Heat pump system and control method therefor

Abstract

A heat pump system according to an aspect of the disclosed invention may comprise: a compressor for compressing a refrigerant; a refrigerant-water heat exchanger in which heat exchange is performed between the compressed refrigerant and introduced water; an expansion valve for expanding refrigerant condensed in the refrigerant-water heat exchanger; an outdoor heat exchanger in which heat exchange is performed between the refrigerant expanded by the expansion valve and outdoor air; a high pressure sensor for sensing a high pressure saturation temperature of the refrigerant compressed in the compressor; an inflow water temperature sensor for sensing the temperature of water entering the refrigerant-water heat exchanger; a condensation temperature sensor for sensing the temperature of the refrigerant condensed in the refrigerant-water heat exchanger; an outdoor temperature sensor for sensing an outdoor temperature; and a control part which determines a reference supercooling degree of the refrigerant on the basis of the sensing results of the outdoor temperature sensor and the inflow water temperature sensor and an operating frequency of the compressor, determines a current supercooling degree of the refrigerant on the basis of the sensing results of the high pressure sensor and the condensation temperature sensor, and compares the reference supercooling degree and the current supercooling degree so as to determine whether there is a leak of the refrigerant.

Description

Heat pump system and its control method

[0001] The disclosed invention relates to a heat pump system and a control method thereof, and is an invention relating to a heat pump type system capable of supplying hot water through heat exchange and a control method thereof.

[0002] Normally, heat naturally moves from high-temperature to low-temperature areas. However, to move heat from low-temperature areas to high-temperature areas, some external action is required. This is the principle of a heat pump. A heat pump utilizes the heat generated and recovered during the cycle of compression, condensation, and evaporation of a refrigerant to provide heating, cooling, and air-to-water supply.

[0003] A multi-type heating and cooling device (hereinafter referred to as an “air conditioning system”) using a heat pump method is composed of an outdoor unit, an indoor unit, and a hydro unit, and uses the heat of the heat pump for indoor floor heating or indoor air heating and cooling.

[0004] Previously, leak detection in heat pump systems was based on the current pressure compared to the saturation pressure when the heat pump system was stopped. However, since the saturation pressure of R290, a propane refrigerant, is relatively low compared to other refrigerants, the absolute value of the pressure difference is small even when detected at the same ratio. Furthermore, when detecting leaks based on the temperature difference of the refrigerant in the heat exchanger when the heat pump system is stopped and after starting, a large amount of refrigerant must leak to be detected.

[0005] Furthermore, for hot water tanks used to provide hot water, continuous operation and shutdown can lead to low energy efficiency due to heat loss. Therefore, energy-saving operation is implemented by considering usage patterns and hot water heat output. However, hot water tanks equipped with energy-saving operation require multiple sensors, increasing the design complexity.

[0006] One aspect of the disclosed invention provides a heat pump system and a control method thereof capable of detecting even a small amount of refrigerant leakage without stopping the heat pump system by determining whether or not there is a refrigerant leakage based on the degree of subcooling of the refrigerant.

[0007] In addition, a heat pump system and a control method thereof are provided that can perform energy-saving operation by predicting hot water usage patterns and hot water usage heat amount without using multiple sensors.

[0008] The technical problems to be achieved in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0009] A heat pump system according to one aspect of the disclosed invention may include a compressor for compressing a refrigerant; a refrigerant-water heat exchanger for heat exchange between the compressed refrigerant and water received; an expansion valve for expanding the refrigerant condensed in the refrigerant-water heat exchanger; an outdoor heat exchanger for heat exchange between the refrigerant expanded in the expansion valve and outdoor air; a high pressure sensor for detecting a high pressure saturation temperature of the refrigerant compressed in the compressor; an inlet temperature sensor for detecting a temperature of water entering the refrigerant-water heat exchanger; a condensation temperature sensor for detecting a temperature of the refrigerant condensed in the refrigerant-water heat exchanger; an outdoor temperature sensor for detecting an outdoor temperature; and a control unit for determining a reference subcooling degree of the refrigerant based on detection results of the outdoor temperature sensor and the inlet temperature sensor and an operating frequency of the compressor, determining a current subcooling degree of the refrigerant based on detection results of the high pressure sensor and the condensation temperature sensor, and comparing the reference subcooling degree with the current subcooling degree to determine whether the refrigerant is leaking.

[0010] FIG. 1 is a diagram showing the configuration of a heat pump system according to one embodiment.

[0011] Figure 2 is a drawing showing the flow of refrigerant during heating operation of a heat pump system according to one embodiment.

[0012] FIG. 3 is a diagram showing the flow of refrigerant during cooling operation of a heat pump system according to one embodiment.

[0013] FIG. 4 is a drawing showing a control block diagram of a heat pump system according to one embodiment of the present disclosure.

[0014] FIG. 5 is a diagram illustrating a plurality of sensors included in a heat pump system according to one embodiment of the present disclosure.

[0015] FIG. 6 is a flowchart illustrating a control method of a heat pump system according to one embodiment of the present disclosure.

[0016] FIG. 7 is a flowchart illustrating a process for controlling an expansion valve to reach a reference superheat level according to one embodiment of the present disclosure.

[0017] FIG. 8 is a flowchart specifically illustrating a process for determining whether there is a refrigerant leak in a heat pump system according to one embodiment of the present disclosure.

[0018] FIG. 9 is a drawing explaining whether or not there is a refrigerant leak depending on the amount of refrigerant according to one embodiment of the present disclosure.

