Heat pump system

Abstract

The present invention relates to a heat pump system. In the present invention, the heat pump system includes a gas-liquid separator (40) interposed between an expander (30) and a second heat exchanger (50), so that a gaseous working fluid separated from the gas-liquid separator (40) flows through an inner lower region, in view of the gravity direction, of the second heat exchanger (50). As described above, when the gaseous working fluid flows through the inner lower region of the second heat exchanger (50), heat exchange does not occur in this region, so that frosting does not occur.

Description

heat pump system

[0001] The present invention relates to a heat pump system, and more particularly, to a heat pump system having improved performance in heating operation.

[0002] In the compressor, condenser, expander, and evaporator that make up the heat pump system, a working fluid is used to cause a phase change, thereby performing heating or cooling operation through heat exchange with the outside.

[0003] The above working fluid undergoes a phase change, absorbing heat as it evaporates from a liquid state to a gaseous state in the evaporator. However, when the working fluid in a gaseous state enters the evaporator, the working fluid has already evaporated, which reduces the performance of the evaporator. In addition, there is a problem that moisture in the air condenses and gathers on the outer surface of the evaporator, especially on the lower part in the direction of gravity, and frost formation occurs.

[0004] To solve this problem, a gas-liquid separator was installed in front of the evaporator, and the gas phase and liquid phase working fluid were separated so that only the liquid phase working fluid passed through the evaporator, and the gas phase working fluid was sent to the suction side of the compressor by installing a valve in a separate pipe.

[0005] However, in the prior art, since gas-liquid separation is performed at an intermediate pressure higher than the evaporation pressure, an additional expander is required, and there was a problem in that it was difficult to make the evaporator inlet side 100% liquid working fluid.

[0006] In addition, the compressor oil mixed in the working fluid becomes a factor that interferes with heat exchange when it enters the evaporator. However, in the conventional technology, the oil could not be separated, and during defrosting or cooling operation, a valve must be used to block the working fluid from flowing back into the pipe through which the gaseous working fluid flows, so there is a problem that separate parts must be included and valve control must be performed.

[0007] Prior art technologies that have the above problems include EP registered patent 3604977 and Japanese published patent 2010-181090.

[0008] The purpose of the present invention is to solve the problems of the prior art as described above, and to ensure that only a liquid working fluid is transferred into a heat exchanger used as an evaporator in a heat pump system.

[0009] The purpose of the present invention is to prevent frost formation on the outer surface of a heat exchanger used as an evaporator in a heat pump system.

[0010] The purpose of the present invention is to enable the flow of a gaseous working fluid between a compressor and a gas-liquid separator without a separate control process.

[0011] The purpose of the present invention is to prevent oil from entering the interior of a heat exchanger used as an evaporator together with a working fluid.

[0012] In order to achieve the above-described purpose, the heat pump system according to the present invention allows a gaseous working fluid that has passed through an expander to flow through a gravity-directed lower region inside a second heat exchanger.

[0013] In the present invention, a gas-liquid separator is used so that only liquid-state working fluid enters the second heat exchanger from the expander.

[0014] In the present invention, the gaseous working fluid separated from the gas-liquid separator is allowed to flow through the lower region inside the second heat exchanger using a separate gas-liquid connection pipe.

[0015] The heat pump system of the present invention may include a first heat exchanger for performing heat exchange between a working fluid and the outside, a second heat exchanger for performing heat exchange between the working fluid and the outside, a compressor for compressing the working fluid between the first heat exchanger and the second heat exchanger, an expander for expanding the working fluid between the first heat exchanger and the second heat exchanger, a four-way valve for transferring the working fluid compressed in the compressor to the first heat exchanger or the second heat exchanger, a gas-liquid separator installed between the expander and the second heat exchanger for separating the gaseous working fluid and the liquid working fluid, and a gas-phase connecting pipe for connecting the gas-liquid separator and the second heat exchanger so that the gaseous working fluid flows in a lower region in the gravity direction of the second heat exchanger.

[0016] Between the above-mentioned gas connection pipe and the second heat exchanger, a pipe having a check valve and a capillary or diaphragm structure is connected in parallel, and the check valve can allow the working fluid to flow only in the direction of the second heat exchanger.

[0017] The above-mentioned gas-liquid connection pipe is connected to a relatively upper portion of the gas-liquid separator, and the gaseous working fluid separated from the gas-liquid separator can flow through the above-mentioned gas-liquid connection pipe.

[0018] In operation where the second heat exchanger operates as an evaporator, a liquid-state working fluid can flow from the gas-liquid separator to the second heat exchanger through a connecting pipe connected to a relatively lower side of the gas-liquid separator.

