Heat storage optimization control method and system of air source heat pump central heating system

Abstract

The invention relates to the field of central heating systems, in particular to a heat storage optimization control method and system for an air source heat pump central heating system. The control method comprises the steps that when the system normally operates, whether the heat storage energy consumption is the lowest or not is predicted, if yes, a'heat charging mode during system operation 'is started, T1 DEG C high-temperature water is stored in the heat storage device, and when the average temperature of a temperature sensor in the heat storage device reaches T3 DEG C, the system is switched to a'system normal operation mode'; before the system is closed and re-started, an air source heat pump unit is started, a preheating mode before the system is put into operation is started, water in the system is heated to T1 DEG C from T2 DEG C and then enters a tail end unit, and when the temperature of a temperature sensor on an inlet pipe of a heat storage device reaches T4 DEG C, the system is switched to a normal system operation mode; in the normal operation mode of the system, hot water generated by the air source heat pump unit only enters the tail end unit, passes through the circulating water pump and then returns to the air source heat pump unit again to be heated.

Description

Technical Field

[0001] This invention relates to the field of centralized heating systems, and in particular to a method and system for optimizing heat storage control in an air source heat pump centralized heating system. Background Technology

[0002] Except in extremely cold regions and some frigid areas, heating is typically turned off in office buildings that are not used all day during winter nights. Due to heat exchange between pipes, equipment, and accessories and the air, the water temperature in the system drops from T1℃ (set value) to below 20℃ overnight. To ensure rapid heating when the system is put into use in the morning, and to quickly reach the set value indoors, the air source heat pump unit needs to be turned on approximately 2 hours in advance to raise the water temperature in the system from below 20℃ to T1℃.

[0003] The above approach has the following two problems: 1. Outdoor temperatures are usually low and humidity is highest in the morning, making it very easy for air source heat pump units to frost over, resulting in low unit energy efficiency; 2. The system is turned on in advance, leading to significant waste of heat from pipes, equipment, and accessories. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method and system for optimizing heat storage control in an air source heat pump centralized heating system.

[0005] In a first aspect, the present invention provides a method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system, comprising the following steps: S1: Monitor the status of air source heat pump units, circulating water pumps, terminal units, and heat storage devices; monitor the signals of electric regulating valves, temperature sensors, and electric two-position valves; monitor outdoor temperature signals; and input the system start-up and shutdown time sequence and predicted 24-hour temperature. S2: When the system is running normally, predict whether the heat storage energy consumption is at its lowest. If so, enter the "system running heat charging mode" and store T1℃ high temperature water in the heat storage device. When the average temperature of the temperature sensor in the heat storage device reaches T3℃, the system switches to the "system running normal mode".

[0006] Thermal energy consumption, unit: kW·h; The value is for heat storage, measured in kW·h, and is determined based on the volume of the heat storage device and the temperature difference. The average energy efficiency of the air source heat pump unit during the heat storage period; S3: Before the system is shut down and restarted, the air source heat pump unit is turned on and enters the "preheating mode before system operation". The air source heat pump unit heats the water in the system from T2℃ to T1℃ in one cycle and then enters the terminal unit. When the temperature sensor on the inlet pipe of the heat storage device reaches T4℃, the system switches to the "normal operation mode". T1, T2, T3 and T4 are all set values. In the "normal system operation mode", the hot water generated by the air source heat pump unit only enters the terminal unit, and after passing through the circulating water pump, it returns to the air source heat pump unit for heating.

[0007] Preferably, in the "system operation heating mode", the hot water generated by the air source heat pump unit enters both the terminal unit and the heat storage device at the same time, and the electric regulating valve on the inlet pipe of the heat storage device adjusts its opening degree according to the temperature sensor.

[0008] Preferably, in the "system operation heat charging mode", the first electric two-position valve and the second electric two-position valve are open, the third electric two-position valve is closed, and the electric regulating valve on the water inlet pipe of the heat storage device adjusts the opening degree according to the first temperature sensor.

[0009] Preferably, T2 = T3 - Δt, where Δt is the temperature drop of the water inside the heat storage device.

[0010] Preferably, in the "system preheating mode", the electric regulating valve and the second electric two-position valve are closed, while the first electric two-position valve and the third electric two-position valve are open.

