Heat pump hot water system and control method thereof

Abstract

The present application relates to a kind of heat pump hot water system and its control method, it relates to heat pump equipment technical field, for solving the problem of refrigerant in heat pump hot water system restricts its performance. Including: heat exchange device, which is filled with water to be exchanged heat;High-temperature refrigerant system, part is set in heat exchange device, it is provided with high-temperature refrigerant in it;Low-temperature refrigerant system, part is set in heat exchange device, it is provided with low-temperature refrigerant in it, system can at least one of high-temperature refrigerant system and low-temperature refrigerant system according to the target water temperature and current ambient temperature set, start.The heat pump hot water system of the present application integrates two sets of refrigerant systems, in high ambient temperature condition, the advantage of high-temperature refrigerant system is exerted, absorbs the heat in air and then exchanges heat with water system, improves water temperature to target temperature.In low ambient temperature condition, low-temperature refrigerant system and high-temperature refrigerant system combined operation, avoid the situation of compressor over-range operation, so that heat pump hot water system can reach ideal working state.

Description

Technical Field

[0001] This invention relates to the field of heat pump equipment technology, and in particular to a heat pump hot water system and its control method. Background Technology

[0002] Currently, heat pump water heating systems typically use a single refrigerant. During actual operation, these systems are easily affected by the characteristics of the refrigerant itself, thus limiting the system's performance and, in severe cases, even causing it to malfunction. For example, high-temperature heat pump systems using high-temperature refrigerants have good high condensing temperature characteristics, but poor evaporation characteristics at low temperatures. The high condensing and low evaporation temperatures result in a large compression ratio, easily exceeding the compressor's normal operating range. Therefore, the heating capacity of high-temperature heat pump water heating systems drops sharply at low ambient temperatures, making it difficult to achieve ideal operating output. Similarly, low-temperature heat pump water heating systems using low-temperature refrigerants struggle to achieve ideal operating output at high ambient temperatures.

[0003] In other words, the refrigerant in the heat pump water heating system limits its performance in related technologies. Summary of the Invention

[0004] This invention provides a heat pump water heating system and its control method, which solves the problem of refrigerant limiting the performance of the heat pump water heating system.

[0005] This invention provides a heat pump water heating system, comprising: a heat exchange device containing hot water to be exchanged; a high-temperature refrigerant system, partially disposed within the heat exchange device, containing a high-temperature refrigerant used to exchange heat with the hot water to heat the water to be output to a first preset temperature; and a low-temperature refrigerant system, partially disposed within the heat exchange device, containing a low-temperature refrigerant used to exchange heat with the hot water to heat the water to be output to a second preset temperature; wherein the first preset temperature is higher than the second preset temperature, and the heat pump water heating system can activate at least one of the high-temperature refrigerant system and the low-temperature refrigerant system to heat the water to be output according to the set target water temperature and the current ambient temperature, so as to meet the user's water demand at different temperatures.

[0006] In one embodiment, the low-temperature refrigerant system includes: a first condenser disposed within a heat exchange device, wherein a low-temperature refrigerant in the first condenser is used to exchange heat with the hot water to be exchanged in the heat exchange device; a first electronic expansion valve connected to the outlet of the first condenser; a first evaporator connected to the first electronic expansion valve; and a first compressor, the inlet of which is connected to the first evaporator, and the outlet of the first compressor connected to the inlet of the first condenser; wherein the low-temperature refrigerant exchanges heat with the hot water to be exchanged in the heat exchange device through the first condenser to heat the water to be output to a second preset temperature.

[0007] In one embodiment, the low-temperature refrigerant system further includes a first gas-liquid separator, the inlet of which is connected to the outlet of a first evaporator, and the outlet of which is connected to the inlet of a first compressor.

[0008] In one embodiment, the high-temperature refrigerant system includes: a second condenser, in which a high-temperature refrigerant is used to exchange heat with the water to be output; a second electronic expansion valve connected to the outlet of the second condenser; a heat exchanger disposed within a heat exchange device and connected to the second electronic expansion valve; and a second compressor, the inlet of which is connected to the heat exchanger, and the outlet of which is connected to the inlet of the second condenser; wherein the heat exchanger serves as a second evaporator, allowing the high-temperature refrigerant within it to evaporate and absorb heat, and the high-temperature refrigerant exchanges heat with the water to be output through the second condenser to heat the water to be output to a first preset temperature.

[0009] In one embodiment, the high-temperature refrigerant system further includes a second gas-liquid separator, the inlet of which is connected to the outlet of the second evaporator, and the outlet of which is connected to the inlet of the second compressor.

[0010] In one embodiment, the heat exchanger serves as a third condenser to release heat from the high-temperature refrigerant within it. The high-temperature refrigerant system further includes: a third evaporator, the inlet of which is connected to the outlet of the third condenser and the inlet of the second compressor, and the outlet of the third evaporator being connected to the inlet of the third condenser; and a first control valve, provided on a connecting pipeline between the outlet of the third evaporator and the inlet of the third condenser, for controlling the on / off state of the outlet of the third evaporator and the inlet of the third condenser.