[0019] The above-mentioned gas connection pipe is connected to one or more flow paths passing through an area corresponding to the inner lower part of the second heat exchanger, so that a gaseous working fluid can flow within the second heat exchanger.

[0020] A first header is installed on one side of the second heat exchanger and is connected to a connecting pipe connected to the gas-liquid separator side, and a second header is installed on the other side of the second heat exchanger and is connected to a connecting pipe connected to the compressor side. The first header and the second header each have a plurality of branch passages so that the working fluid flowing along the plurality of passages can be collected, or the working fluid can be divided and flowed along the plurality of passages.

[0021] An oil recovery pipe may be further provided to connect the above-mentioned gas-liquid separator and the above-mentioned gas-phase connection pipe.

[0022] The above oil recovery pipe is connected to the lowest end of the gas-liquid separator and can collect oil collected at the lower part of the gas-liquid separator in the direction of gravity.

[0023] The present invention relates to a heat pump system comprising a compressor for compressing a working fluid, first and second heat exchangers for performing heat exchange between the working fluid and the outside, and an expander for expanding the working fluid, wherein the working fluid flows in the order of the compressor, the first heat exchanger, the expander, and the second heat exchanger or vice versa, and may include a gas-liquid separator provided between the expander and the second heat exchanger to separate the working fluid in a gaseous state and the working fluid in a liquid state, and a gas-phase connecting pipe for flowing the working fluid in a gaseous state from the gas-liquid separator through an inner lower region in the direction of gravity of the second heat exchanger.

[0024] It may further include a four-way valve for selectively sending the working fluid from the compressor to the first heat exchanger or the second heat exchanger.

[0025] The above gas-liquid separator may further include an oil recovery pipe having one end connected to the lowermost side and the other end connected to the gas-liquid connection pipe.

[0026] The above-mentioned gas connection pipe is connected to one or more flow paths passing through an area corresponding to the inner lower part of the second heat exchanger, so that a gaseous working fluid can flow within the second heat exchanger.

[0027] The above-mentioned gas-liquid connection pipe is connected to a relatively upper portion of the gas-liquid separator, and the gaseous working fluid separated from the gas-liquid separator can flow through the above-mentioned gas-liquid connection pipe.

[0028] Between the above-mentioned gas connection pipe and the second heat exchanger, a pipe having a check valve and a capillary or diaphragm structure is connected in parallel, and the check valve can allow the working fluid to flow only in the direction of the second heat exchanger.

[0029] The heat pump system according to the present invention may have at least one of the following effects.

[0030] In the present invention, the separated gaseous working fluid flows through a path in the lower portion of the heat exchanger before entering the heat exchanger, which functions as an evaporator, and is then sent to the compressor. This configuration prevents frost formation in the lower portion of the heat exchanger during heating operation, thereby improving the operating efficiency of the heat pump system.

[0031] In the present invention, the gaseous working fluid separated from the gas-liquid separator can be delivered to the compressor through a capillary tube and check valve installed in the gas-liquid connection pipe without separate control, and the gaseous working fluid can also be delivered in the reverse direction without separate control. Therefore, the operation of the heat pump system is relatively easy.

[0032] In the present invention, the gaseous working fluid passes only to the lower part of the heat exchanger that functions as an evaporator without heat exchange, and the remaining liquid working fluid passes through multiple passages within the heat exchanger, so that the evaporation performance and pressure loss are greatly improved.

[0033] In addition, since the present invention supplies only a liquid-state working fluid to a heat exchanger that functions as an evaporator by using a gas-liquid separator, a header or manifold that simply separates the flow path can be used at the inlet of the heat exchanger that functions as an evaporator, and a relatively expensive distributor does not need to be used.

[0034] In another embodiment of the present invention, oil separated and positioned at the lowest portion of the gas-liquid separator is delivered to the compressor through a separate oil separation pipe. Therefore, oil is prevented from entering the heat exchanger, which functions as an evaporator, thereby significantly increasing the efficiency of the heat exchanger.

[0035] Figure 1 is a system configuration diagram showing a preferred embodiment of a heat pump system according to the present invention.

[0036] Figure 2 is a system configuration diagram showing another embodiment to which a heat pump system according to the present invention is applied.

[0037] Figure 3 is an operational state diagram showing the heating operation of the embodiment illustrated in Figure 1.

[0038] Figure 4 is an operational state diagram showing the example illustrated in Figure 1 performing cooling operation.

[0039] Figure 5 is an operational state diagram showing the heating operation of the embodiment illustrated in Figure 2.

