Heat pump hot water system capable of dynamically adjusting flow of waste water and clean water

Abstract

The invention discloses a heat pump hot water system capable of dynamically adjusting waste water and clean water flow, which comprises a waste water tank, a water source heat pump water heater and a hot water tank, a liquid level sensor I and a temperature sensor III are arranged in the hot water tank, and a liquid level sensor II is arranged in the waste water tank. A flow meter I, a valve I and a temperature sensor I are arranged on a pipeline, flowing to the hot water tank, of the water source heat pump water heater, and a flow meter II, a valve II and a temperature sensor II are arranged on a pipeline, flowing to the waste water discharging opening, of the water source heat pump water heater. On the premise that the hot water outlet temperature or the waste water discharging temperature is guaranteed, it is guaranteed that the total amount of hot water can meet the user requirement all the time, and meanwhile the higher COP and larger heating capacity are obtained as high as possible as the bathing waste water discharging temperature is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of building energy conservation, and particularly relates to a heat pump hot water system with dynamically adjustable waste water and fresh water flow rates. Background Art

[0002] The energy consumption of residential bathing accounts for about 20% of the building energy consumption. Recycling the waste heat from bathing to produce hot water instead of using fossil energy is of great significance for reducing carbon emissions, and it is a major topic with a wide range, large quantity and remarkable benefits. Researchers in this field use secondary recovery heat pump technology to recover the heat energy in the waste hot water and have applied it in centralized bathing places. However, the discharge temperature of the waste hot water is 13 - 14°C, and the proportion of auxiliary heat source heating is still as high as 33%. Taking electric heating as the auxiliary heat source, the annual cost per ton of hot water is 10.2 yuan.

[0003] The waste heat cascade utilization water source heat pump water heater developed by the applicant adopts the waste heat three - stage cascade recovery technology, which not only recovers all the waste heat in the bathing waste water, but also recovers all the heat energy of 8 - 10°C consumed during the bathing process from the bathing waste water, and the waste water is discharged at a low temperature of 3°C (when the tap water is above 12°C), overcoming the main technical problem of producing the same amount of bathing hot water from the same amount of bathing waste water. However, in northern regions, users also need hot water for washing vegetables in the kitchen and washing in the bathroom in winter, and this part of the waste water generally cannot be collected. Therefore, when using the hot water produced from bathing waste water, the ratio between the two is no longer fixed at 1:1, but needs to be dynamically adjusted according to user needs.

[0004] Therefore, developing a hot water system with dynamically adjustable waste water and fresh water flow rates, which can dynamically adjust the ratio of fresh water to waste water according to the change of the user's hot water consumption, and always ensure that the total amount of hot water can meet the user's needs when using bathing waste water to produce hot water, while obtaining a higher COP and a larger heating capacity as much as possible under the premise of meeting the bathing hot water temperature, is one of the technical problems that need to be urgently solved by those skilled in the art. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a heat pump hot water system with dynamically adjustable waste water and fresh water flow rates. According to the water levels of the waste water tank and the hot water tank, calculate the ratio of fresh water to waste water when producing hot water, and then adjust the electric valve according to this ratio to control the fresh water and waste water flow rates of the heat pump. On the premise of ensuring the hot water outlet temperature or the waste water discharge temperature, ensure that the total amount of hot water can always meet the user's needs, and at the same time, the bathing waste water discharge temperature is as high as possible to obtain a higher COP and a larger heating capacity.

[0006] The technical solution provided by the present invention is as follows: A heat pump water heating system with dynamically adjustable clean water flow rate for wastewater, comprising a wastewater tank, a water source heat pump water heater, and a hot water tank. A liquid level sensor I and a temperature sensor III are arranged in the hot water tank. The hot water tank is also connected to a tap water interface, and a water supply pump is provided on the connecting pipeline. A liquid level sensor II is arranged in the wastewater tank. The water source heat pump water heater is connected to the tap water supply port, the wastewater tank, the hot water tank, and the wastewater discharge port through pipelines. On the pipeline from the water source heat pump water heater to the hot water tank, a flowmeter I, a valve I, and a temperature sensor I are respectively arranged. On the pipeline from the water source heat pump water heater to the wastewater discharge port, a flowmeter II, a valve II, and a temperature sensor II are respectively arranged.

[0007] Preferably, a wastewater pump is arranged on the pipeline between the wastewater tank and the water source heat pump water heater.

[0008] Preferably, it further comprises an auxiliary heating device, which is connected to the hot water tank to form a closed-loop water circuit, and a circulation pump is arranged on the closed-loop water circuit.