[0011] In one embodiment, the high-temperature refrigerant system further includes a second control valve and a connecting pipeline. The second control valve is disposed on the connecting pipeline and located between the first control valve and the inlet of the third condenser. One end of the connecting pipeline is connected to the connecting pipeline and located between the second control valve and the first control valve. The other end of the connecting pipeline is connected to a second electronic expansion valve. By operating the first control valve and the second control valve, the inlet of the third condenser can be connected only to the outlet of the third evaporator, or the inlet of the second evaporator can be connected only to the second electronic expansion valve.

[0012] In one embodiment, the high-temperature refrigerant system has an air-source heat exchange mode and a water-side heat exchange mode. When the high-temperature refrigerant system is in the air-source heat exchange mode, the inlet of the third condenser is connected to the outlet of the third evaporator but not to the second electronic expansion valve. When the high-temperature refrigerant system is in the water-side heat exchange mode, the inlet of the second evaporator is connected to the second electronic expansion valve but not to the outlet of the third evaporator.

[0013] In one embodiment, the heat exchange device has an inlet end and an outlet end, and the heat pump hot water system further includes: a medium-temperature water tank having a first inlet and a first outlet; a first water supply pipeline connected to the inlet end and the first outlet; a second water supply pipeline connected to the outlet end and the first inlet; and a first water pump disposed on the first water supply pipeline or the second water supply pipeline; wherein the first water pump is capable of circulating water from the medium-temperature water tank into the heat exchange device for heating.

[0014] In one embodiment, the medium-temperature water tank further has a second inlet and a second outlet. The heat pump water heating system also includes: a high-temperature water tank having an inlet and an outlet; a third water supply pipeline connected to the second outlet and the inlet of the high-temperature water tank; a fourth water supply pipeline connected to the second inlet and the outlet of the high-temperature water tank; and a second water pump installed on the third or fourth water supply pipeline. The second water pump is capable of circulating water from the medium-temperature water tank into the high-temperature water tank, and a second condenser is installed inside the high-temperature water tank.

[0015] This invention also provides a control method for a heat pump water heating system. The heat pump water heating system includes a high-temperature refrigerant system, a low-temperature refrigerant system, a heat exchange device, a medium-temperature water tank, and a high-temperature water tank. The heat pump water heating system can, based on a set target water temperature T1 and the current ambient temperature T5, activate at least one of the high-temperature refrigerant system and the low-temperature refrigerant system to heat the water to be heated in the heat exchange device. The heated water is then sequentially transported to the medium-temperature water tank and the high-temperature water tank. The control method includes:

[0016] The heat pump water heating system is started.

[0017] Enter the set temperature value;

[0018] The set temperature values ​​include the set target water temperature T1, the set high water temperature value T2, the set low water temperature value T3, and the set low ambient temperature value T4.

[0019] Detect the current temperature value;

[0020] The current temperature values ​​include the current ambient temperature T5, the current medium-temperature water tank temperature T6, and the current high-temperature water tank temperature T7.

[0021] Determine whether the target water temperature T1 is less than the lower water temperature value T3;

[0022] If the target water temperature T1 is less than the low water temperature value T3, the low temperature refrigerant system is started to enter the first low temperature heating program;

[0023] Among them, after the first low-temperature heating program is completed, the process returns to the step of detecting the current temperature value;

[0024] If the target water temperature T1 is not less than the low water temperature value T3, then proceed to the next judgment procedure;

[0025] Determine whether the target water temperature T1 is less than the high water temperature value T2;

[0026] If the target water temperature T1 is greater than the high water temperature value T2, then the process of resetting the target water temperature will begin.

[0027] If the target water temperature T1 is not greater than the high water temperature value T2, proceed to the next judgment procedure;

[0028] Determine whether the current ambient temperature T5 is lower than the lower ambient temperature value T4;

[0029] If the current ambient temperature T5 is lower than the low ambient temperature value T4, the low-temperature refrigerant system will be activated to enter the second low-temperature heating program.

[0030] After the second low-temperature heating program is completed, the high-temperature heating program begins.

[0031] After the high-temperature heating program is completed, the process returns to the step of detecting the current temperature value.

[0032] In one embodiment, the first low-temperature heating process includes the following steps:

[0033] The low-temperature refrigerant system is started;

[0034] The medium-temperature water tank is heated, and the current temperature of the medium-temperature water tank, T6, is detected.

[0035] Determine whether the current medium-temperature water tank temperature T6 is lower than the target water temperature T1;

[0036] If the current medium-temperature water tank temperature T6 is less than the target water temperature T1, return to the previous step until the current medium-temperature water tank temperature T6 is not less than the target water temperature T1.

[0037] If the current temperature of the medium-temperature water tank T6 is not less than the target water temperature T1, the medium-temperature water tank will automatically replenish water to maintain the target water temperature T1.

[0038] In one embodiment, the second low-temperature heating process includes the following steps:

[0039] The low-temperature refrigerant system is started;

[0040] The medium-temperature water tank is heated, and the current temperature of the medium-temperature water tank, T6, is detected.

[0041] Determine whether the current medium-temperature water tank temperature T6 is lower than the low-temperature water value T3-a;

[0042] Where 'a' is a predetermined value;

[0043] If the current medium-temperature water tank temperature T6 is less than the low-temperature water temperature value T3-a, then return to the steps for starting the low-temperature refrigerant system;

[0044] If the current medium-temperature water tank temperature T6 is not less than the low-temperature water value T3-a, then the high-temperature heating program will begin.

