Secondary return air control method and device for process air conditioner
By controlling the opening of the secondary return air valve and the use of the heating valve in real time, the ratio of primary return air to secondary return air is dynamically adjusted, solving the problem of insufficient dehumidification capacity in traditional secondary return air systems and achieving high-efficiency energy saving and precise temperature and humidity control of the air conditioning system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA TOBACCO ZHEJIANG IND CO LTD
- Filing Date
- 2023-11-09
- Publication Date
- 2026-05-29
AI Technical Summary
Traditional secondary return air systems have poor dehumidification capacity, and the production workshop environment of cigarette factories is complex, with temperature and humidity affected by various factors. The unit's operating conditions change frequently, making it difficult to determine the ratio of primary to secondary return air, which leads to increased energy consumption.
The system determines the surface cooling performance protection value in real time, controls the maximum opening of the secondary return air valve, dynamically adjusts the ratio of primary and secondary return air, and reheats the supply air through the heating valve when necessary to ensure that the supply air temperature and humidity meet the requirements.
It improves the dehumidification capacity of the secondary return air system, optimizes the energy efficiency of the air conditioning system, reduces energy consumption, and enhances the accuracy of temperature and humidity control.
Smart Images
Figure CN117329603B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of air conditioning technology, and more specifically, to a method and apparatus for controlling secondary return air in a process air conditioning system. Background Technology
[0002] The air conditioning system in cigarette production workshops needs to meet the temperature and humidity requirements of different stages to ensure stable cigarette quality. Currently, the environmental temperature and humidity control during cigarette production and storage in cigarette factories mainly relies on large-scale process air conditioning systems. Air handling often employs condensation dehumidification, where the return air is mixed with fresh air, and water vapor is condensed on the low-temperature surface of the cooling coil, thus achieving cooling and dehumidification. During this process, to avoid excessively low or uneven air supply temperature, steam reheating is often required to ensure that the temperature and humidity of the treated air reach the required supply air temperature and humidity. However, this method involves a very large amount of system reheating, inevitably causing heat and cold to cancel each other out, leading to a significant increase in energy consumption.
[0003] To address the steam reheating issue in primary return air systems, some process air conditioning systems have introduced a secondary return air treatment method. In this method, a portion of the primary return air bypasses the cooling and dehumidification process via the surface cooling coil, while the remaining portion, after undergoing cooling and dehumidification via the surface cooling coil, mixes with the uncooled primary return air in the supply air duct before being output. This uncooled primary return air is called secondary return air. Secondary return air can save heat and cooling capacity, achieving energy-saving goals.
[0004] However, compared to a primary return air system, the traditional secondary return air system has poor dehumidification capacity. Furthermore, the environment in a cigarette factory production workshop is quite complex, with temperature and humidity affected by various factors such as the unit's operating status, machine heat generation, and the external environment. The unit's operating conditions change frequently, making it difficult to determine the ratio of primary to secondary return air. Summary of the Invention
[0005] This application provides a method and apparatus for controlling secondary return air in a process air conditioner, which determines the surface cooling performance protection value in real time and controls the maximum opening of the secondary return air valve accordingly to ensure the dehumidification capacity of the secondary return air system, thereby dynamically adjusting the ratio of primary return air to secondary return air.
[0006] This application provides a secondary return air control method for process air conditioning, including:
[0007] The data acquisition unit's operating status;
[0008] During unit operation, it is necessary to determine in real time whether the unit is in cooling and dehumidification mode and whether there is excessive cooling.
[0009] If the unit is in cooling and dehumidification mode and there is excessive cooling, the theoretical opening value of the secondary return air valve and the surface cooling performance protection value are calculated in real time, and the minimum value between the surface cooling performance protection value and the initial valve protection opening is determined. Among them, the surface cooling performance protection value is the maximum opening of the secondary return air valve corresponding to the current dehumidification demand of the surface cooler, and the initial valve protection opening is the initial maximum opening of the secondary return air valve determined by comprehensively considering the hardware and system performance.
