Two-stage heat pump cooperative heat supply structure

Abstract

The utility model relates to a two-stage heat pump collaborative heat supply structure, which structurally comprises an air-cooled heat pump, a water source heat pump, a buffer tank and an intermediate circulating pump, the air-cooled heat pump, the buffer tank and the intermediate circulating pump are arranged on a roof, the water source heat pump is arranged below the roof, the intermediate circulating pump is arranged on a pipeline between an outlet of the buffer tank and an inlet of the air-cooled heat pump, and the air-cooled heat pump is arranged on the pipeline. An air-cooled heat pump outlet is connected with a water source heat pump evaporation side inlet through a pipeline, and a water source heat pump evaporation side outlet is connected with a buffer tank inlet through a pipeline. During working, the intermediate circulating pump pumps water from the buffer tank, the water is pressurized and then sent to the air-cooled heat pump, and the water is heated by the air-cooled heat pump and then sent to the evaporator of the water source heat pump for reheating; the circulating water cooled by the water source heat pump evaporator returns to the buffer tank, is pressurized by the intermediate circulating pump, and is started to circulate again. The system has the advantages of being reasonable in structural design and capable of effectively solving the problems of heat source waste, high power distribution cost, poor system stability and the like in the building heat supply field.

Description

Technical Field

[0001] This utility model relates to a stepped heating system structure, specifically a stepped heating system structure based on the coordinated operation of an air-cooled heat pump and a water source heat pump, suitable for building heating and domestic hot water supply scenarios under hot summer and cold winter conditions and cold climates, belonging to the field of building heating technology. Background Technology

[0002] In existing technologies, building heating systems mainly rely on traditional gas boilers, electric heating equipment, and single heat pump technology, and their current application exhibits the following characteristics:

[0003] Gas-fired boilers: In northern regions with centralized heating systems, approximately 65% ​​of buildings still use gas-fired boilers for heating. Gas-fired boilers provide heat through the direct combustion of gas.

[0004] Air source heat pumps: In hot summer and cold winter regions, the application rate of air source heat pumps is increasing year by year. Their operating principle is to absorb heat from the air through the reverse Carnot cycle for heating. They are easy to install and energy-efficient.

[0005] Water source heat pump: The principle of water source heat pump is similar to that of air source heat pump. The difference is that water source heat pump obtains heat from low-temperature water source. Since water has a better heat exchange effect than air, the efficiency of water source heat pump is more objective.

[0006] However, the existing heating technologies mentioned above have significant shortcomings in terms of energy efficiency, economy, and adaptability:

[0007] Although gas-fired boiler heating technology is mature, its combustion efficiency is generally below 90% (measured value). At the same time, due to the high unit cost of gas, the cost of boiler heating is high, and the carbon emission intensity is as high as 0.2 kg CO2 / kWh, making it difficult to meet the "dual carbon" target requirements. In addition, it cannot effectively utilize natural low-grade heat sources.

[0008] A single air-source heat pump experiences excessively low evaporation temperatures in cold weather, leading to a decrease in heating efficiency. When the ambient temperature drops below -5°C, the Coefficient of Performance (COP) plummets from 3.2 to 1.8 (based on data measured by Tsinghua University), necessitating electric auxiliary heating compensation and causing operating costs to surge by over 30%. Furthermore, equipment selection is limited to the worst-case scenario, resulting in a significant increase in investment costs and poor economic efficiency. Additionally, when high-power heat pumps are concentrated on rooftops (air-source heat pumps, requiring air exchange, are often installed on building rooftops in areas with limited outdoor space), the increased power supply distance significantly increases transmission line losses and power distribution line investment.

[0009] While ground source heat pumps can reliably provide 50°C hot water (with a COP of over 4.0), their limited space requirements and high initial investment restrict their application to low-density buildings, making widespread adoption in urban high-rises difficult. Furthermore, their application in renovation and remodeling projects is virtually impossible.