[0045] In one embodiment, the high-temperature refrigerant system has a water-side heat exchange mode, and the high-temperature heating process includes the following steps:

[0046] The high-temperature refrigerant system starts up and executes water-side heat exchange mode;

[0047] The high-temperature water tank is heated, and the current temperature of the high-temperature water tank, T7, is detected.

[0048] Determine whether the current high-temperature water tank temperature T7 is lower than the target water temperature T1;

[0049] If the current high-temperature water tank temperature T7 is less than the target water temperature T1, return to the previous step until the current high-temperature water tank temperature T7 is not less than the target water temperature T1.

[0050] If the current high-temperature water tank temperature T7 is not less than the target water temperature T1, the high-temperature water tank will automatically replenish water to maintain the target water temperature T1.

[0051] In one implementation, the high-temperature refrigerant system has an air-source heat exchange mode. If the current ambient temperature T5 is not less than the low ambient temperature value T4, the high-temperature refrigerant system is started and the air-source heat exchange mode is executed.

[0052] In one implementation, after the high-temperature refrigerant system is started and the air-source heat exchange mode is executed, the following steps are also included:

[0053] The high-temperature water tank is heated, and the current temperature of the high-temperature water tank, T7, is detected.

[0054] Determine whether the current high-temperature water tank temperature T7 is lower than the target water temperature T1;

[0055] If the current high-temperature water tank temperature T7 is less than the target water temperature T1, return to the previous step until the current high-temperature water tank temperature T7 is not less than the target water temperature T1.

[0056] If the current high-temperature water tank temperature T7 is not less than the target water temperature T1, the high-temperature water tank will automatically replenish water to maintain the target water temperature T1.

[0057] Return to the steps for detecting the current temperature value.

[0058] Compared with existing technologies, the advantages of this invention are that, because the heat pump water heating system integrates a high-temperature refrigerant system and a low-temperature refrigerant system—that is, it integrates two refrigerant systems using two different refrigerants—it can adapt to a wide range of water temperature requirements. When the water temperature requirement is low, a single low-temperature refrigerant system can meet the user's needs. When the water temperature requirement is high, under high ambient temperatures, the high-temperature refrigerant system leverages its advantages, absorbing heat from the air and exchanging heat with the water system to raise the water temperature to the target temperature. Under low ambient temperatures, the low-temperature and high-temperature refrigerant systems operate in conjunction, preventing the compressor from operating beyond its range and ensuring that the heat pump water heating system reaches its ideal operating state. This guarantees the stable operation of the heat pump water heating system, providing users with a stable and reliable supply of high-temperature hot water. Furthermore, it avoids the problem of refrigerant limiting the performance of heat pump water heating systems in related technologies. Attached Figure Description

[0059] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0060] Figure 1 This is a schematic diagram of the specific structural composition of the heat pump water heating system in an embodiment of the present invention (the arrows indicate the flow direction of the refrigerant);

[0061] Figure 2 This is a flowchart of the control method for a heat pump water heating system in an embodiment of the present invention.

[0062] Figure label:

[0063] 10. High-temperature refrigerant system; 11. Second electronic expansion valve; 12. Heat exchanger; 13. Second compressor; 14. Second gas-liquid separator; 15. First control valve; 16. Second control valve; 17. Connecting pipeline; 18. Third evaporator; 19. First four-way valve; 20. Heat exchange device; 30. Low-temperature refrigerant system; 31. First electronic expansion valve; 32. First evaporator; 33. First compressor; 34. First gas-liquid separator; 35. Second four-way valve; 40. Medium-temperature water tank; 50. First water supply pipeline; 60. Second water supply pipeline; 70. First water pump; 80. High-temperature water tank; 90. Third water supply pipeline; 100. Fourth water supply pipeline; 110. Second water pump. Detailed Implementation

[0064] The invention will now be further described with reference to the accompanying drawings.

[0065] like Figure 1As shown, the present invention provides a heat pump water heating system, comprising a heat exchange device 20, a high-temperature refrigerant system 10, and a low-temperature refrigerant system 30. The heat exchange device 20 contains hot water to be exchanged; the high-temperature refrigerant system 10 is partially disposed within the heat exchange device 20 and contains a high-temperature refrigerant used for heat exchange with the hot water to heat the water to be output to a first preset temperature; the low-temperature refrigerant system is partially disposed within the heat exchange device 20 and contains a low-temperature refrigerant used for heat exchange with the hot water to heat the water to be output to a second preset temperature. The first preset temperature is higher than the second preset temperature. The heat pump water heating system can activate at least one of the high-temperature refrigerant system and the low-temperature refrigerant system to heat the water to be output based on the set target water temperature and the current ambient temperature, thereby meeting the user's water usage needs at different temperatures.

