Refrigeration and heating control system and method for constant pressure difference circulation

Abstract

The invention belongs to the field of heating and refrigerating, and particularly discloses a constant-pressure-difference circulating refrigerating and heating control system and method.The constant-pressure-difference circulating refrigerating and heating control system comprises a cold and heat source, a buffer water tank, a variable-frequency water pump, a water supply pipeline, at least one tail end heating and refrigerating device and a water return pipeline; the output end of the cold and heat source is connected with the input end of the buffer water tank through a constant-speed pump, an electric control valve is arranged between the water supply pipeline and the tail end heating and refrigerating equipment, and a temperature controller is arranged on the tail end heating and refrigerating equipment; the intelligent electric control valve is additionally arranged at the front end of the tail end heating and refrigerating equipment, intelligent control over the indoor temperature is achieved, when the room temperature is matched with the set temperature, the heat exchange equipment and the water supply pipeline are automatically disconnected, invalid energy consumption is avoided, meanwhile, the variable frequency water pump adjusts the flow pressure according to the real-time opening and closing state of the electric control valve, and the energy consumption is reduced. The constant water pressure difference is achieved, the problem of insufficient flow of far-end equipment is solved, and it is ensured that all tail ends obtain stable flow according to needs.

Description

Technical Field

[0001] The present invention belongs to the field of heating and cooling, and in particular relates to a constant pressure difference cycle cooling and heating control system and method. Background Art

[0002] With the continuous expansion of the scale of modern buildings and the increasing demand for indoor environmental comfort, the importance of cooling and heating systems in buildings has become increasingly prominent.

[0003] Traditional cooling and heating systems often use relatively simple control methods, such as a constant flow operation mode. In this mode, the water pump runs at a constant speed, and the water flow rate remains constant regardless of changes in the actual demand of the terminal heating and cooling equipment. Although this method is simple to control, it has many disadvantages. On the one hand, when the cooling load demand in some areas decreases, the system still supplies cooling capacity at the rated flow rate, resulting in energy waste and increased operating costs. On the other hand, since it is impossible to make targeted adjustments based on the actual temperature conditions of different areas, some areas are prone to overheating or overcooling, affecting the comfort of indoor occupants. Moreover, when some of the terminal heating and cooling equipment stops operating and is disconnected from the system, the water pump still operates at the initial power, causing fluctuations in the difference between the supply pressure and the return water pressure, increasing energy consumption and easily causing structural damage due to the water hammer effect. Summary of the Invention

[0004] The purpose of the present invention is to provide a constant pressure difference circulation cooling and heating control system and method to solve the problem raised in the above background technology that the traditional cooling and heating system water pump runs at a constant speed and it is difficult to achieve a constant supply and return water pressure difference.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A constant pressure difference circulation cooling and heating control system includes a cold and heat source, a return water pipeline, a buffer water tank, a variable frequency water pump, a water supply pipeline, and at least one terminal heating and cooling equipment; the output end of the cold and heat source is connected to the input end of the buffer water tank, the output end of the buffer water tank is connected to the input end of the terminal heating and cooling equipment through the water supply pipeline, the input end of the cold and heat source is connected to the output end of the terminal heating and cooling equipment through the return water pipeline, an electric control valve is provided between the water supply pipeline and the terminal heating and cooling equipment, and a thermostat is provided on the terminal heating and cooling equipment.

[0007] Preferably, a one-way valve is provided between the terminal heating and cooling equipment and the return water pipeline.

[0008] Preferably, pressure sensors are provided between the variable frequency water pump and the water supply pipeline and between the return pipeline and the buffer water tank.

[0009] A constant pressure difference cycle cooling and heating control method includes the above-mentioned constant pressure difference cycle cooling and heating control system, and the control method further includes:

[0010] S1. Obtain temperature data of terminal heating and cooling equipment;

[0011] S2. Calculate the temperature deviation between the temperature data and the preset value, and calculate the opening and closing and opening degree of the corresponding electronically controlled valve according to the temperature deviation calculation result;

[0012] S3. Calculate the speed of the variable frequency water pump according to the opening and closing and opening degree of the electronically controlled valve.