[0040] Figure 6 is an operational state diagram showing the example illustrated in Figure 2 performing cooling operation.

[0041] Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. When designating components in each drawing, it should be noted that, where possible, identical components will be given the same reference numerals, even if they appear in different drawings. Furthermore, when describing embodiments of the present invention, if a detailed description of a related known structure or function is deemed to hinder understanding of the embodiments of the present invention, such detailed description will be omitted.

[0042] 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.

[0043] A preferred embodiment of a heat pump system according to the present invention is described with reference to Fig. 1. In this embodiment, a compressor (10), a first heat exchanger (20), an expander (30), a gas-liquid separator (40), and a second heat exchanger (50) are sequentially connected by connecting pipes (10', 20', 30', 40', 50'), and a working fluid is phase-changed and heat exchanged with the outside while passing through the compressor (10), the first heat exchanger (20), the expander (30), and the second heat exchanger (50) in sequence.

[0044] The compressor (10) compresses the working fluid in a gaseous state to make it into a relatively high temperature, high pressure gaseous state. The outlet side of the compressor (10) is connected to the inlet side of the first heat exchanger (20) through a connecting pipe (10'). The connecting pipe (10') is connected to a four-way valve (12). The working fluid can selectively flow to the first heat exchanger (20) or the second heat exchanger (40) by the four-way valve (12). Drawing reference numeral 14 denotes an accumulator that separates the working fluid in a liquid state and allows the working fluid in a gaseous state to flow to the compressor (10).

[0045] In the first heat exchanger (20), the working fluid transmitted from the compressor (10) through the connecting pipe (10') exchanges heat with the outside. Through this heat exchange, the working fluid becomes a relatively low-temperature, high-pressure liquid. The first heat exchanger (20) functions as a condenser when the heat pump system is in heating operation. A connecting pipe (20') is connected to the outlet of the first heat exchanger (20), and the inlet side of the expander (30) and the first heat exchanger (20) are connected through the connecting pipe (20').

[0046] The above expander (30) receives the working fluid that has passed through the first heat exchanger (20) through the connecting pipe (20'). A connecting pipe (30') is connected to the outlet of the expander (30). The connecting pipe (30') is connected to the gas-liquid separator (40). In the expander (30), the working fluid is expanded to become a liquid state with a relatively low temperature and low pressure. However, not all of the working fluid that exits the expander (30) becomes a liquid state. Therefore, there is also a gaseous working fluid.

[0047] The working fluid from the above expander (30) goes to the gas-liquid separator (40) through the connecting pipe (30'). In the gas-liquid separator (40), the gaseous working fluid and the liquid working fluid are separated. In the gas-liquid separator (40), the liquid working fluid is relatively located at the lower part of the gas-liquid separator (40) due to gravity, and the gaseous working fluid is relatively located at the upper part of the gas-liquid separator (40).

[0048] A connecting pipe (40') is connected to a relatively lower outlet of the above-mentioned gas-liquid separator (40). The connecting pipe (40') is connected to the inlet side of the above-mentioned second heat exchanger (50). A gas-phase connecting pipe (60) is connected to the other outlet of the above-mentioned gas-liquid separator (40), i.e., a relatively upper outlet. A liquid-phase working fluid is transferred to the above-mentioned second heat exchanger (50) through the connecting pipe (40'). A gas-phase working fluid flows through the above-mentioned gas-phase connecting pipe (60).

[0049] The liquid working fluid coming out of the above-mentioned gas-liquid separator (40) flows into the second heat exchanger (50). The second heat exchanger (50) has a first header (52) on one side. The first header (52) has a plurality of branch passages, and these branch passages are connected to respective passages of the second heat exchanger (50). Therefore, the first header (52) separates the working fluid into a plurality of passages and allows it to flow so that heat is exchanged while passing through the inside of the second heat exchanger (50), or the working fluids passing through the inside of the second heat exchanger (50) are collected and allowed to flow as one.

[0050] On the other side of the second heat exchanger (50), there is a second header (54). The second header (54) combines the working fluid flowing through a plurality of branch channels into one and transmits it to a connecting pipe (50'). Alternatively, the second header (54) allows the working fluid transmitted through the connecting pipe (50') to flow through a plurality of channels inside the second heat exchanger (50) during cooling operation.