[0066] In the above configuration, the heat pump water heating system integrates a high-temperature refrigerant system 10 and a low-temperature refrigerant system 30, meaning it integrates two refrigerant systems using two different refrigerants. This allows the heat pump water heating system to adapt to a wide range of water temperature requirements. When the required water temperature is low (less than or equal to 40°C), a single low-temperature refrigerant system 30 can meet the user's needs. When the required water temperature is high (greater than 40°C), under high ambient temperatures (greater than 10°C), the high-temperature refrigerant system 10 takes advantage of absorbing heat from the air and exchanging heat with the water system to raise the water temperature to the target temperature. Under low ambient temperatures (less than or equal to 10°C), the low-temperature refrigerant system 30 and the high-temperature refrigerant system 10 operate together, preventing the compressor from operating beyond its range and ensuring that the heat pump water heating system reaches its ideal operating state. This guarantees the stable operation of the heat pump water heating system, providing users with a stable and reliable supply of high-temperature hot water. Furthermore, it avoids the problem of refrigerant limiting the performance of heat pump water heating systems in related technologies.

[0067] It should be noted that the first preset temperature is a temperature range value, and the second preset temperature is a temperature range value. For example, the second preset temperature setting range is [a℃, b℃), and the first preset temperature setting range is (b℃, c℃), where a < b < c.

[0068] It should be noted that, taking common refrigerants such as R410A and R134A as examples, R410A, as a low-temperature refrigerant, can operate at -35 degrees Celsius, and when working in conjunction with a high-temperature refrigerant system such as R134A, it can provide hot water at around 80 degrees Celsius.

[0069] It should be noted that during heating operation, the heat source of the air source heat pump is the air in the environment. The ambient temperature determines the evaporation pressure of the heat pump system, and the water temperature determines the condensation pressure. The condensation pressure / evaporation temperature is the compressor pressure ratio. The compressor pressure ratio cannot be too high, otherwise it will affect energy efficiency and compressor life.

[0070] It should be noted that the various components in a heat pump water heating system are connected by connecting pipelines.

[0071] Specifically, such as Figure 1 As shown, in one embodiment, the cryogenic refrigerant system 30 includes a first condenser, a first electronic expansion valve 31, a first evaporator 32, and a first compressor 33. The first condenser is disposed within the heat exchange device 20, and the cryogenic refrigerant within the first condenser is used to exchange heat with the hot water to be exchanged within the heat exchange device 20. The first electronic expansion valve 31 is connected to the outlet of the first condenser, the first evaporator 32 is connected to the first electronic expansion valve 31, the inlet of the first compressor 33 is connected to the first evaporator 32, and the outlet of the first compressor 33 is connected to the inlet of the first condenser. The cryogenic refrigerant exchanges heat with the hot water to be exchanged within the heat exchange device 20 through the first condenser to heat it to a second preset temperature.

[0072] Specifically, such as Figure 1 As shown, in one embodiment, the cryogenic refrigerant system 30 further includes a first gas-liquid separator 34, the inlet of which is connected to the outlet of the first evaporator 32, and the outlet of which is connected to the inlet of the first compressor 33. The first gas-liquid separator 34 is used to separate the refrigerant from the outlet of the first evaporator 32 into gas and liquid components.

[0073] Specifically, such as Figure 1 As shown, in one embodiment, the cryogenic refrigerant system 30 further includes a second four-way valve 35, which controls the opening and closing of the inlet of the first gas-liquid separator 34 and the outlet of the first evaporator 32, as well as the opening and closing of the outlet of the first compressor 33 and the inlet of the first condenser.

[0074] Specifically, such as Figure 1 As shown, in one embodiment, the high-temperature refrigerant system 10 includes a second condenser, a second electronic expansion valve 11, a heat exchanger 12, and a second compressor 13. The high-temperature refrigerant in the second condenser is used for heat exchange with the water to be output; the second electronic expansion valve 11 is connected to the outlet of the second condenser; the heat exchanger 12 is disposed within a heat exchange device and is connected to the second electronic expansion valve 11; the inlet of the second compressor 13 is connected to the heat exchanger 12, and the outlet of the second compressor 13 is connected to the inlet of the second condenser. The heat exchanger acts as a second evaporator, allowing the high-temperature refrigerant within it to evaporate and absorb heat. The high-temperature refrigerant exchanges heat with the water to be output through the second condenser to heat the water to a first preset temperature.

[0075] Specifically, such as Figure 1As shown, in one embodiment, the high-temperature refrigerant system 10 further includes a second gas-liquid separator 14, the inlet of which is connected to the outlet of the second evaporator, and the outlet of which is connected to the inlet of the second compressor 13.

[0076] Specifically, such as Figure 1 As shown, in one embodiment, the high-temperature refrigerant system 10 further includes a first four-way valve 19 for controlling the switching and on / off of the liquid circuit.

[0077] It should be noted that the specific working principles of the high-temperature refrigerant system 10 and the low-temperature refrigerant system 30 are existing technologies and will not be elaborated here.

[0078] Specifically, such as Figure 1 As shown, in one embodiment, heat exchanger 12 serves as a third condenser to release heat from the high-temperature refrigerant within it. The high-temperature refrigerant system also includes a third evaporator 18 and a first control valve 15. The inlet of the third evaporator 18 is connected to the outlet of the third condenser and the inlet of the second compressor 13, and the outlet of the third evaporator 18 is connected to the inlet of the third condenser. The first control valve 15 is provided on the connecting pipeline between the outlet of the third evaporator 18 and the inlet of the third condenser for controlling the on / off state of the outlet of the third evaporator 18 and the inlet of the third condenser.

