Heat pump system for preventing freezing of evaporator

Abstract

The present invention relates to a heat pump system for preventing freezing of an evaporator, comprising: a heat source supply unit for supplying a heat source fluid; a heat source flow line through which the heat source fluid flows; a refrigerant line for forming a heating cycle through which a refrigerant flows; an evaporator installed in the refrigerant line in which heat exchanges heat between the heat source fluid flowing through the heat source flow line and the refrigerant flowing through the refrigerant line; a heat pump having a first compressor and a second compressor sequentially installed in the refrigerant line to compress the refrigerant from the evaporator; and a compensation heat exchange unit for exchanging heat between at least a portion of the refrigerant compressed by the first compressor and the heat source fluid flowing toward the evaporator side through the heat source flow line. Through this, freezing on the evaporator side can be prevented by using a portion of the refrigerant from the first compressor of the heat pump.

Description

Technology Field

[0001] The present invention relates to a heat pump system for preventing freezing of an evaporator, and more specifically, to a heat pump system for preventing freezing of an evaporator using a water source. Background Technology

[0002] As hydrothermal energy was included in renewable energy through the amendment of the 2020 Renewable Energy Act, hydrothermal heat pump systems are becoming widely adopted.

[0003] When heating using a water source, an indirect heat exchange method is used by utilizing a secondary fluid because the heat source, such as river water, lake water, or raw tap water, contains a large amount of impurities.

[0004] Here, the secondary fluid can be brine or water, and if it is brine, freezing problems may occur in the water source heat exchanger, and if it is water, freezing problems may occur in the evaporator of the heat pump.

[0005] Although this freezing problem can be prevented to some extent by reducing the delta T on the water side of the evaporator through partial load operation of the heat pump, in the case of turbo compressors applied to large systems, partial load operation is limited by surging phenomena, so a separate technology is required to enable operation even at low delta T.

[0006] This phenomenon poses a risk of freezing as the temperature of the heat source drops below freezing during winter heating operation, and consequently, there is a problem that continuous operation is difficult. Consequently, a separate boiler system must be installed for heating when the water temperature drops in winter, and the winter operating rate of the heat pump decreases. The problem to be solved

[0007] Accordingly, the present invention has been devised to solve the above-mentioned problems, and aims to provide a heat pump system for preventing freezing of an evaporator, which prevents and eliminates freezing phenomena at the outlet side of a heat source fluid, such as a secondary fluid, and ensures continuous operation of heating in winter.

[0008] In addition, another objective of the present invention is to provide a heat pump system for preventing freezing of an evaporator, which enables continuous operation without turning the heat pump on and off, in order to prevent and eliminate freezing phenomena on the evaporator side. means of solving the problem

[0009] The above objective is achieved according to the present invention by a heat pump system for preventing freezing of an evaporator, comprising: a heat source supply unit for supplying a heat source fluid; a heat source flow line through which the heat source fluid flows; a refrigerant line for forming a heating cycle through which a refrigerant flows; an evaporator installed in the refrigerant line in which heat exchanges heat between the heat source fluid flowing through the heat source flow line and the refrigerant flowing through the refrigerant line; a heat pump having a first compressor and a second compressor sequentially installed in the refrigerant line to compress the refrigerant from the evaporator; and a compensation heat exchange unit for heat exchange between at least a portion of the refrigerant compressed by the first compressor and the heat source fluid flowing toward the evaporator through the heat source flow line.

[0010] Here, the heat pump may further include a condenser, a first expansion valve, and a second expansion valve installed sequentially in the refrigerant line along the flow direction of the refrigerant from the second compressor, and a flash tank installed in the refrigerant line between the first expansion valve and the second expansion valve through which the liquid refrigerant from the first expansion valve passes.

[0011] Additionally, the above-mentioned heat source flow line includes an inlet side heat source flow line through which a heat source fluid flows from the heat source supply unit to the evaporator side, and a return side heat source flow line through which a heat source fluid flows from the evaporator to the heat source supply unit side; the above-mentioned compensation heat exchanger may include a first compensation flow line connected to the inlet side heat source flow line through which at least a portion of the heat source fluid flowing through the inlet side heat source flow line flows, a second compensation flow line through which at least a portion of the refrigerant from the first compressor flows, with one side branched from the refrigerant line between the first compressor and the second compressor and the other side connected to the flash tank, through which at least a portion of the refrigerant flows from the first compressor, and a compensation heat exchange module that heat exchanges the heat source fluid flowing through the first compensation flow line with the refrigerant flowing through the second compensation flow line to raise the temperature of the heat source fluid.

[0012] In addition, the compensation heat exchange module may include a compensation heat exchanger that exchanges heat between a heat source fluid and a cold water source fluid flowing through the first compensation flow line and the second compensation flow line, respectively.

