Heat pump system and control method thereof

Abstract

This invention relates to the field of heat pump technology, and discloses a heat pump system and its control method. The heat pump system includes a first circulation loop and a second circulation loop, which are respectively connected to a compressor and form a loop. A condenser, a first throttling device, and a first heat exchanger are sequentially arranged along the refrigerant flow direction in the first circulation loop. A second heat exchanger and a second throttling device are sequentially arranged in the second circulation loop. The second heat exchanger is connected to the compressor outlet, and the second throttling device is connected to the compressor return port. The first and second heat exchangers are adapted to exchange heat with each other. This invention can operate at low ambient temperatures, such as in cold regions or winter, and can improve the evaporation temperature and energy efficiency ratio of the heat pump in low-temperature environments, thereby improving the reliability and stability of the system.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, and more specifically to heat pump systems and their control methods. Background Technology

[0002] With the development of science and technology and the improvement of people's living standards, heat pump technology is increasingly widely used in homes and industries. The heating principle of a heat pump system is based on the reverse Carnot cycle, and its basic working process includes four main steps: compression, condensation, expansion, and evaporation. As a highly efficient and environmentally friendly energy conversion device, heat pumps can extract heat from low-temperature heat sources and transfer it to high-temperature heat sources, and are widely used in heating, cooling, and hot water supply.

[0003] However, traditional heat pump systems experience a significant drop in efficiency or even fail to operate properly when running at low ambient temperatures, such as in cold regions or during winter. This is because the evaporation temperature of the heat pump decreases at low temperatures, leading to increased compressor load, a lower energy efficiency ratio, and severely impacting the system's reliability and stability. Summary of the Invention

[0004] The first technical problem solved by this invention is to provide a heat pump system that effectively solves the problems of low system reliability and low energy efficiency ratio of existing heat pump systems when heating demand is low ambient temperature.

[0005] The second technical problem solved by this invention is to provide a control method for a heat pump system, which effectively solves the problems of low system reliability and low energy efficiency ratio of existing heat pump systems when heating demand is low in ambient temperature.

[0006] The first technical problem mentioned above is solved by the following technical solution:

[0007] A heat pump system includes a first circulation loop and a second circulation loop, which are respectively connected to a compressor and form a loop. The first circulation loop is provided with a condenser, a first throttling device and a first heat exchanger in sequence along the refrigerant flow direction. The second circulation loop is provided with a second heat exchanger and a second throttling device. The second heat exchanger is connected to the outlet of the compressor and the second throttling device is connected to the return port of the compressor. The first heat exchanger and the second heat exchanger are adapted to exchange heat with each other.

[0008] Compared with the prior art, the heat pump system described in this invention has the following beneficial effects: Due to the low ambient temperature, the evaporation capacity of the unit weakens, potentially causing frost to form on the evaporator in low-temperature environments. Simultaneously, if the water temperature is high and the ambient temperature is low, a large compression ratio will occur in the normal heating cycle, leading to increased unit power and decreased product energy efficiency. Therefore, this invention provides a heat pump system that divides the refrigerant into two parts. One part flows through the first circulation loop, i.e., a portion of the refrigerant enters the first throttling device via the condenser. The throttled refrigerant then enters the first heat exchanger for evaporation and finally returns to the compressor to complete the normal heating cycle. Simultaneously, the second throttling device is activated, allowing a portion of the refrigerant to flow through the second circulation loop, i.e., a portion of the refrigerant enters the second heat exchanger. Since the refrigerant directly enters the second heat exchanger from the compressor exhaust and then expands before returning to the compressor via the second throttling device, the surface temperature of the second heat exchanger is higher. The second heat exchanger exchanges heat with the first heat exchanger, increasing the temperature of the first heat exchanger, improving the system's evaporation environment, increasing system efficiency, and reducing the system's compression ratio. Therefore, this invention can operate at low ambient temperatures, such as in cold regions or winter, and can improve the evaporation temperature and energy efficiency ratio of the heat pump in low-temperature environments, thereby improving the reliability and stability of the system.

[0009] In one embodiment, the system further includes a connecting pipeline, a first control valve, and a second control valve. The first control valve is located on the connecting pipeline, and the second control valve is located on the pipeline between the second throttling device and the compressor's return port. One end of the connecting pipeline is connected to the pipeline between the first throttling device and the first heat exchanger, and the other end is connected to the pipeline between the second throttling device and the second control valve.

[0010] In one embodiment, a four-way reversing valve is also included, with two ports of the four-way reversing valve connected to a pipeline between the compressor outlet and the second heat exchanger, and the other two ports of the four-way reversing valve connected to a pipeline between the compressor return port and the second throttling device.