[0019] FIG. 10 is a flowchart illustrating a process for determining whether there is a refrigerant leak based on superheat according to another embodiment of the present disclosure.

[0020] FIG. 11 is a diagram showing the configuration of a heat pump system according to another embodiment of the present disclosure.

[0021] FIG. 12 is a drawing showing a control block diagram of a heat pump system according to another embodiment of the present disclosure.

[0022] FIG. 13 is a flowchart illustrating a control method of a heat pump system according to another embodiment of the present disclosure.

[0023] FIG. 14 is a flowchart illustrating a process for determining a hot water usage time according to another embodiment of the present disclosure.

[0024] FIG. 15 is a drawing illustrating the hot water usage time according to another embodiment of the present disclosure.

[0025] It should be understood that the various embodiments and terms used in this document are not intended to limit the technical features described in this document to specific embodiments, but rather to include various modifications, equivalents, or substitutes of the embodiments.

[0026] In connection with the description of the drawings, similar reference numerals may be used for similar or related components.

[0027] The singular form of a noun corresponding to an item may include one or more of said items, unless the relevant context clearly indicates otherwise.

[0028] In this document, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in that phrase, or all possible combinations thereof.

[0029] The term “and / or” includes any combination of a plurality of related described elements or any one of a plurality of related described elements.

[0030] The terms "part," "module," and "member" may be implemented in hardware or software. Depending on the embodiments, multiple "parts," "modules," or "members" may be implemented as a single component, or a single "part," "module," or "member" may include multiple components.

[0031] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish one component from another and do not qualify the components in any other respect (e.g., importance or order).

[0032] When a component (e.g., a first component) is referred to as being "coupled" or "connected" to another component (e.g., a second component), with or without the terms "functionally" or "communicatively," it means that the component can be connected to the other component directly (e.g., wired), wirelessly, or through a third component.

[0033] The terms “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in this document, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0034] When a component is said to be “connected,” “coupled,” “supported,” or “in contact with” another component, this includes not only cases where the components are directly connected, coupled, supported, or in contact, but also cases where the components are indirectly connected, coupled, supported, or in contact through a third component.

[0035] When we say that a component is "on" another component, this includes not only cases where the component is in contact with the other component, but also cases where there is another component between the two components.

[0036] FIG. 1 is a diagram showing the configuration of a heat pump system according to one embodiment.

[0037] The heat pump system (1) may include a compressor (102), a refrigerant-water heat exchanger (112), an expansion valve (110), an outdoor heat exchanger (108), a flow switching valve (106), and an accumulator (104).

[0038] The compressor (102) compresses low-temperature, low-pressure refrigerant sucked in through the inlet side (102a) to form high-temperature, high-pressure refrigerant, and then discharges the high-temperature, high-pressure refrigerant through the outlet side (102b). The compressor (102) may be configured as an inverter compressor whose compression capacity varies depending on the input frequency, or may be configured as a combination of multiple constant-speed compressors with a constant compression capacity. The inlet side (102a) of the compressor (102) is connected to an accumulator (104), and the outlet side (102b) of the compressor (102) is connected to a flow switching valve (106). The flow switching valve (106) is also connected to the accumulator (104).

[0039] An accumulator (104) may be installed between the inlet side (102a) of the compressor (102) and the oil changeover valve (106). When condensed liquid refrigerant flows in through the oil changeover valve (106), the accumulator (104) temporarily stores a mixture of oil and refrigerant, separates the non-vaporized liquid refrigerant, and prevents the liquid refrigerant from being sucked into the compressor (102), thereby preventing damage to the compressor (102). The gaseous refrigerant separated in the accumulator (104) is sucked into the inlet side (102a) of the compressor (102).

[0040] The refrigerant diverting valve (106) may be configured as a four-way valve, and diverts the flow of refrigerant discharged from the compressor (102) according to the operating mode (cooling or heating), thereby forming a refrigerant flow path required for the operation in the corresponding mode. The refrigerant diverting valve (106) may have a first port (106a) connected to the outlet side (102b) of the compressor (100), a second port (106b) connected to the outdoor heat exchanger (108) side, a third port (106c) connected to the refrigerant-water heat exchanger (112) side, and a fourth port (106d) connected to the accumulator (104) which is the inlet side (102a) of the compressor (100).

[0041] The outdoor heat exchanger (108) operates as a condenser in cooling mode and as an evaporator in heating mode. A first expansion valve (110) is connected to one side of the outdoor heat exchanger (108). An outdoor fan (109) may be installed in the outdoor heat exchanger (108) to increase the heat exchange efficiency between the refrigerant and the outdoor air.

[0042] The expansion valve (110) may be configured as an electronic expansion valve, and may expand the refrigerant, control the flow rate of the refrigerant, and block the flow of the refrigerant if necessary. The expansion valve (110) may be replaced with an expansion device of another structure that performs these functions.

[0043] Inside the refrigerant-water heat exchanger (112), a plurality of heat exchange plates through which the refrigerant passes and a plurality of heat exchange plates through which water passes are installed alternately, and cold water / hot water is generated through heat exchange between the heat exchange plates through which the refrigerant passes and the heat exchange plates through which water passes. The refrigerant compressed by the compressor (102) can be delivered to the refrigerant-water heat exchanger (112). The cold water / hot water generated in the refrigerant-water heat exchanger (112) is supplied to a water supply tank, a fan coil unit, a floor cooling / heating device, etc., and is used for cold water / hot water supply and cooling / heating.