[0013] Additionally, the compensation heat exchange module may include a heat storage tank in which a heat storage fluid is stored internally and a heat source fluid flowing through the first compensation flow line is heated through heat exchange with the heat storage fluid; and a heat storage heat exchanger installed on the second compensation flow line while contained within the heat storage tank and heat-exchanging with the heat storage fluid in the heat storage tank to store the heat storage fluid.

[0014] In addition, the compensation heat exchange module may include: a heat storage tank in which a heat storage fluid is stored internally and a heat source fluid flowing through the first compensation flow line is heated through heat exchange with the heat storage fluid; a heat exchange flow line in which a heat exchange fluid flows to heat exchange with the heat storage fluid in the heat storage tank to heat the heat storage fluid; and a heat storage heat exchanger that heat exchanges the refrigerant flowing through the second compensation flow line with the heat exchange fluid flowing through the heat exchange flow line to heat exchange the heat exchange fluid, thereby heating the heat exchange fluid.

[0015] In addition, it is possible to operate in a heat storage-only mode in which the heat storage tank stores heat according to the operation of the first compressor, with the operation of the second compressor stopped and the flow of refrigerant to the condenser and the first expansion valve blocked.

[0016] Additionally, it further includes a heat source bypass section installed in the heat source flow line to control the flow of the heat source fluid to the heat source heat exchanger; and it is possible to operate in a heat source cut-off heating mode in which, when the flow of the heat source fluid to the heat source heat exchanger is blocked by the heat source bypass section, heat storage in the heat storage tank and heating by the condenser proceed according to the operation of the first compressor and the second compressor.

[0017] In addition, it further includes a heat source bypass section installed in the heat source flow line to control the flow of the heat source fluid to the heat source heat exchanger; and it is possible to operate in a heat source cut-off heat storage standalone mode in which the heat storage tank stores heat according to the operation of the first compressor, while the flow of the heat source fluid to the heat source heat exchanger is blocked by the heat source bypass section and the operation of the second compressor is stopped so that the flow of refrigerant to the condenser and the first expansion valve is blocked.

[0018] And, it operates in either a compensation heat exchange mode in which heat is exchanged between at least a portion of the refrigerant compressed by the first compressor and the water source fluid flowing toward the evaporator side through the water source flow line by the compensation heat exchanger, or a general heating mode in which the flow of the refrigerant compressed by the first compressor is blocked by the compensation heat exchanger; and the output of the first compressor in the compensation heat exchange mode can be controlled to be lower than the output of the first compressor in the general heating mode. Effects of the invention

[0019] According to the above configuration, the present invention provides a heat pump system for preventing freezing of an evaporator, which can prevent freezing on the evaporator side by using a portion of the refrigerant from the first compressor of the heat pump.

[0020] In addition, according to the present invention, a heat pump system for preventing freezing of an evaporator is provided, which enables continuous operation without turning the heat pump on and off in order to prevent and eliminate freezing phenomena on the evaporator side. Brief explanation of the drawing

[0021] FIG. 1 is a diagram showing the configuration of a heat pump system for preventing freezing of an evaporator according to a first embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of a heat pump system for preventing freezing of an evaporator according to a second embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of a heat pump system for preventing freezing of an evaporator according to a third embodiment of the present invention, and FIG. 4 is a drawing for explaining a heat storage standalone mode of a heat pump system for preventing freezing of an evaporator according to a third embodiment of the present invention, and FIG. 5 is a drawing for explaining a heat source blocking thermal storage standalone mode of a heat pump system for preventing freezing of an evaporator according to a third embodiment of the present invention, and FIG. 6 is a diagram illustrating a heat source blocking heating mode of a heat pump system for preventing freezing of an evaporator according to a third embodiment of the present invention. Specific details for implementing the invention

[0022] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the present invention, and the present invention is defined only by the scope of the claims.

[0023] The terms used in this specification are for describing embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. The terms "comprises" and / or "comprising" used in this specification do not exclude the presence or addition of one or more other components in addition to the components mentioned. Throughout the specification, the same reference numerals refer to the same components, and "and / or" includes each of the mentioned components and all combinations of one or more. Although terms such as "first," "second," etc., are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical scope of the invention.

[0024] Unless otherwise defined, all terms used herein (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0025] Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0026] FIG. 1 is a diagram showing the configuration of a heat pump system (10) for preventing freezing of an evaporator (210) according to a first embodiment of the present invention.

[0027] Referring to FIG. 1, a heat pump system (10) according to the first embodiment of the present invention may be configured to include a heat source supply unit (100), a heat source flow line (400), a heat pump (200), and a compensation heat exchange unit (300).

[0028] The heat pump system (10) according to the first embodiment of the present invention is an indirect heat exchange method that does not directly use raw water, and is exemplified by a secondary fluid flowing through a heat pump (200), and the water source fluid becomes the secondary fluid. In addition, the present invention is exemplified by water being applied as the secondary fluid.