[0051] The above-mentioned gas-phase connection pipe (60) is connected to the outlet side of the compressor (10). The above-mentioned gas-phase connection pipe (60) is connected to a passage located relatively lower in the second heat exchanger (50). That is, the gas-phase working fluid flowing through the gas-phase connection pipe (60) flows in a passage located relatively lower in the second heat exchanger (50). Here, the above-mentioned gas-phase connection pipe (60) may be connected to one or more passages located relatively lower in the second heat exchanger (50). This is to allow the gas-phase working fluid to flow in the lower region of the interior of the second heat exchanger (50) so that heat exchange does not occur in the lower region of the second heat exchanger (50). That is, since heat exchange does not occur in the lower region of the second heat exchanger (50), the temperature can be maintained relatively higher than the remaining region of the second heat exchanger (50). Therefore, frost does not occur in the area where the working fluid transmitted through the above-mentioned weather connection pipe (60) flows.

[0052] The working fluid supplied by the above-mentioned gas connection pipe (60) passes through the second heat exchanger (50) and exits to the outside through the gas outlet pipe (60'). The above-mentioned gas outlet pipe (60') can be connected to the inlet side of the above-mentioned compressor (10).

[0053] A check valve (62) and a capillary tube (64) are connected in parallel between the above-mentioned gas-phase connecting pipe (60) and the inlet of the second heat exchanger (50). The check valve (62) allows the gaseous working fluid to flow only from the gas-liquid separator (40) to the second heat exchanger (50) through the above-mentioned gas-phase connecting pipe (60), and prevents it from flowing in the opposite direction. Therefore, when the heat pump system is in cooling or defrosting operation, the working fluid does not flow through the check valve (62). Only a portion of the gaseous working fluid flows through the capillary tube (64). In addition, when in heating operation, the gaseous working fluid mainly flows through the check valve (62), and a portion of the working fluid may flow through the capillary tube (64). For reference, a pipe having a throttling structure may be used instead of the capillary tube (64).

[0054] Next, Fig. 2 illustrates a heat pump system according to another embodiment of the present invention. In this embodiment, a compressor (110), a first heat exchanger (120), an expander (130), a gas-liquid separator (140), and a second heat exchanger (150) are sequentially connected by connecting pipes (110', 120', 130', 140', 150'), and the working fluid undergoes a phase change and exchanges heat with the outside while passing through the compressor (110), the first heat exchanger (120), the expander (130), and the second heat exchanger (150) in that order.

[0055] The compressor (110) compresses the working fluid in a gaseous state to make it into a relatively high temperature, high pressure gaseous state. The outlet side of the compressor (110) is connected to the inlet side of the first heat exchanger (120) through a connecting pipe (110'). The connecting pipe (110') is connected to a four-way valve (112). The working fluid can selectively flow to the first heat exchanger (120) or the second heat exchanger (140) by the four-way valve (112). Drawing reference numeral 114 denotes an accumulator that separates the working fluid in a liquid state and allows the working fluid in a gaseous state to flow to the compressor (110).

[0056] In the first heat exchanger (120), the working fluid transmitted from the compressor (110) through the connecting pipe (110') exchanges heat with the outside. Through this heat exchange, the working fluid becomes a relatively low-temperature, high-pressure liquid. The first heat exchanger (120) functions as a condenser when the heat pump system is in heating operation. A connecting pipe (120') is connected to the outlet of the first heat exchanger (120), and the inlet side of the expander (130) and the first heat exchanger (120) are connected through the connecting pipe (120').

[0057] The above expander (130) receives the working fluid that has passed through the first heat exchanger (120) through the connecting pipe (120'). A connecting pipe (130') is connected to the outlet of the expander (130). The connecting pipe (130') is connected to the gas-liquid separator (140). In the expander (130), the working fluid is expanded to become a liquid state with a relatively low temperature and low pressure. However, not all of the working fluid that exits the expander (130) becomes a liquid state. Therefore, there is also a gaseous working fluid.

[0058] The working fluid from the above expander (130) goes to the gas-liquid separator (140) through the connecting pipe (130'). In the gas-liquid separator (140), the gaseous working fluid and the liquid working fluid are separated. In the gas-liquid separator (140), the liquid working fluid is relatively located at the lower part of the gas-liquid separator (140) due to gravity, and the gaseous working fluid is relatively located at the upper part of the gas-liquid separator (140).

[0059] And, a part of the oil of the compressor (110) flows within the system together with the working fluid, and the oil may be at the lowest side within the gas-liquid separator (140). In this way, the oil may be located at the lowest side within the gas-liquid separator (140). In particular, when the working fluid is relatively light compared to the oil, for example, when it is a working fluid such as R290, it is very easy to separate the oil in this way.