[0044] Figure 2 is a drawing showing the flow of refrigerant during heating operation of a heat pump system according to one embodiment.

[0045] The control unit (10) can operate the euro switching valve (106) to form a refrigerant path in which the first port (106a) and the third port (106c) are connected and the second port (106b) and the fourth port (106d) are connected.

[0046] Accordingly, the refrigerant discharged from the compressor (102) can flow to the refrigerant-water heat exchanger (112) through the flow switching valve (106).

[0047] The refrigerant introduced into the refrigerant-water heat exchanger (112) flows through the refrigerant-water heat exchanger (112) to the outdoor heat exchanger (108). The refrigerant that has passed through the outdoor heat exchanger (108) can be sucked into the compressor (102) again through the flow diverter valve (106).

[0048] Accordingly, the heat pump system (1) can perform heating operation by configuring a refrigerant cycle that circulates in the order of compressor (102) → flow switching valve (106) → refrigerant-water heat exchanger (112) → expansion valve (110) → outdoor heat exchanger (108) → flow switching valve (106) → accumulator (104) → compressor (102).

[0049] The heat pump system (1) of the present invention may further include a subcooling heat exchanger (114).

[0050] The subcooling heat exchanger (114) is positioned between the refrigerant-water heat exchanger (112) and the expansion valve (110) to allow the refrigerant to flow to the compressor (102).

[0051] That is, in this case, the compressor (102) can perform two-stage refrigerant compression.

[0052] The compressor (102) may include a first compression unit into which refrigerant that has passed through a refrigerant-water heat exchanger (112) is introduced and compressed, and a second compression unit into which refrigerant that has passed through the first compression unit and refrigerant that is branched and injected from a subcooling heat exchanger (114) located between the refrigerant-water heat exchanger (112) and the expansion valve (110) are introduced and compressed together.

[0053] That is, refrigerant injection into the compressor (102) through the subcooling heat exchanger (114) can be accomplished by extracting the refrigerant that has passed through the refrigerant-water heat exchanger (112) and injecting only the vapor refrigerant into the injection port of the compressor (102).

[0054] Accordingly, the compressor (102) can additionally compress not only the refrigerant that has passed through the refrigerant-water heat exchanger (112) according to the existing cycle, but also the refrigerant that is branched and injected from the supercooling heat exchanger (114).

[0055] Accordingly, by supplying vapor refrigerant to the injection port of the compressor (102), the efficiency of the compressor (102) can be improved, and by increasing the flow rate of the refrigerant on the condenser side, the capacity of the condenser can be increased. In addition, by further securing the subcooling degree of the refrigerant on the discharge side in the refrigerant-water heat exchanger (112, internal heat exchanger), efficient operation can be performed.

[0056] FIG. 3 is a diagram showing the flow of refrigerant during cooling operation of a heat pump system according to one embodiment.

[0057] The control unit (10) operates the euro switching valve (106) to form a refrigerant path in which the first port (106a) and the second port (106b) are connected and the third port (106c) and the fourth port (106d) are connected.

[0058] Accordingly, the refrigerant discharged from the compressor (102) flows to the indoor unit through the refrigerant changeover valve (106) and the outdoor heat exchanger (108). At this time, the outdoor heat exchanger (108) operates as a condenser.

[0059] The refrigerant introduced into the indoor unit passes through the refrigerant-water heat exchanger (112), and the refrigerant that has passed through the refrigerant-water heat exchanger (112) is again sucked into the compressor (102) through the flow switching valve (106).

[0060] Accordingly, the heat pump system (1) can perform cooling operation by configuring a refrigerant cycle that circulates in the order of compressor (102) → flow switching valve (106) → outdoor heat exchanger (108) → refrigerant-water heat exchanger (112) → flow switching valve (106) → accumulator (104) → compressor (102).

[0061] The above describes the basic configuration of a heat pump system (1) and the flow of refrigerant. Below, a specific operation for detecting refrigerant leakage in a heat pump system (1) is described.

[0062] FIG. 4 is a drawing showing a control block diagram of a heat pump system according to one embodiment of the present disclosure, and FIG. 5 is a drawing showing a plurality of sensors included in a heat pump system according to one embodiment of the present disclosure.

[0063] The heat pump system (1) may include a compressor (102), a refrigerant-water heat exchanger (112), an outdoor heat exchanger (108), an expansion valve (110), and a control unit (10), and the control unit (10) may include a processor (11) and a memory (12).

[0064] Additionally, the heat pump system (1) may further include a high pressure sensor (130), an inlet temperature sensor (126), a condensation temperature sensor (120), an outdoor temperature sensor (122), a low pressure sensor (132), and a compressor suction temperature sensor (124).

[0065] The high pressure sensor (130) can detect the high pressure saturation temperature of the refrigerant compressed in the compressor, and the low pressure sensor (132) can detect the low pressure saturation temperature of the refrigerant entering the compressor.

[0066] The inlet temperature sensor (126) can detect the temperature of water flowing into the refrigerant-water heat exchanger (112) before exchanging heat with the refrigerant in the refrigerant-water heat exchanger (112).

[0067] The condensation temperature sensor (120) can detect the temperature of the condensed refrigerant while exchanging heat with water during the process of passing through the refrigerant-water heat exchanger (112).

[0068] The compressor suction temperature sensor (124) can detect the temperature of the refrigerant entering the compressor.

[0069] The outdoor temperature sensor (122) can detect the outdoor temperature.

[0070] Various pieces of information detected by these multiple sensors can be used in the control process of the control unit (10) described later, and this will be described in detail.