[0011] In one embodiment, the system further includes a first temperature sensor, a second temperature sensor, and a controller. The first temperature sensor is used to collect ambient temperature; the second temperature sensor is used to collect the inlet water temperature of the condenser; the controller is electrically connected to both the first and second temperature sensors; the four-way directional valve, the first control valve, and the second control valve are all solenoid valves; the four-way directional valve is electrically connected to the controller, and the controller controls the switching of the four-way directional valve; the first control valve is electrically connected to the controller, and the controller controls the opening degree of the first control valve; the second control valve is electrically connected to the controller, and the controller controls the opening degree of the second control valve.

[0012] The second technical problem mentioned above is solved by the following technical solution:

[0013] A control method for a heat pump system includes: collecting an ambient temperature Ta, comparing the collected ambient temperature Ta with a preset ambient temperature threshold M to obtain a first determination result; collecting a condenser inlet water temperature Tw, comparing the collected condenser inlet water temperature Tw with a preset minimum water temperature threshold A and a preset maximum water temperature threshold B to obtain a second determination result; and controlling a first throttling device and a second throttling device to switch between a normal heating mode and a low ambient temperature heating mode based on the first determination result and the second determination result.

[0014] Compared with the prior art, the control method of the heat pump system described in this invention has the following advantages: Based on the comparison results of the collected ambient temperature Ta and the preset ambient temperature threshold M, combined with the comparison results of the collected condenser inlet water temperature Tw and the preset minimum water temperature threshold A and the preset maximum water temperature threshold B, this invention controls the opening and closing or reversing of each valve and the start and stop of each device, switching between two heating modes: normal heating mode and low ambient temperature heating mode. Different heating modes can be selected according to different operating conditions, enabling the system to operate at low ambient temperatures, thereby improving the reliability and energy efficiency ratio of the system.

[0015] In one embodiment, when the first determination result is Ta > M and the second determination result is A ≤ Tw ≤ B, the first throttling device is turned on and the second throttling device is turned off to switch to normal heating mode; when the first determination result is Ta ≤ M, both the first throttling device and the second throttling device are turned on to switch to low ambient temperature heating mode.

[0016] The second technical problem mentioned above can also be solved by the following technical solutions:

[0017] A control method for a heat pump system includes: acquiring an ambient temperature Ta, comparing the acquired ambient temperature Ta with a preset ambient temperature threshold M to obtain a first determination result; acquiring a condenser inlet water temperature Tw, comparing the acquired condenser inlet water temperature Tw with a preset minimum water temperature threshold A and a preset maximum water temperature threshold B to obtain a second determination result; and controlling a first throttling device, a second throttling device, a four-way reversing valve, a first control valve, and a second control valve to switch between a normal heating mode, a low ambient temperature heating mode, a low water temperature heating mode, and a high water temperature heating mode, based on the first determination result and the second determination result.

[0018] Compared with the prior art, the control method of the heat pump system described in this invention has the following advantages: Based on the comparison between the collected ambient temperature Ta and the preset ambient temperature threshold M, and combined with the comparison between the collected condenser inlet water temperature Tw and the preset minimum water temperature threshold A and the preset maximum water temperature threshold B, this invention controls the opening and closing or reversing of each valve and the start and stop of each device. It switches between four heating modes: normal heating mode, low ambient temperature heating mode, low water temperature heating mode, and high water temperature heating mode. Different heating modes can be selected according to different operating conditions, enabling the system to operate at low ambient temperatures and meet the heating requirements at low and high water temperatures, thereby improving the reliability and energy efficiency ratio of the system operation.

[0019] In one embodiment, when the first determination result is Ta > M and the second determination result is A ≤ Tw ≤ B, the first throttling device is opened, and the second throttling device, the first control valve, and the second control valve are all closed to switch to the normal heating mode; when the first determination result is Ta ≤ M, the first throttling device, the second throttling device, and the second control valve are all opened, the four-way reversing valve connects the compressor outlet to the second heat exchanger and connects the second control valve to the compressor return port, and the first control valve is closed to switch to the low ambient temperature heating mode.

[0020] In one embodiment, when the first determination result is Ta>M and the second determination result is Tw<A, the first throttling device, the second throttling device and the first control valve are all opened, the four-way reversing valve connects the second heat exchanger to the return port of the compressor, and the second control valve is closed to switch to the low water temperature heating mode.

[0021] In one embodiment, when the first determination result is Ta > M and the second determination result is Tw > B, the first throttling device, the second throttling device, and the first control valve are all opened, the four-way reversing valve connects the compressor outlet to the second heat exchanger, and the second control valve is closed to switch to the high water temperature heating mode. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a heat pump system according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of another heat pump system according to an embodiment of the present invention;

[0025] Figure 3 for Figure 2 The diagram shows the operation of a heat pump system in normal heating mode.

[0026] Figure 4 for Figure 2 The diagram shows the operation of a heat pump system in low ambient temperature heating mode.

[0027] Figure 5 for Figure 2 The diagram shows the operation of a heat pump system in low water temperature heating mode.