[0060] A connecting pipe (140') is connected to a relatively lower outlet of the above-mentioned gas-liquid separator (140). The connecting pipe (140') is connected to the inlet side of the above-mentioned second heat exchanger (150). A gas-phase connecting pipe (160) is connected to the other outlet of the above-mentioned gas-liquid separator (140), that is, the relatively upper outlet. A liquid-phase working fluid is transferred to the above-mentioned second heat exchanger (150) through the connecting pipe (140'). A gas-phase working fluid flows through the above-mentioned gas-phase connecting pipe (160). In addition, an oil return pipe (161) is connected to the lowest end of the above-mentioned gas-liquid separator (140).

[0061] The liquid working fluid coming from the above-mentioned gas-liquid separator (140) flows to the second heat exchanger (150). The second heat exchanger (150) has a first header (152) on one side. The first header (152) has a plurality of branch passages, and these branch passages are connected to respective passages of the second heat exchanger (150). Therefore, the first header (152) separates the working fluid into a plurality of passages and allows it to flow so that heat is exchanged while passing through the interior of the second heat exchanger (150). Alternatively, the working fluid flowing through the plurality of passages inside the second heat exchanger (150) is collected and delivered to the connecting passage (140').

[0062] On the other side of the second heat exchanger (150), there is a second header (154). The second header (154) combines the working fluid flowing through the multiple branch channels and transfers it to the connecting pipe (150'). Alternatively, the second header (154) allows the working fluid transferred through the connecting pipe (150') to flow separately into multiple channels within the second heat exchanger (150).

[0063] The above-mentioned gas-phase connection pipe (160) is connected to the outlet side of the compressor (110). The above-mentioned gas-phase connection pipe (160) is connected to a passage located relatively lower in the second heat exchanger (150). That is, the gas-phase working fluid flowing through the above-mentioned gas-phase connection pipe (160) flows in a passage located relatively lower in the second heat exchanger (150). Here, the above-mentioned gas-phase connection pipe (160) may be connected to one or more passages located relatively lower in the above-mentioned second heat exchanger (150). This is to allow the gas-phase working fluid to flow in a lower region within the above-mentioned second heat exchanger (150) so that heat exchange does not occur in the lower region of the above-mentioned second heat exchanger (150). That is, since heat exchange does not occur in the lower region of the above-mentioned second heat exchanger (150), the temperature can be maintained at a relatively higher level than the remaining region of the above-mentioned second heat exchanger (150). Accordingly, frost does not occur in the area where the working fluid transmitted through the above-mentioned weather connection pipe (160) flows.

[0064] The working fluid supplied by the above-mentioned gas connection pipe (160) passes through the second heat exchanger (150) and exits to the outside through the gas outlet pipe (160'). The above-mentioned gas outlet pipe (160') can be connected to the inlet side of the compressor (110).

[0065] The oil in the gas-liquid separator (140) can flow through the oil recovery pipe (161). The oil recovery pipe (161) is connected to the gas connection pipe (160) and can be delivered to the compressor (110) by passing through the lower part of the second heat exchanger (150) together with the gaseous working fluid.

[0066] A check valve (162) and a capillary tube (164) are connected in parallel between the above-mentioned gas-phase connecting pipe (160) and the inlet of the second heat exchanger (150). The check valve (162) allows the gaseous working fluid to flow only from the gas-liquid separator (140) to the second heat exchanger (150) through the above-mentioned gas-phase connecting pipe (160), and prevents it from flowing in the opposite direction. Therefore, when the heat pump system is in cooling or defrosting operation, the working fluid does not flow through the check valve (162). Only a portion of the gaseous working fluid flows through the capillary tube (164). In addition, when in heating operation, the gaseous working fluid mainly flows through the check valve (162), and a portion of the working fluid may flow through the capillary tube (164). For reference, a pipe with a capillary structure may be used instead of the above capillary tube (164).

[0067] The operation of the heat pump systems according to the present invention having the configuration described above will be described in detail below.

[0068] First, the operation of the heat pump system of the embodiment illustrated in FIG. 1 in heating mode will be described with reference to FIG. 3. In this case, the first heat exchanger (20) operates as a condenser, and the second heat exchanger (50) operates as an evaporator. The relatively high-temperature, high-pressure gaseous working fluid compressed in the compressor (10) flows through the four-way valve (12) to the first heat exchanger (20), and the first heat exchanger (20) releases heat to the outside, thereby becoming a relatively low-temperature, high-pressure liquid working fluid. At this time, the heat released to the outside is used for heating.