[0079] Specifically, such as Figure 1 As shown, in one embodiment, the high-temperature refrigerant system 10 further includes a second control valve 16 and a connecting line 17. The second control valve 16 is disposed on the connecting line and located between the first control valve 15 and the inlet of the third condenser. One end of the connecting line 17 is connected to the connecting line and located between the second control valve 16 and the first control valve 15. The other end of the connecting line 17 is connected to the second electronic expansion valve 11. By operating the first control valve 15 and the second control valve 16, the inlet of the third condenser can be connected only to the outlet of the third evaporator 18, or the inlet of the second evaporator can be connected only to the second electronic expansion valve 11.

[0080] Specifically, such as Figure 1 As shown, in one embodiment, the high-temperature refrigerant system has an air-source heat exchange mode and a water-side heat exchange mode. When the high-temperature refrigerant system is in the air-source heat exchange mode, the inlet of the third condenser is connected to the outlet of the third evaporator 18, but not to the second electronic expansion valve 11. When the high-temperature refrigerant system is in the water-side heat exchange mode, the inlet of the second evaporator is connected to the second electronic expansion valve 11, but not to the outlet of the third evaporator 18.

[0081] Specifically, such as Figure 1As shown, in one embodiment, the heat exchange device 20 has an inlet and an outlet. The heat pump water heating system further includes a medium-temperature water tank 40, a first water supply pipeline 50, a second water supply pipeline 60, and a first water pump 70. The first water supply pipeline 50 is connected to the inlet and the first outlet, and the second water supply pipeline 60 is connected to the outlet and the first inlet. The first water pump 70 is installed in the first water supply pipeline 50. The first water pump 70 can circulate water from the medium-temperature water tank 40 into the heat exchange device 20 for heating.

[0082] Of course, depending on the actual situation, the first water pump 70 can be installed on the second water supply pipeline 60.

[0083] Specifically, such as Figure 1 As shown, in one embodiment, the medium-temperature water tank 40 has a second inlet and a second outlet. The heat pump water heating system also includes a high-temperature water tank 80, a third water supply pipeline 90, a fourth water supply pipeline 100, and a second water pump 110. The high-temperature water tank 80 has an inlet and an outlet; the third water supply pipeline 90 is connected to the second outlet and the inlet of the high-temperature water tank 80. The fourth water supply pipeline 100 is connected to the second inlet and the outlet of the high-temperature water tank 80.

[0084] Specifically, such as Figure 1 As shown, in one embodiment, a second water pump 110 is installed in the third water supply pipeline 90. The second water pump 110 is capable of circulating water from the medium-temperature water tank 40 into the high-temperature water tank 80, and a second condenser is installed in the high-temperature water tank 80.

[0085] Of course, depending on the actual situation, the second water pump 110 can be installed on the fourth water supply pipeline 100.

[0086] It should be noted that, in addition to providing hot water to users as needed, the high-temperature hot water in this application can also achieve high-temperature disinfection and cleaning of the water tanks (high-temperature water tank 80 and medium-temperature water tank 40) through the action of water pumps (first water pump 70 and second water pump 110), thereby improving the user experience. An axial flow fan can be installed on one side of the evaporator in this application for blowing air onto the evaporator.

[0087] like Figure 2 As shown, the present invention also provides a control method for a heat pump water heating system. The control method is used to control the aforementioned heat pump water heating system. The heat pump water heating system can, based on a set target water temperature T1 (set output water temperature) and a current ambient temperature T5 (current external ambient temperature where the heat pump water heating system is located), activate at least one of the high-temperature refrigerant system 10 and the low-temperature refrigerant system 30, and exchange heat with the hot water to be exchanged in the heat exchange device to heat the water to be output in the medium-temperature water tank or the high-temperature water tank. The control method includes:

[0088] The heat pump water heating system is started.

[0089] Enter the set temperature value;

[0090] The set temperature values ​​include the set target water temperature T1 (hereinafter referred to as target water temperature T1), the set high water temperature value T2 (hereinafter referred to as high water temperature value T2), the set low water temperature value T3 (hereinafter referred to as low water temperature value T3), and the set low ambient temperature value T4 (hereinafter referred to as low ambient temperature value T4).

[0091] It should be noted that the high water temperature value T2 is set within the first preset temperature range, and the low water temperature value T3 is set within the second preset temperature range. For example, the high water temperature value T2 is set within [a℃, b℃), and the low water temperature value T3 is set within (b℃, c℃).

[0092] Detect the current temperature value;

[0093] The current temperature values ​​include the current ambient temperature T5, the current medium-temperature water tank temperature T6, and the current high-temperature water tank temperature T7.

[0094] Determine whether the target water temperature T1 is less than the lower water temperature value T3;

[0095] If the target water temperature T1 is less than the low water temperature value T3, the low temperature refrigerant system is started to enter the first low temperature heating program;

[0096] Among them, after the first low-temperature heating program is completed, the process returns to the step of detecting the current temperature value;

[0097] If the target water temperature T1 is not less than the low water temperature value T3, then proceed to the next judgment procedure;

[0098] Determine whether the target water temperature T1 is greater than the high water temperature value T2;

[0099] If the target water temperature T1 is greater than the high water temperature value T2, the process of resetting the target water temperature will begin (i.e., the target water temperature is reset when the unit is out of operating range).

