Double-water-tank hot water system and control method thereof

Abstract

The invention provides a double-water-tank hot water system and a control method thereof.The double-water-tank hot water system comprises a hot water circulating pump assembly, the hot water circulating pump assembly comprises a heating water pump and a heat preservation water pump which are arranged in parallel, and the water inlet end of the heat preservation water pump is connected with the water inlet end of the heating water pump through a first manual valve; when the double-water-tank system shares the heat pump unit, the heating water pump and the heat preservation water pump which are arranged in parallel are adopted, the heating water tank and the heat preservation water tank are separated through the first manual valve between the water pumps, meanwhile, only the heating valve and the heat preservation valve need to be arranged for the heating water tank and the heat preservation water tank respectively, and therefore the number of electric valves is reduced, fault points are reduced, and cost is reduced. And the reliability is higher.

Description

Technical Field

[0001] The present invention belongs to the technical field of hot water systems, and more specifically, relates to a double-tank hot water system and a control method thereof. Background Art

[0002] Traditional hot water systems generally use a single water tank system. In order to take into account the water demand at the end, the single water tank system can only adopt a constant temperature water replenishment mode. It is impossible to achieve energy-saving water replenishment while meeting the user's water demand, and the unit energy efficiency is low.

[0003] Later, a dual water tank system appeared. When a conventional dual water tank system shares a heat pump unit for heating and heat preservation, too many water valves are set and there are many failure points. For example, the patent application with publication number CN114704964A discloses a control method for a dual water tank heat pump hot water system. The system uses two water tanks, and four electric valves are set between the water tanks for switching. Due to the high number of added electric valves, the probability of electric valve failure is high. As long as one of them fails, the system cannot operate normally.

[0004] Therefore, how to design a dual-tank hot water system and its control method that can meet users' water needs while achieving energy-saving water replenishment, reducing failure points and improving reliability is a technical problem that the industry urgently needs to solve. Summary of the invention

[0005] The object of the present invention is to provide a double-tank hot water system and a control method thereof, so as to solve the problem of poor reliability of the existing hot water system.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A double water tank hot water system is provided, comprising:

[0008] Heat pump units;

[0009] A hot water circulation pump assembly, the hot water circulation pump assembly comprising a heating water pump and a heat preservation water pump arranged in parallel, and the water inlet end of the heat preservation water pump is connected to the water inlet end of the heating water pump through a first manual valve;

[0010] A heating water tank, wherein the water outlet of the heating water tank is connected to the water inlet of the heat pump unit through the hot water circulation pump assembly, and the water inlet of the heating water tank is also connected to the water outlet of the heat pump unit through a heating valve;

[0011] The insulated water tank is connected to the user side, the water outlet of the insulated water tank is connected to the water inlet of the heat pump unit through the hot water circulation pump assembly, and the water inlet of the insulated water tank is connected to the water outlet of the heat pump unit through an insulation valve.

[0012] Furthermore, the water inlet end of the heating water tank is also connected to a water supply pipe, and a water supply valve is provided on the water supply pipe.

[0013] Furthermore, the water outlet of the insulated water tank is connected to the user side through a hot water supply pump, and the water inlet of the insulated water tank is connected to the user side through a return pipe provided with a return valve.

[0014] Furthermore, a connecting pipe is provided between the heating water tank and the heat-insulating water tank, and a second manual valve is provided on the connecting pipe.

[0015] Furthermore, it also includes: a solar heating device, which is connected to the heating water tank and is used to heat the heating water tank.

[0016] Furthermore, an auxiliary electric heater is provided at the water outlet of the heat pump unit.

[0017] Furthermore, it is characterized in that the control method comprises:

[0018] Obtaining the working mode of the dual-tank hot water system;

[0019] The start and stop of the heat pump unit, the heating water pump, and the insulation water pump, as well as the opening of the heating valve and the insulation valve are controlled according to the working mode of the dual-tank hot water system.

[0020] Furthermore, when the working mode is the water replenishment heating mode, it is determined that the actual liquid level H1 of the heating water tank reaches the set maximum liquid level H 1max After that, the heat pump unit, the heating water pump and the heating valve are turned on until the actual water temperature t1 of the heating water tank reaches the set maximum temperature t 1max .