[0029] More specifically, the heat source supply unit (100) according to the first embodiment of the present invention may be configured to include a raw water flow line (121, 122) and a heat source heat exchanger (110).

[0030] In one embodiment, the raw water may be river water, lake water, water source water, etc.

[0031] The raw water flow lines (121, 122) according to the first embodiment of the present invention are connected to a raw water pipe (20) through which raw water flows. The raw water flow lines (121, 122) may include an inlet side raw water flow line (121) through which raw water flows toward a heat source heat exchanger (110), and a return side raw water flow line (122) through which raw water flows back to the raw water pipe (20).

[0032] A water source flow line (400) according to the first embodiment of the present invention connects a water source heat exchanger (110) and a heat pump (200) to circulate a water source fluid, which is a secondary fluid, between the water source heat exchanger (110) and the heat pump (200). The water source flow line (400) may include an inlet side water source flow line (410) through which the water source fluid flows from the water source heat exchanger (110) toward the heat pump (200), and a return side water source flow line (420) through which the water source fluid flows back toward the water source heat exchanger (110).

[0033] According to the above configuration, the raw water does not directly exchange heat in the heat pump (200), but rather exchanges heat with the water source fluid in the water source heat exchanger (110), and the water source fluid exchanges heat in the evaporator (210) of the heat pump (200) to be described later. Through this, the influence of foreign substances that may be contained in raw water, such as river water, lake water, or raw water from a water source, can be minimized.

[0034] Here, the heat pump system (10) according to an embodiment of the present invention may be configured to include a fluid pump (P1) for the flow of raw water. In one embodiment, the fluid pump (P1) is exemplified as being installed in an inlet-side raw water flow line (121).

[0035] In addition, the heat pump system (10) according to an embodiment of the present invention may be configured to include a fluid pump (P2) for the flow of a heat source fluid. In one embodiment, the fluid pump is installed in an inlet side heat source flow line (410).

[0036] Meanwhile, the heat pump (200) according to an embodiment of the present invention may include a refrigerant line (260) for forming a heating cycle in which a refrigerant flows. Additionally, the heat pump (200) may be configured to include an evaporator (210) installed in the refrigerant line (260) in which a heat source fluid flowing through a heat source flow line (400) and a refrigerant flowing through the refrigerant line (260) exchange heat.

[0037] Additionally, the heat pump (200) according to an embodiment of the present invention may be configured to include a first compressor (221) and a second compressor (222) that are sequentially installed in a refrigerant line (260) to compress refrigerant from an evaporator (210).

[0038] Here, the compensation heat exchanger (300) can exchange heat between a portion of the refrigerant compressed by the first compressor (221), i.e., the high-temperature, high-pressure gaseous refrigerant, and a water source fluid flowing toward the evaporator (210) through the water source flow line (400).

[0039] Through this, the heat source fluid flowing into the evaporator (210) is heated by the high-temperature, high-pressure gaseous refrigerant, thereby preventing freezing that may occur in the evaporator (210) under conditions where the raw water is at a low temperature.

[0040] In addition, the temperature of the heat source fluid flowing into the evaporator (210) is increased, thereby increasing the temperature of the refrigerant passing through the evaporator (210), which can also increase the efficiency of the compressor.

[0041] Meanwhile, the heat pump (200) may be configured to include a condenser (230), a first expansion valve (241), a second expansion valve (242), and a flash tank (250).

[0042] In the first embodiment of the present invention, along the refrigerant circulation direction, an evaporator (210), a first compressor (221), a second compressor (222), a condenser (230), a first expansion valve (241), a flash tank (250), and a second expansion valve (242) form a heating cycle.

[0043] In one embodiment, a flash tank (250) is installed in a refrigerant line (260) between a first expansion valve (241) and a second expansion valve (242) so that liquid refrigerant from the first expansion valve (241) passes through. Then, the liquid refrigerant flowing into the flash tank (250) is discharged back toward the second expansion valve.

[0044] A condenser (230) according to an embodiment of the present invention increases the temperature of a heating fluid flowing through heating flow lines (711, 712) through heat exchange and supplies it to a heating load (700). Here, a fluid pump (P3) for the flow of heating fluid may be installed in the heating flow lines (711, 712).

[0045] Meanwhile, the compensation heat exchanger (300) according to the first embodiment of the present invention may be configured to include a first compensation flow line (321, 322), a second compensation flow line (331, 332), and a compensation heat exchange module (310).

[0046] The first compensation flow line (321, 322) is connected to the inlet side heat source flow line (410) so that at least a portion of the heat source fluid flowing through the inlet side heat source flow line (410) can flow. Additionally, one side of the second compensation flow line (331, 332) is branched from the refrigerant line (260) between the first compressor (221) and the second compressor (222), and the other side is connected to the flash tank (250) so that at least a portion of the refrigerant from the first compressor (221) can flow.