[0069] The working fluid coming out of the first heat exchanger (20) flows into the expander (30) through the connecting pipe (20'). In the expander (30), the working fluid expands and becomes a liquid state with relatively low temperature and low pressure. The working fluid coming out of the expander (30) flows through the connecting pipe (30') and is delivered to the gas-liquid separator (40). The working fluid delivered into the gas-liquid separator (40) is positioned such that the gaseous working fluid and the liquid working fluid are separated by gravity.

[0070] The working fluid flows into the second heat exchanger (50) through a connecting pipe (40') connected to one outlet of the above-mentioned gas-liquid separator (40). In the second heat exchanger (50), the working fluid in a liquid state with a relatively low temperature and low pressure receives heat from the outside and becomes a gas state with a high temperature and low pressure. Then, it flows through the connecting pipe (50') and enters the compressor (10) through the accumulator (14).

[0071] Meanwhile, a gaseous working fluid flows through a vapor-phase connecting pipe (60) connected to the other outlet of the vapor-liquid separator (40). The gaseous working fluid passes through the check valve (62) and capillary tube (64) or throttling mechanism installed in parallel and is delivered to a flow path passing through the lower part of the second heat exchanger (50). The working fluid exiting the second heat exchanger (50) enters the compressor (10) through the four-way valve (12) and accumulator (14) via the vapor-phase outlet pipe (60').

[0072] In this way, only the liquid-state working fluid flows from the gas-liquid separator (40) to the second heat exchanger (50), and is divided into multiple paths through the first header (52) and flows inside the second heat exchanger (50), so that the evaporation efficiency increases and the heat exchange efficiency increases.

[0073] Meanwhile, since the working fluid passing through the path formed in the lower part of the second heat exchanger (50) through the gaseous connection pipe (60) is in a gaseous state, it does not exchange heat in the second heat exchanger (50). Therefore, the temperature of the lower part of the second heat exchanger (50) may be relatively higher than the temperature of other parts from which evaporation heat is lost. Therefore, frosting does not occur in the lower part of the second heat exchanger (50). For reference, the path through which the working fluid transmitted through the gaseous connection pipe (60) passes through the lower part of the second heat exchanger (50) may be one or more. In any case, it is preferable that these paths be located below the gravity direction of the second heat exchanger (50).

[0074] Next, the operation of the heat pump system of the embodiment illustrated in FIG. 1 in cooling mode will be described with reference to FIG. 4. In this case, the first heat exchanger (20) operates as a generator, and the second heat exchanger (50) operates as a condenser. The relatively high-temperature, high-pressure gaseous working fluid compressed in the compressor (10) flows through the four-way valve (12) to the second heat exchanger (50), and in the second heat exchanger (50), heat is released to the outside to become a relatively low-temperature, high-pressure liquid working fluid.

[0075] The working fluid from the second heat exchanger (50) enters the gas-liquid separator (40) through the connecting pipe (40'). The working fluid that enters the gas-liquid separator (40) flows to the expander (30) through the connecting pipe (30'). In the expander (30), the working fluid expands and becomes a relatively low-temperature, low-pressure liquid state. Next, the working fluid from the expander (30) flows through the connecting pipe (20') and flows to the first heat exchanger (20). The working fluid that flows to the first heat exchanger (20) receives heat from the outside and becomes a high-temperature, low-pressure gaseous state. Here, since the first heat exchanger (20) takes in heat from the outside, a cooling effect occurs outside. The working fluid coming out of the first heat exchanger (20) passes through the four-way valve (12) and accumulator (14) and enters the compressor (10), repeating the process described above.

[0076] Meanwhile, the working fluid does not flow through the lower region of the second heat exchanger (50) via the above-described gas outlet pipe (60'). This is because the working fluid cannot flow from the right to the left in the drawing through the check valve (62). In addition, only a very small amount of the working fluid can move through the capillary tube (64) connected in parallel with the check valve (62).

[0077] Next, the operation of the heat pump system of the embodiment illustrated in FIG. 2 in heating mode will be described with reference to FIG. 5. In this case, the first heat exchanger (120) operates as a condenser, and the second heat exchanger (150) operates as an evaporator. The relatively high-temperature, high-pressure gaseous working fluid compressed in the compressor (110) flows through the four-way valve (112) to the first heat exchanger (120), and the first heat exchanger (120) releases heat to the outside, thereby becoming a relatively low-temperature, high-pressure liquid working fluid. At this time, the heat released to the outside is used for heating.