[0021] Furthermore, in the process of heating the heating water tank by the heat pump unit, the heat pump unit is first controlled to operate according to the reference operating frequency, and the outdoor temperature t 室 > Predicted temperature t 预 If yes, reduce the operating frequency of the heat pump unit; if no, increase the operating frequency of the heat pump unit, wherein the reference operating frequency is related to the predicted temperature t 预 Related.

[0022] Furthermore, when the working mode is the water storage and heat preservation mode, the heating water pump is turned on and the heat preservation valve is opened until the actual liquid level H2 of the heat preservation water tank reaches the set maximum liquid level H 2max Or the actual liquid level H1 of the heating water tank reaches the set minimum liquid level H 1min .

[0023] Furthermore, before starting the heating water pump and opening the insulation valve, the method further includes:

[0024] Determine that the actual water temperature t2 of the thermal insulation water tank is lower than the set minimum temperature t 2min , and the actual water temperature t1 of the heating water tank is higher than the actual water temperature t2 of the insulation water tank.

[0025] Furthermore, before starting the heating water pump and opening the insulation valve, the method further includes:

[0026] Determine that the actual liquid level H2 of the thermal insulation water tank reaches the set minimum liquid level H 2min , and the actual water temperature t1 of the heating water tank is higher than the set maximum temperature t 1max .

[0027] Furthermore, when the user is in the normal water use period, the minimum liquid level H is set 2min is the first level of the thermal insulation water tank, and the maximum liquid level H is set 2max The second level of the thermal insulation water tank;

[0028] When the user is in the peak water consumption period, the minimum liquid level H is set 2min The three levels of the thermal insulation water tank, the maximum liquid level H 2max It is the 4th liquid level of the thermal insulation water tank.

[0029] Furthermore, when the working mode is the heat pump insulation mode, the heat pump unit, the insulation water pump and the insulation valve are turned on until the actual water temperature t2 of the insulation water tank reaches the set maximum temperature t 2max .

[0030] Furthermore, before starting the heat pump unit, the insulation water pump and opening the insulation valve, the method further includes:

[0031] Determine that the actual water temperature t2 of the thermal insulation water tank is lower than the set minimum temperature t 2min , and the actual water temperature t1 of the heating water tank is lower than the actual water temperature t2 of the insulation water tank.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] When the dual water tank system of the present invention shares the heat pump unit, a heating water pump and an insulating water pump are arranged in parallel, and a first manual valve between the water pumps is used to isolate the heating water tank from the insulating water tank. At the same time, only a heating valve and an insulating valve need to be respectively provided for the heating water tank and the insulating water tank, thereby reducing the number of electric valves, thereby reducing the number of failure points and improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0035] Figure 1 A schematic diagram of the structure of the dual water tank system provided by the present invention;

[0036] Figure 2 A schematic diagram of the water replenishment process of the heating water tank provided by the present invention;

[0037] Figure 3 A schematic diagram of the heating process of the heating water tank provided by the present invention;

[0038] Figure 4 A schematic diagram of the heating process of the heat preservation water tank provided by the present invention;

[0039] Among them, the main marks of the drawings in the figure are:

[0040] 1. Heat pump unit; 2. Heating water tank; 3. Insulation water tank; 4. User side;

[0041] 51. Heating water pump; 52. Insulation water pump; 53. Hot water supply pump;

[0042] 61. Heating valve; 62. Insulation valve; 63. Water supply valve; 64. Return valve; 66. First manual valve; 67. Second manual valve;

[0043] 7. Solar heating device;

[0044] 8. Auxiliary electric heater. DETAILED DESCRIPTION

[0045] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0046] like Figure 1 As shown, the dual water tank hot water system proposed by the present invention comprises:

[0047] Heat pump unit 1;

[0048] A hot water circulation pump assembly, the hot water circulation pump assembly comprises a heating water pump 51 and a heat preservation water pump 52 which are arranged in parallel, and the water inlet end of the heat preservation water pump 52 is connected to the water inlet end of the heating water pump 51 through a first manual valve 66;

[0049] A heating water tank 2, the water outlet of the heating water tank 2 is connected to the water inlet of the heat pump unit 1 through a hot water circulation pump assembly, and the water inlet of the heating water tank 2 is also connected to the water outlet of the heat pump unit 1 through a heating valve 61;

[0050] The insulated water tank 3 is connected to the user side 4, and the water outlet end of the insulated water tank 3 is connected to the water inlet end of the heat pump unit 1 through the hot water circulation pump assembly, and the water inlet end of the insulated water tank 3 is connected to the water outlet end of the heat pump unit 1 through the insulation valve 62.

