Air source and sewage source coupling hot water unit control method and system and storage medium

Abstract

The invention relates to the field of regional heat supply systems, in particular to an air source and sewage source coupled hot water unit control method and system and a storage medium. Loads borne by a sewage source heat pump set and an air source heat pump set when the energy efficiency of the sewage source heat pump set and the energy efficiency of the air source heat pump set are the same and the outlet water temperature of the sewage side of the sewage source heat pump set are calculated; and whether the sewage outlet water temperature meets the heat recovery limit or not is judged, the loads borne by the two heat pump sets are recalculated when the sewage outlet water temperature does not meet the heat recovery limit, output of the two heat pump sets is reasonably distributed on the basis of fully recovering sewage heat, and energy efficiency maximization is achieved. Wherein when the load borne by the sewage source heat pump is smaller than 0, the air source heat pump is controlled to bear all loads; and when the load borne by the sewage source heat pump is larger than the total load borne by the hot water unit heat pump, the sewage source heat pump is controlled to bear all loads. Through collaborative optimization control of an air source and a sewage source, sufficient and reasonable recovery of sewage heat energy in a regional heat supply system is ensured, and a hot water unit always operates at the optimal energy efficiency.

Description

Technical Field

[0001] This invention relates to the field of district heating systems, and in particular to a control method, system, and storage medium for a coupled air-source and sewage-source hot water unit. Background Technology

[0002] In district heating systems, wastewater source heat pumps, as a highly efficient technology for recovering low-grade heat energy, possess significant energy-saving and environmental protection potential. However, in actual operation, wastewater sources suffer from poor thermal stability; their temperature and flow rate are easily affected by external factors, leading to fluctuations in heating capacity and making it difficult to continuously meet the heat load demands of users, thus limiting the widespread application of this technology. To overcome this limitation, existing systems often introduce air source heat pumps as auxiliary heat sources to compensate for the uncertainty of wastewater source heating. However, currently, there is a lack of effective control strategies for the coordinated operation of the two heat sources, making it difficult to optimize the overall system performance and energy utilization efficiency. Therefore, there is an urgent need to develop a technical solution capable of achieving coordinated control of two heat sources. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a control method, system and storage medium for air source and sewage source coupled hot water units. Through the coordinated control of the two heat sources, the overall performance and energy utilization efficiency of the system are improved.

[0004] In a first aspect, the present invention provides a control method for a coupled air-source and sewage-source hot water unit, comprising the following steps: The first step is to set the target temperature on the user side of the generator unit. and wastewater heat recovery temperature limits ; The second step is to collect the mass flow rates of purified water and wastewater. Plate heat exchanger clean water side outlet water temperature Wastewater outlet temperature of plate heat exchanger and air temperature ; The third step is to calculate the heating power of the heat pump in the hot water unit. In the formula c The specific heat of water; Fourth step: When the energy efficiency of the wastewater source heat pump unit and the air source heat pump unit is the same, calculate the loads Q2 and Q3 they bear, and the outlet water temperature on the wastewater side of the wastewater source heat pump unit. The outlet water temperature of the wastewater source heat pump unit on the water purification side ; Step 5: Determine if the calculated load Q2 of the wastewater source heat pump unit is greater than 0. If so, proceed to the next step; otherwise, shut down the wastewater source heat pump unit and only operate the air source heat pump unit. Set the outlet water temperature of the air source heat pump unit to the specified value. The process is complete; Step 6: Determine whether the calculated load Q2 borne by the wastewater source heat pump unit is greater than the total load Q borne by the heat pump. If yes, proceed to the next step; otherwise, proceed directly to step 8. Step 7: Determine the calculated wastewater outlet temperature of the wastewater source heat pump unit. Is it greater than or equal to the heat recovery temperature limit? If so, then shut down the air source heat pump unit and only turn on the wastewater source heat pump unit. The wastewater source heat pump unit outlet water temperature setpoint... The process ends here; otherwise, proceed to the next step. Step 8: Recalculate Resolve Q2, Q3 and ; Step 9: Simultaneously turn on the air source heat pump unit and the wastewater source heat pump unit. The setpoint for the wastewater source heat pump unit's outlet water temperature is [value missing]. The setpoint for the outlet water temperature of the air source heat pump unit is taken as follows: The process is now complete.

[0005] Preferably, in the fourth step,

[0006] In the formula, the energy efficiency function of the sewage source heat pump unit heating system is... It is the water outlet temperature on the purified water side. Wastewater inlet temperature And the function of the load Q2, the energy efficiency function of the air source heat pump heating system. It is the water outlet temperature on the purified water side. air temperature And the function of the load Q3 it bears.

[0007] Preferably, in the eighth step, .

[0008] Preferably, the air source and sewage source coupled hot water unit is used in a district heating system.

