Sensor Deployment Method Based On CFD Simulation:Towards Intelligent Control Of Indoor Environment

The construction industry is a large energy consumer in China and has great potential in reducing carbon emissions.Energy consumption of building operation and maintenance systems(Heating,Ventilation,lighting and other systems)accounts for an important proportion in the total energy consumption of buildings,such as HVAC(Heating,Ventilation and Air Conditioning)system,which is used to improve the indoor environment.The energy consumption of HVAC systems is about 40% of the total energy consumption of office buildings.Therefore,efficient management of building energy consumption through intelligent operation and maintenance system is conducive to reducing carbon emissions and achieving the ‘dual carbon’ goal.Sensor technology is a common method for indoor environment monitoring and control.It can obtain indoor environmental parameters through sensors,provide reference for air supply strategy and adjustment of air supply parameters,create a healthy and safe indoor environment,and effectively reduce energy consumption of ventilation and air conditioning system.Because the distribution of air pollutants in building indoor environment varies greatly in time and space,it is the core problem of sensor monitoring to accurately describe the spatial and temporal distribution of indoor physical parameters with a limited number of monitoring points.Therefore,the main purpose of this paper is to investigate the deployment strategy of sensor monitoring points to achieve efficient indoor environment monitoring and prediction,so as to provide scientific basis for the control of building ventilation system.In this work,CFD numerical simulation software is used to build the basic database of carbon dioxide concentration and airflow velocity in ventilation enclosure,and the database is built based on low-dimensional Ventilation Model.In the first step,Fuzzy C-means algorithm was used to cluster the carbon dioxide concentration and air flow velocity in the database,and the spatial distribution characteristics of carbon dioxide under the effect of air flow pattern were analyzed.The second step is to rapidly predict the unsteady process of carbon dioxide diffusion based on the diffusion characteristics obtained from the reduced order model.The main conclusions are as follows:(1)There are three main characteristic zones in the building ventilation enclosure: Main flow zone,with high air velocity and low carbon dioxide concentration;Main diffusion zone,with low air velocity,high pollutant concentration;Well-mixed zone,the air velocity and the pollutant concentration are in a relatively low level.(2)For general ventilation space,three monitoring points placed in the main characteristic areas can accurately represent the corresponding area of carbon dioxide concentration level,the maximum error is 10.7%;(3)The pollutant diffusion process can be approximately described by the main characteristic modes of the reduced order model.Twelve main characteristic modes were used in this paper.(4)The first three eigenmodes of pollutant diffusion represent three processes performing on the ventilation system:(a)The diffusion process of the carbon dioxide source,performing on the main diffusion zone;(b)The dilution process of the ventilation system,performing on the Well-mixed zone;(c)Carbon dioxide transport processes,performing on the three main characteristic regions.(5)The prediction error of carbon dioxide concentration distribution within 36 to 42 seconds based on the main characteristic modes is about 3.26%.When using the data of monitoring points to represent the distribution of carbon dioxide concentration in the 36 th second for prediction,the prediction error is 13.28%.Through investigating the spatial and temporal distribution characteristics of pollutant diffusion process,a general method for selecting monitoring points is given in this work,which provides guidance for rapid and decisive adjustment of ventilation parameters for intelligent operation and maintenance system.It aims to provide theoretical basis and engineering reference for the ventilation design of non-residential buildings such as office buildings and industrial buildings in improving indoor air quality and reducing ventilation energy consumption.