Study On Heat And Humidity Transfer Process Of The Moist Ceramic Particle Roof

As the main intersection between the building and the nature,roof is also the main receiving surface of the solar radiation and the rainfall.The principle of the moist ceramic particle roof is that moist roof can be act as a heat insulator,that is to say,when it is raining,the ceramic particle stores water and when it becoming sunny the water in the material can be evaporated which will take plenty of latent heat out of the roof.This process which will keep the roof in a low temperature level can not only protect the roof from intense solar radiation and the high outdoor temperature but also can prolong the service-life of the waterproof layer.In addition,this kind of roof can also release the pressure of city's rain exhaust system in a certain extent.In a word,the moist ceramic particle roof is helpful to make the building in harmony with the nature.Initialed from the insulation principle analysis on several passive evaporation insulation roof, this paper detailedly discussed the heat and humidity transfer process in the moist ceramic particle roof.In the analysis,the influence of the humidity to the temperature is simplified as the change of the equivalent thermal diffusivityα₂ with the average moisture content of the ceramic particle. Based on the roof's heat transfer process,the heat transfer equations and its corresponding boundary conditions of the moist ceramic particle roof and a common roof are established.The governing equation and boundary conditions are separated by the finite difference method.The heat and humidity transfer process in the moist ceramic particle roof is a coupling process under many kinds of mechanism,and it is very complex to fully and accurately describe it.Therefore, two experimental rooms and two contrast rooms have been built to investigate this problem. Experiment are carried out during July 23 to August 5 in the year 2007 in above rooms.By the analysis of the test results,the following conclusions are obtained:â‘ The indoor air temperature of the test room laying ceramic particle are lower than the common contrast room in any weather conditions,and the daily maximum temperature difference up to 2℃;â‘¡The inside surface temperature of the test room is basically lower than the common contrast room,and the maximum temperature difference up to 3.4℃;â‘¢The change of the outside surface synthetical temperature of the test room is basically consistent with the corresponding contrast room,besides that the ceramic surface temperature of the test room is obviously lower than the outer surface temperature of the contrast room.The maximum temperature difference of the peak time up to 30.2℃and the maximum temperature difference of the foot time up to 6.8℃. Finally,according to the theoretical separating result and the test value of the indoor & outer air temperature,the predicted value of the outside surface synthetical temperature and the inside surface temperature about the above roofs are simulated by the MATLAB language program.The results coincide well with each other which confirmed the accuracy of the governing equations,the boundary conditions and relative parameters.This results can provide a theoretical basis for the quantitative study of the moist ceramic particle roof's heat and humidity transfer process.