[0013] Preferably, the temperature deviation calculation includes:

[0014] ΔT i (t) = T set,i -T i (t)

[0015] Among them, T set，i is the set temperature of the i-th terminal heating and cooling equipment, T i (t) is the measured temperature of the i-th terminal heating and cooling equipment, ΔT i (t) is the temperature deviation.

[0016] Preferably, the calculation of the opening and closing and the opening degree of the corresponding electric control valve according to the calculation results includes:

[0017]

[0018] Among them, V i (t) is the opening of the i-th electronically controlled valve at time t, λ is the closing rate coefficient of the electronically controlled valve, the larger the value, the faster the closing, μ is the opening rate coefficient of the electronically controlled valve, the larger the value, the more aggressive the opening;

[0019]

[0020] Among them, V th It is the opening and closing threshold of the electric control valve.

[0021] Preferably, the speed control of the variable frequency water pump according to the opening and closing and the opening degree of the electric control valve includes:

[0022]

[0023] n base =K·Q demand

[0024] Among them, Q demand is the total required flow, M is the number of currently opened electronically controlled valves, V i is the opening of the i-th electronically controlled valve, C υ，iis the flow coefficient of the i-th electric control valve, K is the system characteristic constant, n base is the speed of the variable frequency water pump.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention realizes intelligent control of indoor temperature by adding an intelligent electric control valve at the front end of the terminal heating and cooling equipment. When the room temperature matches the set temperature, the heat exchange equipment is automatically disconnected from the water supply pipe to avoid ineffective energy consumption. At the same time, the variable frequency water pump adjusts the flow pressure according to the real-time opening and closing status of the electric control valve to achieve a constant water pressure difference, eliminate the problem of insufficient flow of remote equipment, and ensure that each terminal obtains a stable flow as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 It is a flowchart of the method steps of the present invention.

[0030] In the figure: 1. Cold and heat sources; 2. Return water pipeline; 3. Buffer water tank; 4. Variable frequency water pump; 5. Pressure sensor; 6. Water supply pipeline; 7. Electric control valve; 8. Terminal heating and cooling equipment; 9. Thermostat; 10. One-way valve. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0034] As attached Figure 1 As shown:

[0035] Embodiment 1: This embodiment provides a constant pressure difference cycle cooling and heating control system, including a cold and heat source 1, a return water pipe 2, a buffer water tank 3, a variable frequency water pump 4, a water supply pipe 6, and at least one terminal heating and cooling equipment 8; the output end of the cold and heat source 1 is connected to the input end of the buffer water tank 3, the output end of the buffer water tank 3 is connected to the input end of the terminal heating and cooling equipment 8 through the water supply pipe 6, the input end of the cold and heat source 1 is connected to the output end of the terminal heating and cooling equipment 8 through the return water pipe 2, an electric control valve 7 is arranged between the water supply pipe 6 and the terminal heating and cooling equipment 8, and a thermostat 9 is arranged on the terminal heating and cooling equipment 8.

[0036] The variable frequency water pump 4 adopts the HH-HYBP20-52-2.2*3 water pump of Honghui Fluid Equipment;

[0037] The terminal heating and cooling equipment 8 includes radiators, floor heating, fan coil units, etc. When working, the cold and heat source 1 generates a medium, and the variable frequency water pump 4 will transport the medium to all the terminal heating and cooling equipment 8 through the water supply pipe 6 for heating or cooling operation. After heat exchange, the medium will be transported to the buffer water tank 3 through the return pipe 2, and finally returned to the cold and heat source 1 to circulate heating or cooling operation;

[0038] When the temperature reaches a preset value, the thermostat 9 controls the corresponding electric control valve 7 to close, so as to disconnect the current terminal heating and cooling equipment 8 from the water supply pipe 6 and stop delivering the medium to the current terminal heating and cooling equipment 8 to avoid ineffective energy consumption. When the electric control valve 7 is opened and closed, the pumping speed of the variable frequency water pump 4 is synchronously regulated. Specifically, when the electric control valves 7 of several terminal heating and cooling equipment 8 are all open, the pumping speed of the variable frequency water pump 4 reaches the highest speed. When a certain electric control valve 7 is closed, the variable frequency water pump 4 will synchronously reduce the pumping speed. The pumping speed of the variable frequency water pump 4 is adjusted according to the opening and closing of the electric control valve 7, thereby controlling the water pressure and realizing a constant pressure difference cycle. The constant pressure difference is the difference between the water supply pressure and the return water pressure. The power is adjusted according to the actual load, which significantly reduces energy consumption. At the same time, it ensures that each terminal heating and cooling equipment 8 obtains a stable flow when the valve is opened to avoid hydraulic imbalance.