[0071] The compressor compresses the refrigerant, and the refrigerant-water heat exchanger (112) can perform heat exchange between the compressed refrigerant and the received water. The expansion valve (110) can expand the condensed refrigerant by passing it through the refrigerant-water heat exchanger (112).

[0072] An outdoor heat exchanger (108) performs heat exchange between the refrigerant expanded in the expansion valve (110) and the outdoor air, and an outdoor fan (not shown) may be installed in the outdoor heat exchanger (108) to increase the heat exchange efficiency between the refrigerant and the outdoor air.

[0073] The control unit (10) may include a memory (12) that stores a control program and control data for controlling the entire heat pump system (1), including the expansion valve (110) and compressor, and a processor (11) that generates a control signal according to the control program and control data stored in the memory (12). The memory (12) and the processor (11) may be provided as an integrated unit or may be provided separately.

[0074] The memory (12) can store temperature and pressure detected by various sensors, and can store programs and data for controlling the entire heat pump system (1), including the expansion valve (110) and compressor.

[0075] The memory (12) may include volatile memory such as Static Random Access Memory (S-RAM) and Dynamic Random Access Memory (D-RAP) for temporarily storing data. In addition, the memory (12) may include nonvolatile memory such as Read Only Memory (ROM), Erasable Programmable Read Only Memory (EPROM), and Electrically Erasable Programmable Read Only Memory (EEPROM) for long-term storage of data.

[0076] The processor (11) may include various logic circuits and operation circuits, process data according to a program provided from memory (12), and generate a control signal according to the processing result.

[0077] FIG. 6 is a flowchart illustrating a control method of a heat pump system according to one embodiment of the present disclosure.

[0078] The control unit (10) can determine the reference subcooling degree of the refrigerant based on the outdoor temperature detected by the outdoor temperature sensor (122), the inlet temperature detected by the inlet temperature sensor (126), and the operating frequency of the compressor (601).

[0079] The reference subcooling degree is a subcooling degree value for determining whether there is a leak of refrigerant, and can be determined, for example, according to [Mathematical Formula 1] below.

[0080] [Mathematical Formula 1]

[0081] Reference subcooling = {A * inlet temperature - B * outdoor temperature + C * compressor frequency + D} * E

[0082] Here, A represents the inlet temperature coefficient, B represents the outdoor temperature coefficient, C represents the frequency coefficient, D represents a constant term, and E represents a ratio, which may have different values ​​depending on the compressor, refrigerant-water heat exchanger (112), and outdoor heat exchanger (108).

[0083] The control unit (10) can determine the current subcooling degree of the refrigerant based on the high pressure saturation temperature of the refrigerant detected by the high pressure sensor (130) and the temperature of the condensed refrigerant detected by the condensation temperature sensor (120) (603).

[0084] The current supercooling can be determined, for example, according to [Mathematical Formula 2] below.

[0085] [Equation 2]

[0086] Current subcooling = {high pressure saturation temperature - temperature of condensed refrigerant}

[0087] The control unit (10) can determine whether there is a refrigerant leak by comparing the reference subcooling degree calculated according to the above mathematical formula with the current subcooling degree (605).

[0088] Below, the process of controlling the expansion valve (110) to reach the reference superheating degree and then comparing the reference subcooling degree and the current subcooling degree is described in detail.

[0089] FIG. 7 is a flowchart illustrating a process for controlling an expansion valve to reach a reference superheat level according to one embodiment of the present disclosure.

[0090] The present invention determines whether a refrigerant leaks based on its current degree of subcooling. However, since the same amount of refrigerant can have different degrees of subcooling depending on the degree of superheating, it is necessary to maintain a constant degree of superheating before comparing the degrees of subcooling.

[0091] Therefore, the control unit (10) can control the opening of the expansion valve (110) so that the superheat of the refrigerant becomes the reference superheat.

[0092] The reference superheat can be set to an appropriate value to detect refrigerant leakage, for example, 6°C.

[0093] The control unit (10) can determine the superheating degree of the refrigerant based on the low-pressure saturation temperature of the refrigerant detected by the low-pressure sensor (132) and the temperature of the refrigerant entering the compressor detected by the compressor suction temperature sensor (124) (701).

[0094] The superheat of the refrigerant can be determined, for example, according to [Mathematical Formula 3] below.

[0095] [Equation 3]

[0096] Superheat = {Compressor suction temperature - low pressure saturation temperature}

[0097] The control unit (10) can compare the determined superheat of the refrigerant with the reference superheat (703) and control the opening of the expansion valve (110) so that the superheat becomes the reference superheat.

[0098] In general, as the opening of the expansion valve (110) increases, the superheating of the refrigerant can decrease.

[0099] Accordingly, if the superheat of the refrigerant is lower than the reference superheat (example of 703), the control unit (10) can control the opening of the expansion valve (110) to decrease (705) because the superheat must be increased.

[0100] In addition, if the superheat of the refrigerant is higher than the standard superheat (No of 703), the control unit (10) can control the opening of the expansion valve (110) to increase (707) because the superheat must be reduced.

[0101] By controlling the opening of the expansion valve (110) in this way, after the superheating of the refrigerant becomes the standard superheating, the current subcooling degree can be compared with the standard subcooling degree to determine whether the refrigerant is leaking.

[0102] FIG. 8 is a flowchart specifically illustrating a process for determining whether a refrigerant leaks in a heat pump system according to one embodiment of the present disclosure, and FIG. 9 is a diagram explaining whether a refrigerant leaks according to the amount of refrigerant according to one embodiment of the present disclosure.

