Research On Performance Of Floor Radiant Cooling Coupled With Displacement Ventilation System

Buildings’ comfortable indoor environment is one of the important standards for people’s high quality of life.However,traditional HVAC systems are increasingly inadequate to meet people’s requirements for buildings’ indoor environment.Floor radiant cooling coupled with displacement ventilation system which hereinafter referred to as the composite system has gradually caught HVAC workers’ attention as a new air-conditioning system,and has been applied to some buildings with good results.In this paper,the regulation effect of the composite system on indoor thermal environment of ordinary small space and large space buildings such as waiting hall is studied by means of experiment and numerical simulation.The specific research contents and main results are as follows:First of all,the experimental platform of the composite system is built to explore the regulation characteristics of the composite system on the indoor thermal and humid environment of small-space buildings from five aspects: indoor temperature field,speed field,surface temperature of enclosure structure,human thermal comfort and anti-condensation effect.The experimental results show that the addition of the displacement ventilation system can effectively improve the condensation of the radiant floor,and the composite system has a better adjustment effect on the indoor thermal environment of small-space buildings than the conventional up-supply down-return air-conditioning systems as well as better human thermal comfort.Secondly,in order to explore whether the composite system also has excellent performance in large-space buildings like waiting halls,a certain railway station waiting hall is selected as the research object,and Energy Plus is used to calculate its cooling load and determine floor radiation and displacement ventilation parameters.On this basis,a numerical model of the composite system of the waiting hall based on Fluent is established,and the influence of parameters such as outlet,inlet,air supply temperature,air supply speed and floor temperature on the indoor temperature field of the waiting hall under eleven different working conditions is analyzed.The purpose of this paper is to explore the regulation effect of composite system on the thermal environment of large space buildings such as waiting hall.As the simulation results show,the better thermal environment of the waiting room can be created under this conditions:outlet are arranged vertically above the passengers in the two waiting areas,inlet size of 1.2m×0.79 m,0.3m/s air supply speed,273.6K supply air temperature and 297 K floor temperature over the two waiting areas.Finally,it compares and analyzes the adjustment effect of the composite system and the conventional up-supply down-return airconditioning systems on the large-space building environment of the waiting hall under the above-mentioned better working conditions.The simulation results indicate that in the large-space buildings represented by the waiting hall of the railway station,the composite system has a preferable ability to adjust the environmental heat and humidity,and the thermal comfort of the human body is better than that of the conventional up-supply down-return air-conditioning systems.