Air source heat pump central heating system heat storage optimization control method and system

Abstract

The present application relates to the field of central heating system, and particularly relates to a kind of air source heat pump central heating system heat storage optimization control method and system.Control method includes: when system normal operation, whether the minimum energy consumption of heat storage is predicted, if yes, then enter " system running heat charging mode", store T1 ℃ high temperature water in heat storage device, when the average temperature of temperature sensor in heat storage device reaches T3 ℃, system switches to " system normal operation mode "; before system is closed and re-enabled, open air source heat pump unit, enter " system before input operation preheating mode", the water in system is heated from T2 ℃ to T1 ℃ after entering terminal unit, when the temperature of temperature sensor on the inlet pipe of heat storage device reaches T4 ℃, system switches to " system normal operation mode "; under " system normal operation mode", hot water produced by air source heat pump unit only enters terminal unit, and after circulating water pump, it is heated again in air source heat pump unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of central heating system, in particular to a heat storage optimization control method and system of air source heat pump central heating system. BACKGROUND

[0002] Except for severe cold and some cold regions, non-full-time use such as general office buildings usually stop heating at night in winter. Due to the heat exchange between pipes, equipment and accessories and air, the temperature of water in the system is reduced from T1℃ (set value) to below 20℃ after a night. In order to ensure that the indoor temperature can quickly reach the set value when it is put into use in the morning, the air source heat pump unit needs to be started about 2h in advance to raise the water temperature in the system from below 20℃ to T1℃.

[0003] The above method has the following two problems: 1. The outdoor temperature is low and the humidity is highest in the morning, so the air source heat pump unit is easy to frost when using air source heat pump unit, and the unit has low energy efficiency; 2. The system is started in advance, and there is a great waste of heat loss of pipes, equipment and accessories. SUMMARY

[0004] The present application aims to overcome the deficiencies in the prior art and provide a heat storage optimization control method and system of air source heat pump central heating system.

[0005] In a first aspect, the present application provides a heat storage optimization control method of air source heat pump central heating system, comprising the following steps:

[0006] S1: monitoring the state of the air source heat pump unit, the circulating water pump, the terminal unit and the heat storage device, monitoring the signals of the electric regulating valve, the temperature sensor and the electric two-position valve, monitoring the outdoor temperature signal, and inputting the system start-stop time sequence and the predicted 24h temperature;

[0007] S2: when the system is normally running, predicting whether the heat storage energy consumption is the lowest, if yes, entering the "heat charging mode when the system is running", storing T1℃ high temperature water in the heat storage device, and when the average temperature of the temperature sensor in the heat storage device reaches T3℃, the system switches to the "normal system running mode";

[0008]

[0009] The heat storage energy consumption is in units of kW·h;

[0010] The heat storage amount is in units of kW·h, which is determined according to the volume and temperature difference of the heat storage device;

[0011] The average energy efficiency of the air source heat pump unit during the heat storage period;

[0012] S3: starting the air source heat pump unit before the system is reactivated, entering the "preheating mode before the system is put into operation", the air source heat pump unit is heated once, the water in the system is heated from T2℃ to T1℃, 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", wherein T1, T2, T3 and T4 are set values;

[0013] In the "normal operation mode", the hot water generated by the air source heat pump unit only enters the terminal unit and is heated again by the circulating water pump.

[0014] Preferably, in the "heat charging mode during system operation", the hot water generated by the air source heat pump unit enters the terminal unit and the heat storage device at the same time, and the electric regulating valve on the water inlet pipe of the heat storage device adjusts the opening degree according to the temperature sensor.

[0015] Preferably, in the "heat charging mode during system operation", the first electric two-position valve and the second electric two-position valve are opened, 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.

[0016] Preferably, T2 = T3 - Δt, and Δt is the temperature drop of the water inside the heat storage device.

[0017] Preferably, in the "preheating mode before the system is put into operation", the electric regulating valve and the second electric two-position valve are closed, and the first electric two-position valve and the third electric two-position valve are opened.

[0018] Preferably, in the "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 opened.

[0019] Preferably, the calculation formula of the volume of the heat storage device is:

[0020]

[0021]

[0022] In the formula:

[0023] V V is the volume of the heat storage device, unit: m 3 ;

[0024] t T is the preheating time of the system, unit: s;

[0025] v V is the flow rate of the system water supply main in the "preheating mode during system operation", unit: m 3 / s;

[0026] l Total length of water supply and return pipe for the most unfavorable loop of the system, unit: m;

[0027] v 1 is the average flow velocity of the most unfavorable loop, unit: m / s.