[0011] Preferably, in the "system normal operation mode", the electric regulating valve, the first electric two-position valve and the third electric two-position valve are closed, and the second electric two-position valve is open.

[0012] Preferably, the formula for calculating the volume of the heat storage device is:

[0013]

[0014] In the formula: V The volume of the thermal storage device is expressed in cubic meters (m³). 3 ; t System preheating time, in seconds; v The flow rate in the system water supply main under "system preheating mode" is expressed in meters per second. 3 / s; l The total length of the supply and return water pipes for the most unfavorable loop in the system, in meters; v 1 represents the average flow velocity of the most unfavorable loop, in m / s.

[0015] Preferably, after step S3, the method further includes: S4: repeating steps S2-S3.

[0016] In a second aspect, the present invention provides a heat storage optimization control system for an air source heat pump centralized heating system, employing any of the aforementioned heat storage optimization control methods for air source heat pump centralized heating systems.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The air source heat pump centralized heating system heat storage optimization control method of the present invention, by connecting a heat storage device in parallel with a conventional system, predicts whether the heat storage energy consumption is at its lowest and enters the "system operation heat charging mode" to achieve low energy consumption heat charging, and turns on the air source heat pump unit before the system is shut down and restarted to enter the "system preheating mode" to preheat in advance, which can achieve economical and energy-saving operation of buildings that are not used all day.

[0018] Especially in centralized heating systems, it can prevent air source heat pump units from operating continuously under low temperature and high humidity conditions when the system is turned on for preheating in the morning, thus avoiding significant heat loss from pipes, equipment, and accessories. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the air source heat pump centralized heating system described in this invention.

[0020] Figure 2 This is a schematic diagram of the heat charging mode during operation of the air source heat pump centralized heating system described in this invention.

[0021] Figure 3 This is a schematic diagram of the preheating mode before operation of the air source heat pump centralized heating system described in this invention.

[0022] Figure 4 This is a schematic diagram of the normal operation mode of the air source heat pump centralized heating system described in this invention.

[0023] Figure 5 This is a flowchart of the heat storage optimization control method for the air source heat pump centralized heating system described in Embodiment 1 of the present invention.

[0024] Figure 6 This is a flowchart of the heat storage optimization control method for the air source heat pump centralized heating system described in Embodiment 2 of the present invention.

[0025] Figure 7 The figures show the load variation curves of the system unit under the conventional system and the control method of this invention.

[0026] Figure 8 The diagram shows the typical daily unit power curves of the system under conventional methods and the control method of this invention.

[0027] Marked in the image: 1: Air source heat pump unit; 2: Circulating water pump; 3: Terminal units; 4: Heat storage device; 5: Electric regulating valve; 61: First temperature sensor; 62: Second temperature sensor; 63: Third temperature sensor; 71: First electric two-position valve; 72: Second electric two-position valve; 73: Third electric two-position valve. Detailed Implementation

[0028] 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.

[0029] 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.

[0030] 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 0.2mm-1mm, preferably within 0.2mm-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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] Example 1 A method for optimizing heat storage control in an air source heat pump centralized heating system, applicable to an air source heat pump centralized heating system, such as... Figure 1As shown, the air source heat pump centralized heating system connects a heat storage device 4 in parallel with a conventional system. It includes an air source heat pump unit 1, a circulating water pump 2, terminal units 3, a heat storage device 4, an electric regulating valve 5, a first temperature sensor 61, a second temperature sensor 62, a third temperature sensor 63, a first electric two-position valve 71, a second electric two-position valve 72, and a third electric two-position valve 73. Other components for normal system operation, such as a constant pressure water supply device, a water treatment device, and other sensors, are also included. Figure 1 It is no longer reflected in the text.

[0035] Among them, multiple air source heat pump units 1, multiple circulating water pumps 2, and multiple terminal units 3 are connected in parallel.

[0036] The electric regulating valve 5 is installed on the inlet pipeline of the heat storage device 4 in the heat charging mode. It is used to regulate the flow rate into the heat storage device 4 and ensure the flow rate into the terminal unit 3 so as not to affect its heating effect.