[0047] The compensation heat exchange module (310) heats the heat source fluid flowing through the first compensation flow line (321, 322) and the refrigerant flowing through the second compensation flow line (331, 332) to raise the temperature of the heat source fluid.

[0048] In the first embodiment of the present invention, the compensation heat exchange module (310) is configured in the form of a compensation heat exchanger as shown in FIG. 1.

[0049] To explain more specifically, in one embodiment, the first compensation flow line (321, 322) may be configured to include a first inlet-side compensation flow line (321) and a first return-side compensation flow line (322). One side of the first inlet-side compensation flow line (321) is branched off from the inlet-side heat source flow line (410), and the other side is connected to the primary side inlet of the compensation heat exchanger. Then, one side of the first return-side compensation flow line (322) is connected to the primary side outlet of the compensation heat exchanger, and the other side is connected again to the inlet-side heat source flow line (410).

[0050] In one embodiment, the first inlet-side compensation flow line (321) and the inlet-side heat source flow line (410) may be connected through a first 3-way valve. Here, the first 3-way valve (323) may be configured to control the flow of the heat source fluid to the first inlet-side compensation flow line (321).

[0051] The second compensation flow line (331, 332) may be configured to include a second inlet-side compensation flow line (331) and a second return-side compensation flow line (332). One side of the second inlet-side compensation flow line (331) is branched from the refrigerant line (260) between the first compressor (221) and the second compressor (222), and the other side is connected to the secondary side inlet of the compensation heat exchanger. Then, one side of the second return-side compensation flow line (332) is connected to the secondary side outlet of the compensation heat exchanger, and the other side is connected to the flash tank (250).

[0052] In one embodiment, the second inlet-side compensation flow line (331) and the refrigerant line (260) are connected through a second 3-way valve (333). Additionally, a switching valve (334) that controls the flow of refrigerant through the second inlet-side compensation flow line (331) may be installed in the second inlet-side compensation flow line (331).

[0053] According to the above configuration, the flow of water source fluid and refrigerant to the first compensation flow line (321, 322) and the second compensation flow line (331, 332) is controlled by the first 3-way valve (323) and the switching valve (334), thereby enabling control of whether the compensation heat exchanger (300) operates.

[0054] For example, under conditions where the temperature of the raw water is lowered, the flow of the heat source fluid and the refrigerant can be allowed through the operation of the first 3-way valve (323) and the switching valve (334) to the first compensation flow line (321, 322) and the second compensation flow line (331, 332), thereby controlling the heat source fluid to be heated by the refrigerant.

[0055] Therefore, by allowing the heat source fluid, which has been heated by heat exchange with the refrigerant, to flow into the evaporator (210), it is possible to prevent freezing phenomena that may occur on the side of the evaporator (210).

[0056] Hereinafter, a heat pump system (10) according to a second embodiment of the present invention will be described with reference to FIG. 2.

[0057] The heat pump system (10) according to the second embodiment of the present invention has a different configuration of the compensation heat exchanger (300) from the first embodiment, and the remaining configuration corresponds to the first embodiment, so the description thereof is omitted.

[0058] A compensation heat exchanger (300) according to a second embodiment of the present invention may be configured to include a first compensation flow line (321, 322), a second compensation flow line (331, 332), and a compensation heat exchange module (310a).

[0059] The first compensation flow line (321, 322) is connected to the inlet side heat source flow line (410) so that at least a portion of the heat source fluid flowing through the inlet side heat source flow line (410) can flow. Additionally, one side of the second compensation flow line (331, 332) is branched from the refrigerant line (260) between the first compressor (221) and the second compressor (222), and the other side is connected to the flash tank (250) so that at least a portion of the refrigerant from the first compressor (221) can flow.

[0060] The compensation heat exchange module (310) heats the heat source fluid flowing through the first compensation flow line (321, 322) and the refrigerant flowing through the second compensation flow line (331, 332) to raise the temperature of the heat source fluid.

[0061] In the second embodiment of the present invention, the compensation heat exchange module (310a) is exemplified as including a heat storage tank (311a) and a heat storage heat exchanger (312a), as shown in FIG. 2.

[0062] A heat storage tank (311a) according to the second embodiment of the present invention may store a heat storage fluid inside. The heat storage fluid stored in the heat storage tank (311a) exchanges heat with a heat source fluid flowing through the first compensation flow line (321, 322) to raise the temperature of the heat source fluid.

[0063] The heat storage heat exchanger (312a) is installed on the second compensation flow line (331, 332) while being contained within the heat storage tank (311a). Then, the heat storage heat exchanger (312a) exchanges heat with the heat storage fluid inside the heat storage tank (311a) using the refrigerant flowing in through the second compensation flow line (331, 332), thereby storing heat in the heat storage fluid.