[0009] Preferably, the district heating system is a hot water system for public buildings.

[0010] In a second aspect, the present invention provides a control system for an air-source and wastewater-source coupled hot water unit, employing any of the aforementioned air-source and wastewater-source coupled hot water unit control methods.

[0011] In a third aspect, the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform any of the aforementioned air-source and wastewater-source coupled hot water unit control methods.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention ensures the full and rational recovery of wastewater heat energy through coordinated and optimized control of air and wastewater sources, keeping the hot water unit operating at its optimal energy efficiency. Especially in district heating systems, it enables centralized energy utilization of wastewater, improving the energy efficiency of the heating system and reducing overall energy consumption. Attached Figure Description

[0013] Figure 1 This is a flowchart of the control method for a coupled air source and sewage source hot water unit according to the present invention.

[0014] Figure 2 This is a system schematic diagram of the air source and sewage source coupled hot water unit described in this invention.

[0015] Figure 3 This is a system schematic diagram of the 75kW air source and sewage source coupled hot water unit described in Embodiment 2 of the present invention.

[0016] Figure 4 This is a schematic diagram of the average energy efficiency (COP) of a heat pump using different control methods of the present invention.

[0017] Marked in the image: 1: Plate heat exchanger; 2: Wastewater source heat pump unit; 2-1-1~2-n-1: Variable frequency compressor for wastewater source; 2-1-2~2-n-2: Clean water side sleeve heat exchanger; 2-1-3~2-n-3: Electronic expansion valve for wastewater source; 2-1-4~2-n-4: Wastewater side sleeve heat exchanger; 3: Air source heat pump unit; 3-1-1~3-n-1: Air source inverter compressor; 3-1-2~3-n-2: Four-way directional valve; 3-1-3~3-n-3: Clean water side sleeve heat exchanger; 3-1-4~3-n-4: Air source electronic expansion valve; 3-1-5~3-n-5: Finned heat exchanger. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0019] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," and "outer," etc., used in the description of specific embodiments of the present invention to indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, and for enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0020] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0021] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0022] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0023] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0024] Example 1 A control method for an air-source and wastewater-source coupled hot water unit is provided for the coordinated control of such a unit. The system schematic diagram of the air-source and wastewater-source coupled hot water unit is shown below. Figure 2 As shown. The air source and sewage source coupled hot water unit adopts a three-stage gradient heating system design. The first stage heating system is a plate heat exchanger 1 preheating system, which consists of plate heat exchangers 1, where sewage and purified water complete heat exchange. The sewage temperature is determined by... Reduce to The purified water temperature is determined by... Rise to The second stage is the wastewater source heat pump group 2 heating system, which includes one or more wastewater source heat pumps connected in series. It consists of a wastewater source variable frequency compressor 2-1-1~2-n-1, a clean water side shell-and-tube heat exchanger 2-1-2~2-n-2, a wastewater source electronic expansion valve 2-1-3~2-n-3, and a wastewater side shell-and-tube heat exchanger 2-1-4~2-n-4. Wastewater from plate heat exchanger 1 enters the wastewater side shell-and-tube heat exchanger 2-1-4~2-n-4 to release heat, further reducing its temperature. Then, the water is discharged from the unit. Simultaneously, the preheated purified water undergoes secondary heating in the purified water side shell-and-tube heat exchangers 2-1-2~2-n-2, with the temperature increasing from... Rise to The third stage is the air source heat pump group 3 heating system, which includes one or more air source heat pumps connected in series. It consists of an air source inverter compressor 3-1-1~3-n-1, a four-way reversing valve 3-1-2~3-n-2, a clean water side shell-and-tube heat exchanger 3-1-3~3-n-3, an air source electronic expansion valve 3-1-4~3-n-4, and a finned heat exchanger 3-1-5~3-n-5. The purified water, after secondary heating, enters the clean water side shell-and-tube heat exchanger 3-1-3~3-n-3 of the air source heat pump for final heating. The purified water temperature is... Heat to , to be supplied to users. Figure 2 middle, For hot water pipes, It is a sewage pipe.

[0025] First, let's describe the physical representation of each parameter. The initial temperature of the purified water is... The temperature after preheating is After being heated by the sewage source heat pump unit, the temperature is After being heated by the air source heat pump unit, the temperature is The target temperature for purified water outlet is [value missing]. The initial temperature of the wastewater was... After passing through plate heat exchanger 1, the temperature decreases to After passing through the wastewater source heat pump unit, the temperature drops to The wastewater heat recovery temperature limit is ; Energy efficiency function of wastewater source heat pump heating system It is the water outlet temperature on the purified water side. Wastewater inlet temperature And the function of the load Q2. Energy efficiency function of an air source heat pump heating system. It is the water outlet temperature on the purified water side. air temperature The specific heat of water is a function of the load Q3 it bears. This indicates that the mass flow rates of wastewater and purified water are the same. express.