[0051] The advantage of this design is that when the dual water tank system shares the heat pump unit 1, a parallel arrangement of the heating water pump 51 and the insulation water pump 52 is used, and the first manual valve 66 between the water pumps is used to separate the heating water tank 2 from the insulation water tank 3. At the same time, only the heating valve 61 and the insulation valve 62 need to be set for the heating water tank 2 and the insulation water tank 3 respectively, which reduces the number of electric valves, thereby reducing the number of failure points and improving reliability. For the dual water tank system with independent heating and insulation, the heating water tank 2 realizes energy-saving water replenishment, improves the energy efficiency of the unit by 10%-15%, and the insulation water tank 3 guarantees the user's real-time water demand; the heat pump unit 1 can heat the heating water tank 2 and keep the insulation water tank 3 warm, reducing the number of units; the heating water pump 51 and the insulation water pump 52 are standby for each other, which increases reliability and reduces water pump redundancy.

[0052] In actual application, a first temperature sensor and a first liquid level sensor are also configured for the heating water tank 2 to respectively detect the actual water temperature t1 and the actual liquid level H1 of the heating water tank 2. A second temperature sensor and a second liquid level sensor are also configured for the insulation water tank 3 to respectively detect the actual water temperature t2 and the actual liquid level H2 of the insulation water tank 3.

[0053] like Figure 1 As shown, in a preferred embodiment of the present invention, the water inlet end of the heating water tank 2 is connected to a water supply pipe, and a water supply valve 63 is provided on the water supply pipe.

[0054] The advantage of this design is that the heat preservation water tank 3 can be replenished with water in time to prevent the water tank from being emptied and dry burning.

[0055] like Figure 1 As shown, in a preferred embodiment of the present invention, the water outlet end of the insulated water tank 3 is connected to the user side 4 through a hot water supply pump 53, and the water inlet end of the insulated water tank 3 is connected to the user side 4 through a return pipe provided with a return valve 64.

[0056] The advantage of this design is that while the insulated water tank 3 supplies hot water to the user side 4, the excess water in the user side 4 can be recovered and sent to the insulated water tank 3 through the return pipe, thereby realizing water recycling.

[0057] At the same time, a pressure sensor is provided on the hot water supply pipeline between the hot water supply pump 53 and the user side 4, and a third temperature sensor, such as a temperature sensing package, is also provided on the return pipe. There are two hot water supply pumps 53, which are arranged in parallel, one of which is used as a main pump and the other as a backup pump. When the main pump fails, the backup pump can be used, which can improve the system reliability.

[0058] like Figure 1 As shown, in a preferred embodiment of the present invention, a connecting pipe is provided between the heating water tank 2 and the insulation water tank 3, and a second manual valve 67 is provided on the connecting pipe.

[0059] The advantage of this design is that when the automatic control system fails, the second manual valve 67 is opened to connect the heating water tank 2 with the insulation water tank 3, ensuring the water level balance between the water tanks and preventing one of the water tanks from being emptied and the other from overflowing.

[0060] like Figure 1 As shown, in a preferred embodiment of the present invention, the dual water tank hot water system further comprises: a solar heating device 7 , which is connected to the heating water tank 2 and is used to heat the heating water tank 2 .

[0061] The advantage of this design is that: in combination with the solar heating device 7, the solar energy can be preferentially utilized through the timing and liquid control, the water replenishment temperature of the heating water tank 2 is low, and the low-temperature solar energy can be fully utilized at night and in winter.

[0062] like Figure 1 As shown, in a preferred embodiment of the present invention, an auxiliary electric heater 8 is provided at the water outlet of the heat pump unit 1 .

[0063] The advantage of this design is that electric heating and heat pump are used for synchronous heating at low temperatures, and the ratio is set according to investment and operation analysis, reducing the initial investment in the heat pump by 9%-11%.

[0064] Based on the specific structure of the above dual-tank hot water system, the control method of the dual-tank hot water system is described in detail below:

[0065] See also Figures 2 to 4 In some embodiments of the present invention, a control method for a dual-tank hot water system includes:

[0066] Get the working mode of the dual-tank hot water system;

[0067] According to the working mode of the double water tank hot water system, the start and stop of the heat pump unit, the heating water pump, the insulation water pump and the opening of the heating valve and the insulation valve are controlled.

