Research On Phase Change Energy Storage Building Wall Thermal Properties And Suitability Assessment

At present, the building energy consumption has accounted for about 30% of the social total energy consumption, building energy efficiency is becoming more and more important, building external wall thermal insulation is the important way to realize energy saving. But there are problems such as short service life,fire retardancy,etc. Phase change energy storage wall as a new type of energy-saving wall, has superior thermal control effect, better stability, and long service life,etc. Research on phase change wall to promote the development of wall energy saving technology and application is of great significance. Formulation and mixture of paraffin composite phase change materials, the preparation technology of phase change energy storage ceramsite, phase change energy storage ceramsite, phase change energy storage mortar and wall thermal properties, propriate phase change temperatures of different orientation walls were studied by experiments and numerical simulation,and the applicability of the phase change wall was evaluated, the main conclusions are as follows:(1) After two kinds of paraffin composite phase change materials of formula, the mixture ratio design and DSC test, the formula of paraffin composite phase change materials and the mixture ratio were determined, and negative pressure adsorption at low temperature phase change energy storage ceramsite preparation technology was determined through experimental research. The portland cement package ceramsite topical styrene acrylic emulsion encapsulation technology of encapsulation was optimizedly determined through high temperature leakage test from four kinds of encapsulation process optimization.(2) The influence on the thermal conductivity, specific heat, compressive strength, density of phase change energy storage mortar under the condition of different dosage of phase change ceramsite was experimentally studied. Thermal conductivity, compressive strength, density decrease with the phase change ceramsite increasing, but specific heat increacses with the increasing of the phase change ceramsite.(3) Use outdoor air synthetic temperature as the boundary conditions and consider the influence of different towards sun radiation othernesses of appropriate phase change temperature of the wall. And take the typical city nanjing as an example in hot summer and cold winter zone. The temperature distribution of different orientation walls was simulated by ANSYS. The appropriate phase change temperatures in air conditioning season of the east, west, south, north four orientation walls were determined, respectively, 33.3℃, 35.36℃, 33.3℃and 30.3℃.(4) The thermal performances of phase change energy storage wall and ordinary mortar wall of the same thickness were measured through the contrast test. The outdoor temperature wave delay time of phase change wall and ordinary mortar wall were 10.3 h,5.6 h,and their attenuation coefficients were 0.08, 0.179. The internal surface average heat flux density of two kinds of wall was respectively 6.4 W/m2, 9.2 W/m2. The average heat transfer coefficients of phase change energy storage wall and ordinary mortar wall were respectively 0.642 W/(m2·K), 1.86 W/(m2·K). The thermal performances of phase change wall are superior to ordinary mortar wall’s.(5) The suitability evaluation model of the wall containning four factors: the energy saving, efficiency, fireproof performance and the construction difficulty applicability was established by applying the analytic hierarchy process(AHP), and three types of wall thermal insulation systems------phase change wall, extruded polystyrene board and rock wool composite wall thermal insulation system with the same coefficient of heat transfer have been carried on the suitability evaluation, the results show that the comprehensive performances of phase change wall are better than the other two kinds of walls.