[0026] like Figure 1 As shown, the control method for the air source and sewage source coupled hot water unit, with the goal of optimal energy efficiency, includes the following steps: The first step is to set the target temperature on the user side of the generator unit. and wastewater heat recovery temperature limits .

[0027] The second step is to collect the mass flow rates of purified water and wastewater. Plate heat exchanger clean water side outlet water temperature Wastewater outlet temperature of plate heat exchanger and air temperature .

[0028] The third step is to calculate the heating power of the heat pump in the hot water unit. .

[0029] Fourth step: When the energy efficiency of the wastewater source heat pump unit and the air source heat pump unit is the same, calculate the loads Q2 and Q3 they bear, and the outlet water temperature on the wastewater side of the wastewater source heat pump unit. The outlet water temperature of the wastewater source heat pump unit on the water purification side ;

[0030] Step 5: Determine if the calculated load Q2 of the wastewater source heat pump unit is greater than 0. If so, proceed to the next step; otherwise, shut down the wastewater source heat pump unit and only operate the air source heat pump unit. Set the outlet water temperature of the air source heat pump unit to the specified value. The process is now complete.

[0031] Step 6: Determine whether the calculated load Q2 borne by the wastewater source heat pump unit is greater than the total load Q borne by the heat pump. If so, proceed to the next step; otherwise, proceed directly to step 8.

[0032] Step 7: Determine the calculated wastewater outlet temperature of the wastewater source heat pump unit. Is it greater than or equal to the heat recovery temperature limit? If so, then shut down the air source heat pump unit and only turn on the wastewater source heat pump unit. The wastewater source heat pump unit outlet water temperature setpoint... If yes, the process ends; otherwise, proceed to the next step.

[0033] Step 8, due to the temperature of the sewage effluent It should not be lower than the limit. Recalculate Resolve Q2, Q3 and ; .

[0034] Step 9: Simultaneously turn on the air source heat pump unit and the wastewater source heat pump unit. The setpoint for the wastewater source heat pump unit's outlet water temperature is [value missing]. The setpoint for the outlet water temperature of the air source heat pump unit is taken as follows: The process is now complete.

[0035] This invention calculates the load borne by the wastewater source heat pump unit and the air source heat pump unit when their energy efficiencies are the same, as well as the outlet water temperature on the wastewater side of the wastewater source heat pump unit. It then determines whether the wastewater outlet temperature meets the heat recovery limit. If not, it recalculates the load borne by each heat pump unit. Based on the full recovery of wastewater heat, it rationally allocates the output of the two heat pump units to maximize energy efficiency. Specifically, when the load borne by the wastewater source heat pump is less than 0, the air source heat pump is controlled to bear all the load; when the load borne by the wastewater source heat pump is greater than the total load borne by the hot water unit heat pumps, the wastewater source heat pump is controlled to bear all the load. Through the coordinated optimization control of the air source and wastewater sources, it ensures the full and rational recovery of wastewater heat energy in the district heating system, keeping the hot water unit operating at optimal energy efficiency.

[0036] This invention ensures the full and rational recovery of wastewater heat energy through coordinated and optimized control of air and wastewater sources, keeping the hot water unit operating at its optimal energy efficiency. Especially in district heating systems, it enables centralized energy utilization of wastewater, improving the energy efficiency of the heating system and reducing overall energy consumption.

[0037] Example 2 Based on Example 1, taking a dual-heat-source hot water unit with a rated heating capacity of 75kW as an example, the system schematic diagram is as follows: Figure 3 As shown, the sewage source heat pump group heating system has two sewage source heat pumps connected in series, and the air source heat pump group heating system has two air source heat pumps connected in series. For hot water pipes, This is a sewage pipe. The initial temperature of the purified water is... The temperature after preheating is The initial temperature of the wastewater was After passing through plate heat exchanger 1, the temperature decreases to Energy efficiency of wastewater source heat pump heating system Energy efficiency of air source heat pump heating system Ambient temperature Specific heat of water Wastewater and purified water mass flow rates The target temperature for purified water outlet is [value missing]. The limit for heat recovery of wastewater temperature is The specific control process is as follows.

[0038] The first step is to set the target temperature on the user side of the generator unit. Wastewater heat recovery temperature limit ; The second step is to collect the mass flow rates of purified water and wastewater. Plate heat exchanger clean water side outlet water temperature Wastewater outlet temperature of plate heat exchanger and air temperature ; The third step is to calculate the heating power of the heat pump in the hot water unit. ; The fourth step is to solve the problem using the following formula. This involves determining the loads Q2 and Q3 borne by the wastewater source heat pump unit and the air source heat pump unit, respectively, when their energy efficiencies are the same, and the outlet water temperature on the wastewater side of the wastewater source heat pump unit. The outlet water temperature on the purified water side .