[0028] Figure 6 for Figure 2 The diagram shows the operation of the heat pump system in high water temperature heating mode.

[0029] Figure 7 For the purposes of this invention embodiment Figure 1 A flowchart of a control method for a heat pump system is shown.

[0030] Figure 8 For the purposes of this invention embodiment Figure 2 The flowchart shows a control method for a heat pump system.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Compressor; 2. Condenser; 3. First throttling device; 4. Second throttling device; 5. Combined heat exchanger; 51. First heat exchanger; 52. Second heat exchanger; 53. Fan; 6. Four-way reversing valve; 7. First control valve; 8. Second control valve; 9. Connecting pipeline; 10. First branch; 20. Second branch; 30. Third branch; 40. Fourth branch. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Traditional heat pump systems often exhibit significant shortcomings when operating under conditions of high outlet water temperature and low ambient temperature, mainly in the following aspects:

[0035] 1. Operation at low ambient temperatures: In cold regions or during winter, the efficiency of traditional heat pump systems drops significantly due to low ambient temperatures, and they may even fail to operate normally. In low-temperature environments, the evaporation temperature of the heat pump decreases, leading to increased compressor load, a decreased energy efficiency ratio, and severely impacting the system's reliability and stability.

[0036] 2. System Reliability: Traditional heat pump systems are relatively simple in design and lack flexibility, making it impossible to dynamically adjust system parameters according to actual operating conditions. This leads to significant fluctuations in system performance under different operating conditions, making them prone to failure and affecting normal user operation.

[0037] 3. Energy Efficiency Ratio (EER): Although heat pump systems have a higher EER compared to traditional heating methods, under certain conditions, such as high-load operation or extreme ambient temperatures, the EER still needs further improvement. Improving the EER of a heat pump system not only saves energy but also reduces operating costs, thereby increasing the user's economic benefits.

[0038] 4. The system operates in a single mode, and its performance fluctuates greatly under different operating conditions, making it prone to failure and resulting in low system reliability, which affects normal use by users.

[0039] 5. High-temperature requirements: Traditional heat pump systems are often difficult to design to meet users' demands for high-temperature hot water. In some applications, such as industrial hot water supply and high-temperature heating, users need heat pump systems to provide hot water at higher temperatures, while traditional heat pump systems typically have lower outlet temperatures and cannot reach the required temperature levels.

[0040] To address the aforementioned problems, this invention provides a heat pump system that, by introducing a combined heat exchanger structure, dynamically adjusts the function of each heat exchanger according to actual conditions during system operation. This maximizes the improvement of heat pump operating conditions and enhances system reliability and stability. Simultaneously, this heat pump system improves the outlet water temperature and energy efficiency ratio to a certain extent, meeting users' demands for high-performance heat pump systems.

[0041] The following is combined Figures 1 to 8 The following describes embodiments of the present invention.

[0042] According to an embodiment of the present invention, a heat pump system is provided, comprising a first circulation loop and a second circulation loop respectively connected to a compressor 1 and forming a loop. The first circulation loop is provided with a condenser 2, a first throttling device 3 and a first heat exchanger 51 sequentially arranged along the refrigerant flow direction. The second circulation loop is provided with a second heat exchanger 52 and a second throttling device 4. The second heat exchanger 52 is connected to the outlet of the compressor 1, and the second throttling device 4 is connected to the return port of the compressor 1. The first heat exchanger 51 and the second heat exchanger 52 are adapted to exchange heat with each other.

[0043] Reference Figures 1 to 6 The arrows in the diagram indicate the direction of refrigerant flow.

[0044] The heat pump system provided in this embodiment of the invention can operate in both normal heating mode and low ambient temperature heating mode.

[0045] Specifically, the normal heating mode is used when only the first circulation loop is running. The refrigerant circulation direction in compressor 1 is: compressor 1, condenser 2, first throttling device 3, first heat exchanger 51, compressor 1.

[0046] The specific working principle is as follows:

[0047] Compressor 1 compresses the low-pressure, low-temperature refrigerant gas into a high-pressure, high-temperature gas. This high-pressure, high-temperature refrigerant gas enters condenser 2, where it exchanges heat with the medium requiring heating (such as indoor air or water), transferring heat to the indoor air or water to achieve a heating effect. After heat exchange, the refrigerant's temperature and pressure decrease, becoming a high-pressure, low-temperature liquid. This high-pressure, low-temperature refrigerant liquid rapidly expands through the first throttling device 3, causing its pressure and temperature to drop sharply, becoming a low-pressure, low-temperature liquid. The first heat exchanger 51 acts as an evaporator. Subsequently, the low-pressure, low-temperature refrigerant liquid absorbs heat from the surrounding environment in the first heat exchanger 51, its temperature rises, and it evaporates into a low-pressure, low-temperature gas, then returns to compressor 1 to continue the cycle. This completes one normal heating cycle.