[0100] If the target water temperature T1 is not greater than the high water temperature value T2, proceed to the next judgment procedure;

[0101] Determine whether the current ambient temperature T5 is lower than the lower ambient temperature value T4;

[0102] If the current ambient temperature T5 is lower than the low ambient temperature value T4, the low-temperature refrigerant system will be activated to enter the second low-temperature heating program.

[0103] After the second low-temperature heating program is completed, the high-temperature heating program begins.

[0104] After the high-temperature heating program is completed, the process returns to the step of detecting the current temperature value. Specifically, as follows: Figure 1 As shown, in one embodiment, the first low-temperature heating process includes the following steps:

[0105] The low-temperature refrigerant system is started;

[0106] The medium-temperature water tank is heated, and the current temperature of the medium-temperature water tank, T6, is detected.

[0107] Determine whether the current medium-temperature water tank temperature T6 is lower than the target water temperature T1;

[0108] If the current medium-temperature water tank temperature T6 is less than the target water temperature T1, return to the previous step until the current medium-temperature water tank temperature T6 is not less than the target water temperature T1.

[0109] If the current temperature of the medium-temperature water tank T6 is not less than the target water temperature T1, the medium-temperature water tank will automatically replenish water to maintain the target water temperature T1.

[0110] It should be noted that the medium-temperature water tank 40 in this application has an automatic water replenishment function and can be replenished with water from the outside.

[0111] Specifically, such as Figure 2 As shown, in one embodiment, the second low-temperature heating process includes the following steps:

[0112] The low-temperature refrigerant system is started;

[0113] The medium-temperature water tank is heated, and the current temperature of the medium-temperature water tank, T6, is detected.

[0114] Determine whether the current medium-temperature water tank temperature T6 is lower than the low-temperature water value T3-a;

[0115] Where 'a' is a predetermined value;

[0116] If the current medium-temperature water tank temperature T6 is less than the low-temperature water temperature value T3-a, then return to the steps for starting the low-temperature refrigerant system;

[0117] If the current medium-temperature water tank temperature T6 is not less than the low-temperature water value T3-a, then the high-temperature heating program will begin.

[0118] It should be noted that when the ambient temperature is low and the set water temperature is high, activating the high-temperature refrigerant system alone would result in an excessively high pressure ratio. The high-temperature refrigerant system will then absorb heat from the medium-temperature water tank (water temperature > ambient temperature) to reduce its pressure ratio. This requires that the water temperature in the medium-temperature water tank not be too low. This is to prevent the water in the tank from freezing, and also because a low medium-temperature water temperature will lower the evaporation temperature of the high-temperature refrigerant system, increasing the pressure ratio. Therefore, it is necessary to first determine the water temperature in the medium-temperature water tank. If the water temperature is low, activate the low-temperature refrigerant system first; if the water temperature is high, activate the high-temperature refrigerant system directly.

[0119] Specifically, such as Figure 1 As shown, in one embodiment, the high-temperature refrigerant system 10 has a water-side heat exchange mode, and the high-temperature heating process includes the following steps:

[0120] The high-temperature refrigerant system starts up and executes water-side heat exchange mode;

[0121] The high-temperature water tank is heated, and the current temperature of the high-temperature water tank, T7, is detected.

[0122] Determine whether the current high-temperature water tank temperature T7 is lower than the target water temperature T1;

[0123] If the current high-temperature water tank temperature T7 is less than the target water temperature T1, return to the previous step until the current high-temperature water tank temperature T7 is not less than the target water temperature T1.

[0124] If the current high-temperature water tank temperature T7 is not less than the target water temperature T1, the high-temperature water tank will automatically replenish water to maintain the target water temperature T1.

[0125] It should be noted that the high-temperature water tank 80 in this application has an automatic water replenishment function and can be replenished with water from the outside.

[0126] Specifically, such as Figure 1 As shown, in one embodiment, the high-temperature refrigerant system 10 has an air source heat exchange mode. If the current ambient temperature T5 is not less than the low ambient temperature value T4, the high-temperature refrigerant system is started and the air source heat exchange mode is executed.

[0127] Specifically, such as Figure 2 As shown, in one embodiment, after the high-temperature refrigerant system is started and the air-source heat exchange mode is executed, the following steps are further included:

[0128] The high-temperature water tank is heated, and the current temperature of the high-temperature water tank, T7, is detected.

[0129] Determine whether the current high-temperature water tank temperature T7 is lower than the target water temperature T1;

[0130] If the current high-temperature water tank temperature T7 is less than the target water temperature T1, return to the previous step until the current high-temperature water tank temperature T7 is not less than the target water temperature T1.

[0131] If the current high-temperature water tank temperature T7 is not less than the target water temperature T1, the high-temperature water tank will automatically replenish water to maintain the target water temperature T1.

[0132] Return to the steps for detecting the current temperature value.

[0133] The heat pump water heating system and its control method described in this application achieve precise temperature control and high energy efficiency. By judging the target water temperature and the current ambient temperature, the operating mode is switched to supply hot water. This greatly satisfies users' different water temperature needs. Compared with ordinary single-stage compression cycle systems, it leverages the advantage of cascade systems (the heat pump water heating system in this application) in its wide applicable ambient temperature range, while providing a wider range of heat sources. This makes it particularly suitable for regions with large latitudinal spans and significant ambient temperature variations.