[0010] Based on the above, there are two key gaps in the existing technology system:

[0011] Lack of graded utilization of heat sources: The low-grade environmental heat sources (such as air) are not integrated with the medium-grade waste heat (condensate, return water waste heat) in a temperature gradient, resulting in the waste of high-grade electrical energy.

[0012] Insufficient spatial layout and energy efficiency coupling design: The equipment deployment did not take into account the relationship between building space characteristics (low temperature zone on the roof, constant temperature zone in the underground) and power distribution costs, making it difficult to improve the overall economic efficiency of the system.

[0013] The above analysis reveals the deep-seated contradictions in the current heating sector regarding energy efficiency bottlenecks, power distribution economics, and system synergy. Utility Model Content

[0014] This utility model proposes a two-stage heat pump synergistic heating structure, which aims to overcome the above-mentioned shortcomings of the existing technology and take into account both the system's thermodynamic efficiency and engineering economy.

[0015] The technical solution of this utility model is a two-stage heat pump synergistic heating structure, which includes an air-cooled heat pump, a water source heat pump, a buffer tank, and an intermediate circulation pump. The air-cooled heat pump, buffer tank, and intermediate circulation pump are installed on the roof, while the water source heat pump is installed below the roof. The intermediate circulation pump is installed on the pipeline between the outlet of the buffer tank and the inlet of the air-cooled heat pump. The outlet of the air-cooled heat pump is connected to the evaporator-side inlet of the water source heat pump via a pipeline, and the outlet of the water source heat pump's evaporator-side is connected to the inlet of the buffer tank via a pipeline. During operation, the intermediate circulation pump draws water from the buffer tank, pressurizes it, and sends it to the air-cooled heat pump. After being heated by the air-cooled heat pump, the water goes to the evaporator of the water source heat pump for reheating. The circulating water, after absorbing heat and cooling down in the evaporator of the water source heat pump, returns to the buffer tank, and is then pressurized by the intermediate circulation pump to start the recirculation process.

[0016] Preferably, there is more than one air-cooled heat pump. Each air-cooled heat pump inlet is connected to the same air-cooled heat pump inlet main pipe through an air-cooled heat pump inlet branch pipe. The air-cooled heat pump inlet main pipe is connected to an intermediate circulation pump. Each air-cooled heat pump outlet is connected to the same air-cooled heat pump outlet main pipe through an air-cooled heat pump outlet branch pipe. The air-cooled heat pump outlet main pipe is connected to the first inlet of the water source heat pump.

[0017] Preferably, a bypass pipe with a bypass valve is connected between the inlet main pipe and the outlet main pipe of the air-cooled heat pump. This ensures that the water source heat pump can maintain the necessary water flow when the number of air-cooled heat pumps is adjusted.

[0018] Preferably, an electric valve is installed on the outlet branch pipe of the air-cooled heat pump. This facilitates interlocking start / stop control with the main unit.

[0019] Preferably, a first pressure sensor is installed on the inlet main pipe of the air-cooled heat pump, and a second pressure sensor is installed on the outlet main pipe of the air-cooled heat pump between the connection with the bypass pipe and the connection with the outlet branch pipe of the air-cooled heat pump. This facilitates the implementation of the differential pressure frequency conversion strategy of the intermediate circulation pump, ensuring that each unit receives sufficient flow when the number of air-cooled heat pumps in operation changes.

[0020] Preferably, the buffer tank is equipped with a first temperature sensor. This facilitates the control of the air-cooled heat pump's booster / subtractor.

[0021] Preferably, a second temperature sensor is installed on the main outlet pipe of the air-cooled heat pump between the connection point to the bypass pipe and the connection point to the first inlet of the water source heat pump, and a third temperature sensor is installed on the pipe between the first outlet of the water source heat pump and the inlet of the buffer tank. Both the second and third temperature sensors are located close to the water source heat pump. This facilitates the opening of the bypass valve and the auxiliary frequency conversion control of the intermediate circulation pump.