[0103] As described above, the control unit (10) determines the reference subcooling degree of the refrigerant based on the outdoor temperature detected by the outdoor temperature sensor (122), the inlet temperature detected by the inlet temperature sensor (126), and the operating frequency of the compressor (801), and can determine the current subcooling degree of the refrigerant based on the high-pressure saturation temperature of the refrigerant detected by the high-pressure sensor (130) and the temperature of the condensed refrigerant detected by the condensation temperature sensor (120) (803).

[0104] The control unit (10) can determine that a refrigerant leak has occurred (807) when the current subcooling degree of the refrigerant is less than the reference subcooling degree (example of 805).

[0105] Referring to FIG. 9, if the current subcooling of the refrigerant is higher than the reference subcooling (thick solid line) (thin solid line), it can be determined that there is no refrigerant leakage, and if the current subcooling of the refrigerant is lower than the reference subcooling (thick solid line) (dotted line), it can be determined that there is a refrigerant leakage.

[0106] The control unit (10) can stop the operation of the compressor to stop the operation of the heat pump system (1) when it is determined that a refrigerant leak has occurred (809).

[0107] FIG. 10 is a flowchart illustrating a process for determining whether there is a refrigerant leak based on superheat according to another embodiment of the present disclosure.

[0108] As described above, the superheating degree of the refrigerant can be controlled by controlling the opening degree of the expansion valve (110).

[0109] However, if the current superheat of the refrigerant is higher than the reference superheat (example of 1003) even though the opening of the expansion valve (110) is at the maximum (1001), the control unit (10) can determine that a refrigerant leak has occurred (1005).

[0110] Since the higher the amount of refrigerant leakage, the higher the superheat level is formed, so even though the opening of the expansion valve (110) is at the maximum and the superheat level of the refrigerant should be very low, if it is higher than the standard superheat level, it can be determined that a refrigerant leakage has occurred.

[0111] The control unit (10) can stop the operation of the compressor to stop the operation of the heat pump system (1) if it is determined that a refrigerant leak has occurred (1007).

[0112] According to one disclosed embodiment, even a small amount of refrigerant leakage can be detected without stopping the heat pump system (1) by determining whether or not there is a refrigerant leakage based on the degree of subcooling of the refrigerant.

[0113] FIG. 11 is a diagram showing the configuration of a heat pump system according to another embodiment of the present disclosure.

[0114] Hot water generated through the heat pump system (1) can be used for heating and hot water supply by a 3-way valve (136).

[0115] For example, hot water generated through a heat pump system (1) can be supplied to a radiator for indoor space heating, and can be supplied as hot water through a hot water tank (116).

[0116] Another embodiment of the present disclosure describes a case of supplying hot water through a hot water tank (116). Generally, hot water generated in a heat pump system (1) can be increased in temperature to match the temperature of water actually used by a user through a heat exchanger inside the hot water tank (116).

[0117] In the case of the hot water tank (116) for providing such hot water, if the temperature inside the hot water tank (116) is lower than the user-set temperature, the heat pump system (1) is operated, and if the temperature inside the hot water tank (116) is higher than the user-set temperature, the heat pump system (1) is stopped. Since the energy efficiency may be low due to heat loss if continuous operation and stopping are repeated like this, energy-saving operation is implemented by considering the learning of usage patterns and the amount of hot water heat. However, in the case of the hot water tank (116) equipped with an energy-saving operation function, a number of sensors were required in the past, which could increase the design configuration.

[0118] Hereinafter, a heat pump system (1) capable of performing energy-saving operation by predicting hot water usage patterns and hot water usage heat amount without using a plurality of sensors according to another embodiment of the present disclosure is described.

[0119] FIG. 12 is a drawing showing a control block diagram of a heat pump system according to another embodiment of the present disclosure, and FIG. 13 is a flowchart showing a control method of a heat pump system according to another embodiment of the present disclosure.

[0120] The heat pump system (1) may further include a hot water tank (116) that supplies hot water and a hot water tank inlet temperature sensor (134) that detects the temperature of water entering the hot water tank (116). The hot water tank inlet temperature sensor (134) may be provided in the vicinity close to the hot water tank (116).

[0121] When the hot water tank inlet temperature sensor (134) detects the temperature of water entering the hot water tank (116) (1301), the control unit (10) can determine whether to use hot water and the hot water use time based on the detection result of the hot water tank (116) inlet temperature (1303).

[0122] The control unit (10) can learn (1305) the hot water usage pattern based on the determined hot water usage and hot water usage time, thereby promoting the operation of an optimized heat pump system (1).

[0123] Below, the process of determining the hot water usage time is described.

[0124] FIG. 14 is a flowchart illustrating a process for determining a hot water usage time according to another embodiment of the present disclosure, and FIG. 15 is a drawing illustrating a hot water usage time according to another embodiment of the present disclosure.

[0125] As described above, the hot water tank intake temperature sensor (134) is installed around the hot water tank (116) and can normally maintain a relatively high temperature due to heat conducted from the hot water tank (116).

[0126] However, when a user uses the hot water, the temperature detected by the hot water tank inlet temperature sensor (134) may decrease rapidly as cold water flows into the hot water tank (116).

[0127] Based on these temperature changes, it is possible to determine whether or not to use the hot water heater and for how long.

