Method for controlling domestic water temperature, control system, wall-mounted boiler and storage medium

Abstract

The present invention discloses a method for controlling the temperature of domestic water in a wall-mounted boiler, comprising the following steps: respectively detecting the inlet water temperature, the actual outlet water temperature and the water flow rate of the wall-mounted boiler; taking the first temperature difference of the actual outlet water temperature relative to the preset outlet water temperature as the input quantity, obtaining the calculated temperature difference as the output quantity through a PID control algorithm, and obtaining the first required heat quantity by multiplying the calculated temperature difference and the water flow rate; when the water flow rate changes with the water flow rate difference, obtaining the second required heat quantity by multiplying the second temperature difference of the inlet water temperature relative to the preset outlet water temperature and the water flow rate difference; calculating the total required heat quantity from the first required heat quantity and the second required heat quantity, and adjusting the amount of gas supplied to the burner of the wall-mounted boiler so that after the actual outlet water temperature reaches the preset outlet water temperature for the first time, the first temperature difference is always between the overheating threshold value and the overshoot threshold value. The present invention also discloses a corresponding control system, a wall-mounted boiler and a computer-readable storage medium. The user experience can be improved.

Description

Technical Field

[0001] The present invention relates to a method for controlling the temperature of domestic water in a wall-mounted boiler, a corresponding control system and a wall-mounted boiler comprising such a control system. In addition, the present invention also relates to a corresponding computer-readable storage medium. Background Art

[0002] A wall-mounted boiler is also known as a gas-fired heating water heater. The wall-mounted boiler generates heat by burning gas and transfers the heat to water via a heat exchanger. Generally, a wall-mounted boiler has a heating function, i.e., a function for heating a building or room, and a hot water function, i.e., a function for heating domestic water.

[0003] In recent years, wall-mounted boilers have attracted more and more attention due to their advantages of energy saving and significantly improving the quality of life. Despite this, there is still room for improvement in existing wall-mounted boilers, especially in the temperature control of domestic water. Existing wall-mounted boilers mainly consider the time to reach the preset water outlet temperature. However, in the actual use of wall-mounted boilers, the water outlet temperature often fluctuates after turning on the faucet and before the temperature of domestic water stabilizes, which may even scald the user in severe cases. This leads to a poor user experience and reduces safety. In addition, in existing wall-mounted boilers, boundary conditions such as water inlet temperature, water flow, etc. are usually set to constant values ​​and the influence of factors such as region and season is not considered. This will also have an adverse effect on the temperature control of domestic water. Summary of the invention

[0004] Therefore, the object of the present invention is to provide an improved method for controlling the temperature of domestic water in a wall-mounted boiler. The object of the present invention is also to provide a corresponding control system, a corresponding wall-mounted boiler and a corresponding computer-readable storage medium.

[0005] According to a first aspect of the present invention, a method for controlling the temperature of domestic water in a wall-mounted boiler is provided. The method comprises the following steps:

[0006] A method for controlling the temperature of domestic water in a wall-mounted boiler (100), the method comprising the following steps:

[0007] a) Detect the water inlet temperature, actual water outlet temperature and water flow of the wall-mounted boiler respectively;

[0008] b) taking a first temperature difference between the actual outlet water temperature and the preset outlet water temperature as an input, obtaining a calculated temperature difference as an output through a PID control algorithm, and obtaining a first required heat quantity by multiplying the calculated temperature difference and the water flow rate;

[0009] c) when the water flow rate is changed by the water flow rate difference, a second required heat is obtained by multiplying a second temperature difference of the inlet water temperature relative to the preset outlet water temperature by the water flow rate difference; and

[0010] d) A total heat demand is calculated from the first heat demand and the second heat demand, and the amount of gas supplied to the burner of the wall-mounted boiler is adjusted based on the total heat demand, so that after the actual water outlet temperature reaches the preset water outlet temperature for the first time, a first temperature difference of the actual water outlet temperature relative to the preset water outlet temperature is always between the overheating threshold and the overshoot threshold.