[0037] The first temperature sensor 61 is used to measure the temperature of the mixed water entering the terminal unit 3 and the heat storage device 4. Since the water in the heat storage tank is low temperature before charging, if the temperature of the mixed water measured by the first temperature sensor 61 is too low, it means that the flow rate entering the heat storage device 4 is too large and the flow rate entering the terminal unit 3 is too small. In order to avoid the aforementioned situation from causing the heating effect of the terminal unit 3 to decrease, the flow rate entering the heat storage device 4 needs to be adjusted.

[0038] The second temperature sensor 62 is used to measure the average temperature of the heat storage device 4. When the average temperature of the heat storage device 4 reaches the set value, it means that the heat storage device 4 has completed the heat charging. In the heat charging mode, the electric regulating valve 5 on the inlet pipeline of the heat storage device 4 is closed to stop heat storage.

[0039] The third temperature sensor 63 is used to measure the temperature at the inlet of the heat storage device 4 in the preheating mode, in order to determine whether the low-temperature water in the system equipment, pipes, etc. has been completely replaced. When the third temperature sensor 63 reaches the set value, it means that it has been completely replaced, the water no longer passes through the heat storage device 4, and the water valve on the branch connected to the heat storage device 4 is closed.

[0040] like Figure 5 As shown, the heat storage optimization control method for the air source heat pump centralized heating system includes the following steps: S1: Monitor the status of air source heat pump unit 1, circulating water pump 2, terminal unit 3, and heat storage device 4; monitor the signals of electric regulating valve 5, first temperature sensor 61, second temperature sensor 62, third temperature sensor 63, first electric two-position valve 71, second electric two-position valve 72, and third electric two-position valve 73; monitor the outdoor temperature signal; and input the system start-up and shutdown time sequence and the predicted 24-hour temperature. S2: During normal system operation, predict whether the thermal energy consumption is at its minimum. If so, enter the "system operation charging mode" and store high-temperature water at T1℃ in the thermal storage device 4. When the average temperature of the temperature sensor in the thermal storage device 4 reaches T3℃, the system switches to the "normal system operation mode". Specifically: When the system is running, it stores a certain amount of high-temperature water at T1℃ in the heat storage device 4 when the heat storage energy consumption is at its lowest. The system principle is as follows: Figure 2 As shown, hot water generated by multiple air source heat pump units 1 simultaneously enters the terminal unit 3 and the heat storage device 4. The first electric two-position valve 71 and the second electric two-position valve 72 are opened, and the third electric two-position valve 73 is closed. The electric regulating valve 5 on the inlet pipe of the heat storage device 4 adjusts its opening according to the first temperature sensor 61. Considering that the internal temperature distribution of the heat storage device 4 is difficult to achieve completely uniformity, when the average temperature of the second temperature sensor 62 inside the heat storage device 4 reaches T3℃, the system switches to the "normal system operation mode".

[0041] The formula for predicting thermal energy consumption is as follows:

[0042] Thermal energy consumption, unit: kW·h; The value is for heat storage, measured in kW·h, and is determined based on the volume of the heat storage device and the temperature difference. This represents the average energy efficiency of the air source heat pump unit during the heat storage period.

[0043] In the optional scheme, the formula for calculating the volume of the thermal storage device can be:

[0044]

[0045] In the formula: V The volume of the thermal storage device is expressed in cubic meters (m³). 3 ; t System preheating time, in seconds; v The flow rate in the system water supply main under "system preheating mode" is expressed in meters per second. 3 / s; l The total length of the supply and return water pipes for the most unfavorable loop in the system, in meters; v 1 represents the average flow velocity of the most unfavorable loop, in m / s.

[0046] In an alternative solution, the volume of the thermal storage device can also be simplified to 1.5 times the system water volume.