[0068] The advantage of this design is that by controlling the start and stop of the heat pump unit, heating water pump, insulation water pump, and the opening of the heating valve and insulation valve, the dual water tank hot water system is placed in different working modes, with a wide range of applications and higher reliability.

[0069] The working modes of the dual water tank hot water system are divided into four modes: water replenishment heating mode, water storage insulation mode, heat pump insulation mode, and manual mode.

[0070] like Figure 1 , Figure 2 , Figure 3 As shown, in some embodiments of the present invention, when the working mode is the water replenishment heating mode, it is determined that the actual liquid level H1 of the heating water tank reaches the set maximum liquid level H 1max After that, turn on the heat pump unit, the heating water pump and the heating valve until the actual water temperature t1 of the heating water tank reaches the set maximum temperature t 1max .

[0071] In actual applications, the heating water tank adopts an energy-saving water replenishment mode, and the average temperature of the water tank is about 20°C lower than the constant temperature water replenishment mode, which improves the energy efficiency of the unit by 10%-15%.

[0072] like Figure 2 As shown, the actual liquid level H1 of the heating water tank is detected. When the actual liquid level H1 ≤ the set minimum liquid level H 1min When the actual liquid level H1 = the set maximum liquid level H 1max When the water supply valve is turned on, close the water supply valve.

[0073] Furthermore, in the process of heating the heating water tank by the heat pump unit, the heat pump unit is first controlled to operate according to the reference operating frequency, and the outdoor temperature t 室 > Predicted temperature t 预 If yes, reduce the operating frequency of the heat pump unit; if no, increase the operating frequency of the heat pump unit, where the reference operating frequency is related to the predicted temperature t 预 Related.

[0074] The advantage of this design is that the heat pump unit uses variable frequency regulation and adjusts the variable frequency operation according to the external temperature. The energy efficiency of the unit increases by 1% for every 1HZ reduction, and the annual energy saving is 11%.

[0075] It should be understood that if Figure 3 As shown, the unit's frequency conversion is mainly for the heating mode, that is, frequency conversion is required when heating water, and full frequency operation is tried to be performed when keeping warm, so as to achieve rapid insulation and meet usage requirements.

[0076] It should be noted that air temperature and water temperature are interrelated and affect each other. As air temperature rises, water temperature also rises; in summer, the temperature difference between air temperature and water temperature is generally 1.5-2.5 degrees, and may reach 3.5-4 degrees at high temperatures (the sun has a greater impact). In winter, the temperature difference between the two is about 0-2.5 degrees. According to the relationship between air temperature and water temperature, the temperature is low at night and the water temperature is also low. According to the annual load calculation, except for the winter operation time of more than 14 hours, 83% of the time is less than 14 hours. Considering the daily heating hours of 14 hours and the insulation energy consumption, the total operation hours for the whole day are about 18 hours. In other words, you can avoid producing water during the low temperature and low water temperature at night in one day, and try to produce water during the daytime to reduce the water production load and improve the energy efficiency of the unit. Since the temperature and water temperature change throughout the year, the heating amount required by the unit is different every day, and the operating frequency of the unit needs to be controlled every day is also different. Due to the relationship between the temperature and the water temperature, a formula for the temperature and water temperature can be listed, and the two variables can be changed into the temperature (i.e., the room temperature t) and a variable, and the relationship between the unit water output M1 = f(t) is listed. Specifically, according to the calculation formula Q = CM1Δt, C is the specific heat capacity of water (i.e., C is a constant), M1 is the unit water output, Δt refers to the temperature difference of water heating (referring to the temperature difference of water from tap water temperature to the set temperature, such as 50°C), and Q is the heating amount of the unit. Since Q is related to the outdoor temperature t, and the tap water temperature is related to the outdoor temperature t, the difference between the two is about two degrees, so M1 is only related to the outdoor temperature t, and the relationship between M1 and the outdoor temperature t can be obtained.