[0011] In the framework of the present invention, "overheating threshold" is understood as the limit value of the temperature difference between the maximum actual water outlet temperature and the preset water outlet temperature after the actual water outlet temperature reaches the preset water outlet temperature for the first time, and "overshoot threshold" is understood as the limit value of the temperature difference between the minimum actual water outlet temperature and the preset water outlet temperature after the actual water outlet temperature reaches the preset water outlet temperature for the first time.

[0012] Compared with the prior art, by setting the overheating threshold and the overshoot threshold, the range of the actual outlet water temperature can be limited and the phenomenon of alternating hot and cold water can be avoided. With the method according to the present invention, the preset outlet water temperature can be reached more quickly when the user changes the hot water demand, the temperature of the domestic water in the wall-mounted boiler can be controlled more accurately, and the user experience can be improved.

[0013] According to an exemplary embodiment of the present invention, the PID control algorithm is a fuzzy PID control algorithm or a feedforward PID control algorithm.

[0014] According to an exemplary embodiment of the present invention, the coefficients of the PID control algorithm are obtained through experiments and / or empirical data and are pre-stored in the controller of the wall-mounted boiler.

[0015] According to an exemplary embodiment of the present invention, different coefficients of the PID control algorithm are selected accordingly for different operation modes of the wall-mounted boiler, wherein the operation mode is selected from the following modes: cooling operation mode, heating mode, and preheating mode.

[0016] According to an exemplary embodiment of the present invention, the overheat threshold and the overshoot threshold are respectively ±1.5°C.

[0017] The second aspect of the present invention proposes a control system for controlling the temperature of domestic water in a wall-mounted boiler, the control system having a controller and an inlet water temperature sensor, an outlet water temperature sensor, and a water flow sensor connected to the controller, the control system being configured to implement the method according to the present invention.

[0018] According to an exemplary embodiment of the present invention, the control system further comprises an input device configured to input a preset outlet water temperature.

[0019] The third aspect of the present invention proposes a wall-mounted boiler, which includes a water supply pipeline, a drainage pipeline, a heat exchanger, a burner and a control system according to the present invention, wherein the water supply pipeline and the drainage pipeline are respectively connected to the heat exchanger, wherein the water inlet temperature sensor of the control system is arranged at the water supply pipeline and the water outlet temperature sensor and water flow sensor of the control system are arranged at the drainage pipeline, and the burner is configured to receive a signal about the total required heat from the controller of the control system and transfer the corresponding heat to the heat exchanger according to the signal.

[0020] According to an exemplary embodiment of the present invention, another water flow sensor is additionally arranged at the water supply line.

[0021] A third aspect of the present invention provides a computer-readable storage medium having program instructions stored thereon. When the program instructions are executed by a processor, the processor is caused to execute the method according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be described in more detail below with reference to the accompanying drawings, so that the principles, features and advantages of the present invention can be better understood. In the accompanying drawings:

[0023] Figure 1 A schematic diagram showing a wall-mounted boiler according to an exemplary embodiment of the present invention;

[0024] Figure 2 A schematic block diagram showing a method for controlling the temperature of domestic water according to an exemplary embodiment of the present invention;

[0025] Figure 3 A schematic graph showing changes in domestic water temperature over time according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial technical effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and multiple exemplary embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the scope of protection of the present invention.

[0027] Figure 1 FIG. 1 shows a schematic diagram of a wall-mounted boiler 100 according to an exemplary embodiment of the present invention. Figure 1As shown, the wall-mounted boiler 100 includes a controller 10, a heat exchanger 20 and a burner 30, wherein the heat exchanger 20 is connected to a water supply pipeline 21 and a drainage pipeline 22 respectively, the water supply pipeline is configured to supply water having an inlet water temperature to the heat exchanger 20, and the drainage pipeline is configured to discharge domestic water having an actual outlet water temperature from the heat exchanger 20. The water in the heat exchanger 20 is heated by means of the heat transferred by the burner 30. The burner 30 generates heat by burning gas, and the gas is supplied to the burner 30 through the gas supply pipeline 31. According to the configuration of the wall-mounted boiler 100, the heat exchanger 20 can be exemplarily configured as a shell and tube heat exchanger or a plate heat exchanger.