[0064] More specifically, one side of the first inlet-side compensation flow line (321) branches off from the inlet-side heat source flow line (410), and the other side flows into the heat storage tank (311a). Then, one side of the first return-side compensation flow line (322) is discharged from the heat storage tank (311a), and the other side is connected again to the inlet-side heat source flow line (410). Here, the first inlet-side compensation flow line (321) and the first return-side compensation flow line (322) are connected within the heat storage tank (311a).

[0065] And, one side of the second inlet-side compensation flow line (331) is branched off from the refrigerant line (260) between the first compressor (221) and the second compressor (222), and the other side is connected to the inlet of the thermal storage heat exchanger (312a). And, one side of the second return-side compensation flow line (332) is connected to the outlet of the thermal storage heat exchanger (312a), and the other side is connected to the flash tank (250).

[0066] As in the first embodiment, the first inlet-side compensation flow line (321) and the inlet-side heat source flow line (410) can be connected through the first 3-way valve. Here, the first 3-way valve (323) can be configured to control the flow of the heat source fluid to the first inlet-side compensation flow line (321).

[0067] And, as an example, the second inlet-side compensation flow line (331) and the refrigerant line (260) are connected through the second 3-way valve (333). Additionally, a switching valve (334) that controls the flow of refrigerant through the second inlet-side compensation flow line (331) may be installed in the second inlet-side compensation flow line (331).

[0068] According to the above configuration, the refrigerant from the first compressor (221) heats up the heat storage fluid inside the heat storage tank (311a) through the heat storage heat exchanger (312a), and the heated heat storage fluid heats up the heat source fluid flowing through the first compensation flow line (321, 322).

[0069] Here, a detailed explanation of the heat storage of the heat storage fluid will be provided later.

[0070] Hereinafter, a heat pump system (10) according to a third embodiment of the present invention will be described with reference to FIG. 3.

[0071] The heat pump system (10) according to the third embodiment of the present invention has a different configuration of the compensation heat exchanger (300) from the first embodiment, and the remaining configuration corresponds to the first embodiment, so the description thereof is omitted.

[0072] A compensation heat exchanger (300) according to a third embodiment of the present invention may be configured to include a first compensation flow line (321, 322), a second compensation flow line (331, 332), and a compensation heat exchange module (310b).

[0073] The first compensation flow line (321, 322) is connected to the inlet side heat source flow line (410) so that at least a portion of the heat source fluid flowing through the inlet side heat source flow line (410) can flow. Additionally, one side of the second compensation flow line (331, 332) is branched from the refrigerant line (260) between the first compressor (221) and the second compressor (222), and the other side is connected to the flash tank (250) so that at least a portion of the refrigerant from the first compressor (221) can flow.

[0074] The compensation heat exchange module (310b) heats the heat source fluid flowing through the first compensation flow line (321, 322) and the refrigerant flowing through the second compensation flow line (331, 332) to raise the temperature of the heat source fluid.

[0075] In the third embodiment of the present invention, the compensation heat exchange module (310b) is exemplified as including a heat storage tank (311b), a heat storage heat exchanger (312b), and heat exchange flow lines (341, 342), as shown in FIG. 3.

[0076] A heat storage tank (311b) according to the third embodiment of the present invention may store a heat storage fluid inside. The heat storage fluid stored in the heat storage tank (311b) exchanges heat with a heat source fluid flowing through the first compensation flow line (321, 322) to raise the temperature of the heat source fluid.

[0077] Unlike the second embodiment, the heat storage heat exchanger (312b) may be placed outside the heat storage tank (311b). Here, the heat storage heat exchanger (312b) heat exchanges the refrigerant flowing through the second compensation flow line (331, 332) with the heat exchange fluid flowing through the heat exchange flow line (341, 342) to raise the temperature of the heat exchange fluid.

[0078] More specifically, one side of the inlet heat exchange flow line (341) is discharged from the heat storage tank (311b), and the other side is connected to the primary side inlet of the heat storage heat exchanger (312b). Then, one side of the return heat exchange flow line (342) is connected to the primary side outlet of the heat storage heat exchanger (312b), and the other side is introduced into the heat storage tank (311b). Here, the inlet heat exchange flow line (341) and the return heat exchange flow line (342) are connected inside the heat storage tank (311b), so that the heat exchange fluid flowing inside can exchange heat with the heat storage fluid. Here, a fluid pump (P4) for the flow of the heat exchange fluid may be installed in the inlet heat exchange flow line (341).

[0079] And, one side of the second inlet-side compensation flow line (331) is branched off from the refrigerant line (260) between the first compressor (221) and the second compressor (222), and the other side is connected to the secondary side inlet of the heat storage heat exchanger (312b). And, one side of the second return-side compensation flow line (332) is connected to the secondary side outlet of the heat storage heat exchanger (312b), and the other side is connected to the flash tank (250).

[0080] Here, the second inlet-side compensation flow line (331) and the refrigerant line (260) are connected via the second 3-way valve (333). Additionally, a switching valve (334) that controls the flow of refrigerant through the second inlet-side compensation flow line (331) may be installed in the second inlet-side compensation flow line (331).