[0077] The principle of frequency conversion control of the unit is to first predict the temperature of the next day (i.e. the predicted temperature t 预 ), according to the relationship between air temperature and water temperature, combined with the unit capacity correction curve, calculate the unit water production M1 within 14 hours a day (excluding 4 hours of insulation). The water quota can be used to calculate the daily water demand M0, where M0 is a fixed value. The reference operating frequency η0 of the heat pump unit is calculated based on M0 / M1. On the second day, the heat pump unit is controlled to operate according to the reference operating frequency η0, and the outdoor temperature t is detected every hour. 室 , the outdoor temperature t 室 and predicted temperature t 预 For comparison, if the outdoor temperature is t 室 Greater than the predicted temperature t 预 , indicating that the actual capacity of the unit is greater than the predicted capacity, then the operating frequency η1 of the heat pump unit is reduced; if the outdoor temperature t 室 Less than the predicted temperature t 预 , indicating that the actual capacity of the unit is less than the predicted capacity, then the operating frequency η1 of the heat pump unit is increased. Taking the reduction of the operating frequency η1 of the heat pump unit as an example, when the hourly temperature on the second day is higher than the predicted temperature t 预 , according to the outdoor temperature t室 Calculate the actual water production, using the original predicted water production / actual water production = η repair, then the operating frequency η1 = η0*η repair.

[0078] The advantage of this design is that, based on load forecasts and the unit's operating capacity, the operating frequency of the heat pump unit can be adjusted according to the external temperature, thus saving system operating energy consumption.

[0079] like Figure 4 As shown, in some embodiments of the present invention, when the working mode is the water storage and heat preservation mode, the heating water pump is turned on and the heat preservation valve is opened until the actual liquid level H2 of the heat preservation water tank reaches the set maximum liquid level H 2max Or the actual liquid level H1 of the heating water tank reaches the set minimum liquid level H 1min .

[0080] The advantage of this design is that the water temperature of the insulation water tank is increased by introducing the high-temperature water in the heating water tank into the insulation water tank.

[0081] like Figure 4 As shown, in a feasible embodiment of the present invention, before starting the heating water pump and opening the insulation valve, it also includes:

[0082] Determine that the actual water temperature t2 of the insulation water tank is lower than the set minimum temperature t 2min , and the actual water temperature t1 of the heating water tank is higher than the actual water temperature t2 of the insulation water tank.

[0083] In actual applications, when the water temperature of the insulation water tank decreases, if the water temperature of the heating water tank is higher than that of the insulation water tank, the heat pump unit cannot be turned on because it detects the water temperature of the heating water tank. The high-temperature water in the heating water tank is directly mixed into the insulation water tank to increase the water temperature of the insulation water tank. After that, when the heating water tank is pumped to the lowest liquid level, the water replenishment network is triggered to replenish water. When a large amount of cold water is replenished into the heating water tank, when the water temperature of the heating water tank drops to the start-up temperature of the heat pump unit, the heat pump can be turned on to insulate the insulation water tank and enter the heat pump insulation mode.

[0084] like Figure 3 As shown, in another feasible embodiment of the present invention, before starting the heating water pump and opening the insulation valve, it also includes:

[0085] Make sure the actual liquid level H2 of the insulation water tank reaches the set minimum liquid level H 2min , and the actual water temperature t1 of the heating water tank is higher than the set maximum temperature t 1max .

[0086] In practical applications, when the water temperature of the heating water tank reaches the set temperature, for example, the maximum temperature t 1max , water can be pumped from the heating water tank to the insulation water tank.

[0087] In some embodiments of the present invention, when the user is in the normal water use period, the minimum liquid level H is set. 2min For the first level of the insulation water tank, set the maximum liquid level H 2max It is the 2nd level of the insulation water tank;

[0088] When the user side is in the peak water consumption period, set the minimum liquid level H 2min For the 3-level liquid level of the insulation water tank, set the highest liquid level H 2max There are 4 liquid levels in the insulation water tank.

[0089] In actual applications, different liquid levels of the thermal water tank can be preset according to user habits. For example, when water consumption is low in the early morning and morning, a lower liquid level H can be preset. 2min With H 2max , that is, level 1 and level 2. If the level of the insulation water tank is lower than level 1, the fully loaded unit will be heated to give priority to water demand. After reaching level 1, it will operate at normal frequency. Peak water consumption starts at 19:00 at night, and a higher level H can be preset from 13:00 to 23:00 in the afternoon. 2min With H 2max , that is, the 3rd and 4th gear liquid levels. If the liquid level of the insulation water tank is lower than the 3rd gear liquid level, the unit will be fully loaded to start heating, and the frequency will be adjusted according to the temperature after reaching the 3rd gear liquid level. Since the frequency conversion is tested according to 14 hours a day, considering that the insulation is running for about 18 hours in total, since the outdoor temperature during the day is generally higher than at night, and the water consumption in the early morning and morning is less or no water, the lowest liquid level can be set in the early morning and morning, and the unit operation can be minimized.