[0028] Preferably, after S3, the method further comprises: S4: repeating steps S2-S3.

[0029] In a second aspect, the present application provides a heat storage optimization control system for an air source heat pump central heating system, which adopts any of the heat storage optimization control methods for the air source heat pump central heating system.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] The heat storage optimization control method for the air source heat pump central heating system of the present application can realize low-energy charging by predicting whether the heat storage energy consumption is the lowest and entering the "system running heat charging mode", starting the air source heat pump unit before the system is closed and restarted, and entering the "system preheating mode before system operation", so that the economic and energy-saving operation of the building used in a non-full time period can be realized.

[0032] In particular, in the central heating system, the air source heat pump unit can be prevented from continuously operating in low-temperature and high-humidity conditions when the system is started and preheated in the morning, and large heat loss of pipes, equipment and accessories can be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The figure is a schematic diagram of the air source heat pump central heating system of the present application.

[0034] Figure 2 The figure is a schematic diagram of the "system running heat charging mode" of the air source heat pump central heating system of the present application.

[0035] Figure 3 The figure is a schematic diagram of the "system preheating mode before system operation" of the air source heat pump central heating system of the present application.

[0036] Figure 4 The figure is a schematic diagram of the "normal operation mode" of the air source heat pump central heating system of the present application.

[0037] Figure 5 The figure is a flow chart of the heat storage optimization control method for the air source heat pump central heating system of the present application.

[0038] Figure 6 The figure is a flow chart of the heat storage optimization control method for the air source heat pump central heating system of the present application.

[0039] Figure 7 The system unit load variation curve for the conventional system and the system under the control method of the present application.

[0040] Figure 8 The typical daily system unit power curve chart for the conventional method and the control method of the present application.

[0041] Markings in the figure:

[0042] 1: Air source heat pump unit;

[0043] 2: Circulating water pump;

[0044] 3: Terminal unit;

[0045] 4: Heat storage device;

[0046] 5: Electric regulating valve;

[0047] 61: First temperature sensor;

[0048] 62: Second temperature sensor;

[0049] 63: Third temperature sensor;

[0050] 71: First electric two-position valve;

[0051] 72: Second electric two-position valve;

[0052] 73: Third electric two-position valve. DETAILED DESCRIPTION

[0053] The present application will be further described in conjunction with specific embodiments. However, it should not be understood that the scope of the above-mentioned subject matter of the present application is limited to the following embodiments, and any technology realized based on the content of the present application falls within the scope of the present application.

[0054] In the description of the specific embodiments of the present application, the orientation or position relationship terms such as "up", "down", "left", "right", "center", "inner", "outer" and the like appear without special indication, which are expressed based on the orientation or position relationship shown in the drawings, or the orientation or position relationship used when the product / equipment / device of the present application is placed. These orientation or position relationship terms are only used to facilitate the description of the present application scheme or simplify the description in the specific embodiments, to facilitate the quick understanding of the scheme by the technicians, and should not be understood as indicating or implying that the specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore should not be understood as a limitation on the present application.

[0055] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel", "coaxial" and the like appear in the terms, it does not mean that the corresponding device / component / element is absolutely horizontal or vertical or overhanging or parallel or coaxial, but can be slightly inclined or deviated, as long as it does not affect the normal function of the related component. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", not that the structure must be completely horizontal, but can be slightly inclined; "coaxial" means that two components are coaxially arranged as much as possible, and move in a coaxial or approximately coaxial manner when the relative position changes. Alternatively, it can be simplified to understand that the corresponding device / component / element is arranged in the "horizontal", "vertical", "overhanging", "parallel", "coaxial" direction, which can have an error / bias of ±10% relative to the corresponding direction, more preferably an error / bias of ±8%, more preferably an error / bias of ±6%, more preferably an error / bias of ±5%, more preferably an error / bias of ±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 / bias range, it can still achieve its role in the present application.

[0056] In addition, the terms "first", "second", "third" and the like in the terms are only used to distinguish the same or similar components for description, and should not be understood as emphasizing or implying the relative importance of the specific components.