[0047] S3: Before restarting the system after shutdown, turn on air source heat pump unit 1 and enter the "preheating mode before system operation". Air source heat pump unit 1 heats the water in the system in one cycle, raising it from T2℃ to T1℃ before it enters the terminal unit. When the temperature of the third temperature sensor 63 on the inlet pipe of the heat storage device 4 reaches T4℃, the system switches to the "normal operation mode". T1, T2, T3, and T4 are all set values. Specifically: Optionally, the heating unit can be turned on approximately 30 minutes before the system is officially put into operation. The low-temperature water in the pipes, equipment, and accessories is quickly replaced by the high-temperature water in the heat storage device 4. The air source heat pump unit 1 can heat the water in the system from T2℃ to T1℃ in one cycle. The system schematic diagram is shown below. Figure 3 As shown. Considering the heat exchange between the heat storage device 4 and the surrounding air, after a period of time, the water temperature inside the heat storage device 4 will drop by Δt, approximately 2℃. The hot water at (T3-2)℃ inside the heat storage device 4 is pumped by the circulating water pump 2 into the air source heat pump unit 1, where it is raised to T1℃ before entering the terminal unit 3. The electric regulating valve 5 and the second electric double-position valve 72 are closed, while the first electric double-position valve 71 and the third electric double-position valve 73 are opened. When the temperature of the third temperature sensor 63 on the inlet pipe of the heat storage device 4 reaches T4℃, the system switches to the "normal system operation mode".

[0048] In the "normal system operation mode", the hot water generated by the air source heat pump unit 1 only enters the terminal unit 3, and the circulating water enters the air source heat pump unit 1 for heating after passing through the circulating water pump 2.

[0049] The schematic diagram of the system during normal operation is as follows: Figure 4 As shown, the hot water generated by the air source heat pump unit 1 only enters the terminal unit 3, and after passing through the circulating water pump 2, it returns to the air source heat pump unit 1 for heating. The electric regulating valve 5, the first electric double-position valve 71 and the third electric double-position valve 73 are closed, and the second electric double-position valve 72 is opened.

[0050] In an optional implementation, when the predicted thermal energy consumption is at its lowest, the system reverts to the "system running heat charging mode"; before the system is shut down and restarted, it reverts to the "system preheating mode" and so on.

[0051] Parameter description: T1: System design water supply temperature, unit: °C; T2: System design return water temperature, unit: °C; T3: Average temperature of heat stored in the heat storage device, unit: °C; T4: The temperature at which the water in the system is completely replaced, in °C.

[0052] The average temperature T3 of the heat storage device 4 can vary according to the heating design temperatures T1 and T2. The heat storage device 4 can be a hot water storage tank or other structures and phase change materials.

[0053] The air source heat pump centralized heating system heat storage optimization control method of the present invention, by connecting a heat storage device 4 in parallel with a conventional system, predicts whether the heat storage energy consumption is at its lowest and enters the "system operation heat charging mode" to achieve low energy consumption heat charging, and turns on the air source heat pump unit before the system is shut down and restarted to enter the "system preheating mode" to preheat in advance, which can achieve economic and energy-saving operation of buildings that are not used all day.

[0054] Especially in centralized heating systems, it can prevent air source heat pump units from operating continuously under low temperature and high humidity conditions when the system is turned on for preheating in the morning, thus avoiding significant heat loss from pipes, equipment, and accessories.

[0055] Example 2 Based on Example 1, taking an office building in Chengdu as an example, the design parameters for a typical air source heat pump heating system are as follows: T1=45℃, T2=40℃, T3=42℃, T4=38℃, τ1=9:00, τ2=7:00. Its control logic diagram is as follows: Figure 6 As shown.

[0056] In the "system operation heating mode", the hot water generated by the air source heat pump unit 1 simultaneously enters the terminal unit 3 and the heat storage device 4. The first electric two-position valve 71 and the second electric two-position valve 72 are open, and the third electric two-position valve 73 is closed. The electric regulating valve 5 on the inlet pipe of the heat storage device 4 adjusts its opening according to the first temperature sensor 61. For example, it first determines whether the temperature of the first temperature sensor 61 is between 38 and 40°C (set value). If so, it maintains the opening of the electric regulating valve 5. If not, it then determines whether the temperature of the first temperature sensor 61 is less than 38°C (set value). If so, it reduces the opening of the electric regulating valve 5. If not, it increases the opening of the electric regulating valve 5.