[0078] The working fluid coming out of the first heat exchanger (120) flows into the expander (130) through the connecting pipe (120'). In the expander (130), the working fluid expands and becomes a liquid state with a relatively low temperature and low pressure. The working fluid coming out of the expander (130) flows through the connecting pipe (130') and is delivered to the gas-liquid separator (140). The working fluid delivered into the gas-liquid separator (140) is separated into a gaseous working fluid and a liquid working fluid by gravity and positioned.

[0079] The working fluid flows into the second heat exchanger (150) through a connecting pipe (140') connected to one outlet of the above-mentioned gas-liquid separator (140). In the second heat exchanger (150), the working fluid in a liquid state with a relatively low temperature and low pressure receives heat from the outside and becomes a gas state with a high temperature and low pressure. Then, it flows through the connecting pipe (150') and enters the compressor (110) through the accumulator (114).

[0080] Meanwhile, a gaseous working fluid flows through a vapor-phase connecting pipe (160) connected to the other outlet of the vapor-liquid separator (140). The gaseous working fluid passes through the check valve (162) and capillary tube (164) or throttling mechanism installed in parallel and is delivered to a flow path passing through the lower part of the second heat exchanger (150). The working fluid exiting the second heat exchanger (150) enters the compressor (110) through the four-way valve (112) and accumulator (114) via the vapor-phase outlet pipe (160').

[0081] In this way, only the liquid-state working fluid flows from the gas-liquid separator (140) to the second heat exchanger (150), and is divided into multiple paths through the first header (152) and flows within the second heat exchanger (150), thereby increasing the evaporation efficiency and thus the heat exchange efficiency.

[0082] Meanwhile, since the working fluid passing through the path formed in the lower part of the second heat exchanger (150) through the above-mentioned gaseous connection pipe (160) is in a gaseous state, it does not exchange heat in the second heat exchanger (150). Accordingly, the temperature of the lower part of the second heat exchanger (150) may be relatively higher than the temperature of other parts from which evaporation heat is lost. Accordingly, frosting does not occur in the lower part of the second heat exchanger (150). For reference, the path through which the working fluid transmitted through the above-mentioned gaseous connection pipe (160) passes through the lower part of the second heat exchanger (150) may be one or more. In any case, it is preferable that these paths be located below the gravity direction of the second heat exchanger (150).

[0083] And, in this embodiment, the oil separated in the gas-liquid separator (140) flows through the oil return pipe (161) connected to the lowermost part of the gas-liquid separator (140). The oil coming out of the gas-liquid separator (140) passes through the oil return pipe (161), the check valve (162) and the capillary tube (164), and enters the suction side of the compressor (110) through the gas outlet pipe (160'). Therefore, the oil does not flow through the passage in the part of the second heat exchanger (150) where heat exchange with the outside takes place, thereby increasing the heat exchange efficiency.

[0084] Next, the operation of the heat pump system of the embodiment illustrated in FIG. 2 in cooling mode will be described with reference to FIG. 6. In this case, the first heat exchanger (120) operates as a generator, and the second heat exchanger (150) operates as a condenser. The relatively high-temperature, high-pressure gaseous working fluid compressed in the compressor (110) flows through the four-way valve (112) to the second heat exchanger (150), and in the second heat exchanger (150), heat is released to the outside to become a relatively low-temperature, high-pressure liquid working fluid.

[0085] The working fluid from the second heat exchanger (150) enters the gas-liquid separator (140) through the connecting pipe (140'). The working fluid that enters the gas-liquid separator (140) flows to the expander (130) through the connecting pipe (130'). In the expander (130), the working fluid expands and becomes a relatively low-temperature, low-pressure liquid state. Next, the working fluid from the expander (130) flows through the connecting pipe (120') and into the first heat exchanger (120). The working fluid that flows into the first heat exchanger (120) receives heat from the outside and becomes a high-temperature, low-pressure gaseous state. Here, since the first heat exchanger (120) takes in heat from the outside, a cooling effect occurs outside. The working fluid coming out of the first heat exchanger (120) passes through the four-way valve (112) and accumulator (114) and enters the compressor (110), repeating the process described above.

[0086] Meanwhile, the working fluid does not flow through the lower region of the second heat exchanger (150) via the above-described gas outlet pipe (160'). This is because the working fluid cannot flow from the right to the left in the drawing through the check valve (162). In addition, only a very small amount of the working fluid can move through the capillary tube (164) connected in parallel with the check valve (162).