[0009] Compared with the prior art, the present invention has the following technical advantages: (1) The present invention uses bath waste heat as the main heat source, fully utilizes the waste heat to produce hot water, and only starts to use auxiliary heating to heat the clean water to the set temperature after the wastewater discharge temperature has reached 3°C. Regardless of how the user's water consumption changes, the present invention automatically calculates the ratio of clean water to wastewater during hot water production, and then adjusts the electric valve according to this ratio to control the clean water and wastewater flow rates of the heat pump. On the premise of ensuring the hot water outlet temperature or the wastewater discharge temperature, it ensures that the total amount of hot water can always meet the user's needs. It can not only produce bath hot water at a ratio of 1:1, but also produce domestic hot water at a ratio of 1:X (clean water flow rate, X≥1). It not only provides hot water supply for users' bathing, but also meets the domestic hot water needs including kitchens and lavatories.

[0010] (2) On the premise of meeting the hot water outlet temperature, the present invention works at the maximum flow rate as much as possible, and the system has better heating capacity and COP. In the case where the hot water outlet temperature cannot be met, the outlet ratio is still maintained, and the water temperature in the auxiliary heating water tank is raised to the required temperature through auxiliary heating to meet the water volume and temperature requirements of hot water supply. Description of the Drawings

[0011] Figure 1 It is the structural schematic diagram of the present invention Wherein: 1. Wastewater tank 2. Water source heat pump water heater 3. Hot water tank 4. Liquid level sensor I 5. Temperature sensor III 6. Liquid level sensor II 7. Flowmeter I 8. Valve I 9. Temperature sensor I 10. Flowmeter II 11. Valve II 12. Temperature sensor II 13. Auxiliary heating device 14. Circulation pump 15. Wastewater pump 16. Water supply pump 17. Wastewater delivery pipe 18. Control valve 19. Wastewater discharge port pipe. Embodiment

[0012] The present invention will be further described below in conjunction with specific embodiments and the accompanying drawings.

[0013] As Figure 1 shown, the present invention discloses a heat pump hot water system with dynamically adjustable clear water flow rate of wastewater, which includes a wastewater tank 1, a water source heat pump hot water machine 2, and a hot water tank 3. A liquid level sensor I 4 and a temperature sensor III 5 are arranged in the hot water tank 3. The hot water tank 3 is also connected to a tap water interface (not marked in the figure), and a water supply pump 16 is arranged on the connecting pipeline. A liquid level sensor II 6 is arranged in the wastewater tank 1. The wastewater tank 1 is connected to a wastewater conveying pipe 17 to store waste hot water as a heat source. A wastewater pump 15 pumps the waste hot water in the wastewater tank 1 into the water source heat pump hot water machine 2 for heat exchange on the pipeline between the wastewater tank 1 and the water source heat pump hot water machine 2. Users can install a control valve 18 between the wastewater pump 15 and the wastewater tank 1 according to needs to regulate the flow rate of waste hot water transportation; the water source heat pump hot water machine 2 is respectively connected to a tap water interface (not marked in the figure), the wastewater tank 1, the hot water tank 3, and a wastewater discharge port pipe 19. On the pipeline where the water source heat pump hot water machine 2 flows to the hot water tank 3, a flow meter I 7, a valve I 8, and a temperature sensor I 9 are respectively arranged. On the pipeline where the water source heat pump hot water machine 2 flows to the wastewater discharge pipe 19, a flow meter II 10, a valve II 11, and a temperature sensor II 12 are respectively arranged.

[0014] As a preferred solution of the present invention, it further includes an auxiliary heating device 13, which is connected to the hot water tank 3 to form a closed-loop water circuit. A circulation pump 14 is arranged on the closed-loop water circuit. When the hot water temperature in the hot water tank 3 is lower than the set temperature, the auxiliary heating device 13 circulates and heats the hot water in the hot water tank 3 to the set temperature.

[0015] In the present invention, the flow meter I 7 and the flow meter II 10 are electromagnetic flow meters, the valve I 8 and the valve II 11 are electric control valves. The input end of the controller (which can be a control board, a PLC, or an industrial control computer) of the hot water system is connected to the liquid level sensor I 4 (the reading is set as h1), the liquid level sensor II 6 (the reading is set as h2), the temperature sensor I 9 (the reading is set as t1), the temperature sensor II 12 (the reading is set as t2), the temperature sensor III 5 (the reading is set as t3), the flow meter I 7 (the reading is set as q1), and the flow meter II 10 (the reading is set as q2); the output end of the controller is connected to the valve I 8 (the opening value is set as S1), the valve II 11 (the opening value is set as S2), the auxiliary heating device 13, and the circulation pump 14.

[0016] The cross-sectional areas of the hot water tank 3 and the wastewater tank 1 are s1 and s2 respectively, and the highest water level of the hot water tank 3 is h3.

[0017] The working process of the hot water system in the present invention is as follows: 1. When the system is just started, the initial opening degrees of the valve I 8 and the valve II 11 are set to 80%, the water source heat pump hot water machine 2 works, and the auxiliary heating device does not work.

[0018] 2. The system reads and saves the values of h1, h2, t1, t2, t3, q1, q2, S1, and S2.