[0028] like Figure 1 As shown, an inlet water temperature sensor 1 is arranged at the water supply pipeline 21, and the inlet water temperature sensor is configured to detect the inlet water temperature of the water supplied to the heat exchanger 20. An outlet water temperature sensor 2 and a water flow sensor 3 are respectively arranged at the drainage pipeline 22, and the outlet water temperature sensor is configured to detect the outlet water temperature of the water flowing out of the heat exchanger 20, and the water flow sensor is configured to detect the drainage flow or the expected hot water flow. Exemplarily, the inlet water temperature sensor 1 and the outlet water temperature sensor 2 are both configured as low-inertia temperature sensors, thereby advantageously reducing the errors caused by the thermal inertia of the elements of these temperature sensors. In addition, it is also conceivable to arrange another water flow sensor at the water supply pipeline 21 for detecting the water supply flow. The water flow sensor is exemplarily configured as a Hall sensor.

[0029] like Figure 1 As shown, the temperature signals or water flow signals detected by the water inlet temperature sensor 1, the water outlet temperature sensor 2 and the water flow sensor 3 are transmitted to the controller 10. In addition, the preset water outlet temperature is input into the controller 10 by way of example through the input device 4. By way of example, the overheating threshold and overshoot threshold of domestic water can also be preset by way of the input device 4. The controller 10 analyzes and processes these signals using a PID control algorithm, generates a control signal for controlling the temperature of domestic water and transmits the control signal to the burner 30, thereby changing the amount of gas supplied to the burner 30 via the gas supply pipeline 31 and thereby correspondingly adjusting the amount of heat transferred to the heat exchanger 20. This is explained in more detail below. According to an exemplary embodiment of the present invention, a control system is composed of the controller 10, the water inlet temperature sensor 1, the water outlet temperature sensor 2, the water flow sensor 3 and the input device 4, for implementing the method for controlling the temperature of domestic water in the wall-mounted boiler 100 according to the present invention.

[0030] Figure 2FIG. 1 is a schematic block diagram of a method for controlling the temperature of domestic water of a wall-mounted boiler 100 according to an exemplary embodiment of the present invention. Figure 2 As shown, the preset outlet water temperature T of domestic water is input through the input device 4 of the control system. DHWset The inlet water temperature T of the water supplied to the heat exchanger 20 is detected by the inlet water temperature sensor 1. DCW The actual outlet water temperature T of the water discharged from the heat exchanger 20 is detected by the outlet water temperature sensor 2. DHW , and the water flow rate v is detected by the water flow sensor 3. When the user changes the hot water demand, for example, the user changes the opening degree of the faucet, the water flow rate change, that is, the water flow rate difference Δv, can be detected by the water flow sensor 3.

[0031] like Figure 2 As shown, when the actual outlet water temperature T DHW With the preset water outlet temperature T DHWset When they are inconsistent, the controller 10 calculates the difference between the two, i.e., the first temperature difference ΔT1. With the first temperature difference ΔT1 as input, the PID control algorithm stored in the controller 10 is used to obtain the adjusted calculated temperature difference ΔT r , and the temperature difference ΔT is calculated by r The product of the water flow v gives the first required heat W1, that is, W1 = ΔT r *v. Here, the PID control algorithm performs proportional (P), integral (I) and differential (D) operations according to the input first temperature difference ΔT1, and the action coefficients involved are the proportional coefficient Kp, the integral coefficient Ki and the differential coefficient Kd. The control accuracy of the PID control algorithm is mainly affected by these three coefficients. Specifically, the proportional operation is used to respond to the deviation of the system, that is, the first temperature difference ΔT1, according to the proportional coefficient Kp. The proportional operation can speed up the adjustment and reduce the error, but may reduce the stability of the system; the integral operation is used to eliminate the steady-state error of the system; the differential operation is used to reflect the rate of change of the system deviation signal and perform advance adjustment, thereby improving the dynamic performance of the system.