[0128] Specifically, the control unit (10) can determine to start using the hot water if the difference between the water temperature (1401) of the hot water tank (116) at a first point in time and the water temperature (1401) of the hot water tank (116) at a second point in time, which is a predetermined period after the first point in time, is greater than the first temperature (example of 1403) (1405).

[0129] Here, the predetermined period can be set to an appropriate time to determine whether to use the hot water, for example, it can be 10 seconds.

[0130] Additionally, the first temperature can be set to an appropriate temperature for determining whether to use hot water, for example, 1℃.

[0131] That is, if the difference between the water temperature of the hot water tank (116) at the first point in time and the water temperature of the hot water tank (116) at the second point in time, 10 seconds later, is 1°C or more, the control unit (10) may determine that the temperature has decreased rapidly and decide to start using the hot water. Here, the start point of using the hot water may be the second point in time.

[0132] When a user or the like stops using the hot water supply, the temperature detected by the hot water tank inlet temperature sensor (134) may increase again as the cold water flow into the hot water tank (116) ends.

[0133] Specifically, the control unit (10) may determine to terminate the use of hot water if the difference between the water temperature (1407) of the hot water tank (116) at the third point in time and the water temperature (1407) of the hot water tank (116) at the fourth point in time, which is a predetermined period before the third point in time, is equal to or greater than the second temperature (example of 1409) (1411).

[0134] Here, the predetermined period can be set to an appropriate time to determine whether to terminate the use of the hot water heater, for example, it can be 10 seconds.

[0135] Additionally, the second temperature can be set to an appropriate temperature to determine whether to terminate the use of the hot water heater, for example, 0.5℃.

[0136] That is, if the difference between the water temperature of the hot water tank (116) at the third point in time and the water temperature of the hot water tank (116) at the fourth point in time, which is 10 seconds earlier, is 0.5°C or more, the control unit (10) may determine that the temperature has increased and decide to terminate the use of hot water. Here, the time point of termination of hot water use may be the third point in time.

[0137] The control unit (10) can determine the hot water use time based on the hot water use start time and the hot water use end time (1413).

[0138] That is, as shown in FIG. 15, the time between the second time point when the difference between the water temperature of the hot water tank (116) at the first time point and the water temperature of the hot water tank (116) at the second time point is greater than or equal to the first temperature, and the third time point when the difference between the water temperature of the hot water tank (116) at the third time point and the water temperature of the hot water tank (116) at the fourth time point, which is a predetermined period before the third time point, is greater than or equal to the second temperature, can be determined as the hot water use time.

[0139] The control unit (10) can learn the hot water usage pattern and determine the amount of heat used for hot water to operate the optimized heat pump system (1).

[0140] This amount of heat used for hot water can be determined, for example, through [Mathematical Formula 4] below.

[0141] [Equation 4]

[0142] Heat used for hot water = Heat generated - Heat loss - (Current heat for hot water - Previous heat for hot water)

[0143] The control unit (10) can determine the amount of hot water used and learn the hot water use pattern based on the determined amount of hot water used and the hot water use time.

[0144] For example, let's assume that the hot water consumption is 1000 calories. If the hot water was used four times, each for 10, 20, 30, and 40 minutes, the hot water consumption for each hour can be determined and stored as 100, 200, 300, and 400, respectively.

[0145] By determining and learning the user's hot water usage pattern in this way, the amount of hot water stored can be predicted and the optimized operation and stop of the heat pump system can be performed to save energy.

[0146] According to another disclosed embodiment, energy-saving operation can be performed by predicting hot water usage patterns and hot water usage heat amount without using multiple sensors, thereby reducing costs and simplifying design while performing energy-saving operation.

[0147] A heat pump system according to one embodiment may include a compressor for compressing a refrigerant; a refrigerant-water heat exchanger for heat exchange between the compressed refrigerant and received water; an expansion valve for expanding the refrigerant condensed in the refrigerant-water heat exchanger; an outdoor heat exchanger for heat exchange between the refrigerant expanded in the expansion valve and outdoor air; a high pressure sensor for detecting a high pressure saturation temperature of the refrigerant compressed in the compressor; an inlet temperature sensor for detecting a temperature of water entering the refrigerant-water heat exchanger; a condensation temperature sensor for detecting a temperature of the refrigerant condensed in the refrigerant-water heat exchanger; an outdoor temperature sensor for detecting an outdoor temperature; and a control unit for determining a reference subcooling degree of the refrigerant based on detection results of the outdoor temperature sensor and the inlet temperature sensor and an operating frequency of the compressor, determining a current subcooling degree of the refrigerant based on detection results of the high pressure sensor and the condensation temperature sensor, and comparing the reference subcooling degree and the current subcooling degree to determine whether the refrigerant is leaking.

[0148] According to the present disclosure, even a small amount of refrigerant leakage can be detected without stopping the heat pump system by determining whether or not there is a refrigerant leakage based on the degree of subcooling of the refrigerant.

[0149] The above control unit can determine that a leak of the refrigerant has occurred when the current subcooling degree of the refrigerant is less than the reference subcooling degree.

[0150] The above control unit can stop the operation of the compressor when it is determined that a leak of the refrigerant has occurred.

[0151] The above control unit controls the opening of the expansion valve so that the superheating of the refrigerant becomes the reference superheating, and after the superheating of the refrigerant becomes the reference superheating, compares the reference subcooling and the current subcooling to determine whether the refrigerant is leaking.

[0152] The compressor further includes a low-pressure sensor for detecting a low-pressure saturation temperature of the compressed refrigerant in the compressor; and a compressor suction temperature sensor for detecting a temperature of the refrigerant entering the compressor; wherein the control unit can determine a superheating degree of the refrigerant based on detection results of the low-pressure sensor and the compressor suction temperature sensor.