[0057] In the "preheating mode before system operation" mode, the hot water at (T3-2)℃ in the heat storage device 4 is pumped by the circulating water pump 2 into the air source heat pump unit 1 and then raised to T1℃ before entering the terminal unit 3. The electric regulating valve 5 and the second electric double-position valve 72 are closed, while the first electric double-position valve 71 and the third electric double-position valve 73 are open. First, it is determined whether the temperature of the third temperature sensor 63 has reached 38℃ (set value). If so, the system switches to the "normal system operation mode". If not, it is further determined whether the system operation time is greater than 60 minutes (set value). If so, the system switches to the "normal system operation mode". If not, the electric regulating valve 5 and the second electric double-position valve 72 remain closed, while the first electric double-position valve 71 and the third electric double-position valve 73 remain open.

[0058] The load change curves of the conventional system and the system using this method are as follows: Figure 7 As shown, the corresponding unit power is as follows Figure 8 As shown, the typical daily energy consumption of an air-source heat pump centralized heating system controlled using this method is approximately 90% of that of a conventional system.

[0059] Example 3 A heat storage optimization control system for an air source heat pump centralized heating system, employing the heat storage optimization control method for an air source heat pump centralized heating system as described in any of Examples 1-2.

[0060] 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 within the protection scope of the present invention.

Claims

1. A method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system, characterized in that, Includes the following steps: S1: Monitor the status of air source heat pump units, circulating water pumps, terminal units, and heat storage devices; monitor the signals of electric regulating valves, temperature sensors, and electric two-position valves; monitor outdoor temperature signals; and input the system start-up and shutdown time sequence and predicted 24-hour temperature. S2: When the system is running normally, predict whether the heat storage energy consumption is at its lowest. If so, enter the "system running heat charging mode" and store T1℃ high temperature water in the heat storage device. When the average temperature of the temperature sensor in the heat storage device reaches T3℃, the system switches to the "system running normal mode". Thermal energy consumption, unit: kW·h; The value is for heat storage, measured in kW·h, and is determined based on the volume of the heat storage device and the temperature difference. The average energy efficiency of the air source heat pump unit during the heat storage period; S3: Before the system is shut down and restarted, the air source heat pump unit is turned on and enters the "preheating mode before system operation". The air source heat pump unit heats the water in the system from T2℃ to T1℃ in one cycle and then enters the terminal unit. When the temperature sensor on the inlet pipe of the heat storage device reaches T4℃, the system switches to the "normal operation mode". T1, T2, T3 and T4 are all set values. In the "normal system operation mode", the hot water generated by the air source heat pump unit only enters the terminal unit, and after passing through the circulating water pump, it returns to the air source heat pump unit for heating.

2. The method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system according to claim 1, characterized in that, In the "system operation heating mode", the hot water generated by the air source heat pump unit enters both the terminal unit and the heat storage device. The electric regulating valve on the inlet pipe of the heat storage device adjusts its opening degree according to the temperature sensor.

3. The method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system according to claim 2, characterized in that, In the "system operation heat charging mode", the first electric two-position valve and the second electric two-position valve are open, the third electric two-position valve is closed, and the electric regulating valve on the water inlet pipe of the heat storage device adjusts the opening degree according to the first temperature sensor.

4. The method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system according to claim 1, characterized in that, T2 = T3 - Δt, where Δt is the temperature drop of the water inside the heat storage device.

5. The method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system according to claim 4, characterized in that, In the "preheating mode before system operation" mode, the electric regulating valve and the second electric two-position valve are closed, while the first electric two-position valve and the third electric two-position valve are open.

6. The method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system according to claim 1, characterized in that, In the "normal system operation mode", the electric regulating valve, the first electric two-position valve and the third electric two-position valve are closed, and the second electric two-position valve is open.

7. The method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system according to claim 1, characterized in that, The formula for calculating the volume of a thermal storage device is: In the formula: V The volume of the thermal storage device is expressed in cubic meters (m³). 3 ; t System preheating time, in seconds; v The flow rate in the system water supply main under "system preheating mode" is expressed in meters per second. 3 / s; l The total length of the supply and return water pipes for the most unfavorable loop in the system, in meters; v 1 represents the average flow velocity of the most unfavorable loop, in m / s.

8. The method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system according to any one of claims 1-7, characterized in that, Following S3, the following is also included: S4: Repeat steps S2-S3.

9. A heat storage optimization control system for an air source heat pump centralized heating system, characterized in that, The heat storage optimization control method for air source heat pump centralized heating system as described in any one of claims 1-8 is adopted.

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