[0032] According to an exemplary embodiment of the present invention, the PID control algorithm is a fuzzy PID control algorithm, which is implemented by combining a traditional PID control algorithm with fuzzy logic. Specifically, the first temperature difference ΔT1 and the rate of change calculated thereby are continuously detected during the operation of the wall-mounted boiler 100, and then the first temperature difference and the error rate of change are used as inputs to obtain the corresponding correction values ​​ΔKp, ΔKi, and ΔKd of the three coefficients Kp, Ki, and Kd of the PID output according to a specific fuzzy rule, thereby achieving real-time adjustment of the PID action coefficient and meeting the self-tuning requirements. This enables the temperature control of domestic water to have good dynamic and static performance and improves the stability, response speed, and stability accuracy of the system. Of course, other PID control algorithms that are considered meaningful by those skilled in the art can also be considered, such as a feedforward PID control algorithm, whose output is correspondingly used as a feedforward variable, thereby improving the system response speed and reducing the feedback control pressure.

[0033] According to an exemplary embodiment of the present invention, the coefficients of the PID control algorithm are derived from experimental data and / or empirical data. Of course, the action coefficients and fuzzy rules can also be obtained by other methods that are considered meaningful by those skilled in the art, such as by computer simulation. The coefficients of the PID control algorithm are pre-stored in the controller 10, for example, a complete action coefficient table and a fuzzy rule base and corresponding relationships with various boundary conditions are established in the controller. This allows for rapid response to various situations and requirements. Alternatively, it is also possible to consider obtaining relevant action coefficients and fuzzy rules from the outside via a wireless network.

[0034] According to an exemplary embodiment of the present invention, the wall-mounted boiler 100 has different operation modes: a cold operation mode, a heating mode, and a preheating mode. In the cold operation mode, the wall-mounted boiler only implements the function of heating domestic water; in the heating mode, the wall-mounted boiler implements the function of heating domestic water while implementing the heating function, thereby making full use of the heat of the water used for heating. This heating mode is usually used in winter; in the preheating mode, the domestic water is preheated. Different coefficients of the PID control algorithm are applicable to different operation modes of the wall-mounted boiler. The temperature control of domestic water can be implemented more accurately by adapting the operation mode of the wall-mounted boiler to the coefficient of the PID control algorithm. Exemplarily, a mode selection device for changing the operation mode of the wall-mounted boiler 100 is configured in the wall-mounted boiler 100. This can more flexibly meet the needs of users and save energy to a certain extent.

[0035] like Figure 2 As shown, when the water flow rate v detected by the water flow sensor 3 changes, that is, when the user changes the opening degree of the faucet, the water flow difference Δv is obtained, and the inlet water temperature T DCW Relative to the preset water outlet temperature T DHWsetThe product of the second temperature difference ΔT2 and the water flow difference Δv is used to obtain the second required heat W2, that is, W2=(T DHWset -T DCW Here, when the opening degree of the faucet increases, that is, the water flow v becomes larger, the second required heat W2 is a positive value; when the opening degree of the faucet decreases, that is, the water flow v becomes smaller, the second required heat W2 is a negative value.

[0036] like Figure 2 As shown, the total heat requirement W is obtained from the first heat requirement W1 and the second heat requirement W2. s The controller 10 will calculate the total required heat W s The signal is sent to the burner 30, thereby adjusting the amount of gas supplied to the burner 30 by the gas supply pipeline 31. The heat generated by the burner 30 is changed by adjusting the amount of gas, thereby controlling the heat transferred from the burner 30 to the heat exchanger 20 and controlling the temperature of the domestic water discharged from the heat exchanger 20.

[0037] According to an exemplary embodiment of the present invention, the above steps can be performed sequentially in different orders or simultaneously.

[0038] Figure 3 A schematic graph showing changes in temperature of domestic water over time according to an exemplary embodiment of the present invention is shown.