[0019] 3. Calculate the flow rate ratio of clean water to wastewater: k = (h3 - h1) × s1 ÷ (h2 × s2).

[0020] 4. Adjust the opening of regulating valve II 11 so that q1 ÷ q2 = k × (1 ± 5%), and the method is as follows: (1) If q1 ÷ q2 > k × 1.05, gradually increase the opening of valve II 11 by a certain proportion (such as 5%) until q1 ÷ q2 ≤ k × 1.05. If the opening of valve II 11 is adjusted to 100% and q1 ÷ q2 ≤ k × 1.05 is still not achieved, then gradually decrease the opening of valve I 8 by a certain proportion (such as 5%) until q1 ÷ q2 ≤ k × 1.05.

[0021] (2) If q1 ÷ q2 < k × 0.95, gradually decrease the opening of valve II 11 by a certain proportion (such as 5%) until q1 ÷ q2 ≥ k × 0.95.

[0022] 5. If t1 - the preset hot water temperature > 2°C, then simultaneously increase the openings of valve I 8 and valve II 11 and keep the flow rate ratio unchanged so that t1 - the preset hot water temperature ≥ 2°C, and the method is as follows: The first step: Simultaneously increase the openings of valve I 8 and valve II 11 by a certain proportion (such as 5%, and the proportions of valve I and valve II can be different).

[0023] The second step: If q1 ÷ q2 > k × 1.05, then gradually increase the opening of valve II 11 by a certain proportion (such as 2%) until q1 ÷ q2 ≤ k × 1.05. Or, if q1 ÷ q2 < k × 0.95, gradually increase the opening of valve I 8 by a certain proportion (such as 2%) until q1 ÷ q2 ≥ k × 0.95.

[0024] The third step: If it is still t1 - the preset hot water temperature > 2°C, then return to the first step and execute until t1 - the preset hot water temperature ≤ 2°C.

[0025] 6. If t1 - the preset hot water temperature < 0°C, then simultaneously decrease the openings of valve I 8 and valve II 11 and keep the flow rate ratio unchanged so that t1 - the preset hot water temperature ≥ 0°C, and the method is as follows: The first step: Simultaneously decrease the openings of valve I 8 and valve II 11 by a certain proportion (such as 5%, and the proportions of valve I 8 and valve II 11 can be different).

[0026] Step 2: If q1÷q2 > k×1.05, then gradually reduce the opening of valve Ⅰ 8 by a certain proportion (such as 2%) until q1÷q2 ≤ k×1.05. Or, if q1÷q2 < k×0.95, gradually reduce the opening of valve Ⅱ 11 by a certain proportion (such as 2%) until q1÷q2 ≥ k×0.95.

[0027] Step 3: If it is still the case that t1 - preset hot water temperature < 0, then return to Step 1 and execute until t1 - preset hot water temperature ≥ 0.

[0028] 7. The system reads and saves the values of h1, h2, t1, t2, t3, q1, q2, S1, and S2. Calculate the ratio of the clean water flow rate to the wastewater flow rate: k = (h3 - h1)×s1÷(h2×s2), and then return to Step 5 of the process for execution.

[0029] 8. During the adjustment process, if t2 ≤ 3°C, stop the adjustment until t2 > 5°C, and then start the adjustment again.

[0030] 9. During the operation of the system, if t3 - preset water tank temperature < 0, then start the auxiliary heating until t3 - preset water tank temperature ≥ 2°C.

Claims

1. A heat pump water heating system with dynamically adjustable clear water flow rate of wastewater, characterized in that: it includes a wastewater tank, a water source heat pump water heater, and a hot water tank. A liquid level sensor Ⅰ and a temperature sensor Ⅲ are arranged in the hot water tank. The hot water tank is also connected to a tap water interface, and a water supply pump is arranged on the connecting pipeline; a liquid level sensor Ⅱ is arranged in the wastewater tank. The water source heat pump water heater is respectively connected to the tap water supply port, the wastewater tank, the hot water tank, and the wastewater discharge port pipelines. On the pipeline where the water source heat pump water heater flows to the hot water tank, a flow meter Ⅰ, a valve Ⅰ, and a temperature sensor Ⅰ are respectively arranged. On the pipeline where the water source heat pump water heater flows to the wastewater discharge port, a flow meter Ⅱ, a valve Ⅱ, and a temperature sensor Ⅱ are respectively arranged.

2. The heat pump water heating system with dynamically adjustable clear water flow rate of wastewater according to claim 1, characterized in that: a wastewater pump is arranged on the pipeline between the wastewater tank and the water source heat pump water heater.

3. The heat pump water heating system with dynamically adjustable clear water flow rate of wastewater according to claim 1, characterized in that: it further includes an auxiliary heating device, which is connected to the hot water tank to form a closed-loop water circuit, and a circulation pump is arranged on the closed-loop water circuit.

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