[0090] like Figure 4 As shown, in some embodiments of the present invention, when the working mode is the heat pump insulation mode, the heat pump unit, the insulation water pump and the insulation valve are turned on until the actual water temperature t2 of the insulation water tank reaches the set maximum temperature t 2max .

[0091] The advantage of this design is that the heat pump unit is used to heat the insulated water tank, thereby increasing the water temperature of the insulated water tank.

[0092] like Figure 4 As shown, in a feasible embodiment of the present invention, before starting the heat pump unit, the insulation water pump and opening the insulation valve, it also includes:

[0093] Determine that the actual water temperature t2 of the insulation water tank is lower than the set minimum temperature t 2min , and the actual water temperature t1 of the heating water tank is lower than the actual water temperature t2 of the insulation water tank.

[0094] In practical applications, when the actual water temperature t2 of the insulation water tank is lower than the set minimum temperature t 2min，And the actual water temperature t1 of the heating water tank is lower than the actual water temperature t2 of the insulation water tank. At this time, the heat pump unit is running in the heating mode. You can first turn on the insulation water pump and open the insulation valve. After the insulation water pump and the insulation valve are both turned on or opened, turn off the heating water pump and the heating valve to enter the heat pump insulation mode.

[0095] In some embodiments of the present invention, when the working mode is manual mode, the heat pump unit, the insulation water pump, the bypass manual valve of the heating valve, the bypass manual valve of the insulation valve, the first manual valve, and the second manual valve are opened, and the heat pump unit heats the heating water tank and the insulation water tank.

[0096] The advantage of this design is that when one water pump fails, the other can be turned on to ensure water demand. The two water pumps serve as backup for each other, reducing the number of backup pumps. By opening the second manual valve between the heating water tank and the insulation water tank, the two water tanks are connected to prevent the water tanks from being emptied or overflowing. While the heat pump unit heats the two water tanks, the entire system network is heated in a circulating manner, ensuring that hot water circulates evenly throughout the network, reducing dead corners in the waterway, and preventing the generation of Legionella.

[0097] In actual application, when the automatic control system fails, the bypass hand valve of the heating valve and the insulation valve is opened, and the bypass hand valve of the water supply valve is also opened, and the float valve is used to control the maximum liquid level of the water tank.

[0098] The operation process of the double-tank hot water system is described in detail below using an application example of the present invention.

[0099] 1) User-side hot water supply process: 6:00-24:00, detect the return pipe water temperature t3. When t3<40℃, open the return valve and detect whether the hot water supply pump is on. If it is on, it will be opened and closed according to the user pressure control. If it is closed, an opening command will be issued and it will run at the lowest frequency, such as 30HZ; when t3≥44℃, close the return valve and the hot water supply pump will be opened and closed according to the user pressure control. 24:00-6:00, when the user does not use water, an antifreeze cycle is used, and the outdoor temperature t 室 When the temperature is less than ≤4℃ and the return pipe water temperature t3≤10℃, open the hot water supply pump and the return valve to enter the antifreeze cycle. When t3≥15℃, close the antifreeze cycle.

[0100] 2) Heating process of water tank heat pump: When the actual water temperature of the heating water tank t1≤45℃, turn on the heat pump unit, the heating water pump and the heating valve. 室 Adjust the operating frequency of the heat pump unit and the water pump frequency in time; when t1≥50℃, turn off the heat pump unit, heating water pump and heating valve.

[0101] 3) Heating water tank filling process: Detect the actual liquid level H1 of the heating water tank. When H1 ≤ the set minimum liquid level H 1min When H 1＝ Set the maximum liquid level H 1max When the water supply valve is turned on, close the water supply valve.

[0102] 4) Insulated water tank heat pump heating process: detect the actual water temperature t1 of the heating water tank and the actual water temperature t2 of the insulated water tank. When t2≤45℃ and t1≤t2, the heat pump unit is turned on. After turning on the insulated water pump for two minutes, open the insulation valve and turn off the heating water pump and the heating valve; when t2≥50℃, turn off the insulation water pump and the insulation valve.