[0039] exist Figure 3 In the illustrated embodiment, the water flow rate v does not change. The water supplied to the heat exchanger 20 has an inlet water temperature T DCW And the water flowing out of the heat exchanger 20 has an actual water outlet temperature T DHW The temperature of domestic water that the user wants to achieve is the preset water outlet temperature T DHWset .

[0040] Depend on Figure 3 The actual outlet water temperature T DHW It can be seen from the time-varying curve that when the wall-mounted boiler 100 is running, the water in the heat exchanger 20 first undergoes an initial rapid heating stage, during which the actual outlet water temperature T DHW The temperature rises rapidly until the actual outlet water temperature T DHW The temperature change reaches the preset water outlet temperature T DHWset Relative to the inlet water temperature T DCW 90% of the temperature difference, i.e. T DHW =(T DHWset -T DCW )*0.9+T DCW In this case, the actual outlet water temperature can be expressed as T 90％ Generally, when the actual outlet water temperature T DHW Reach T90％ When t0 is reached, it can be considered that the domestic water has reached the desired target temperature. The duration of the initial heating stage is the initial heating time t0.

[0041] The water in the heat exchanger 20 then undergoes a temperature stabilization phase, during which the actual water outlet temperature T DHW Superheat ΔT o and overshoot ΔT u Here, the superheat ΔT o The actual outlet water temperature T DHW First time reaching T DHWset +1℃ actual water outlet temperature T DHW The maximum value is relative to the preset water outlet temperature T DHWset The temperature difference, while the overshoot ΔT u The actual outlet water temperature T DHW First time reaching T DHWset Actual outlet water temperature after -1℃ T DHW The minimum value is relative to the preset water outlet temperature T DHWset For example, by adjusting the wall-mounted boiler 100 so that the actual water outlet temperature T DHW Relative to the preset water outlet temperature T DHWset The temperature difference, that is, the first temperature difference ΔT1 is always within the overheating threshold ΔT o_lim and overshoot threshold ΔT u_lim Here, the overheating threshold ΔT o_lim and overshoot threshold ΔT o_lim The temperature stabilization stage lasts for the temperature stabilization time t1 until the temperature of the domestic water, i.e., the actual outlet water temperature T DHW For example, always at T DHWset The range is ±1° C. Of course, other values ​​that are considered meaningful by a person skilled in the art are also conceivable.

[0042] The following shows operating results according to an exemplary embodiment of the invention under different boundary conditions, wherein during operation the tap is continuously open and there is a steady, constant water flow.

[0043]

[0044]

[0045] In heating mode 1, the heating water inflow temperature is 55°C and the return temperature is 40°C, and in heating mode 2, the heating water inflow temperature is 75°C and the return temperature is 60°C. In these two heating modes, the heating of domestic water is started only after the heating water inflow temperature and the return temperature have reached stability for 5 minutes. In the preheating mode, the preheating temperature is set to 60°C.

[0046] It can be seen from the above table that according to the method of the present invention, the actual outlet water temperature T DHW Superheat ΔT o and overshoot ΔT u All are less than or equal to 1.5℃, that is, at the overheating threshold ΔT o_lim and overshoot threshold ΔT u_lim This means that users will not feel the domestic water is hot or cold during the temperature stabilization stage.

[0047] Furthermore, it can be clearly seen that according to the method according to the invention, the actual outlet water temperature T DHW Can reach T in no more than 40 seconds, or even no more than 25 seconds 90％ In other words, the target temperature is approximately reached and stabilized within no more than 90 seconds, or even no more than 60 seconds. This can also meet the existing standards for wall-mounted boilers, such as GB25034-2010 and EN15502-1.

[0048] Of course, the above boundary conditions or various parameters are only exemplary and can be changed within an appropriate range according to different situations without impairing the desired technical effect.

[0049] The above explanation of the embodiments only describes the invention within the framework of the examples. Of course, the individual features of the embodiments can be freely combined with one another as long as it makes technical sense, without departing from the framework of the invention.