[0057] In addition, in the description of the embodiments of the present application, "several", "a plurality of", "several" represent at least 2. It can be 2, 3, 4, 5, 6, 7, 8, 9, etc. Any case, it can even be more than 9.

[0058] In addition, in the description of the technical solutions of the present application, unless otherwise specified / limited / limited, the terms "set", "install", "connect", "connect", "set", "lay", "arrange" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, which can be welding, riveting, bolting, screwing and other commonly used connection means in the art. The connection can be mechanical connection, electrical connection or communication connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the communication between two elements.

[0059] Embodiment 1

[0060] A heat storage optimization control method of an air source heat pump central heating system is suitable for an air source heat pump central 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.

[0061] Among them, multiple air source heat pump units 1, multiple circulating water pumps 2, and multiple terminal units 3 are connected in parallel.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] like Figure 5 As shown, the heat storage optimization control method for the air source heat pump centralized heating system includes the following steps:

[0067] 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.

[0068] S2: When the system is running normally, it is predicted whether the heat storage energy consumption is the lowest. If yes, it enters the "system running heat charging mode", stores T1℃ high temperature water in the heat storage device 4, and when the average temperature of the temperature sensor in the heat storage device 4 reaches T3℃, the system switches to the "system normal running mode". Specifically:

[0069] The system stores a certain amount of T1℃ high temperature water in the heat storage device 4 when the heat storage energy consumption is the lowest, and the system principle is as shown in Figure 2 The hot water generated by the plurality of air source heat pump units 1 enters the terminal unit 3 and the heat storage device 4 at the same time, 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 water inlet pipe of the heat storage device 4 is adjusted according to the opening degree of the first temperature sensor 61. Considering that the internal temperature distribution of the heat storage device 4 is difficult to reach complete uniformity, when the average temperature of the second temperature sensor 62 in the heat storage device 4 reaches T3℃, the system switches to the "system normal running mode".

[0070] The calculation formula of predicting the heat storage energy consumption is:

[0071]

[0072] The heat storage energy consumption is kW·h;

[0073] The heat storage amount is kW·h, which is determined according to the volume of the heat storage device and the temperature difference;

[0074] The average energy efficiency of the air source heat pump unit during the heat storage period.

[0075] In an optional scheme, the calculation formula of the volume of the heat storage device can be:

[0076]

[0077]

[0078] In the formula:

[0079] V The volume of the heat storage device is m 3 ;

[0080] t The system preheating time is s;

[0081] v The flow rate of the system water supply main pipe in the "system running preheating mode" is m 3 / s;

[0082] lTotal length of water supply and return pipe for the most unfavorable loop of the system, unit: m;

[0083] v 1 is the average flow rate of the most unfavorable loop, unit: m / s.

[0084] In an optional solution, the volume of the heat storage device can also be simplified to 1.5 times the water volume of the system.

[0085] S3: Start the air source heat pump unit 1 before the system is closed and re-enabled, enter the "preheating mode before the system is put into operation", and the air source heat pump unit 1 is heated once to heat the water in the system from T2℃ to T1℃ and then enter 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" of the system. T1, T2, T3, and T4 are all set values. Specifically:

[0086] Optionally, start the heating unit about 30 minutes before the system is formally put into operation. The low-temperature water in the pipeline, equipment, and accessories is quickly replaced by the high-temperature water in the heat storage device 4. The air source heat pump unit 1 is heated once to heat the water in the system from T2℃ to T1℃. The system schematic diagram is shown in Figure 3 Taking into account 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, which is about 2℃. The (T3-2)℃ hot water in the heat storage device 4 enters the air source heat pump unit 1 after being circulated by the circulating water pump 2, and is raised to T1℃ before entering the terminal unit 3. The electric regulating valve 5 and the second electric two-position valve 72 are closed, and the first electric two-position valve 71 and the third electric two-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 operation mode" of the system.

[0087] In the "normal operation mode" of the system, 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 again after being circulated by the circulating water pump 2.

[0088] The schematic diagram of the system in normal operation is shown in Figure 4 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 again after being circulated by the circulating water pump 2. The electric regulating valve 5, the first electric two-position valve 71, and the third electric two-position valve 73 are closed, and the second electric two-position valve 72 is opened.

[0089] In an optional embodiment, when the predicted heat storage energy consumption is the lowest, the system returns to the "heat charging mode during system operation"; before the system is closed and re-enabled, it returns to the "preheating mode before the system is put into operation", and so on.