[0153] The above control unit can determine that a leak of the refrigerant has occurred if the current superheating degree of the refrigerant is higher than the reference superheating degree when the opening degree of the expansion valve is at the maximum.

[0154] A hot water tank for supplying hot water; and a hot water tank inlet temperature sensor for detecting the temperature of water entering the hot water tank; further comprising: the control unit can determine whether to use hot water and the hot water use time based on the detection result of the hot water tank inlet temperature.

[0155] According to the present disclosure, energy-saving operation can be performed by predicting hot water usage patterns and hot water usage heat amounts without using multiple sensors, thereby reducing costs and simplifying design while performing energy-saving operation.

[0156] The above control unit may determine to start using the hot water if the difference between the hot water tank intake temperature at a first point in time and the hot water tank intake temperature at a second point in time, which is a predetermined period after the first point in time, is equal to or greater than the first temperature.

[0157] The above control unit may determine to terminate the use of hot water if the difference between the water temperature of the hot water tank at a third point in time and the water temperature of the hot water tank at a fourth point in time, which is a predetermined period before the third point in time, is equal to or greater than the second temperature.

[0158] The above control unit can determine the hot water use time based on the hot water use start time and the hot water use end time.

[0159] The above control unit can determine the amount of hot water used and learn the hot water use pattern based on the amount of hot water used and the hot water use time.

[0160] A method for controlling a heat pump system according to one embodiment includes a compressor for compressing a refrigerant; a refrigerant-water heat exchanger for heat exchange between the compressed refrigerant and incoming water; an expansion valve for expanding the refrigerant condensed in the refrigerant-water heat exchanger; an outdoor heat exchanger for heat exchange between the refrigerant expanded in the expansion valve and outdoor air; a high pressure sensor for detecting a high pressure saturation temperature of the refrigerant compressed in the compressor; an inlet temperature sensor for detecting a temperature of water entering the refrigerant-water heat exchanger; a condensation temperature sensor for detecting a temperature of the refrigerant condensed in the refrigerant-water heat exchanger; and an outdoor temperature sensor for detecting an outdoor temperature. The method may include determining a reference subcooling degree of the refrigerant based on detection results of the outdoor temperature sensor and the inlet temperature sensor and an operating frequency of the compressor; determining a current subcooling degree of the refrigerant based on detection results of the high pressure sensor and the condensation temperature sensor; and comparing the reference subcooling degree and the current subcooling degree to determine whether the refrigerant is leaking.

[0161] Determining whether the refrigerant leaks may include determining that a leak of the refrigerant has occurred if the current subcooling degree of the refrigerant is less than the reference subcooling degree.

[0162] It may further include stopping the operation of the compressor when it is determined that a leak of the refrigerant has occurred.

[0163] The method further includes controlling the opening degree of the expansion valve so that the superheating degree of the refrigerant becomes a reference superheating degree; and determining whether the refrigerant leaks may include determining whether the refrigerant leaks by comparing the reference subcooling degree and the current subcooling degree after the superheating degree of the refrigerant becomes the reference superheating degree.

[0164] The compressor further includes a low-pressure sensor for detecting a low-pressure saturation temperature of the compressed refrigerant in the compressor; and a compressor suction temperature sensor for detecting a temperature of the refrigerant entering the compressor; and the superheating of the refrigerant becoming a reference superheating may include determining the superheating of the refrigerant based on detection results of the low-pressure sensor and the compressor suction sensor.

[0165] Determining whether the refrigerant leaks may include determining that a leak of the refrigerant has occurred if the current superheat of the refrigerant is higher than the reference superheat when the opening of the expansion valve is at its maximum.

[0166] It may further include a hot water tank supplying hot water; and a hot water tank inlet temperature sensor detecting the temperature of water entering the hot water tank; and determining whether to use hot water and the hot water use time based on the detection result of the hot water tank inlet temperature.

[0167] Determining the above hot water use time may include determining to start hot water use when the difference between the hot water tank intake temperature at a first time point and the hot water tank intake temperature at a second time point that is a predetermined period after the first time point is equal to or greater than the first temperature.

[0168] Determining the above hot water use time may include determining that hot water use is to be terminated if the difference between the hot water tank intake temperature at a third point in time and the hot water tank intake temperature at a fourth point in time, which is a predetermined period before the third point in time, is equal to or greater than the second temperature.

[0169] Determining the hot water use time may include determining the hot water use time based on the hot water use start time and the hot water use end time.

[0170] It may further include determining the amount of hot water used; and learning a hot water use pattern based on the amount of hot water used and the amount of hot water used time.

[0171] According to one aspect of the disclosed invention, by determining whether there is a refrigerant leak based on the degree of subcooling of the refrigerant, even a small amount of refrigerant leakage can be detected without stopping the heat pump system.

[0172] According to another aspect of the disclosed invention, it is possible to perform energy-saving operation by predicting hot water usage patterns and hot water usage heat amount without using a plurality of sensors, thereby achieving cost reduction and design simplification while performing energy-saving operation.

[0173] Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium storing computer-executable instructions. The instructions may be stored in the form of program code, and when executed by a processor, may generate program modules to perform the operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

[0174] Computer-readable storage media include all types of storage media that store instructions that can be deciphered by a computer. Examples include read-only memory (ROM), random access memory (RAM), magnetic tape, magnetic disks, flash memory, and optical data storage devices.