[0048] Specifically, the low ambient temperature heating mode operates when the first and second circulation loops are running simultaneously. A portion of the refrigerant in compressor 1 flows through the first circulation loop, with the following flow direction: compressor 1, condenser 2, first throttling device 3, first heat exchanger 51, compressor 1. The other portion flows through the second circulation loop, with the following flow direction: compressor 1, second heat exchanger 52, second throttling device 4, compressor 1.

[0049] The specific working principle is as follows:

[0050] The working principle of the first circulation loop is the same as that of the ordinary heating mode described above.

[0051] The working principle of the second circulation loop: Due to the low ambient temperature, the evaporation capacity of the unit is weakened. Therefore, the first heat exchanger 51 may frost in the low temperature environment. At the same time, if the water temperature is high and the ambient temperature is low, the normal heating cycle will produce a large compression ratio, which will lead to an increase in unit power and a decrease in product energy efficiency. Therefore, the refrigerant of the unit is divided into two parts. One part goes through the first circulation loop, that is, a part of the refrigerant enters the first throttling device 3 through the condenser 2. The throttled refrigerant enters the first heat exchanger 51 for evaporation and finally returns to the compressor 1 to complete the normal heating cycle. At the same time, the second throttling device 4 is opened, and the other part goes through the second circulation loop, that is, a part of the refrigerant is discharged from the compressor 1 directly into the second heat exchanger 52, the second throttling device 4 and then returns to the compressor 1. Here, the second heat exchanger 52 is used as a condenser to achieve the condensation effect. The surface temperature of the second heat exchanger 52 is relatively high. The high-temperature and high-pressure refrigerant gas exchanges heat with the first heat exchanger 51 in the second heat exchanger 52, supplementing the first heat exchanger 51 with heat, increasing the temperature of the first heat exchanger 51, improving the system evaporation environment, increasing system efficiency, and reducing the system compression ratio.

[0052] The heat pump system provided in this embodiment of the invention, by setting a second circulation loop and setting a second heat exchanger 52 on the second circulation loop that is arranged side by side with the first heat exchanger 51 and can exchange heat with each other, when the low ambient temperature heating mode is selected, the first circulation loop and the second circulation loop operate simultaneously. Relying on the heat exchange between the second heat exchanger 52 and the first heat exchanger 51, the heat required for refrigerant evaporation of the first heat exchanger 51 can be supplemented, the evaporation environment of the system can be improved, the compression ratio of the system can be reduced, and the system efficiency can be improved.

[0053] Furthermore, if the water temperature is high and the evaporation temperature is low, the opening of the second throttling device 4 can be adjusted as needed to control the amount of refrigerant return gas injected, improve the system pressure ratio, and enhance the system's operational reliability, capacity, and energy efficiency.

[0054] This invention can operate at low ambient temperatures, such as in cold regions or during winter, and can improve the evaporation temperature and energy efficiency ratio of the heat pump in low-temperature environments, thereby enhancing the system's reliability and stability. Furthermore, this invention can switch between normal heating mode and low ambient temperature heating mode according to different ambient temperatures, ensuring high system reliability and normal user operation.

[0055] Specifically, in this embodiment, the condenser 2 is a plate heat exchanger. The condenser 2 has a first channel for the flow of refrigerant and a second channel for the flow of water, the first channel being connected to a first circulation loop.

[0056] In some embodiments, a four-way reversing valve 6 is also included, with two ports of the four-way reversing valve 6 connected to a pipeline between the outlet of the compressor 1 and the second heat exchanger 52, and the other two ports of the four-way reversing valve 6 connected to a pipeline between the return port of the compressor 1 and the second throttling device 4.

[0057] By setting the four-way reversing valve 6, the pipeline can be reversed. In the low ambient temperature heating mode, the second circulation loop operates, and the refrigerant circulation direction is: compressor 1, four-way reversing valve 6, second heat exchanger 52, second throttling device 4, four-way reversing valve 6, compressor 1.

[0058] Furthermore, the second circulation loop includes a first branch 10, a second branch 20, a third branch 30, and a fourth branch 40 connected in sequence. One end of the first branch 10 is connected to the outlet of the compressor 1, and the other end is connected to the first port of the four-way reversing valve 6. One end of the second branch 20 is connected to the second port of the four-way reversing valve 6, and the other end is connected to one end of the third branch 30. The other end of the third branch 30 is connected to the third port of the four-way reversing valve 6. One end of the fourth branch 40 is connected to the fourth port of the four-way reversing valve 6, and the other end is connected to the return port of the compressor 1.

[0059] Specifically, in this embodiment, the second heat exchanger 52 and the second throttling device 4 are both located on the second branch 20, and the second control valve 8 is located on the third branch 30. For example... Figure 4 As shown, in the low ambient temperature heating mode, the second throttling device 4 is located downstream of the second heat exchanger 52 in the second circulation loop.