[0087] Even though all components constituting the embodiments according to the present invention have been described as being combined or operating in combination, the present invention is not necessarily limited to such embodiments. That is, within the scope of the purpose of the present invention, all components may be selectively combined and operated one or more times. In addition, terms such as "include," "comprise," or "have" described above, unless specifically stated to the contrary, mean that the corresponding component may be inherent, and therefore should be interpreted as including other components rather than excluding other components. All terms, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the art to which the present invention pertains, unless otherwise defined. Commonly used terms, such as terms defined in a dictionary, should be interpreted as being consistent with the contextual meaning of the related technology, and shall not be interpreted in an ideal or overly formal sense, unless explicitly defined in the present invention.

[0088] The above description is merely an illustrative illustration of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate, rather than limit, the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

Claims

1. A first heat exchanger that performs heat exchange between the working fluid and the outside, A second heat exchanger that performs heat exchange between the working fluid and the outside, A compressor that compresses a working fluid between the first heat exchanger and the second heat exchanger, An expander that expands the working fluid between the first heat exchanger and the second heat exchanger, A four-way valve that transfers the compressed working fluid from the compressor to the first heat exchanger or the second heat exchanger, A gas-liquid separator installed between the above expander and the second heat exchanger to separate the gaseous working fluid and the liquid working fluid, A heat pump system including a gas-phase connecting pipe that connects the gas-liquid separator and the second heat exchanger to allow a gaseous working fluid to flow in the lower region of the gravity direction of the second heat exchanger.

2. A heat pump system in which, in paragraph 1, a pipe having a check valve and a capillary tube or a capillary structure is connected in parallel between the gas connection pipe and the second heat exchanger, and the check valve allows the working fluid to flow only in the direction of the second heat exchanger.

3. In the second paragraph, the gas-phase connection pipe is connected to a relatively upper portion of the gas-liquid separator, and the heat pump system in which the gaseous working fluid separated from the gas-liquid separator flows through the gas-phase connection pipe.

4. A heat pump system in which, in the first paragraph, the second heat exchanger operates as an evaporator, a liquid-state working fluid flows from the gas-liquid separator to the second heat exchanger through a connecting pipe connected to a relatively lower side of the gas-liquid separator.

5. In the first paragraph, the gas connection pipe is connected to one or more flow paths passing through an area corresponding to the inner lower part of the second heat exchanger, and is a heat pump system that causes a gaseous working fluid to flow within the second heat exchanger.

6. In the first paragraph, a first header is installed on one side of the second heat exchanger and is connected to a connecting pipe connected to the gas-liquid separator side, and a second header is installed on the other side of the second heat exchanger and is connected to a connecting pipe connected to the compressor side, wherein the first header and the second header are each provided with a plurality of branch channels to collect the working fluid flowing along the plurality of channels or to divide the working fluid and flow along the plurality of channels.

7. A heat pump system according to any one of paragraphs 1 to 6, further comprising an oil recovery pipe to connect the gas-liquid separator and the gas-phase connection pipe.

8. In the 7th paragraph, the oil recovery pipe is connected to the lowest end of the gas-liquid separator and is a heat pump system that collects oil collected in the lower part of the gas-liquid separator in the direction of gravity.

9. Compressor that compresses the working fluid, First and second heat exchangers that perform heat exchange between the working fluid and the outside, Includes an expander that expands the working fluid, In a heat pump system in which the working fluid flows in the order of the compressor, the first heat exchanger, the expander, and the second heat exchanger or vice versa, A gas-liquid separator provided between the above expander and the second heat exchanger to separate the gaseous working fluid and the liquid working fluid, A heat pump system including a gas-phase connecting pipe that causes the gaseous working fluid from the above-mentioned gas-liquid separator to flow through the gravity-directed inner lower region of the above-mentioned second heat exchanger.

10. A heat pump system further comprising a four-way valve for selectively sending the working fluid from the compressor to the first heat exchanger or the second heat exchanger in the 9th paragraph.

11. A heat pump system further comprising an oil recovery pipe having one end connected to the lowermost side of the gas-liquid separator and the other end connected to the gas-phase connection pipe in the 9th paragraph.

12. In the 9th paragraph, the gas connection pipe is connected to one or more flow paths passing through an area corresponding to the inner lower part of the second heat exchanger, and is a heat pump system that causes a gaseous working fluid to flow within the second heat exchanger.

13. In the 9th paragraph, the gas-phase connection pipe is connected to a relatively upper portion of the gas-liquid separator, and the heat pump system in which the gaseous working fluid separated from the gas-liquid separator flows through the gas-phase connection pipe.

14. A heat pump system according to any one of paragraphs 9 to 13, wherein a pipe having a check valve and a capillary tube or a capillary structure is connected in parallel between the gas connection pipe and the second heat exchanger, and the check valve allows the working fluid to flow only in the direction of the second heat exchanger.

Images