[0103] 5) Pumping water from the heating water tank to the insulation water tank: Detect the actual water temperature t1 of the heating water tank and the actual water temperature t2 of the insulation water tank. When t2≤45℃ and t1>t2, the heat pump unit has not reached the start-up temperature. Turn on the heating water pump, open the insulation valve, and pump water from the heating water tank to the insulation water tank until the water temperature of the insulation water tank reaches the set maximum temperature or the liquid level of the insulation water tank reaches the set maximum level or the liquid level of the heating water tank reaches the set minimum level. From 24:00 to 6:00, the set water temperature range of the heating water tank and the insulation water tank is 45℃-50℃ (reduce the unit start-up).

[0104] If the actual liquid level H2 of the thermal insulation water tank is judged to have reached the set maximum liquid level H 2max , the set maximum liquid level H is not reached 2max Then turn on the heating water pump and insulation valve to pump water. 23:00-13:00, when H2≤1 level, turn on the heating water pump and insulation valve until H2 reaches 2 level. 13:00-23:00, when H2≤3 level, turn on the heating water pump and insulation valve until H2 reaches 4 level.

[0105] Anti-dry heating: When the actual liquid level H1 of the heating water tank is less than the set minimum liquid level H 1min When the actual liquid level H2 of the thermal insulation water tank is less than the set minimum liquid level H 2min The heat pump unit and insulation water pump will not start.

[0106] In practical applications, the H of the heating tank 1min Can be set to 0.3 meters, H 1max It can be set to 1.8 meters, the 1st liquid level of the insulation water tank can be set to 0.3 meters, the 2nd liquid level can be set to 0.8 meters, the 3rd liquid level can be set to 1.3 meters, and the 4th liquid level can be set to 1.8 meters.

[0107] The present invention adopts a double water tank system, and the heating water tank and the insulation water tank share the heat pump unit for heating. The water pump assembly is changed from the conventional one-in-one to the heating water pump and the insulation water pump being mutually standby, thereby reducing two electric valves and reducing the number of fault points. The heating water pump is responsible for the circulation of the heating water tank and pumping water from the heating water tank to the insulation water tank, and the insulation water pump is responsible for the insulation circulation of the insulation water tank. When the automatic control system fails, the entire system can be circulated by turning on any one pump. The heat pump unit controls the on and off according to the water temperature of the heating water tank. When the water temperature of the heating water tank reaches the set temperature upper limit, the heating water pump pumps water to the insulation water tank. When the water temperature of the insulation water tank is lower than the set temperature lower limit, there are two modes, one is to pump water from the heating water tank and mix it with the insulation water tank, and the other is to heat the insulation water tank directly by the heat pump unit. The liquid level and water temperature of the insulation water tank can be controlled by timing to reduce the heat loss of the insulation water tank during low water consumption.

[0108] Moreover, the dual water tank system provided by the present invention realizes energy-saving water replenishment of the heat pump unit and reduces the energy consumption of the unit by 10%-15%. And according to the real-time water demand of the user, during the night time when the water consumption is less, a lower liquid level of the insulation water tank is set to reduce the temperature difference between the water tank and the outside world, and reduce the heat dissipation loss of the water tank. At the same time, the water temperature of the circulating return water pipeline is reduced. Since the contact area between the return water pipe and the outside world is large, the heat dissipation loss is fast. By reducing the water temperature of the circulating return water pipeline, the heat loss of the pipeline can be reduced. For occasions where hot water is not used at night, only the antifreeze mode of the pipeline is set to reduce the insulation energy consumption of the pipeline. For occasions without peak and valley electricity prices, try to reduce the opening of the heat pump unit at night. Due to the large temperature difference between day and night, the operating efficiency of the heat pump unit at night is low, and the operating time of the heat pump unit during the low temperature period is reduced. The heat pump unit is turned on at around 6 o'clock in the morning to heat up to ensure the water demand in the morning.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Double water tank hot water system, characterized in that: include: Heat pump units; A hot water circulation pump assembly, the hot water circulation pump assembly comprising a heating water pump and a heat preservation water pump arranged in parallel, and the water inlet end of the heat preservation water pump is connected to the water inlet end of the heating water pump through a first manual valve; A heating water tank, wherein the water outlet of the heating water tank is connected to the water inlet of the heat pump unit through the hot water circulation pump assembly, and the water inlet of the heating water tank is also connected to the water outlet of the heat pump unit through a heating valve; The insulated water tank is connected to the user side, the water outlet of the insulated water tank is connected to the water inlet of the heat pump unit through the hot water circulation pump assembly, and the water inlet of the insulated water tank is connected to the water outlet of the heat pump unit through an insulation valve.

