Ventilation Optimal Design Under The Conditions Of Indoor Occupants’ Walking And Numbers Varying

Background:People spend about 90%of their time in enclosed environments.For special indoor environments where calls for high cleanliness,such as operating room,bio-clean treatment unit,nurseries,etc.,the impact of human activity factors on the spread of indoor contaminants should be considered to enhance the personal protection of weakly immune populations.Current researches on IAQ show that indoor human activities have strong influence on surrounding air flow and affect the distribution of indoor pollutants.The application of dynamic mesh simulation method has been widely applied for objects’ moving,which is not CPU-friendly in calculation as well as complex meshing required.In addition,due to the uncertainty of the numbers and locations of indoor personnel,the demand for ventilation should be changed.However,traditional ventilation systems could not adjust the ventilation system according to indoor demands,which would result "over-ventilation" or "insufficiency of ventilation".Therefore,ventilation control strategy decided by indoor human factors has important research significance for removing indoor pollutants,improving indoor air quality,and reducing building energy consumption.Methods&Main topics:In our study,the influence of two conditions of human activities on the indoor pollutants,distribution were studied.Firstly,the momentum source method was proposed for studying the influence of movement of human on the distribution of indoor particulate matters.Next,the effect of indoor locations and numbers on indoor CO2 distribution was studied.The combination of CFD and artificial neural network was used to predict the indoor CO2 concentration distribution for optimizing the indoor ventilation system.Main conclusions:Momentum source method applied for the simulating human walking on indoor pollutant distribution(1)The CFD numerical results in this paper are agreed well with the experimental results.The maximum error is controlled within 5%.(2)Compared with dynamic mesh method,using the momentum source method could save 40%～90%calculation cost for investigating the influence of human walking on indoor airflow and pollutant diffusion.Momentum source method could also be applied for the numerical simulation of piston wind caused by subway’s moving in tunnel.(3)Human’s walking has a relatively short impact on the surrounding air flow,and the changed airflow would affect the transportation of the contaminants indoors.Ventilation simulation and optimization under occupants’ numbers varying(1)The error of prediction results and numerical simulation results kept within 6%.(2)The linear ventilation model of pollutants could reduce numerical simulation examples and provide theoretical support for the optimization of ventilation under the conditions of the distribution of complex pollution sources.Research significance:In this study,the momentum source method was applied for simulating the impact of moving objects on the surrounding airflow patterns,which reduced the calculation costs and provided a new method for indoor airflow distribution.The CFD and neural network were combined for predicting the concentration of indoor contaminants to complete the indoor demand ventilation system,which means it has done some theoretical research for DCV.