The Research Of Energy-saving Roof That Combined Phase Change Materials And Reflective Thermal Insulation Coatings

Phase change materials(PCM) and reflective thermal insulation coatings used in construction field not only can effectively reduce energy consumption of buildings, but also can improve indoor thermal comfort. This paper aims to study a kind of energy-saving roof combined PCM and reflective thermal insulation coatings.The study included the development of new PCM and encapsulating method, the design and construction scheme of energy-saving roof, the experiment and analysis of full-scale rooms, and the establishment of Trnsys heat transfer models, etc.At first, we expounded the thermal insulation theory of the energy-saving roof. Then the appropriate reflective thermal insulation coatings have been choosed according to relevant specifications, and suitable PCM have been made up, senior fatty acid and high carbon alcohol as raw material, based on the theory of eutectic mixture and differential scanning calorimetry(DSC). And an encapsulating devices, PE-RT pipe and pipe fittings with thermal connection, have been designed to meet the request for utilization of PCM. The design and construction method of the roof have been confirmed based on the thermal insulation theory of the energy-saving roof. The roof structure was base layer, waterproof layer, binding mortar layer, PCM layer, anti-crack mortar layer and reflective thermal insulation coatings layer, from the inside to the outside. Three full-scale rooms were built, 1#(PCM roof), 2#(CR roof), and 3#(PCR roof), to test and analysize the thermal properties of energy-saving roof. The outdoor climate parameters, the roof temperature and heat flow and other parameters were tested under the condition of closed door and window. Comparative study shows that the energy-saving roof comparied with other roofs, the peak internal surface temperature reduce about 0.26℃~0.58℃, the peak internal surface heat flux reduce about 1.28W/m2~2.85W/m2, the correlation coefficient between internal surface temperature and outdoor temperature/solar radiation reduce about 4.36%~50.48%. It has been proved that the energy-saving roof not only has good heat insulation effect, but also has good ability of shielding the the impact of outside world.An energy-saving roof heat transfer model is established based on Trnsys to make up for the experimental limitations and guide the design and research work. It can be found that the consistency degree between the simulated values and measured values lies in 91.94%~97.22%, which means that the established model has higher accuracy, from the results of error analysis and B-A consistency analysis. Finally, the heat transfer conditions of an ordinary roof were simulated using the established model. It can be found that the daily transfer heat of the energy-saving roof was averagely lower than the ordinary roof about 17.89%.