[0039] When the demand for the terminal heating and cooling equipment 8 is low, the buffer water tank 3 can temporarily store the medium to avoid pressure fluctuations caused by frequent start and stop of the cold and heat source 1.

[0040] Specifically, a one-way valve 10 is provided between the terminal heating and cooling equipment 8 and the return water pipeline 2 .

[0041] The one-way valve 10 can prevent the medium in the return water pipe 2 from flowing back into the terminal heating and cooling equipment 8.

[0042] Specifically, pressure sensors 5 are provided between the variable frequency water pump 4 and the water supply pipeline 6 and between the return water pipeline 2 and the buffer water tank 3 .

[0043] As can be seen from the above, the pressure sensor 5 located in the water supply pipe 6 will detect the water supply pressure of the system, and the pressure sensor 5 located in the return pipe 2 will detect the return pressure of the system, thereby calculating the constant pressure difference, further verifying the adjustment of the variable frequency water pump 4, and improving the control accuracy. The pressure sensor 5 uses Asmik's MIK-P300G sensor.

[0044] As attached Figure 2 As shown:

[0045] Embodiment 2: This embodiment provides a constant pressure difference cycle cooling and heating control method, including the above-mentioned constant pressure difference cycle cooling and heating control system, and the control method further includes:

[0046] S1. Obtain temperature data of the terminal heating and cooling equipment 8;

[0047] Each terminal heating and cooling device 8 is equipped with a thermostat 9 to monitor the temperature of the area where it is located in real time and transmit the data to the central controller, providing accurate local temperature feedback, providing a data basis for subsequent valve and water pump control, and ensuring the real-time and regional nature of temperature control.

[0048] S2. Calculate the temperature deviation between the temperature data and the preset value, and calculate the opening and closing and opening degree of the corresponding electric control valve 7 according to the temperature deviation calculation result;

[0049] Temperature deviation calculation includes:

[0050] ΔT i (t) = T set,i -T i (t)

[0051] Among them, T set，i is the set temperature of the i-th terminal heating and cooling equipment 8, T i (t) is the measured temperature of the i-th terminal heating and cooling equipment 8, ΔT i (t) is the temperature deviation, which determines the direction of valve action (positive value indicates energy supply, negative value indicates energy stop).

[0052] Quantify the terminal energy supply demand and provide a direct basis for valve opening and closing to avoid overcooling or overheating.

[0053] Calculating the opening and closing and opening degree of the corresponding electric control valve 7 according to the calculation results includes:

[0054]

[0055] Among them, V i(t) is the opening degree of the i-th electric control valve 7 at time t, λ is the closing rate coefficient of the electric control valve 7, the larger the value, the faster the closing, μ is the opening rate coefficient of the electric control valve 7, the larger the value, the more aggressive the opening;

[0056] When the temperature does not meet the standard, it responds quickly and increases the valve opening linearly, quickly increasing the cold or hot flow and shortening the heating or cooling time. When the temperature meets the standard, it closes smoothly and exponentially decays the valve opening to avoid pressure fluctuations caused by sudden flow drops, reducing water hammer effects and pressure oscillations.

[0057]

[0058] Among them, V th It is the opening and closing threshold of the electric control valve 7, which prevents the valve from frequently shaking at the critical opening.

[0059] Avoid high-frequency oscillation of the valve in the low opening range (such as 3% to 7%) to extend the life of the valve.

[0060] S3. Calculate the rotation speed of the variable frequency water pump 4 according to the opening and closing and opening degree of the electric control valve 7.

[0061] The speed of the variable frequency water pump 4 is regulated according to the opening and closing and opening degree of the electric control valve 7, including:

[0062]

[0063] n base =K·Q demand

[0064] Among them, Q demand is the total required flow, M is the number of currently opened electric control valves 7, V i is the opening of the i-th electric control valve 7, C υ，i is the flow coefficient of the i-th electric control valve 7, K is the system characteristic constant, which is related to the pipeline resistance and pump efficiency. It is calibrated through experiments. The calibration method is to measure the flow rate and the corresponding speed when the valve is fully open. Then K is the speed divided by the flow rate, n base is the speed of the variable frequency water pump 4.

