Simulation And Experimental Study Of Radiant Cooling/Heating Combined With Dedicated Outdoor Air Supply Systems

With the development of new HVAC technologies,the high temperature radiant cooling combined with displacement ventilation air conditioning system has been used in China,while the heating system is also spread.However,neither the traditional convection heating system or radiant heating system in the winter without fresh air supply.As a result,many issues appear such as hypoxia,high temperature and low humidity and health non-compliance.It can not meet a comfortable and healthy indoor environment in modern building.Therefore,this article will explore the radiant heating combining the high-temperature radiant cooling with displacement ventilation systems in the winter,while displacement ventilation system provides fresh air for indoor conditions.CFD simulation is used for radiant heating system and displacement ventilation composite system under different installation methods.It focuses on comparative analysis of the temperature and humidity stratification and the comfort in winter roof radiation,radiant floor and wall radiation.It vertifies the correctness and reliability of the results through simulation experiments.In this paper,we build a mathematical model to study the velocity field,temperature and humidity field and the indoor comfort in College of Urban Construction,in Wuhan University of Science and Technology.Setting the design parameters of indoor air according to the heat load and the indoor comfort of air-conditioning room in winter in Wuhan.Simulation is used for the velocity field,the temperature and humidity field of work area around the body body according to air temperature,relative humidity wall temperature of 5 kinds of working conditions.indices GB50736-2012 given draw comfort optimal conditions.It draws the most comfortable condition according to the thermal comfort indices PPD-PMV which combined with ISO7730 and “civil heating,ventilation and air conditioning design specifications" GB50736-2012.The result shows that the displacement ventilation air velocity is 0.15 m / s air temperature is 19 ~ 20 ?,relative air humidity is 50% in winter.It meets the requirements that the temperature difference is less than 3 ?in vertical direction from 0.1m to 1.1m when the surface temperature of low-temperature radiant heating wall is 25 ?.On this basis,this paper comparative studies the low-temperature radiant floor heating and low temperature radiant ceiling heating which respectively combined with displacement ventilation composite system.The result shows that the comfort is highest when combined the radiant floor heating system with the displacement ventilation system composite of three systems in the same conditions and boundary conditions,followed by radiation wall and the ceiling radiation is worst.This paper studies the temperature field and relative humidity field in wall,floor and ceiling radiant cooling combined with the displacement ventilation system composite on radiant cooling condition,and calculating the indoor dew point temperature.The result shows that the three systems does not appear condensation which justifying the reasonable parameters can avoid condensation in radiant cooling system.It is significant of the result in this study to improve the indoor comfort and the air quality in heating season and it can provide a reference design and theoretical basis for low temperature wall heating and displacement ventilation composite application.