[0010] If the theoretical opening value of the secondary return air valve is greater than the minimum value, then the minimum value will be used as the opening command value of the secondary return air valve.
[0011] Preferably, the secondary return air control method further includes:
[0012] Collect the temperature of the mixed air;
[0013] If the temperature of the mixed air is lower than the required temperature, the heating valve on the air supply duct will be opened.
[0014] Preferably, the theoretical opening value of the secondary return air valve is determined by a scaling factor, a first proportional value, and a first integral value, wherein the first proportional value and the first integral value are determined by the difference between the current ambient temperature and the set temperature.
[0015] Preferably, the surface cooling performance protection value is determined by a second proportional value and a second integral value, which are determined by the difference between the current ambient temperature and the set temperature.
[0016] Preferably, if the unit is not in operation, is not in cooling and dehumidification mode, or is not in excessive cooling mode, the opening command value of the secondary return air valve is cleared to zero.
[0017] This application also provides a secondary return air control device for a process air conditioner, including a status acquisition module, an operating condition judgment module, a calculation module, and an output module;
[0018] The status acquisition module is used to collect the operating status of the unit;
[0019] The operating condition judgment module is used to determine in real time whether the unit is in cooling and dehumidification mode and whether there is excessive cooling when the unit is running.
[0020] The calculation module is used to calculate the theoretical opening value and surface cooling performance protection value of the secondary return air valve in real time when the unit is in cooling and dehumidification mode and there is excessive cooling. It also determines the minimum value between the surface cooling performance protection value and the initial valve protection opening. The surface cooling performance protection value is the maximum opening of the secondary return air valve that meets the current dehumidification requirements of the surface cooler. The initial valve protection opening is the maximum opening of the initial secondary return air valve determined by comprehensively considering hardware and system performance.
[0021] The output module is used to take the minimum value as the opening command value of the secondary return air valve when the theoretical opening value of the secondary return air valve is greater than the minimum value.
[0022] Preferably, the secondary return air control device further includes a temperature acquisition module and a control module;
[0023] The temperature acquisition module is used to collect the temperature of the mixed air.
[0024] The control module is used to open the heating valve on the air supply duct when the temperature of the mixed air is lower than the required temperature value.
[0025] Preferably, the theoretical opening value of the secondary return air valve is determined by a scaling factor, a first proportional value, and a first integral value, wherein the first proportional value and the first integral value are determined by the difference between the current ambient temperature and the set temperature.
[0026] Preferably, the surface cooling performance protection value is determined by a second proportional value and a second integral value, which are determined by the difference between the current ambient temperature and the set temperature.
[0027] Preferably, the secondary return air control device further includes a zeroing module, which is used to zero the opening command value of the secondary return air valve when the unit is in a non-operating state, the unit is not in a cooling and dehumidification state, or the unit is not in an excessive cooling state.
[0028] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description
[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.
[0030] Figure 1 A flowchart of the secondary return air control method for the process air conditioning provided in this application;
[0031] Figure 2 A structural diagram of the secondary return air control device for the process air conditioning provided in this application. Detailed Implementation
[0032] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the present application.
[0033] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.
[0034] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.
[0035] In all the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.
[0036] This application provides a method and apparatus for controlling secondary return air in a process air conditioning system. It determines the surface cooling performance protection value in real time and controls the maximum opening of the secondary return air valve accordingly to ensure the dehumidification capacity of the secondary return air system, thereby dynamically adjusting the ratio of primary and secondary return air. Based on the above, if the temperature of the mixed air does not meet the requirements, a heating valve is activated to heat the mixed air, ensuring that the final output water vapor meets the actual needs.
[0037] It should be noted that in the secondary return air system, the main primary return air duct has a first branch pipe connected to the input end of the surface cooler and a second branch pipe connected to the supply air duct. The first branch pipe is equipped with a constant air volume valve for switching and regulating the primary return air volume entering the surface cooler. The second branch pipe is equipped with a secondary return air valve for switching and regulating the secondary return air volume entering the supply air duct. The sum of the primary and secondary return air volumes is the total duct volume. The output end of the surface cooler is connected to the supply air duct via a pipe. The supply air duct is equipped with a heating valve; opening the heating valve can reheat the water vapor in the supply air duct.