[0065] The flow demand of all open valves is calculated based on the square root characteristic of valve opening-flow rate, which accurately reflects the instantaneous flow demand of the system and provides a feedforward basis for water pump speed regulation. The flow demand is linearly mapped to the water pump speed to ensure that the flow supply matches the demand. Through the gradual opening and closing of the valves, the room temperature changes smoothly without sudden changes, and it effectively avoids the water hammer effect caused by the sudden drop of water pump speed due to the simultaneous closure of multiple valves.

[0066] It is important to note that the construction and arrangement of the present application shown in a number of different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, as well as parameter values (e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, directional changes, etc.) without departing substantially from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structures. Other replacements, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0067] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (i.e., those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0068] It will be appreciated that in the development of any actual embodiment, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will, for those of ordinary skill having the benefit of this disclosure, be a routine undertaking of design, fabrication, and production without undue experimentation.

[0069] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A constant pressure difference cycle cooling and heating control system, characterized in that: It comprises a cold and hot source (1), a return water pipeline (2), a buffer water tank (3), a variable frequency water pump (4), a water supply pipeline (6), and at least one terminal heating and cooling device (8); The output end of the cold and heat source (1) is connected to the input end of the buffer water tank (3), the output end of the buffer water tank (3) is connected to the input end of the terminal heating and cooling equipment (8) through a water supply pipeline (6), the input end of the cold and heat source (1) is connected to the output end of the terminal heating and cooling equipment (8) through a return water pipeline (2), an electric control valve (7) is provided between the water supply pipeline (6) and the terminal heating and cooling equipment (8), and a thermostat (9) is provided on the terminal heating and cooling equipment (8).

2. A constant pressure difference cycle cooling and heating control system according to claim 1, characterized in that: A one-way valve (10) is provided between the terminal heating and cooling equipment (8) and the return water pipeline (2).

3. The constant pressure difference cycle cooling and heating control system according to claim 1, characterized in that: Pressure sensors (5) are provided between the variable frequency water pump (4) and the water supply pipeline (6), and between the return pipeline (2) and the buffer water tank (3).

4. A constant pressure difference cycle cooling and heating control method, characterized in that: A constant pressure difference cycle cooling and heating control system according to any one of claims 1 to 3, wherein the control method further comprises: S1, obtaining temperature data of the terminal heating and cooling equipment (8); S2, performing temperature deviation calculation on the temperature data and the preset value, and calculating the opening and closing and the opening degree of the corresponding electric control valve (7) according to the temperature deviation calculation result; S3. Calculating the rotation speed of the variable frequency water pump (4) according to the opening and closing and the opening degree of the electric control valve (7).

5. A constant pressure difference cycle cooling and heating control method according to claim 4, characterized in that: The temperature deviation calculation includes: ΔT i (t)=T set,i -T i (t) Among them, T set，i is the set temperature of the i-th terminal heating and cooling equipment (8), T i (t) is the measured temperature of the i-th terminal heating and cooling equipment (8), ΔT i (t) is the temperature deviation.

6. A constant pressure difference cycle cooling and heating control method according to claim 5, characterized in that: The calculation of the opening and closing and the opening degree of the corresponding electric control valve (7) according to the calculation result includes: Among them, V i (t) is the opening of the i-th electric control valve (7) at time t, λ is the closing rate coefficient of the electric control valve (7), the larger the value, the faster the closing, μ is the opening rate coefficient of the electric control valve (7), the larger the value, the more aggressive the opening; Among them, V th is the opening and closing threshold of the electric control valve (7).

7. A constant pressure difference cycle cooling and heating control method according to claim 6, characterized in that: The method of regulating the rotation speed of the variable frequency water pump (4) according to the opening and closing and the opening degree of the electric control valve (7) includes: n base =K·Q demand Among them, Q demand is the total required flow, M is the number of currently opened electric control valves (7), V i is the opening of the i-th electric control valve (7), C υ，i is the flow coefficient of the i-th electric control valve (7), K is the system characteristic constant, n base is the speed of the variable frequency water pump (4).

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