[0060] A four-way reversing valve 6 can connect the first branch 10 and the second branch 20, as well as the third branch 30 and the fourth branch 40, thus connecting the second circulation loop. It can also connect the second branch 20 and the fourth branch 40 to achieve a low-temperature heating mode; the specific working principle will be explained later.

[0061] In some embodiments, the system further includes a connecting pipe 9, a first control valve 7, and a second control valve 8. The first control valve 7 is disposed on the connecting pipe 9, and the second control valve 8 is disposed on the pipe between the second throttling device 4 and the return port of the compressor 1. One end of the connecting pipe 9 is connected to the pipe between the first throttling device 3 and the first heat exchanger 51, and the other end is connected to the pipe between the second throttling device 4 and the second control valve 8.

[0062] Specifically, in this embodiment, when operating the low ambient temperature heating mode, the first control valve 7 is closed, the second control valve 8 is open, and the four-way reversing valve 6 connects the outlet of the compressor 1 with the second heat exchanger 52 and connects the second control valve 8 with the return port of the compressor 1. That is, the first branch 10 and the second branch 20 are connected, and the third branch 30 and the fourth branch 40 are connected.

[0063] The heat pump system is equipped with a connecting pipe 9, which connects the first circulation loop and the second circulation loop. A first control valve 7 is installed on the connecting pipe 9. In addition, the heat pump system is also equipped with a second control valve 8. By controlling the opening and closing of the first control valve 7 and the second control valve 8, as well as the switching of the four-way reversing valve 6, the system can realize low water temperature heating mode and high water temperature heating mode.

[0064] The specific control and working principle of the low water temperature heating mode are as follows:

[0065] The first control valve 7 is open, the second control valve 8 is closed, and the four-way reversing valve 6 connects the second heat exchanger 52 to the return port of the compressor 1, that is, it connects the second branch 20 and the fourth branch 40, thus forming the third circulation loop. The second circulation loop is disconnected. The refrigerant circulation direction in the third circulation loop is: compressor 1, condenser 2, first throttling device 3, first control valve 7, second throttling device 4, second heat exchanger 52, four-way reversing valve 6, compressor 1. When the first and third circulation loops are running simultaneously, it is a low water temperature heating mode.

[0066] Specifically, the refrigerant expanded from the first throttling device 3 is divided into two paths. One part flows to the condenser 2 and goes through the first circulation loop, while the other part flows into the second throttling device 4 through the first control valve 7 to become a low-temperature, low-pressure refrigerant liquid. Subsequently, it evaporates into a low-temperature, low-pressure gas in the second heat exchanger 52 and returns to the compressor 1 through the four-way reversing valve 6 to complete one cycle.

[0067] Specifically, when the inlet water temperature of condenser 2 is low, the low water temperature heating mode is operated. At this time, the heat pump system has a large condensing capacity, so the heat pump system needs a large evaporating capacity. Therefore, after the refrigerant passes through the first throttling device 3, part of it flows to the first heat exchanger 51, and the other part flows to the second heat exchanger 52 through the first control valve 7. At this time, both the first heat exchanger 51 and the second heat exchanger 52 are evaporators, and the system's evaporating capacity is greatly enhanced, which can match the high condensing capacity of the heat pump system and improve the system's heating capacity and efficiency.

[0068] The specific control and working principle of the high water temperature heating mode are as follows:

[0069] The first control valve 7 is open, the second control valve 8 is closed, and the four-way reversing valve 6 connects the outlet of compressor 1 to the second heat exchanger 52, that is, it connects the first branch 10 and the second branch 20, thus forming the fourth circulation loop, and the second circulation loop is disconnected. The refrigerant circulation direction in the fourth circulation loop is: compressor 1, four-way reversing valve 6, second heat exchanger 52, second throttling device 4, first control valve 7, first heat exchanger 51, compressor 1. When the first and fourth circulation loops are running simultaneously, it is a high water temperature heating mode.

[0070] Specifically, the high-temperature, high-pressure refrigerant gas flowing out of compressor 1 is divided into two paths. One part flows to condenser 2 and goes through the first circulation loop, while the other part flows into the second heat exchanger 52 through the four-way reversing valve 6. At this time, the heat exchanger is used as condenser 2. The refrigerant after heat exchange becomes a low-temperature, high-pressure liquid. Then, it expands into a low-temperature, low-pressure liquid in the second throttling device 4, flows into the first heat exchanger 51 through the first control valve 7 and evaporates into a low-temperature, low-pressure gas. Finally, it returns to compressor 1 to complete one cycle.