[0022] Preferably, the water source heat pump is equipped with a heat-side circulation pump on the condenser side. This pump is used for circulation and supply to the heating user side, delivering hot water to the end user.

[0023] The advantages of this utility model are: its reasonable structural design effectively solves problems such as heat source waste, high power distribution costs, and poor system stability in the field of building heating. Specifically:

[0024] 1) It achieves progressive cascade heating, and the air-cooled heat pump only produces low-temperature hot water. The equipment also has high thermodynamic efficiency in cold weather.

[0025] 2) By adopting a graded control + buffer tank heat storage, a two-stage relay mode is formed. The heat storage tank is used first, which can significantly reduce the fluctuation of heating effect. At the same time, the equipment operates away from extreme conditions, making the heating more stable and reliable.

[0026] 3) Roof heat pumps only require medium temperature output, which can reduce the total power distribution load. Basement water source heat pumps can be directly connected to the power distribution room, resulting in a lower line loss rate and reducing the overall comprehensive power distribution cost.

[0027] 4) The actual operating conditions of the air-cooled heat pump are far from the extreme operating conditions of the unit, making the equipment safer and more efficient, and with low dependence on electric auxiliary heating. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the dual-stage heat pump synergistic heating structure of this utility model.

[0029] In the diagram, 1 is the roof dividing line, 2 is the air-cooled heat pump, 21 is the electric valve, 3 is the water source heat pump, 4 is the buffer tank, 5 is the intermediate circulation pump, 61 is the first pressure sensor, 62 is the second pressure sensor, 7 is the bypass valve, 81 is the first temperature sensor, 82 is the second temperature sensor, 83 is the third temperature sensor, and 9 is the thermal circulation pump. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to embodiments and specific implementation methods.

[0031] like Figure 1 As shown, a two-stage heat pump synergistic heating structure includes an air-cooled heat pump 2, a water source heat pump 3, a buffer tank 4, and an intermediate circulation pump 5. The air-cooled heat pump 2, the buffer tank 4, and the intermediate circulation pump 5 are installed on the roof, while the water source heat pump 3 is installed below the roof. The intermediate circulation pump 5 is installed on the pipeline between the outlet of the buffer tank 4 and the inlet of the air-cooled heat pump 2. The outlet of the air-cooled heat pump 2 is connected to the evaporator-side inlet of the water source heat pump 3 through a pipeline, and the evaporator-side outlet of the water source heat pump 3 is connected to the inlet of the buffer tank 4 through a pipeline.

[0032] As needed, one or more air-cooled heat pumps 2 can be installed. The inlet of each air-cooled heat pump 2 is connected to the same air-cooled heat pump inlet main pipe through an air-cooled heat pump inlet branch pipe. The air-cooled heat pump inlet main pipe is connected to the intermediate circulation pump 5. The outlet of each air-cooled heat pump 2 is connected to the same air-cooled heat pump outlet main pipe through an air-cooled heat pump outlet branch pipe. The air-cooled heat pump outlet main pipe is connected to the first inlet of the water source heat pump 3. A bypass pipe with a bypass valve 7 is connected between the air-cooled heat pump inlet main pipe and the air-cooled heat pump outlet main pipe to form a pressure differential bypass device, which can ensure that the water source heat pump 3 can still maintain the necessary water flow when the number of air-cooled heat pumps 1 is adjusted.

[0033] During operation, the intermediate circulation pump 5 draws water from the buffer tank 4, pressurizes it, and sends it to the air-cooled heat pump 1. After being heated by the air-cooled heat pump 1, the water goes to the evaporator of the water source heat pump 3 for reheating. The circulating water, after absorbing heat and cooling down in the evaporator of the water source heat pump 3, returns to the buffer tank 4, and is then pressurized by the intermediate circulation pump 5 to start the recirculation process.