[0081] Then, one side of the first inlet-side compensation flow line (321) branches off from the inlet-side heat source flow line (410), and the other side flows into the heat storage tank (311b). Then, one side of the first return-side compensation flow line (322) is discharged from the heat storage tank (311b), and the other side is connected again to the inlet-side heat source flow line (410). Here, the first inlet-side compensation flow line (321) and the first return-side compensation flow line (322) are connected within the heat storage tank (311b).

[0082] In one embodiment, the first inlet-side compensation flow line (321) and the inlet-side heat source flow line (410) may be connected through a first 3-way valve. Here, the first 3-way valve (323) may be configured to control the flow of the heat source fluid to the first inlet-side compensation flow line (321).

[0083] According to the above configuration, the refrigerant from the first compressor (221) exchanges heat with the heat exchange fluid in the heat storage heat exchanger (312b) to raise the temperature of the heat exchange fluid, and the heat exchange fluid stores heat in the heat storage tank (311b).

[0084] And, the heat storage fluid in the heat storage tank (311b) exchanges heat with the heat source fluid, thereby raising the temperature of the heat source fluid, so that the heat source fluid with a raised temperature can flow into the evaporator (210).

[0085] Below, an operating mode of a heat pump system (10) according to an embodiment of the present invention utilizing the third embodiment shown in FIG. 3 will be described.

[0086] FIG. 4 is a drawing for explaining the heat storage-only mode of a heat pump system (10) for preventing freezing of an evaporator (210) according to the third embodiment of the present invention.

[0087] In the heat storage-only mode of the heat pump system (10) according to an embodiment of the present invention, the operation of the second compressor (222) is stopped, and the flow of refrigerant to the condenser (230) and the first expansion valve (241) is blocked. In this case, the supply of heating to the heating load (700), i.e., the supply of heating fluid, is also blocked.

[0088] Then, as the first compressor (221) operates, the refrigerant from the first compressor (221) flows into the compensation heat exchanger (300), and the heat storage tank (311b) is heated as described above. At this time, the heating cycle, that is, the circulation of the refrigerant, follows a path that passes through the evaporator (210), the compressor, the heat storage heat exchanger (312b), the flash tank (250), and the second expansion valve (242), and then flows back into the evaporator (210).

[0089] The above-mentioned heat storage-only mode maximizes the heat storage efficiency of the heat storage tank (311b) when heating supply to the heating load (700) is not required, thereby increasing the effect of preventing freezing of the evaporator (210) when operating in the heating mode thereafter.

[0090] FIG. 5 is a drawing for explaining the heat source blocking heat storage only mode of a heat pump system (10) for preventing freezing of an evaporator (210) according to the third embodiment of the present invention.

[0091] The heat source blocking heat storage only mode of the heat pump system (10) according to an embodiment of the present invention is defined as operation in a state where the heat source fluid is bypassed without passing through the heat source heat exchanger (110) in the heat storage only mode shown in FIG. 4.

[0092] More specifically, as previously explained, the operation of the second compressor (222) is stopped, thereby blocking the flow of refrigerant to the condenser (230) and the first expansion valve (241). In this case, the heating supply to the heating load (700), i.e., the supply of heating fluid, is also blocked.

[0093] Then, as the first compressor (221) operates, the refrigerant from the first compressor (221) flows into the compensation heat exchanger (300), and the heat storage tank (311b) is heated as described above. At this time, the heating cycle, that is, the circulation of the refrigerant, follows a path that passes through the evaporator (210), the compressor, the heat storage heat exchanger (312b), the flash tank (250), and the second expansion valve (242), and then flows back into the evaporator (210).

[0094] In addition, to prevent the heat source fluid from flowing toward the heat source heat exchanger (110), the heat pump system (10) according to an embodiment of the present invention may be configured to include a heat source bypass section (500).

[0095] Here, the heat source bypass section (500) is installed in the heat source flow line (400) and can control the flow of the heat source fluid toward the heat source heat exchanger (110).

[0096] In one embodiment, the heat source bypass section (500) may include a bypass line (510) connecting an inlet side heat source flow line (410) and a return side heat source flow line (420). Additionally, the heat source bypass section (500) may include a bypass valve (520) that controls the flow of the heat source fluid through the heat source bypass line (510).

[0097] According to the above configuration, by operating the bypass valve (520), a path can be selected in which the water source fluid flows through the evaporator (210) and the bypass line (510), or flows through the evaporator (210) and the water source heat exchanger (110).

[0098] Here, in the heat source blocking heat storage only mode, the flow of the heat source fluid to the heat source heat exchanger (110) is blocked by the heat source bypass section (500). Therefore, the heat source fluid flows through the evaporator (210) and the bypass line (510), so that heat exchange with the raw water does not occur in the heat source heat exchanger (110).

