Research On The Influence Of The Structure Of Micro-porous Radiation Metal Panel On The Heat Transfer Characteristics

Micro-porous metal roof radiant air-conditioning system is a new form of radiant air-conditioning system,which uses air as the energy carrier and combines the radiation heat transfer with convection heat transfer.It is more energy efficient and comfortable than the traditional radiant air-conditioning.The plenum chamber constructed by micro-porous panels and walls is the heat-storage place of this radiant air-conditioning system,its heat transfer capability have direct effect on the heat transfer efficiency between the micro-porous metal roof radiant air-conditioning system and the indoor.Effects of the plenum chamber structure on the flow and heat transfer characteristics of the carrying-energy air are studied in this dissertation.In this dissertation,the flow and heat transfer characteristics of the plenum chamber are theoretically analyzed.The supply air velocity and temperature,geometric structure of the plenum chamber,the orifice rate and diameter of micro-porous panel,panel materials are the significant factors on the heat transfer and flow characteristics of the carrying-energy in the plenum chamber.At the same time,the influence of metal material's performance on heat transfer and the installation method of the pore panels are analyzed,it is concluded that the aluminum materials is the most suitable for micro-porous metal panel under considering all factors.In order to obtain the temperature distribution inside the plenum chamber,the temperature distribution of the pore panels and the discharge of the air,the lab platform for heat transfer of the micro-porous metal roof radiant air-conditioning system is designed and built.The experiment is conducted on the supply air temperature of 12?,the supply air volume of 510m3/h from 680m3/h respectively in summer.The experiment results indicate the temperature distribution inside the plenum is more uniform,the temperature difference is less than 2 ?.The temperature distribution of the panel is not uniform,The maximum temperature difference is about 2.5 ?.The volume of air entering the air-conditioning zone is about 2% of the amount of the supply air,the ventilation frequency is 0.68h-1 and 0.52h-1 respectively,and the amountof air that is not enough to provide the amount of air necessary to provide a room for the amount of air,therefore the independent fresh air inlet is needed.And then,the flow and heat transfer characteristics of the carrying-energy air in the plenum chamber are studied by using CFD numerical simulation,and the conclusion of the numerical simulation is consistent with the experimental results.The flow and heat transfer characteristics of the carrying-energy air in the plenum chamber during the different types of panel,different heights and different pore sizes are studied by numerical simulation in this dissertation.The heat transfer efficiency of the micro-porous metal roof radiant air conditioning system is the best by comprehensive consideration.The heat transfer efficiency is the best of 350 mm compared to the heat transfer and flow in the plenum chamber of 300 mm,350mm,400 mm,450mm and 500 mm.Compared to the heat transfer efficiency of the same orifice rate under different diameter of2 mm,3mm,4mm,it is concluded that the heat transfer effect of the diameter of 2mm is better.Through the above research which can provide theoretical support and experimental basis for the design of the roof plenum chamber,it is significant to promote the application of the micro-porous metal roof radiant air-conditioning system.