[0050] Other advantages and alternative embodiments of the present invention are obvious to those skilled in the art. Therefore, the present invention is not limited to the specific details, representative structures and exemplary embodiments shown and described in its broader sense. On the contrary, those skilled in the art can make various modifications and substitutions without departing from the basic spirit and scope of the present invention.

Claims

1. A method for controlling the temperature of domestic water in a wall-mounted boiler (100), the method comprising the following steps: a) respectively detecting the water inlet temperature (T DCW ), actual outlet water temperature (T DHW ) and water flow (v); b) The actual water outlet temperature (T DHW ) relative to the preset water outlet temperature (T DHWset ) as the input, and the calculated temperature difference (ΔT1) as the output is obtained through the PID control algorithm. r ), and the temperature difference (ΔT r ) and the water flow rate (v) to obtain the first required heat (W1); c) When the water flow rate (v) changes with the water flow rate difference (Δv), the inlet water temperature (T DCW ) relative to the preset water outlet temperature (T DHWset ) and the water flow difference (Δv) to obtain a second required heat (W2); and d) Calculate the total heat requirement (W1) from the first heat requirement (W1) and the second heat requirement (W2) s ), and based on the total heat demand (W s ) adjusts the amount of gas supplied to the burner (30) of the wall-mounted boiler (100) so that at the actual water outlet temperature (T DHW ) reaches the preset water outlet temperature (T DHWset ) after which the actual outlet water temperature (T DHW ) relative to the preset water outlet temperature (T DHWset ) is always within the overheating threshold value (ΔT o_lim ) and overshoot threshold (ΔT u_lim ), the overheating threshold (ΔT o_lim ) is the actual outlet water temperature (T DHW ) reaches the preset water outlet temperature (T DHWset ) relative to the preset water outlet temperature (T DHWset ) of the temperature difference, the overshoot threshold (ΔT u_lim ) is the actual outlet water temperature (T DHW ) reaches the preset water outlet temperature (T DHWset ) relative to the preset water outlet temperature (T DHWset ) is the limit value of the temperature difference.

2. The method according to claim 1, wherein: The PID control algorithm is a fuzzy PID control algorithm or a feedforward PID control algorithm.

3. The method according to claim 1 or 2, wherein: The coefficients of the PID control algorithm are obtained through experiments and / or empirical data and are pre-stored in the controller (10) of the wall-mounted boiler (100).

4. The method according to claim 1 or 2, wherein: Different coefficients of the PID control algorithm are selected accordingly for different operating modes of the wall-mounted boiler (100), wherein the operating mode is selected from the following modes: cold operating mode, heating mode, and preheating mode.

5. The method according to claim 1 or 2, wherein: The overheating threshold (ΔT o_lim ) and the overshoot threshold (ΔT u_lim ) are ±1.5℃ respectively.

6. A control system for controlling the temperature of domestic water in a wall-mounted boiler (100), the control system comprising a controller (10) and an inlet water temperature sensor (1), an outlet water temperature sensor (2), and a water flow sensor (3) connected to the controller (10), the control system being configured to implement the method according to any one of claims 1 to 5.

7. The control system according to claim 6, wherein: The control system also includes a circuit configured to input a preset water outlet temperature (T DHWset ) of the input device (4).

8. A wall-mounted boiler (100), comprising a water supply pipeline (21), a drainage pipeline (22), a heat exchanger (20), a burner (30) and a control system according to claim 6 or 7, wherein: The water supply pipeline (21) and the drainage pipeline (22) are respectively connected to the heat exchanger, wherein the water inlet temperature sensor (1) of the control system is arranged at the water supply pipeline (21), the water outlet temperature sensor (2) and the water flow sensor (3) of the control system are arranged at the drainage pipeline (22), and the burner (30) is configured to receive information about the total required heat (W) from the controller (10) of the control system. s ) and transfers corresponding heat to the heat exchanger (20) according to the signal.

9. The wall-mounted boiler (100) according to claim 8, wherein: A further water flow sensor is additionally arranged on the water supply line (21). 10 . A computer-readable storage medium having program instructions stored thereon, which, when executed by a processor, causes the processor to execute the method according to claim 1 .

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