[0038] The primary return air is cooled and dehumidified by a surface cooler via a constant air volume valve, while the secondary return air is mixed with the treated primary return air via a secondary return air valve. This application adjusts the ratio of primary and secondary return air through the linkage control of the secondary return air valve and the constant air volume valve, so that the air supply state point meets the process requirements of the production workshop.
[0039] like Figure 1 As shown, the secondary return air control method for process air conditioning provided in this application includes:
[0040] S110: Collect the operating status of the unit. If the unit is in operation, execute S120; otherwise, execute S1100.
[0041] S120: Under the operating status of the unit, determine in real time whether the unit is in cooling and dehumidification mode and whether there is excessive cooling. If the unit is in cooling and dehumidification mode and there is excessive cooling, then execute S130; otherwise, if the unit is not in cooling and dehumidification mode or there is no excessive cooling, then execute S1100.
[0042] S130: Temperature control of the secondary return air system is enabled. At this time, the theoretical opening value U of the secondary return air valve and the surface cooling performance protection value U are calculated in real time. hlm2 And determine the surface cooling performance protection value U. hlm2 and initial valve protection opening U hlm1 The minimum value MIN(U) hlm1 U hlm2 ).
[0043] Since opening the secondary return air valve will affect the system's dehumidification effect, in order to ensure that the supply air temperature and humidity meet the process requirements, the system calculates the theoretical opening value U of the secondary return air valve based on the current parameters, and at the same time calculates the surface cooling performance protection value U. hlm2 To ensure system performance. Among these, the surface cooling performance protection value U... hlm2 The maximum opening of the secondary return air valve is set to meet the current dehumidification requirements of the surface cooler. This value changes in real time based on the cooling and dehumidification effect of the surface cooler. The initial valve protection opening is a fixed value, determined by comprehensively considering hardware and system performance to set the initial maximum opening of the secondary return air valve.
[0044] Specifically, by comparing the ambient temperature and humidity t,h with the set state t set h set Simultaneously calculate the theoretical opening value U of the secondary return air valve and the surface cooling performance protection value U. hlm2 .
[0045] In t < t set At that time, the theoretical opening value U of the secondary return air valve is determined by the scaling factor n, the first proportional value u1, and the first integral value u2. The first proportional value u1 and the first integral value u2 are determined by the current ambient temperature t and the set temperature t. set The difference determines:
[0046] U = n(u1 + u2)
[0047] u1=a·Δt
[0048] u2=b·∫0 T ΔtdT
[0049] Δt=t set -t
[0050] where u2∈[-a·Δt, MIN(U hlm1 U hlm2 ) / na·Δt], integration continues only when u2 is within the specified range; n is the scaling factor, which is determined in real time by the temperature difference before and after the surface cooler (i.e., the surface cooling effect), and the coefficients a and b are fixed values.
[0051] Cooling performance protection value U hlm2 From the second proportional value u h1Second integral value u h2 Determined, the second proportional value u h1 Second integral value u h2 The current ambient temperature t and the set temperature t set The difference determines:
[0052] U hlm2 =u h1 +u h2
[0053] u h1 =a2·Δt
[0054] u h2 =b2·∫0 T ΔtdT
[0055] Among them, u h2 ∈[-a2Δt,U hlm1 -a2Δt], only when u h2 Integration continues only when the specified interval is within which the coefficients a2 and b2 are fixed values.
[0056] S140: Determine whether the theoretical opening value U of the secondary return air valve is greater than the minimum value MIN (U hlm1 U hlm2 If yes, then execute S150; otherwise, execute S160.