[0039]

[0040] Seek

[0041] Fifth, the wastewater source heat pump unit assumes a load Q2 greater than 0, proceed to the next step.

[0042] Step 6: If the load Q2 borne by the wastewater source heat pump unit is less than the total load Q borne by the heat pump, proceed directly to step 8.

[0043] Step 8: Recalculate and re-obtain

[0044] Step 9: Simultaneously turn on the air source heat pump unit and the wastewater source heat pump unit. The setpoint for the wastewater source heat pump unit's outlet water temperature is [value missing]. The setpoint for the outlet water temperature of the air source heat pump unit is taken as follows: .

[0045] Under this operating condition, using the control method of this invention, the average COP of the unit's heat pump is approximately 5.83, the average COP using an air-source heat pump unit is 5.34, and the average COP using a wastewater-source heat pump unit is 4.13. Figure 4 As shown. Compared with the control methods that prioritize air source heat pump units and wastewater source heat pump units, the control method of the present invention improves the COP of the heat pump by 9.2% and 45.7%, respectively.

[0046] Example 3 A control system for an air-source and wastewater-source coupled hot water unit, employing the air-source and wastewater-source coupled hot water unit control method as described in any of Examples 1-2.

[0047] Example 4 A computer-readable storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device on which the computer-readable storage medium is located to perform the air-source and sewage-source coupled hot water unit control method as described in Examples 1-2.

[0048] 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 scope of protection of the present invention.

Claims

1. A control method for a coupled air-source and sewage-source hot water unit, characterized in that, Includes the following steps: The first step is to set the target temperature on the user side of the generator unit. and wastewater heat recovery temperature limits ; The second step is to collect the mass flow rates of purified water and wastewater. Plate heat exchanger clean water side outlet water temperature Wastewater outlet temperature of plate heat exchanger and air temperature ; The third step is to calculate the heating power of the heat pump in the hot water unit. In the formula c The specific heat of water; Fourth step: When the energy efficiency of the wastewater source heat pump unit and the air source heat pump unit is the same, calculate the loads Q2 and Q3 they bear, and the outlet water temperature on the wastewater side of the wastewater source heat pump unit. The outlet water temperature of the wastewater source heat pump unit on the water purification side ; Step 5: Determine if the calculated load Q2 of the wastewater source heat pump unit is greater than 0. If so, proceed to the next step; otherwise, shut down the wastewater source heat pump unit and only operate the air source heat pump unit. Set the outlet water temperature of the air source heat pump unit to the specified value. The process is complete; Step 6: Determine whether the calculated load Q2 borne by the wastewater source heat pump unit is greater than the total load Q borne by the heat pump. If so, proceed to the next step. Otherwise, proceed directly to step eight; Step 7: Determine the calculated wastewater outlet temperature of the wastewater source heat pump unit. Is it greater than or equal to the heat recovery temperature limit? If so, then shut down the air source heat pump unit and only turn on the wastewater source heat pump unit. The wastewater source heat pump unit outlet water temperature setpoint... The process is complete; Otherwise, proceed to the next step; Step 8: Recalculate Resolve Q2, Q3 and ; Step 9: Simultaneously turn on the air source heat pump unit and the wastewater source heat pump unit. The setpoint for the wastewater source heat pump unit's outlet water temperature is [value missing]. The setpoint for the outlet water temperature of the air source heat pump unit is taken as follows: The process is now complete.

2. The control method for a coupled air source and wastewater source hot water unit according to claim 1, characterized in that, In the fourth step, In the formula, the energy efficiency function of the sewage source heat pump unit heating system is... It is the water outlet temperature on the purified water side. Wastewater inlet temperature And the function of the load Q2, the energy efficiency function of the air source heat pump heating system. It is the water outlet temperature on the purified water side. air temperature And the function of the load Q3 it bears.

3. The control method for a coupled air source and wastewater source hot water unit according to claim 2, characterized in that, In the eighth step, 。 4. The control method for a coupled air source and wastewater source hot water unit according to any one of claims 1-3, characterized in that, The air source and sewage source coupled hot water unit is used in a district heating system.

5. The control method for a coupled air source and wastewater source hot water unit according to claim 4, characterized in that, The district heating system is a hot water system for public buildings.

6. A control system for a coupled air-source and wastewater-source hot water unit, characterized in that, The control method for air source and sewage source coupled hot water units as described in any one of claims 1-5 is adopted.

7. A computer-readable storage medium, characterized in that, The system includes a stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform the air-source and wastewater-source coupled hot water unit control method as described in any one of claims 1-5.

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