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CN-121980694-A - Guide plate optimization design method for indoor ventilation

CN121980694ACN 121980694 ACN121980694 ACN 121980694ACN-121980694-A

Abstract

The invention discloses an optimization design method of a deflector for indoor ventilation, which comprises the following steps of giving ventilation system parameters according to conditions, solving an indoor ventilation optimization equation by utilizing a numerical method to obtain an optimal flow field corresponding to the lowest concentration of pollutants, obtaining a streamline corresponding to flow ratio parameters at an air supply outlet, and determining the shape of a final deflector according to the streamline shape and the set height. The method is suitable for any indoor ventilation system, any pollutant and any pollution source quantity, can obviously reduce the pollutant concentration of a breathing zone in a given system by arranging the guide plate, and has the advantages of simple implementation process, good performance index, good expansibility, strong practicability and the like.

Inventors

  • CHEN KAI
  • WANG SHENGJIE
  • WU XIAOLING

Assignees

  • 华南理工大学

Dates

Publication Date
20260505
Application Date
20251215

Claims (10)

  1. 1. The optimized design method of the deflector for indoor ventilation is characterized by comprising the following steps of: S1, giving indoor ventilation system parameters including the shape and size of an indoor system, physical parameters and boundary conditions of ventilation air, the number, size and pollutant release rate of indoor objects, the flow rate and inlet pollutant concentration of the ventilation air, the pump work coefficient of the ventilation air, optimization targets, flow rate proportion parameters for controlling the shape of a guide plate and the bottom end height of the guide plate; s2, solving an indoor ventilation optimization equation by adopting a numerical method to obtain an optimal flow field corresponding to the lowest pollutant concentration; S3, obtaining a streamline corresponding to the flow proportion parameter in the optimal flow field at the air supply outlet, and arranging a guide plate with the same shape as the streamline at the position of the streamline; s4, translating the guide plate upwards to enable the top end of the guide plate to be consistent with the top end of the air supply outlet, and cutting off the part of the guide plate with the height lower than the bottom end of the guide plate, wherein the guide plate is finally designed.
  2. 2. The method according to claim 1, wherein in the step S2, the indoor ventilation optimization equation includes continuity equation, momentum equation, concentration diffusion equation and lagrangian multiplier equation of the breathing zone and the non-breathing zone.
  3. 3. The method of optimizing design of a baffle for indoor ventilation according to claim 2, wherein the control equations of the breathing zone and the non-breathing zone are as follows: the continuity equation is expressed as: ; The momentum equation is expressed as: ; The concentration diffusion equation is expressed as: ; The Lagrangian multiplier equation is expressed as: ; Wherein, the 、 、 Respectively representing the air density, the effective dynamic viscosity of the air and the concentration diffusion coefficient of pollutants in the air; a velocity vector representing the air flow; the hamiltonian is represented by a graph, Indicating the divergence of the velocity field, Representing a velocity gradient; Representing pressure; Indicating the concentration of the contaminant; representing lagrangian multipliers; representing the pumping coefficient of the ventilation air; the source term representing the lagrangian multiplier equation.
  4. 4. A method of optimizing design of a baffle for indoor ventilation according to claim 3, wherein the source term of lagrangian multiplier equations for the breathing zone and the non-breathing zone is as follows: the source items of the breathing zone are: ; the source items of the non-respiratory region are: ; Wherein, the 、 Representing two reference concentrations; representing an exponential constant greater than 0.
  5. 5. The method for optimizing design of a deflector for indoor ventilation according to claim 3, wherein the boundary conditions of the concentration diffusion equation in the indoor ventilation optimization equation include: the first boundary condition is an air supply outlet, and the concentration of pollutants is 0; the second boundary condition is that the concentration gradient of the pollutant is 0, the concentration flow of the pollutant is constant, the concentration flow of the pollutant is 0, and the concentration flow of the pollutant is not pollution; Coupling boundary condition-contaminant concentration is continuous at the interface of the breathing zone and the non-breathing zone.
  6. 6. The method for optimizing design of a baffle for indoor ventilation according to claim 3, wherein the boundary conditions of the lagrangian multiplier equation include: The first boundary condition is that the value of a Lagrangian multiplier at an air supply outlet is 0; the second type of boundary conditions is that the gradient of the Lagrangian multiplier is 0 at an air outlet, and the gradient of the Lagrangian multiplier is 0 at a pollution source and a non-pollution source; coupling boundary condition-Lagrangian multiplier is continuous at the interface of the breathing zone and the non-breathing zone.
  7. 7. The method of optimizing design of an indoor ventilation-oriented baffle according to claim 4, wherein the reference concentration is in the Lagrange's multiplier equation of the breathing zone And The requirements are as follows: 。
  8. 8. The method of optimizing design of indoor ventilation-oriented baffle plate as claimed in claim 4, wherein in Lagrange's multiplier equation of the breathing zone, when the index γ is taken as 1, the average concentration of pollutants in the breathing zone is the lowest Above 5, the optimization targets the highest concentration of contaminants in the breathing zone to be the lowest.
  9. 9. The method of optimizing design of a baffle for indoor ventilation according to claim 1, wherein the flow ratio parameter controlling the shape of the baffle is greater than 0 and less than 1.
  10. 10. The method of optimizing design of an indoor ventilation-oriented baffle according to claim 1, wherein the height of the bottom end of the baffle is not lower than the highest height of the breathing zone so as not to affect the activities of indoor personnel.