[0134] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A control method for a heat pump water heating system, characterized in that, The heat pump water heating system includes a high-temperature refrigerant system, a low-temperature refrigerant system, a heat exchange device, a medium-temperature water tank, and a high-temperature water tank. The heat pump water heating system can, based on a set target water temperature T1 and the current ambient temperature T5, activate at least one of the high-temperature refrigerant system and the low-temperature refrigerant system to exchange heat with the hot water to be exchanged in the heat exchange device, thereby heating the water to be output in the medium-temperature water tank or the high-temperature water tank. The control method includes: The heat pump water heating system is started. Enter the set temperature value; The set temperature values ​​include the set target water temperature T1, the set high water temperature value T2, the set low water temperature value T3, and the set low ambient temperature value T4. Detect the current temperature value; The current temperature value includes the current ambient temperature T5, the current medium-temperature water tank temperature T6, and the current high-temperature water tank temperature T7. Determine whether the target water temperature T1 is less than the low water temperature value T3; If the target water temperature T1 is less than the low water temperature value T3, then the low-temperature refrigerant system is started to enter the first low-temperature heating program; Among them, after the first low-temperature heating program is completed, the process returns to the step of detecting the current temperature value; If the target water temperature T1 is not less than the low water temperature value T3, then proceed to the next judgment procedure; Determine whether the target water temperature T1 is less than the high water temperature value T2; If the target water temperature T1 is greater than the high water temperature value T2, then the process of resetting the target water temperature will begin. If the target water temperature T1 is not greater than the high water temperature value T2, then proceed to the next judgment procedure; Determine whether the current ambient temperature T5 is less than the low ambient temperature value T4; If the current ambient temperature T5 is less than the low ambient temperature value T4, then the low-temperature refrigerant system is started to enter the second low-temperature heating program; After the second low-temperature heating program is completed, the high-temperature heating program begins. After the high-temperature heating procedure is completed, the process returns to the step of detecting the current temperature value. The high-temperature refrigerant system has an air source heat exchange mode. If the current ambient temperature T5 is not less than the low ambient temperature value T4, the high-temperature refrigerant system is started and the air source heat exchange mode is executed.

2. The control method according to claim 1, characterized in that, The first low-temperature heating process includes the following steps: The low-temperature refrigerant system is started; The medium-temperature water tank is heated, and the current temperature T6 of the medium-temperature water tank is detected; Determine whether the current medium-temperature water tank temperature T6 is less than the target water temperature T1; If the current medium-temperature water tank temperature T6 is less than the target water temperature T1, then return to the previous step until the current medium-temperature water tank temperature T6 is not less than the target water temperature T1; If the current medium-temperature water tank temperature T6 is not less than the target water temperature T1, the medium-temperature water tank will automatically replenish water to maintain the target water temperature T1.

3. The control method according to claim 1, characterized in that, The second low-temperature heating process includes the following steps: The low-temperature refrigerant system is started; The medium-temperature water tank is heated, and the current temperature T6 of the medium-temperature water tank is detected; Determine whether the current medium-temperature water tank temperature T6 is less than the low-temperature water value T3-a; Wherein, 'a' is a predetermined value; If the current medium-temperature water tank temperature T6 is less than the low-temperature water temperature value T3-a, then return to the step of starting the low-temperature refrigerant system; If the current medium-temperature water tank temperature T6 is not less than the low-temperature water value T3-a, then the high-temperature heating program will begin.

4. The control method according to claim 1, characterized in that, The high-temperature refrigerant system has a water-side heat exchange mode, and the high-temperature heating procedure includes the following steps: The high-temperature refrigerant system is started up to execute the water-side heat exchange mode. The high-temperature water tank is heated, and the current temperature T7 of the high-temperature water tank is detected; Determine whether the current high-temperature water tank temperature T7 is less than the target water temperature T1; If the current high-temperature water tank temperature T7 is less than the target water temperature T1, then return to the previous step until the current high-temperature water tank temperature T7 is not less than the target water temperature T1; If the current high-temperature water tank temperature T7 is not less than the target water temperature T1, the high-temperature water tank will automatically replenish water to maintain the target water temperature T1.

5. The control method according to claim 1, characterized in that, After the high-temperature refrigerant system is started and the air-source heat exchange mode is executed, the following steps are also included: The high-temperature water tank is heated, and the current temperature T7 of the high-temperature water tank is detected; Determine whether the current high-temperature water tank temperature T7 is less than the target water temperature T1; If the current high-temperature water tank temperature T7 is less than the target water temperature T1, then return to the previous step until the current high-temperature water tank temperature T7 is not less than the target water temperature T1; If the current high-temperature water tank temperature T7 is not less than the target water temperature T1, the high-temperature water tank will automatically replenish water to maintain the target water temperature T1. Return to the steps for detecting the current temperature value.