[0057] S150: Set the minimum value MIN(U) hlm1 U hlm2 The opening command value of the secondary return air valve is used to dynamically adjust the value to meet the dehumidification effect of the surface cooler, thereby ensuring the dehumidification capacity of the secondary return air system and solving the problem of poor dehumidification capacity in the existing secondary return air system.
[0058] S160: Use the theoretical opening value U of the secondary return air valve as the opening command value of the secondary return air valve.
[0059] It should be noted that since the total air volume of the second branch where the secondary return air valve is located and the first branch where the constant air volume valve is located is equal to the total air volume of the primary return air main, the opening command value of the secondary return air valve can be determined once the opening command value of the secondary return air valve is determined. This allows the ratio of primary return air to secondary return air to be determined. In other words, by dynamically determining the opening command value of the secondary return air valve, the ratio of primary return air to secondary return air can be dynamically adjusted, achieving fine control of the secondary return air valve, effectively improving the accuracy of temperature and humidity control, and reducing the cooling and heating consumption within the system unit.
[0060] S170: Collects the temperature of the mixed air in the air supply duct.
[0061] S180: Determine if the temperature of the mixed air is lower than the required temperature. If yes, proceed to S190; otherwise, keep the heating valve locked and end the process.
[0062] S190: Controls the opening of the heating valve on the air supply duct.
[0063] If the temperature of the mixed air is lower than the required temperature, it means that the current water vapor only meets the dehumidification requirement but not the temperature requirement. In this case, the heating valve is turned on to heat the mixed air to meet the requirements, thereby further optimizing the energy-saving effect of the air conditioning unit.
[0064] S1100: Clear the opening command value of the secondary return air valve to zero.
[0065] When the system does not detect a fan operation signal (i.e., the unit is in a non-operational state), or the temperature control enable is canceled (e.g., because the unit is not in cooling and dehumidification mode or the unit is not in an excessive cooling situation), the secondary return air valve command value is cleared to zero, and the relevant control parameters are initialized.
[0066] Based on the above-mentioned secondary return air control method for process air conditioning, this application also provides a secondary return air control device for process air conditioning. For example... Figure 2 As shown, the secondary return air control device for the process air conditioner includes a status acquisition module 210, an operating condition judgment module 220, a calculation module 230, and an output module 240.
[0067] The status acquisition module 210 is used to acquire the operating status of the unit.
[0068] The operating condition judgment module 220 is used to determine in real time whether the unit is in cooling and dehumidification condition and whether there is excessive cooling when the unit is running.
[0069] The calculation module 230 is used to calculate in real time the theoretical opening value and the surface cooling performance protection value of the secondary return air valve when the unit is in cooling and dehumidification mode and there is excessive cooling. It then determines the minimum value between the surface cooling performance protection value and the initial valve protection opening. The surface cooling performance protection value is the maximum opening of the secondary return air valve corresponding to the current dehumidification requirements of the surface cooler, and the initial valve protection opening is the initial maximum opening of the secondary return air valve determined by comprehensively considering hardware and system performance.
[0070] The output module 240 is used to take the minimum value as the opening command value of the secondary return air valve when the theoretical opening value of the secondary return air valve is greater than the minimum value.
[0071] Preferably, the secondary return air control device further includes a temperature acquisition module 250 and a control module 260.
[0072] The temperature acquisition module 250 is used to acquire the temperature of the mixed air.
[0073] The control module 260 is used to control the heating valve on the air supply channel to open when the temperature of the mixed air is lower than the required temperature value.
[0074] Preferably, the theoretical opening value of the secondary return air valve is determined by a scaling factor, a first proportional value, and a first integral value, wherein the first proportional value and the first integral value are determined by the difference between the current ambient temperature and the set temperature.
[0075] Preferably, the scaling factor is determined in real time by the temperature difference between the front and rear of the surface cooler.
[0076] Preferably, the surface cooling performance protection value is determined by a second proportional value and a second integral value, which are determined by the difference between the current ambient temperature and the set temperature.
