Effect Of The Cooled Ceiling On Pollutant Concentrations In Rooms With Cooled Ceiling And Displacement Ventilation Combined Systems

A combined cooled ceiling(CC) and displacement ventilation(DV) system has the advantages of both displacement ventilation in enhancing indoor air quality and cooled ceiling in improving indoor thermal comfort,to some extent,such a system is also beneficial to energy conservation.As one of the prime pollutants indoors,CO₂ can deteriorate indoor air quality.Therefore,exploring the transportation and distribution of CO₂ could give some advises for improving indoor air quality.The indoor airflow pattern,the temperature field and indoor CO2 concentration distribution in a displacement ventilation room are simulated and analyzed by employing a computational fluid dynamic(CFD) model under different working conditions.In order to investigate and analyze the indoor air quality and thermal environment in CC/DV rooms,two different heat resources were considered,and the load accounted by the cooled ceiling is varied.The result shows that the load accounted by the cooled ceiling exists a minimum percentage,the indoor concentration arrives the minimum value under this percentage.A numerical simulation has been carried out to explore the relation between the indoor air quality and the variation of the operating parameters of DV systems such as supply air temperatures and inlet velocities.The results indicate that the displacement ventilation has great influences on indoor CO₂ concentration distribution.The numerical method employed can be considered as a reference for indoor air quality control in a displacement ventilation room.In addition,it can also be used to find appropriate strategies for optimizing the indoor airflow patterns.