Roof Radiation Composite Displacement Ventilation Cooling System Thermal Environment Simulation,

Radiation cooling system, with low operating cost, can provide excellent indoor thermal environment. Displacement ventilation with high ventilation efficiency, can provide high indoor air quality. Reasonable combination of both can make best use of the advantages and bypass the disadvantages. Also it has a good energy saving effect. Therefore, as a new air conditioning, roof radiant cooling and displacement ventilation air conditioning system has caused more and more attention at home and abroad. This paper established a mathematical model of composite system and used FLUENT software to do some related calculations.First, in order to compare the indoor thermal environmental status under the combination of displacement ventilation and radiant cooling variables which include ceiling, floor and wall, this thesis aims to establish an indoor numerical model for cooling system, and to conduct different cooling numerical simulations with the help of DTRM radiant model. The comparison of indoor vertical temperature difference, blowing sense, PMV-PPD index and energy use efficiency shows that under the same parameters, ceiling radiant cooling system holds the best thermal comfort index, while radiant floor cooling system, which holds the poorest thermal comfort index, is the most efficient in terms of energy use. The calculation in the thesis provides certain theoretial proof to the reasonable optimization of different systems.Indoor thermal environmental conditions of separate displacement ventilation, separate roof radiant cooling and the two combined systems were campared here. The comparison of indoor vertical temperature difference, energy use efficiency, PMV-PPD index shows that separate system can meet the cooling requirements when the load is small but only the composite system can meet the requirement of good indoor thermal comfort in the case of large load. Then, this article analyzed the impact of the composite system cooling parameters such as roof temperature, air temperature and air speed on indoor air quality and thermal comfort of human body. Air parameter change influenced more on the workspace.According to the cooling characteristics of composite system, the analysis of the system for applicability, energy consumption and economy shows that composite system can be put into effect efficiently in general civil construction such as rooms, offices, residentials and schools and has great energy potential.The results of this work are significant for roof radiant cooling and displacement ventilation system design, application and promotion.