[0077] Preferably, the secondary return air control device further includes a zeroing module 270, which is used to zero the opening command value of the secondary return air valve when the unit is in a non-operating state, the unit is not in a cooling and dehumidification state, or the unit does not have an excessive cooling situation.
[0078] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.
Claims
1. A method for controlling secondary return air in a process air conditioning system, characterized in that, include: The data acquisition unit's operating status; During unit operation, it is necessary to determine in real time whether the unit is in cooling and dehumidification mode and whether there is excessive cooling. If the unit is in cooling and dehumidification mode and there is excessive cooling, the theoretical opening value of the secondary return air valve and the surface cooling performance protection value are calculated in real time, and the minimum value between the surface cooling performance protection value and the initial valve protection opening is determined; wherein, the surface cooling performance protection value is the maximum opening of the secondary return air valve corresponding to meeting the current dehumidification requirements of the surface cooler, and the initial valve protection opening is the initial maximum opening of the secondary return air valve determined by comprehensively considering hardware and system performance; If the theoretical opening value of the secondary return air valve is greater than the minimum value, then the minimum value is used as the opening command value of the secondary return air valve.
2. The secondary return air control method for process air conditioning according to claim 1, characterized in that, Also includes: Collect the temperature of the mixed air; If the temperature of the mixed air is lower than the required temperature value, the heating valve on the air supply channel will be opened.
3. The secondary return air control method for process air conditioning according to claim 1, characterized in that, The theoretical opening value of the secondary return air valve is determined by a scaling factor, a first proportional value, and a first integral value. The first proportional value and the first integral value are determined by the difference between the current ambient temperature and the set temperature.
4. The secondary return air control method for process air conditioning according to claim 1, characterized in that, The surface cooling performance protection value is determined by a second proportional value and a second integral value, which are determined by the difference between the current ambient temperature and the set temperature.
5. The secondary return air control method for process air conditioning according to claim 1, characterized in that, If the unit is not in operation, is not in cooling and dehumidification mode, or is not in excessive cooling mode, then the opening command value of the secondary return air valve will be cleared to zero.
6. A secondary return air control device for a process air conditioner, characterized in that, It includes a status acquisition module, a working condition judgment module, a calculation module, and an output module; The status acquisition module is used to collect the operating status of the unit; The operating condition judgment module is used to determine in real time whether the unit is in a cooling and dehumidification condition and whether there is excessive cooling when the unit is in operation. The calculation module is used to calculate the theoretical opening value and surface cooling performance protection value of the secondary return air valve in real time when the unit is in cooling and dehumidification mode and there is excessive cooling. It also determines the minimum value between the surface cooling performance protection value and the initial valve protection opening. The surface cooling performance protection value is the maximum opening of the secondary return air valve that meets the current dehumidification requirements of the surface cooler. The initial valve protection opening is the initial maximum opening of the secondary return air valve determined by comprehensively considering hardware and system performance. The output module is used to take the minimum value as the opening command value of the secondary return air valve when the theoretical opening value of the secondary return air valve is greater than the minimum value.
7. The secondary return air control device for process air conditioning according to claim 6, characterized in that, It also includes a temperature acquisition module and a control module; The temperature acquisition module is used to acquire the temperature of the mixed air; The control module is used to control the heating valve on the air supply channel to open when the temperature of the mixed air is lower than the required temperature value.
8. The secondary return air control device for process air conditioning according to claim 6, characterized in that, The theoretical opening value of the secondary return air valve is determined by a scaling factor, a first proportional value, and a first integral value. The first proportional value and the first integral value are determined by the difference between the current ambient temperature and the set temperature.
9. The secondary return air control device for process air conditioning according to claim 6, characterized in that, The surface cooling performance protection value is determined by a second proportional value and a second integral value, which are determined by the difference between the current ambient temperature and the set temperature.
10. The secondary return air control device for process air conditioning according to claim 6, characterized in that, It also includes a zeroing module, which is used to zero the opening command value of the secondary return air valve when the unit is in a non-operating state, the unit is not in a cooling and dehumidification state, or the unit is not in an excessive cooling state.