[0071] Specifically, when the inlet water temperature of condenser 2 is high, the high water temperature heating mode is operated. At this time, the condensing capacity of the heat pump system is small, so the heat pump system needs a more suitable evaporating capacity. Therefore, a portion of the refrigerant flows to the first heat exchanger 51 after heat exchange in condenser 2 and throttling through the first throttling device 3. At this time, the first heat exchanger 51 is the evaporator. Since the condensing capacity and evaporating capacity of the product are mismatched, it is easy to cause system abnormalities. At this time, the second throttling device 4 is opened and the first control valve 7 is opened. A portion of the refrigerant flows out from compressor 1 and enters the second heat exchanger 52. At this time, the second heat exchanger 52 is the condenser 2, which condenses this portion of refrigerant. After throttling through the second throttling device 4, it mixes with the refrigerant after throttling through condenser 2 and enters the first heat exchanger 51 for evaporation to supplement the evaporator evaporation demand of the system and ensure the normal operation of the system. The refrigerant flows out of the first heat exchanger 51 and returns to compressor 1.

[0072] The heat pump system provided in this embodiment can maximize the high-temperature outlet water temperature of the system while ensuring normal system operation when operating in high water temperature heating mode.

[0073] In some embodiments, the system further includes a first temperature sensor, a second temperature sensor, and a controller. The first temperature sensor is used to collect the ambient temperature; the second temperature sensor is used to collect the inlet water temperature of the condenser 2; the controller is electrically connected to both the first and second temperature sensors; the four-way reversing valve 6, the first control valve 7, and the second control valve 8 are all solenoid valves; the four-way reversing valve 6 is electrically connected to the controller, and the controller controls the reversing of the four-way reversing valve 6; the first control valve 7 is electrically connected to the controller, and the controller controls the opening degree of the first control valve 7; the second control valve 8 is electrically connected to the controller, and the controller controls the opening degree of the second control valve 8.

[0074] Specifically, the controller compares the ambient temperature collected by the first temperature sensor with the preset ambient temperature threshold M in the controller. When the collected ambient temperature is lower than M, the low ambient temperature heating mode is executed.

[0075] The controller compares the inlet water temperature of condenser 2 collected by the second temperature sensor with a preset inlet water temperature threshold, and executes any one of the following modes based on the comparison result: normal heating mode, low water temperature heating mode, or high water temperature heating mode. Specifically, the controller can control the four-way reversing valve 6 to switch to different conduction states according to different operating conditions, and control the opening and closing of the first control valve 7 and the second control valve 8 to execute a certain heating mode.

[0076] In some embodiments, the first throttling device 3 and / or the second throttling device 4 are expansion valves.

[0077] In other embodiments, the first throttling device 3 and / or the second throttling device 4 is a combination of an expansion valve and a solenoid valve.

[0078] When both the first throttling device 3 and the second throttling device 4 are a combination of an expansion valve and a solenoid valve, the first throttling device 3 and the second throttling device 4 are electrically connected to the controller. The controller controls the start and stop of the first throttling device 3 and the second throttling device 4, and controls the opening degree of the first throttling device 3 and the second throttling device 4 according to the operating requirements of different working conditions, so as to control the flow rate of refrigerant.

[0079] In some embodiments, the heat pump system further includes a negative pressure fan 53, the negative pressure fan 53 and the second heat exchanger 52 are respectively disposed on opposite sides of the first heat exchanger 51; the second heat exchanger 52 is located on the air inlet side.

[0080] Specifically, the first heat exchanger 51, the second heat exchanger 52, and the negative pressure fan 53 constitute a combined heat exchange device 5.

[0081] According to an embodiment of the present invention, in another aspect, a control method for the heat pump system in the above technical solutions is also provided, comprising:

[0082] Collect the ambient temperature Ta, compare the collected ambient temperature Ta with the preset ambient temperature threshold M, and obtain the first judgment result;

[0083] The inlet water temperature Tw of condenser 2 is collected, and the collected inlet water temperature Tw of condenser 2 is compared with the preset minimum water temperature threshold A and the preset maximum water temperature threshold B to obtain the second judgment result.

[0084] Based on the first and second determination results, the first throttling device 3 and the second throttling device 4 are controlled to switch between normal heating mode and low ambient temperature heating mode.

[0085] The flowchart of the control method of the heat pump system is as follows: Figure 7 As shown.

[0086] The control method for the heat pump system provided in this embodiment of the invention controls the opening and closing or reversing of each valve and the start and stop of each device based on the comparison results of the collected ambient temperature Ta and the preset ambient temperature threshold M, combined with the comparison results of the collected inlet water temperature Tw of the condenser 2 and the preset minimum water temperature threshold A and the preset maximum water temperature threshold B. It switches between two modes: normal heating mode and low ambient temperature heating mode. Different heating modes can be selected according to different operating conditions, enabling the system to operate at low ambient temperatures. At the same time, it improves the reliability and energy efficiency ratio of the system operation.

[0087] In some embodiments, the method includes: when the first determination result is Ta>M and the second determination result is A≤Tw≤B, controlling the first throttling device 3 to open and the second throttling device 4 to close, so as to switch to normal heating mode; when the first determination result is Ta≤M, controlling both the first throttling device 3 and the second throttling device 4 to open, so as to switch to low ambient temperature heating mode.