[0175] The disclosed embodiments have been described with reference to the attached drawings as described above. Those skilled in the art will understand that the present invention can be implemented in forms other than the disclosed embodiments without altering the technical spirit or essential features of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

Claims

1. A compressor that compresses the refrigerant; A refrigerant-water heat exchanger in which heat exchange takes place between the compressed refrigerant and the received water; An expansion valve for expanding the refrigerant condensed in the above refrigerant-water heat exchanger; An outdoor heat exchanger in which heat exchange takes place between the refrigerant expanded in the expansion valve and the outdoor air; A high pressure sensor that detects the high pressure saturation temperature of the refrigerant compressed in the above compressor; An inlet temperature sensor for detecting the temperature of water entering the refrigerant-water heat exchanger; A condensation temperature sensor for detecting the temperature of the condensed refrigerant in the above refrigerant-water heat exchanger; An outdoor temperature sensor that detects the outdoor temperature; and A heat pump system comprising: a control unit which determines a reference subcooling degree of the refrigerant based on detection results of the outdoor temperature sensor and the inlet temperature sensor and an operating frequency of the compressor, determines a current subcooling degree of the refrigerant based on detection results of the high pressure sensor and the condensation temperature sensor, and compares the reference subcooling degree with the current subcooling degree to determine whether the refrigerant is leaking.

2. In paragraph 1, The above control unit, A heat pump system wherein a leakage of the refrigerant is determined to have occurred when the current subcooling degree of the refrigerant is less than the reference subcooling degree.

3. In paragraph 2, The above control unit, A heat pump system that stops operation of the compressor when it is determined that a refrigerant leak has occurred.

4. In paragraph 1, The above control unit, A heat pump system that controls the opening of the expansion valve so that the superheat of the refrigerant becomes a reference superheat, and compares the reference subcooling with the current subcooling after the superheat of the refrigerant becomes the reference superheat, thereby determining whether there is a leak of the refrigerant.

5. In paragraph 4, A low pressure sensor for detecting the low pressure saturation temperature of the refrigerant compressed in the compressor; and Further comprising a compressor suction temperature sensor for detecting the temperature of the refrigerant entering the compressor; The above control unit, A heat pump system that determines the superheating degree of the refrigerant based on the detection results of the low pressure sensor and the compressor suction temperature sensor.

6. In paragraph 4, The above control unit, A heat pump system that determines that a leakage of the refrigerant has occurred when the current superheat of the refrigerant is higher than the reference superheat when the opening of the expansion valve is at the maximum.

7. In paragraph 1, A hot water tank supplying hot water; and Further comprising a hot water tank inlet temperature sensor for detecting the temperature of water entering the hot water tank; The above control unit, A heat pump system that determines whether to use hot water and the time for using hot water based on the detection result of the water temperature in the above hot water tank.

8. In paragraph 7, The above control unit, A heat pump system that determines to start using hot water if the difference between the hot water tank intake temperature at a first point in time and the hot water tank intake temperature at a second point in time after a predetermined period from the first point in time is equal to or greater than the first temperature.

9. In paragraph 8, The above control unit, A heat pump system that determines to terminate use of hot water if the difference between the hot water tank intake temperature at a third point in time and the hot water tank intake temperature at a fourth point in time, which is a predetermined period before the third point in time, is equal to or greater than the second temperature.

10. In paragraph 9, The above control unit, A heat pump system that determines the hot water use time based on the hot water use start time and the hot water use end time.

11. In paragraph 10, The above control unit, A heat pump system that determines hot water usage heat amount and learns hot water usage patterns based on the hot water usage heat amount and the hot water usage time.

12. A control method of a heat pump system comprising: a compressor for compressing a refrigerant; a refrigerant-water heat exchanger in which heat exchange occurs between the compressed refrigerant and the received water; an expansion valve for expanding the refrigerant condensed in the refrigerant-water heat exchanger; an outdoor heat exchanger in which heat exchange occurs between the refrigerant expanded in the expansion valve and outdoor air; a high pressure sensor for detecting a high pressure saturation temperature of the refrigerant compressed in the compressor; an inlet temperature sensor for detecting the temperature of water entering the refrigerant-water heat exchanger; a condensation temperature sensor for detecting the temperature of the refrigerant condensed in the refrigerant-water heat exchanger; and an outdoor temperature sensor for detecting an outdoor temperature; Determine the reference subcooling degree of the refrigerant based on the detection results of the outdoor temperature sensor and the inlet temperature sensor and the operating frequency of the compressor; Determine the current subcooling degree of the refrigerant based on the detection results of the high pressure sensor and the condensation temperature sensor; A method for controlling a heat pump system, comprising: comparing the reference subcooling degree with the current subcooling degree to determine whether there is a leak of the refrigerant.

13. In paragraph 12, Determining whether the above refrigerant leaks or not is: A control method of a heat pump system, comprising determining that a leakage of the refrigerant has occurred when the current subcooling degree of the refrigerant is less than the reference subcooling degree.

14. In paragraph 13, A method of controlling a heat pump system, further comprising: stopping the operation of the compressor when it is determined that a leakage of the refrigerant has occurred.

15. In paragraph 12, Further comprising: controlling the opening of the expansion valve so that the superheat of the refrigerant becomes a reference superheat; Determining whether the above refrigerant leaks or not is: A control method for a heat pump system, comprising: determining whether there is a leak of the refrigerant by comparing the current subcooling with the reference superheating after the superheating of the refrigerant becomes the reference superheating.

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