[0034] In the specific design,

[0035] 1) The air-cooled heat pump 2 is installed on the outdoor roof. An electric valve 21 is installed on the outlet branch pipe of the air-cooled heat pump, which can be easily interlocked with the main unit for start-stop control.

[0036] 2) The intermediate circulation pump 5 is used to provide the flow power of circulating water between the air-cooled heat pump 2 and the water source heat pump 3 loop. It is installed between the buffer tank 4 and the air-cooled heat pump 2. The inlet of the intermediate circulation pump 5 is connected to the outlet of the buffer tank 4, and the outlet is connected to the inlet pipe of the air-cooled heat pump.

[0037] 3) The first pressure sensor 6 is installed on the inlet main pipe of the air-cooled heat pump, and the second pressure sensor 62 is installed on the outlet main pipe of the air-cooled heat pump between the connection with the bypass pipe and the connection with the outlet branch pipe of the air-cooled heat pump. This facilitates the execution of the differential pressure frequency conversion strategy of the intermediate circulation pump 5 and ensures that each unit can obtain sufficient flow when the number of air-cooled heat pumps 1 in operation changes.

[0038] 4) The second temperature sensor 82 is installed on the main outlet pipe of the air-cooled heat pump between the connection point with the bypass pipe and the connection point with the first inlet of the water source heat pump 3. The third temperature sensor 83 is installed on the pipeline between the first outlet of the water source heat pump 3 and the inlet of the buffer tank 4. Both the second temperature sensor 82 and the third temperature sensor 83 are installed close to the water source heat pump 3 to facilitate the opening of the bypass valve 7 and the auxiliary frequency conversion control of the intermediate circulation pump 5.

[0039] 5) The buffer tank 4 is located between the water source heat pump 3 and the suction port of the intermediate circulation pump 5, and is equipped with a first temperature sensor 81 to facilitate the control of the air-cooled heat pump 1.

[0040] 6) The water source heat pump 3 is installed on the ground floor or in the basement of the building, close to the refrigeration room and the power distribution room.

[0041] 7) A heat-side circulation pump 9 is installed on the condenser side of the water source heat pump 3 for circulation and supply to the heating user side, supplying hot water to the end. Example

[0042] By using a stepped heat source quality enhancement technology, the heating process is decomposed into two temperature gradients:

[0043] Primary heat pump (roof): Utilizes ambient air to generate a medium-temperature heat source (15-25℃), reducing the compression ratio requirement and improving operating efficiency under low-temperature conditions (COP≥3.2, -10℃ environment).

[0044] Secondary heat pump (underground): Uses a medium-temperature heat source as the evaporator side heat source to produce high-temperature hot water (40-60℃), and the compression ratio is reduced to 60%-70% of that of conventional systems.

[0045] After adopting the above design, spatial decoupling power distribution optimization design and intelligent collaborative control are employed.

[0046] Technical benefits: The roof-mounted air-cooled heat pump significantly reduces power consumption and overall power costs; the use of staged heating reduces thermodynamic losses to below 25%, improving the overall heating efficiency of the system.

[0047] In terms of specific operation, an air-cooled heat pump is installed on the building roof. The air-cooled heat pump produces low-temperature hot water (the outlet water temperature is controlled at around 20°C) by exchanging heat with the outdoor air. Even in cold winter weather, the low condensing temperature can achieve high heating efficiency.

[0048] A water source heat pump is installed in the machine room in the basement of the building or in a suitable location on the first floor. The condenser side of the water source heat pump is connected to the building's heating terminals to provide users with a heat source of a specified grade (outlet water temperature of about 50℃, temperature adjustable).

[0049] A circulating pipeline system connects the rooftop air-cooled heat pump and the ground floor water-source heat pump, with a buffer tank connected in series in the pipeline to increase the system's water capacity and improve the stability of the coupled heating system. A circulating water pump is installed before the rooftop air-cooled heat pump's water inlet, and both the circulating water pump and the buffer tank are located on the roof.