[0099] Therefore, when the temperature of the raw water is extremely low or when ice forms on the evaporator (210), heat exchange with the raw water is blocked, thereby allowing the temperature on the evaporator (210) side to be raised more effectively.

[0100] FIG. 6 is a diagram illustrating a heat source blocking heating mode of a heat pump system (10) for preventing freezing of an evaporator (210) according to a third embodiment of the present invention.

[0101] In the heat source blocking heating mode according to an embodiment of the present invention, while the flow of the heat source fluid to the heat source heat exchanger (110) is blocked by the heat source bypass unit (500), the heating fluid is supplied to the heating load (700), and the compensation heat exchange unit (300) is operated. That is, the first compressor (221) and the second compressor (222) operate to perform heat storage in the heat storage tank (311b) and heating by the condenser (230).

[0102] Meanwhile, in the heat pump system (10) according to an embodiment of the present invention, as previously described, heat exchange is performed between at least a portion of the refrigerant compressed by the first compressor (221) and the water source fluid flowing toward the evaporator (210) through the water source flow line (400) by the compensation heat exchanger (300). This is defined as a compensation heat exchange mode. Here, in the compensation heat exchange mode, the heating fluid that has been heat-exchanged in the condenser (230) according to the operation of the heating cycle is supplied to the heating load (700).

[0103] In addition, the heat pump system (10) according to the embodiment of the present invention can operate in a general heating mode in which the flow of refrigerant compressed by the first compressor (221) to the compensation heat exchanger (300) is blocked. That is, heating fluid is supplied to the heating load (700) according to the operation of the heating cycle while the compensation heat exchanger (300) is not operating.

[0104] Here, the output of the first compressor (221) in the compensation heat exchange mode, for example, the rotational speed or capacity, is controlled to be lower than the output of the first compressor (221) in the general heating mode. Through this, the COP of the entire heating cycle can be reduced, thereby reducing the total power consumption.

[0105] To explain more specifically with reference to Fig. 7, Fig. 7 (a) is the pH diagram in normal heating mode, and Fig. 7 (b) is the pH diagram in compensated heat exchange mode.

[0106] Referring to Figure 7 (a), the heating capacity, compressor work, and Coefficient of Performance (COP) in general heating mode can be expressed as [Equation 1], respectively.

[0107] [Mathematical Formula 1]

[0108]

[0109] Here, QA is the heating capacity in normal heating mode, and W A is the compression work in normal heating mode, and COP A is the COP in normal heating mode, and m and h are the mass flow rate and enthalpy, respectively.

[0110] The heating capacity, compressor work, and Coefficient of Performance (COP) in the compensated heat exchange mode can be expressed as [Equation 2], respectively.

[0111] [Mathematical Formula 2]

[0112]

[0113] In [Mathematical Equation 2], Q B is the heating capacity in compensated heat exchange mode, and W B is the compression work in the compensated heat exchange mode, and COP B is the COP in the compensated heat exchange mode.

[0114] Therefore, when the rotational speed of the first compressor (221) decreases and the discharge temperature decreases, the mass flow rate passing through the first compressor (221) decreases, and while the total heating capacity decreases, the COP increases, thereby allowing the total power consumption to be reduced.

[0115] Here, Q of [Equation 2] B , W B , and COP B The derivation process of can be expressed as [Mathematical Equation 3].

[0116] [Mathematical Formula 3]

[0117]

[0118] Although some embodiments of the present invention have been illustrated and described, those skilled in the art will understand that modifications can be made to these embodiments without departing from the principles or spirit of the invention. The scope of the invention will be defined by the appended claims and their equivalents. Explanation of the symbols

[0119] 10: Heat pump system 20: Raw water pipe 100 : Water source supply unit 110 : Water source heat exchanger 121: Inlet side raw water flow line 122: Return side raw water flow line 200: Heat pump 210: Evaporator 221: 1st Compressor 222: 2nd Compressor 230: Condenser 241: First expansion valve 242: Second expansion valve 250: Flash tank 260: Refrigerant line 300: Compensated heat exchanger 310, 310a, 310b: Compensated heat exchange module 311a, 311b: Thermal storage tanks 312a, 312b: Thermal storage heat exchangers 321: 1st inflow-side compensated flow line 322: 1st return-side compensated flow line 323: 1st 3-way valve 331: Second inflow-side compensated flow line 332: Second return-side compensated flow line 333: Second 3-way valve 334: Switching valve 341: Inlet side heat exchange flow line 342: Return side heat exchange flow line 400: Water source flow line 410: Inlet side heat source flow line 420: Return side heat source flow line 500: Bypass section 510: Bypass line 520: Bypass valve 700: Heating load 711, 712: Heating flow line