2. The dual-tank hot water system according to claim 1, characterized in that: The water inlet end of the heating water tank is also connected to a water supply pipe, and a water supply valve is arranged on the water supply pipe.

3. The dual-tank hot water system according to claim 1, characterized in that: The water outlet of the insulated water tank is connected to the user side through a hot water supply pump, and the water inlet of the insulated water tank is connected to the user side through a return pipe provided with a return valve.

4. The dual-tank hot water system according to claim 1, characterized in that: A connecting pipe is provided between the heating water tank and the heat-insulating water tank, and a second manual valve is provided on the connecting pipe.

5. The dual water tank hot water system according to claim 1, characterized in that: Also includes: A solar heating device is connected to the heating water tank and is used to heat the heating water tank.

6. The dual-tank hot water system according to claim 1, characterized in that: An auxiliary electric heater is arranged at the water outlet of the heat pump unit.

7. The control method of a dual water tank hot water system according to any one of claims 1 to 6, characterized in that: The control method comprises: Obtaining the working mode of the dual-tank hot water system; The start and stop of the heat pump unit, the heating water pump, and the insulation water pump, as well as the opening of the heating valve and the insulation valve are controlled according to the working mode of the dual-tank hot water system.

8. The control method of the dual-tank hot water system according to claim 7, characterized in that: When the working mode is the water replenishment heating mode, it is determined that the actual liquid level H1 of the heating water tank reaches the set maximum liquid level H 1max After that, the heat pump unit, the heating water pump and the heating valve are turned on until the actual water temperature t1 of the heating water tank reaches the set maximum temperature t 1max .

9. The control method of the dual-tank hot water system according to claim 8, characterized in that: In the process of heating the heating water tank by the heat pump unit, the heat pump unit is first controlled to operate according to the reference operating frequency, and the outdoor temperature t 室 > Predicted temperature t 预 If yes, reduce the operating frequency of the heat pump unit; if no, increase the operating frequency of the heat pump unit, wherein the reference operating frequency is related to the predicted temperature t 预 Related.

10. The control method of the dual-tank hot water system according to claim 7, characterized in that: When the working mode is the water storage and heat preservation mode, the heating water pump is turned on and the heat preservation valve is opened until the actual liquid level H2 of the heat preservation water tank reaches the set maximum liquid level H 2max Or the actual liquid level H1 of the heating water tank reaches the set minimum liquid level H 1min .

11. The control method of the dual-tank hot water system according to claim 10, characterized in that: Before starting the heating water pump and opening the insulation valve, the method further includes: Determine that the actual water temperature t2 of the thermal insulation water tank is lower than the set minimum temperature t 2min , and the actual water temperature t1 of the heating water tank is higher than the actual water temperature t2 of the insulation water tank.

12. The control method of the dual-tank hot water system according to claim 11, characterized in that: Before starting the heating water pump and opening the insulation valve, the method further includes: Determine that the actual liquid level H2 of the thermal insulation water tank reaches the set minimum liquid level H 2min , and the actual water temperature t1 of the heating water tank is higher than the set maximum temperature t 1max .

13. The control method of the dual-tank hot water system according to claim 12, characterized in that: When the user is in the normal water use period, the minimum liquid level H is set 2min is the first level of the thermal insulation water tank, and the maximum liquid level H is set 2max The second level of the thermal insulation water tank; When the user is in the peak water consumption period, the minimum liquid level H is set 2min The three levels of the thermal insulation water tank, the maximum liquid level H 2max It is the 4th liquid level of the thermal insulation water tank.

14. The control method of the dual-tank hot water system according to claim 7, characterized in that: When the working mode is the heat pump insulation mode, the heat pump unit, the insulation water pump and the insulation valve are turned on until the actual water temperature t2 of the insulation water tank reaches the set maximum temperature t 2max .

15. The control method of the dual water tank hot water system according to claim 14, characterized in that: Before starting the heat pump unit, the insulation water pump and opening the insulation valve, the method further includes: Determine that the actual water temperature t2 of the thermal insulation water tank is lower than the set minimum temperature t 2min , and the actual water temperature t1 of the heating water tank is lower than the actual water temperature t2 of the insulation water tank.

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