[0050] Temperature and pressure sensors are installed in the system to monitor the system's operating status in real time and automatically adjust the operating parameters of each heat source to achieve automatic, efficient, and energy-saving operation of the entire system.

[0051] The specific implementation steps are as follows:

[0052] 1) Install an air-cooled heat pump on the roof. The capacity is determined based on the heating capacity under the most unfavorable operating conditions. The heating conditions are 20℃ / 15℃ to improve heating efficiency and reduce power consumption.

[0053] 2) A water source heat pump is installed on the ground floor of the building. The condenser side of the water source heat pump is connected to the heat-consuming terminal, and the evaporator side is connected in a loop to the condenser side of the air-cooled heat pump. A hot water circulation pump set is installed on the condenser side of the water source heat pump.

[0054] 3) An intermediate circulation pump and a hot water buffer tank are installed on the roof. The intermediate circulation pump is installed in the pipeline before the inlet of the air-cooled heat pump. The circulating water is pressurized by the intermediate circulation pump and then sent to the air-cooled heat pump for heating. The low-temperature hot water produced by heating is then sent to the evaporator of the water source heat pump to be used as the low-temperature heat source of the water source heat pump. The buffer tank is installed before the suction inlet of the intermediate circulation pump to store the medium-temperature heat medium (15-25℃) prepared by the roof heat pump. It plays a role in stabilizing the circulating water temperature, reducing system fluctuations, and mitigating the impact of ambient temperature fluctuations on the underground heat pump. The heat storage loss rate is ≤3% / 24h.

[0055] 4) Power is distributed from the ground floor power distribution room to the roof air-cooled heat pump and the ground floor water source heat pump respectively;

[0056] 5) Both the intermediate circulation pump and the hot water circulation pump are equipped with frequency converters to achieve variable frequency operation.

[0057] 6) Necessary monitoring sensors such as temperature and pressure are installed in the system loop, and the entire system is operated in an energy-efficient and high-performance manner through intelligent collaborative control technology;

[0058] 7) The specific logic method of intelligent collaborative control is as follows:

[0059] ① The roof air-cooled heat pump is controlled according to the return water temperature. When the return water temperature is lower than the set value (after a delay), the air-cooled heat pump is turned on; otherwise, one air-cooled heat pump is turned off.

[0060] ② The start-stop and outlet electric valve of the air-cooled heat pump are interlocked. When the air-cooled heat pump needs to be turned on, the matching electric valve opens in advance. When the air-cooled heat pump needs to be turned off, the matching electric valve closes with a delay.

[0061] ③ The intermediate circulation pump is controlled by a combination of pressure difference and temperature difference. The pressure difference setting value meets the safe operation requirements of both air-cooled heat pumps and water source heat pumps. When the number of air-cooled heat pumps decreases, the pressure difference between the inlet and outlet main pipes of the air-cooled heat pumps increases, the intermediate circulation pump reduces its operating frequency, and at the same time monitors the temperature difference between the inlet and outlet of the water source heat pump evaporator side. When the temperature difference exceeds the set value, the bypass valve is slowly opened to prevent the operation of the water source heat pump from being affected by the reduction in the number of air-cooled heat pumps. When the temperature difference between the inlet and outlet of the water source heat pump enters a reasonable range, the bypass valve stops operating.

[0062] ④ The water source heat pump is controlled according to the outlet water temperature on the condenser side. The outlet water temperature is adjustable. If the temperature is lower than the outlet water temperature, the unit will be loaded; if the temperature is higher than the outlet water temperature, the unit will be unloaded. When multiple water source heat pump units are used, the addition and subtraction strategy can also be implemented.

[0063] ⑤ The system intelligently judges the load changes of the day based on outdoor temperature forecasts and daily heating demand changes, and loads or reduces the load of air-cooled heat pumps and water source heat pumps in advance to cope with peak demand. The system allows different control parameters to be set for different time periods to execute differentiated control objectives.