Claims

Claim 1 A heat pump system for preventing freezing of an evaporator comprises: a heat source supply unit for supplying a heat source fluid; a heat source flow line through which the heat source fluid flows; a refrigerant line for forming a heating cycle through which a refrigerant flows; an evaporator installed in the refrigerant line in which heat exchanges heat between the heat source fluid flowing through the heat source flow line and the refrigerant flowing through the refrigerant line; a heat pump having a first compressor and a second compressor sequentially installed in the refrigerant line to compress the refrigerant from the evaporator; and a compensation heat exchange unit for heat exchange between at least a portion of the refrigerant compressed by the first compressor and the heat source fluid flowing toward the evaporator side through the heat source flow line; wherein the heat pump further comprises a condenser, a first expansion valve, and a second expansion valve sequentially installed in the refrigerant line along the direction of refrigerant flow from the second compressor, and a flash tank installed in the refrigerant line between the first expansion valve and the second expansion valve through which liquid refrigerant from the first expansion valve passes; and wherein the heat source A heat pump system for preventing freezing of an evaporator, characterized in that the flow line includes an inlet side heat source flow line through which a heat source fluid flows from the heat source supply unit to the evaporator side, and a return side heat source flow line through which a heat source fluid flows from the evaporator to the heat source supply unit side; and the compensation heat exchanger includes a first compensation flow line connected to the inlet side heat source flow line through which at least a portion of the heat source fluid flowing through the inlet side heat source flow line flows, a second compensation flow line through which at least a portion of the refrigerant from the first compressor flows, with one side branched from the refrigerant line between the first compressor and the second compressor and the other side connected to the flash tank, through which at least a portion of the refrigerant flows from the first compressor, and a compensation heat exchange module that heat exchanges the heat source fluid flowing through the first compensation flow line with the refrigerant flowing through the second compensation flow line to raise the temperature of the heat source fluid. Claim 2 delete Claim 3 delete Claim 4 A heat pump system for preventing evaporator freezing according to claim 1, wherein the compensation heat exchange module comprises a compensation heat exchanger that exchanges heat between a heat source fluid and a refrigerant flowing through the first compensation flow line and the second compensation flow line, respectively. Claim 5 A heat pump system for preventing freezing of an evaporator according to claim 1, wherein the compensation heat exchange module comprises: a heat storage tank in which a heat storage fluid is stored internally and a heat source fluid flowing through the first compensation flow line is heated through heat exchange with the heat storage fluid; and a heat storage heat exchanger installed on the second compensation flow line while contained within the heat storage tank and heat-exchanging with the heat storage fluid within the heat storage tank to store the heat storage fluid. Claim 6 A heat pump system for preventing freezing of an evaporator according to claim 1, wherein the compensation heat exchange module comprises: a heat storage tank in which a heat storage fluid is stored internally and a heat source fluid flowing through the first compensation flow line is heated through heat exchange with the heat storage fluid; a heat exchange flow line in which a heat exchange fluid flows to heat exchange with the heat storage fluid in the heat storage tank to heat the heat storage fluid; and a heat storage heat exchanger that heat exchanges the heat exchange fluid flowing through the second compensation flow line with a refrigerant flowing through the second compensation flow line to heat exchange the heat exchange fluid, thereby heating the heat exchange fluid. Claim 7 A heat pump system for preventing evaporator freezing, characterized in that, in claim 5 or 6, the operation of the second compressor is stopped and the flow of refrigerant to the condenser and the first expansion valve is blocked, and the heat storage tank is able to operate in a heat storage-only mode according to the operation of the first compressor. Claim 8 A heat pump system for preventing evaporator freezing, characterized in that, in claim 5 or 6, it further includes a heat source bypass unit installed in the heat source flow line to control the flow of the heat source fluid to the heat source supply unit; and, while the flow of the heat source fluid to the heat source supply unit is blocked by the heat source bypass unit, the heat storage of the heat storage tank and heating by the condenser proceed according to the operation of the first compressor and the second compressor. Claim 9 A heat pump system for preventing evaporator freezing, characterized in that, in claim 5 or 6, it further includes a heat source bypass unit installed in the heat source flow line to control the flow of the heat source fluid to the heat source supply unit; and the system is capable of operating in a heat source cut-off heat storage only mode in which the heat storage tank stores heat according to the operation of the first compressor, while the flow of the heat source fluid to the heat source supply unit is blocked by the heat source bypass unit and the operation of the second compressor is stopped so that the flow of refrigerant to the condenser and the first expansion valve is blocked. Claim 10 A heat pump system for preventing evaporator freezing according to claim 1, wherein the system operates in either a compensation heat exchange mode in which heat is exchanged between at least a portion of the refrigerant compressed by the first compressor and a water source fluid flowing toward the evaporator side through the water source flow line by the compensation heat exchanger, or a general heating mode in which the flow of the refrigerant compressed by the first compressor is blocked by the compensation heat exchanger; wherein the output of the first compressor in the compensation heat exchange mode is controlled to be lower than the output of the first compressor in the general heating mode.

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