Description

Guide plate optimization design method for indoor ventilation Technical Field The invention belongs to the field of indoor ventilation, and relates to an optimization design method of a deflector for indoor ventilation. Background Most of the daily life and work of people spend indoors, the indoor air quality influences the physical and mental health of people, and the good indoor air quality can ensure the physical health, work and learning efficiency of people. Indoor air pollutants are an important factor affecting indoor air quality, and an excessive pollutant concentration can harm human health, and asthma and even cancer can be caused when serious, so that people need to take measures to reduce the pollutant concentration and improve the indoor air quality. Ventilation is an effective method for reducing the concentration of pollutants, the process of removing pollutants by ventilation is a convection mass transfer process, the indoor flow field can influence the diffusion of the pollutants, and the effect of removing the pollutants by ventilation can be effectively improved by optimally designing the indoor flow field. At present, most researches obtain different indoor flow fields by changing the positions of the ventilation openings, and obtain a better design by comparing the distribution of pollutants corresponding to different flow fields. Qin et al studied the effect of the position of the air outlet on the pollutant removal effect in the impingement jet ventilation system for the intensive classrooms, and found that the indoor air quality was best when the air outlet was only arranged on the ceiling on the same side as the air supply outlet, and the pollutant removal effect was superior to the case of uniformly arranging a plurality of air outlets on the ceiling. As shown in the results, for rooms with larger space such as classrooms, the position of the air outlet is determined according to the indoor flow field, and the key is that the air outlet is arranged near the area with high pollutant concentration （Chao Qin, Yuanping He, Jian Li, Wei-Zhen Lu. Mitigation of breathing contaminants: Exhaust location optimization for indoor space with impinging jet ventilation supply [J]. Journal of Building Engineering,2023,69,106250.）.. For rented rooms or offices and other environments, a user cannot adjust the ventilation system at will, and then the indoor flow field can be changed by adjusting the indoor layout, so that the pollutant concentration is reduced. Zhuang et al studied the effect of changing the indoor furniture layout on indoor air quality given a ventilation system, compared the indoor flow fields and contaminant concentration fields for three furniture layouts, and as a result, shown that the furniture layout can affect the indoor air flow fields and the temperature fields, and the air quality of the breathing zone can be significantly improved by adjusting the furniture layout without changing the ventilation system （Ruining Zhuang, Xiangdong Li, Jiyuan Tu. CFD study of the effects of furniture layout on indoor air quality under typical office ventilation schemes [J]. Building Simulation,2014,7,263-275.）. The thought of changing the optimal design of the indoor ventilation system is that different flow fields are obtained by carrying out trial adjustment on the position of the ventilation opening or the indoor layout, pollutant removal effects of the different flow fields are compared, and finally a better result is obtained. The thinking is empirical and lacks unified theoretical guidance. Chen et al scholars analyze the relationship between the indoor flow field and the pollutant concentration field, define the mass transfer potential capacity dissipation function, take the extremum of the mass transfer potential capacity dissipation function as the optimization target, utilize the variation principle to deduce the equation that the optimal flow field should meet, then obtain the optimal flow field through numerical solution, be used for guiding scholars such as improving the indoor flow field （Qun Chen, Jianxun Ren, Zengyuan Guo. Field synergy analysis and optimization of decontamination ventilation designs [J]. International Journal of Heat and Mass Transfer,2008,51,873-881.）.Hu to take the minimum indoor SVOC average concentration as the optimization target, utilize the variation principle and numerical solution method to obtain the indoor optimal flow field, adjust the air inlet and outlet position according to the optimal flow field, the indoor SVOC concentration after optimization is reduced from 0.33 mg/m 3 to 0.23 mg/m3（Kang Hu, Qun Chen. Ventilation optimization for reduction of indoor semi-volatile organic compound concentration based on the variational principle [J]. Building and Environment,2015,94,676-682.）. In summary, the indoor flow field is optimized by using the variation optimization equation, so that the pollutant concentration can be effectively reduced, and th