[0064] This invention decouples low-temperature heat source preparation from high-temperature heating and optimizes the spatial layout of the equipment, thereby fundamentally solving the industry problem of balancing thermodynamic efficiency and engineering economy in traditional systems.

[0065] This utility model aims to solve the problems existing in the application of heat pump technology in the field of building heating, such as the mismatch between heat source quality and heating demand, poor economic efficiency of power distribution system, and poor adaptability to extreme climate.

[0066] This invention achieves breakthroughs in energy efficiency, cost optimization, and enhanced reliability in the heating sector through three major technological innovations: graded utilization of heat source quality, optimized spatial layout, and intelligent collaborative control. It systematically solves the long-standing problems of high energy consumption, high cost, and low adaptability in building heating, providing an innovative technological path for clean heating in cold winter regions.

[0067] All of the components described above are existing technologies, and those skilled in the art can use any model and existing design that can achieve their corresponding functions.

[0068] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present utility model, and these all fall within the protection scope of the present utility model.

Claims

1. A two-stage heat pump cogeneration structure, characterized by, It includes an air-cooled heat pump (2), a water source heat pump (3), a buffer tank (4), and an intermediate circulation pump (5). The air-cooled heat pump (2), the buffer tank (4), and the intermediate circulation pump (5) are installed on the roof. The water source heat pump (3) is installed below the roof. The intermediate circulation pump (5) is installed on the pipeline between the outlet of the buffer tank (4) and the inlet of the air-cooled heat pump (2). The outlet of the air-cooled heat pump (2) is connected to the evaporation side inlet of the water source heat pump (3) through a pipeline. The evaporation side outlet of the water source heat pump (3) is connected to the inlet of the buffer tank (4) through a pipeline.

2. A two-stage heat pump and heating structure according to claim 1, characterized in that, The air-cooled heat pump (2) is more than one unit. The inlet of each air-cooled heat pump (2) is connected to the same air-cooled heat pump inlet main pipe through an air-cooled heat pump inlet branch pipe. The air-cooled heat pump inlet main pipe is connected to the intermediate circulation pump (5). The outlet of each air-cooled heat pump (2) is connected to the same air-cooled heat pump outlet main pipe through an air-cooled heat pump outlet branch pipe. The air-cooled heat pump outlet main pipe is connected to the first inlet of the water source heat pump (3).

3. A two-stage heat pump and heating structure according to claim 2, wherein, A bypass pipe with a bypass valve (7) is connected between the inlet main pipe and the outlet main pipe of the air-cooled heat pump.

4. A two-stage heat pump and heating structure according to claim 2, wherein, An electric valve (21) is installed on the outlet branch pipe of the air-cooled heat pump.

5. A two-stage heat pump and heating structure according to claim 3, wherein, A first pressure sensor (61) is installed on the inlet main pipe of the air-cooled heat pump, and a second pressure sensor (62) is installed on the outlet main pipe of the air-cooled heat pump between the connection with the bypass pipe and the connection with the outlet branch pipe of the air-cooled heat pump.

6. The two-stage heat pump synergistic heating structure as described in claim 1, characterized in that, The buffer tank (4) is equipped with a first temperature sensor (8).

7. A two-stage heat pump and heating structure according to claim 3, wherein A second temperature sensor (82) is installed on the air-cooled heat pump outlet main pipe between the connection point with the bypass pipe and the connection point with the first inlet of the water source heat pump (3). A third temperature sensor (83) is installed on the pipeline between the first outlet of the water source heat pump (3) and the inlet of the buffer tank (4). Both the second temperature sensor (82) and the third temperature sensor (83) are close to the water source heat pump (3).

8. A two-stage heat pump and heating structure according to claim 1, characterized in that, The water source heat pump (3) is equipped with a heat-side circulation pump (9) on the condensing side.

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