[0090] Parameter description:

[0091] T1: system design supply water temperature, unit: ℃;

[0092] T2: system design return water temperature, unit: ℃;

[0093] T3: average temperature of heat storage device, unit: ℃;

[0094] T4: determination temperature of water replacement in the system, unit: ℃.

[0095] The average temperature T3 of heat storage of the heat storage device 4 can be changed according to the heat supply design temperature T1 and T2, and the heat storage device 4 can adopt a heat storage water tank or other structures and phase change materials.

[0096] The heat storage optimization control method of the air source heat pump central heating system provided by the application can realize low energy consumption heat charging by predicting whether the heat storage energy consumption is the lowest and entering the "system running heat charging mode", starting the air source heat pump unit before the system is closed and restarted and entering the "system preheating mode before system operation", and preheating in advance, so that the economic and energy-saving operation of the building used in a non-full time period can be realized.

[0097] In particular, in the central heating system, the air source heat pump unit can be prevented from continuously operating in low temperature and high humidity conditions when the system is started and preheated in the morning, and large heat loss of pipes, equipment and accessories can be avoided.

[0098] Example 2

[0099] Based on example 1, taking an office building in Chengdu as an example, the typical air source heat pump heating system design parameter values are as follows: T1=45℃, T2=40℃, T3=42℃, T4=38℃, τ1=9:00, τ2=7:00. The control logic diagram is as shown in Figure 6 .

[0100] In the "system running heat charging mode", the hot water generated by the air source heat pump unit 1 enters the terminal unit 3 and the heat storage device 4 at the same time, the first electric double-position valve 71 and the second electric double-position valve 72 are opened, the third electric double-position valve 73 is closed, and the electric regulating valve 5 on the water inlet pipe of the heat storage device 4 is adjusted according to the first temperature sensor 61. For example, first determine whether the temperature of the first temperature sensor 61 is 38-40℃ (set value), if yes, keep the opening degree of the electric regulating valve 5, if no, then determine whether the temperature of the first temperature sensor 61 is <38℃ (set value), if yes, reduce the opening degree of the electric regulating valve 5, if no, increase the opening degree of the electric regulating valve 5.

[0101] In the preheating mode, the hot water in the heat storage device 4 (T3-2) °C is lifted to T1 °C by the air source heat pump unit 1 and then enters the terminal unit 3. The electric regulating valve 5 and the second electric two-position valve 72 are closed, and the first electric two-position valve 71 and the third electric two-position valve 73 are opened. First, it is determined whether the temperature of the third temperature sensor 63 reaches 38 °C (set value). If yes, the system switches to the normal operation mode. If no, it is further determined whether the system has been running for more than 60 min (set value). If yes, the system switches to the normal operation mode. If no, the electric regulating valve 5 and the second electric two-position valve 72 remain closed, and the first electric two-position valve 71 and the third electric two-position valve 73 remain opened.

[0102] The conventional system and the system unit load variation curve controlled by the method are shown in FIG. 2, and the corresponding unit power is shown in FIG. 3. Figure 7 Figure 8 The air source heat pump central heating system controlled by the method has a typical daily energy consumption of about 90% of that of the conventional system.

[0103] Embodiment 3

[0104] An air source heat pump central heating system heat storage optimization control system, which adopts the air source heat pump central heating system heat storage optimization control method as described in any one of embodiments 1-2.

[0105] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.​

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, expressed 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 "system operation heating mode", the hot water generated by the air source heat pump unit enters the terminal unit and the heat storage device at the same time. The electric regulating valve on the inlet pipe of the heat storage device adjusts the opening according to the temperature sensor. The first electric double-position valve and the second electric double-position valve are opened, and the third electric double-position valve is closed. The first temperature sensor measures the temperature of the mixed water after entering the terminal unit and the heat storage device. The electric regulating valve on the inlet pipe of the heat storage device adjusts the opening according to the first temperature sensor. In the "system preheating mode", the electric regulating valve and the second electric two-position valve are closed, and the first electric two-position valve and the third electric two-position valve are open. 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. 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.

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

3. 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.

4. The method for optimizing and controlling the heat storage of an air-source heat pump centralized heating system according to any one of claims 1-3, characterized in that, Following S3, the following is also included: S4: Repeat steps S2-S3.

5. 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 1-4 is adopted.

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