and be re-introduced into the first indoor heat exchanger (21) through the refrigerant passage (100).

[0137] In the defrosting operation mode for the outdoor cycle of the two-stage compression heat pump device according to the present invention, the first indoor expansion valve (26) can operate in a full-open state to ensure smooth flow of the secondary refrigerant.

[0138] Since the indoor compressor (24) remains in a stopped state and does not operate during the defrost operation mode, the secondary refrigerant does not flow to the indoor compressor (24). As a result, power consumption due to the operation of the indoor compressor (24) can be minimized.

[0139] In this way, the defrost operation mode is set to operate until the end point, and when the defrost operation mode is ended, the indoor compressor (24) that was not in operation can be operated again to switch to hot water supply mode. This becomes possible.

[0140] According to an embodiment of the present invention, by performing the refrigerant flow of the indoor cycle (2) by natural convection using a thermosyphon system and implementing the defrosting operation of the outdoor cycle (1), the high-temperature, gaseous secondary refrigerant from the first indoor heat exchanger (21) is directly supplied to the second indoor heat exchanger (22) by natural convection through the bypass unit (300), thereby minimizing the time required to condense the gaseous secondary refrigerant.

[0141] In addition, the defrosting operation mode can be quickly performed by quickly exchanging heat between the high-temperature, gaseous secondary refrigerant in the second indoor heat exchanger (22) and the primary refrigerant of the outdoor cycle (1) through the bypass unit (300).

[0142]

[0143] The above description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims

1. 1 Outdoor cycle in which the primary refrigerant and outside air exchange heat; and It includes an indoor cycle in which a secondary refrigerant and water supplied from outside at high temperature exchange heat. A first indoor heat exchanger installed on a refrigerant path within the above indoor cycle, wherein the secondary refrigerant evaporates through heat exchange with the high-temperature water and changes into a gas phase and circulates; A second indoor heat exchanger installed on a refrigerant path within the indoor cycle, wherein the secondary refrigerant supplied from the first indoor heat exchanger in a gaseous state is condensed through heat exchange with the primary refrigerant within the outdoor cycle and circulated by changing into a liquid phase; and A two-stage compression heat pump device comprising a bypass unit installed between the first indoor heat exchanger and the second indoor heat exchanger and supplying the secondary refrigerant of the first indoor heat exchanger to the second indoor heat exchanger by natural convection.

2. In paragraph 1, A two-stage compression heat pump device further comprising a liquid path so that the liquid secondary refrigerant in the second indoor heat exchanger moves to the first indoor heat exchanger by gravity.

3. In paragraph 1, The above bypass unit, A two-stage compression heat pump device branched and connected between the suction end of the first indoor heat exchanger and the discharge end of the second indoor heat exchanger.

4. In paragraph 3, The above bypass unit, A two-stage compression heat pump device arranged on a path through which the secondary refrigerant supplied from the first indoor heat exchanger is supplied into the second indoor heat exchanger.

5. In paragraph 4, The above bypass unit, A bypass pipe for bypassing the secondary refrigerant in a gaseous state evaporated in the first indoor heat exchanger; and A two-stage compression heat pump device including a bypass valve that selectively opens and closes the bypass pipe.

6. In any one of paragraphs 1 to 5, The above bypass unit is a two-stage compression heat pump device configured to be selected and operated in the defrost operation mode of the outdoor cycle.

7. In paragraph 6, The above first indoor heat exchanger is located on the ground, The above second indoor heat exchanger is a two-stage compression heat pump device located above the above first indoor heat exchanger.

8. In paragraph 1, A two-stage compression heat pump device in which the indoor compressor of the indoor cycle is in a stopped state and not operating during the defrost operation mode of the outdoor cycle.

9. In paragraph 7, The above second indoor heat exchanger is, A two-stage compression heat pump device in which the height (H2) from the ground and the height (H1) of the liquid refrigerant section stored in the second indoor heat exchanger are placed higher than the height of the first indoor heat exchanger (21).

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