[0088] Specifically, the first determination result is Ta > M, indicating that the ambient temperature is normal under the current operating conditions. Taking A = 30℃ and B = 45℃ as an example, if the inlet water temperature Tw of condenser 2 is within the temperature range of 30℃ to 45℃, then the normal heating mode is operated. At this time, only the first circulation loop is connected, and the other loops are disconnected.

[0089] Specifically, the first determination result is Ta≤M, indicating that the ambient temperature under the current operating conditions is low. Taking M as -10℃ as an example, the collected ambient temperature Ta≤-10℃, at which point the low ambient temperature heating mode is run, that is, both the first and second circulation loops are connected and running.

[0090] According to an embodiment of the present invention, in another aspect, a control method for the heat pump system in the above technical solutions is also provided, comprising:

[0091] Collect the ambient temperature Ta, compare the collected ambient temperature Ta with the preset ambient temperature threshold M, and obtain the first judgment result;

[0092] The inlet water temperature Tw of condenser 2 is collected, and the collected inlet water temperature Tw of condenser 2 is compared with the preset minimum water temperature threshold A and the preset maximum water temperature threshold B to obtain the second judgment result.

[0093] Based on the first and second determination results, the first throttling device 3, the second throttling device 4, the four-way reversing valve 6, the first control valve 7, and the second control valve 8 are controlled to switch between normal heating mode, low ambient temperature heating mode, low water temperature heating mode, and high water temperature heating mode.

[0094] The flowchart of the control method of the heat pump system is as follows: Figure 8 As shown.

[0095] The control method for the heat pump system provided in this embodiment of the invention controls the opening and closing or reversal of each valve and the start and stop of each device based on the comparison results of the collected ambient temperature Ta with the preset ambient temperature threshold M, and the comparison results of the collected inlet water temperature Tw of the condenser 2 with the preset minimum water temperature threshold A and the preset maximum water temperature threshold B. It switches between four modes: normal heating mode, low ambient temperature heating mode, low water temperature heating mode, and high water temperature heating mode. Different heating modes can be selected according to different operating conditions, so that the system can operate at low ambient temperatures and meet the heating requirements of low and high water temperatures. At the same time, it improves the reliability and energy efficiency ratio of the system operation.

[0096] In some embodiments, when the first determination result is Ta>M and the second determination result is A≤Tw≤B, the first throttling device 3 is opened, and the second throttling device 4, the first control valve 7 and the second control valve 8 are all closed, so as to switch to the normal heating mode.

[0097] It should be noted that since the second throttling device 4, the first control valve 7, and the second control valve 8 are all closed, the second circulation loop is in an open state. Therefore, there is no need to change the conduction state of the four-way reversing valve 6.

[0098] When the first determination result is Ta≤M, the first throttling device 3, the second throttling device 4, and the second control valve 8 are all opened. The four-way reversing valve 6 connects the outlet of the compressor 1 with the second heat exchanger 52 and connects the second control valve 8 with the return port of the compressor 1. The first control valve 7 is closed to switch to the low ambient temperature heating mode.

[0099] The control methods for normal heating mode and low ambient temperature heating mode are the same as those described above, and will not be repeated here.

[0100] In some embodiments, when the first determination result is Ta > M and the second determination result is Tw < A, the first throttling device 3, the second throttling device 4 and the first control valve 7 are all opened, the four-way reversing valve 6 connects the second heat exchanger 52 with the return port of the compressor 1, and the second control valve 8 is closed to switch to the low water temperature heating mode.

[0101] Specifically, the first determination result is Ta > M, indicating that the ambient temperature is normal under the current operating conditions. Taking A = 30℃ as an example, when the inlet water temperature Tw of condenser 2 is less than 30℃, the low water temperature heating mode is operated. At this time, the first circulation loop and the third circulation loop are connected and running.

[0102] In some embodiments, when the first determination result is Ta > M and the second determination result is Tw > B, the first throttling device 3, the second throttling device 4 and the first control valve 7 are all opened, the four-way reversing valve 6 connects the outlet of the compressor 1 with the second heat exchanger 52, and the second control valve 8 is closed to switch to the high water temperature heating mode.

[0103] Specifically, the first determination result is Ta > M, indicating that the ambient temperature is normal under the current operating conditions. Taking B = 45℃ as an example, when the inlet water temperature Tw of condenser 2 is greater than 45℃, the high water temperature heating mode is operated. At this time, the first circulation loop and the fourth circulation loop are connected and running.

[0104] The control method provided in this invention provides four heating modes based on the ambient temperature and the condenser inlet water temperature, in order to further improve the reliability and energy efficiency ratio of the heat pump system.