6. A heat pump water heating system for implementing the control method according to any one of claims 1-5, characterized in that, include: A heat exchange device containing hot water to be exchanged; as well as A high-temperature refrigerant system is partially installed in the heat exchange device, which contains a high-temperature refrigerant. The high-temperature refrigerant is used to exchange heat with the hot water to be exchanged, so as to heat the water to be output to a first preset temperature. as well as A low-temperature refrigerant system is partially installed in the heat exchange device, which contains a low-temperature refrigerant. The low-temperature refrigerant is used to exchange heat with the hot water to be exchanged, so as to heat the water to be output to a second preset temperature. Wherein, the first preset temperature is higher than the second preset temperature, and the heat pump water heating system can start at least one of the high-temperature refrigerant system and the low-temperature refrigerant system to heat the water to be output according to the set target water temperature and the current ambient temperature, so as to meet the user's water needs at different temperatures.

7. The heat pump water heating system according to claim 6, characterized in that, The low-temperature refrigerant system includes: A first condenser is disposed within the heat exchange device, wherein the low-temperature refrigerant within the first condenser is used to exchange heat with the hot water to be exchanged within the heat exchange device; and A first electronic expansion valve is connected to the outlet of the first condenser; and A first evaporator, connected to the first electronic expansion valve; and The first compressor has its inlet connected to the first evaporator, and its outlet connected to the inlet of the first condenser. The low-temperature refrigerant exchanges heat with the hot water to be exchanged in the heat exchange device through the first condenser to heat the water to be output to the second preset temperature.

8. The heat pump water heating system according to claim 7, characterized in that, The low-temperature refrigerant system further includes a first gas-liquid separator, the inlet of which is connected to the outlet of the first evaporator, and the outlet of which is connected to the inlet of the first compressor.

9. The heat pump water heating system according to claim 6, characterized in that, The high-temperature refrigerant system includes: A second condenser, wherein the high-temperature refrigerant within the second condenser is used for heat exchange with the water to be output; and A second electronic expansion valve is connected to the outlet of the second condenser; and A heat exchanger, disposed within the heat exchange device and connected to the second electronic expansion valve; and The second compressor has its inlet connected to the heat exchanger and its outlet connected to the inlet of the second condenser. The heat exchanger serves as a second evaporator, allowing the high-temperature refrigerant inside to evaporate and absorb heat. The high-temperature refrigerant then exchanges heat with the water to be output through the second condenser, heating the water to be output to the first preset temperature.

10. The heat pump water heating system according to claim 9, characterized in that, The high-temperature refrigerant system also includes a second gas-liquid separator, the inlet of which is connected to the outlet of the second evaporator, and the outlet of which is connected to the inlet of the second compressor.

11. The heat pump water heating system according to claim 9, characterized in that, The heat exchanger serves as a third condenser to release heat from the high-temperature refrigerant within it. The high-temperature refrigerant system further includes: A third evaporator, the inlet of which is connected to the outlet of the third condenser and the inlet of the second compressor, and the outlet of the third evaporator being connected to the inlet of the third condenser; and A first control valve is installed on the connecting pipeline between the outlet of the third evaporator and the inlet of the third condenser, for controlling the on / off state of the outlet of the third evaporator and the inlet of the third condenser.

12. The heat pump water heating system according to claim 11, characterized in that, The high-temperature refrigerant system further includes a second control valve and a connecting pipeline. The second control valve is disposed on the connecting pipeline and located between the first control valve and the inlet of the third condenser. One end of the connecting pipeline is connected to the connecting pipeline and located between the second control valve and the first control valve. The other end of the connecting pipeline is connected to the second electronic expansion valve. By operating the first control valve and the second control valve, the inlet of the third condenser can be connected only to the outlet of the third evaporator, or the inlet of the second evaporator can be connected only to the second electronic expansion valve.

13. The heat pump water heating system according to claim 12, characterized in that, The high-temperature refrigerant system has an air-source heat exchange mode and a water-side heat exchange mode. When the high-temperature refrigerant system is in the air-source heat exchange mode, the inlet of the third condenser is connected to the outlet of the third evaporator, but not to the second electronic expansion valve. When the high-temperature refrigerant system is in the water-side heat exchange mode, the inlet of the second evaporator is connected to the second electronic expansion valve, but not to the outlet of the third evaporator.

14. The heat pump water heating system according to claim 9, characterized in that, The heat exchange device has an inlet end and an outlet end, and the heat pump hot water system further includes: The medium-temperature water tank has a first inlet and a first outlet; and A first water supply pipeline is connected to the water inlet and the first water outlet; and A second water supply pipeline is connected to the outlet and the first inlet; and The first water pump is installed on the first water supply pipeline or the second water supply pipeline; The first water pump can circulate the water in the medium-temperature water tank into the heat exchange device for heating.

15. The heat pump water heating system according to claim 14, characterized in that, The medium-temperature water tank also has a second inlet and a second outlet, and the heat pump water heating system further includes: A high-temperature water tank, having an inlet and an outlet; and The third water supply pipeline is connected to the second water outlet and the inlet of the high-temperature water tank; and The fourth water supply pipeline is connected to the second water inlet and the outlet of the high-temperature water tank; and The second water pump is installed on the third or fourth water supply pipeline; The second water pump is capable of circulating water from the medium-temperature water tank into the high-temperature water tank, and the second condenser is installed inside the high-temperature water tank.

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