[0105] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0106] The specific embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A heat pump system, characterized in that, It includes a first circulation loop and a second circulation loop that are respectively connected to the compressor (1) and form a loop. The first circulation loop is provided with a condenser (2), a first throttling device (3) and a first heat exchanger (51) in sequence along the refrigerant flow direction. The second circulation loop is provided with a second heat exchanger (52) and a second throttling device (4). The second heat exchanger (52) is connected to the outlet of the compressor (1), and the second throttling device (4) is connected to the return port of the compressor (1). The first heat exchanger (51) and the second heat exchanger (52) are adapted to exchange heat with each other.

2. The heat pump system according to claim 1, characterized in that, It also includes a connecting pipe (9), a first control valve (7) and a second control valve (8). The first control valve (7) is located on the connecting pipe (9), and the second control valve (8) is located on the pipe between the second throttling device (4) and the return port of the compressor (1). One end of the connecting pipe (9) is connected to the pipe between the first throttling device (3) and the first heat exchanger (51), and the other end is connected to the pipe between the second throttling device (4) and the second control valve (8).

3. The heat pump system according to claim 2, characterized in that, It also includes a four-way reversing valve (6), two of which are connected to the pipeline between the outlet of the compressor (1) and the second heat exchanger (52), and the other two of which are connected to the pipeline between the return port of the compressor (1) and the second throttling device (4).

4. The heat pump system according to claim 3, characterized in that, Also includes: The first temperature sensor is used to collect ambient temperature; The second temperature sensor is used to collect the inlet water temperature of the condenser (2); The controller is electrically connected to the first temperature sensor and the second temperature sensor, respectively. The four-way reversing valve (6), the first control valve (7) and the second control valve (8) are all solenoid valves; The four-way reversing valve (6) is electrically connected to the controller, and the controller controls the reversing of the four-way reversing valve (6). The first control valve (7) is electrically connected to the controller, and the controller controls the opening degree of the first control valve (7); The second control valve (8) is electrically connected to the controller, and the controller controls the opening degree of the second control valve (8).

5. A control method for a heat pump system according to claim 1, characterized in that, include: Collect the ambient temperature Ta, compare the collected ambient temperature Ta with the preset ambient temperature threshold M, and obtain the first judgment result; Collect the inlet water temperature Tw of the condenser (2), compare the collected inlet water temperature Tw of the condenser (2) with the preset minimum water temperature threshold A and the preset maximum water temperature threshold B, and obtain the second judgment result; Based on the first determination result and the second determination result, the first throttling device (3) and the second throttling device (4) are controlled to switch between normal heating mode and low ambient temperature heating mode.

6. The control method according to claim 5, characterized in that, include: When the first determination result is Ta>M and the second determination result is A≤Tw≤B, the first throttling device (3) is turned on and the second throttling device (4) is turned off to switch to the normal heating mode; When the first determination result is Ta≤M, the first throttling device (3) and the second throttling device (4) are both turned on to switch to the low ambient temperature heating mode.

7. A control method for a heat pump system as described in claim 3 or 4, characterized in that, include: Collect the ambient temperature Ta, compare the collected ambient temperature Ta with the preset ambient temperature threshold M, and obtain the first judgment result; Collect the inlet water temperature Tw of the condenser (2), compare the collected inlet water temperature Tw of the condenser (2) with the preset minimum water temperature threshold A and the preset maximum water temperature threshold B, and obtain the second judgment result; Based on the first determination result and the second determination result, control the first throttling device (3), the second throttling device (4), the four-way reversing valve (6), the first control valve (7) and the second control valve (8) to switch between normal heating mode, low ambient temperature heating mode, low water temperature heating mode and high water temperature heating mode.

8. The control method according to claim 7, characterized in that, When the first determination result is Ta>M and the second determination result is A≤Tw≤B, the first throttling device (3) is opened, and the second throttling device (4), the first control valve (7) and the second control valve (8) are all closed, so as to switch to the normal heating mode; When the first determination result is Ta≤M, the first throttling device (3), the second throttling device (4), and the second control valve (8) are all opened. The four-way reversing valve (6) connects the outlet of the compressor (1) with the second heat exchanger (52) and connects the second control valve (8) with the return port of the compressor (1). The first control valve (7) is closed to switch to the low ambient temperature heating mode.

9. The control method according to claim 7, characterized in that, When the first determination result is Ta>M and the second determination result is Tw<A, the first throttling device (3), the second throttling device (4) and the first control valve (7) are all opened, the four-way reversing valve (6) connects the second heat exchanger (52) with the return port of the compressor (1), and the second control valve (8) is closed to switch to the low water temperature heating mode.

10. The control method according to claim 7, characterized in that, When the first determination result is Ta>M and the second determination result is Tw>B, the first throttling device (3), the second throttling device (4) and the first control valve (7) are all opened, the four-way reversing valve (6) connects the outlet of the compressor (1) with the second heat exchanger (52), and the second control valve (8) is closed to switch to the high water temperature heating mode.

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