Solar Energy Heating Study On The Light Weight Building Made By Phase Change Material Wall In The Qingzang Altiplano North Area

A great deal of dispersible sentry, soldier barrack and unaided barracks quarter at the northern region of Qinghai and Tibet plateau; it is lengthy and extreme cold in winter. The consumption of equipmentses, materials and fuels for heating are very big in winter.Because of being unsuitable for the energy efficiency concentrated type heating way,many dispersible type barracks mainly adopt the independent fuel boiler heating facilities.Some sentry even do not adopt heating systems,which severity endanger the life safety of soldiers.The solar radiation energy is the most important influence factor to the building indoor environment.The northern region of Qinghai and Tibet plateau is most rich region for solar energy resources in our country, so it is a very important energy efficiency way to exploit the solar energy for heating in the dispersible sentry, soldier barrack and unaided barracks.Due to the scurvinessc transportation condition, high building material conveyance cost, and short construction period it is difficult to adopt the tradition construct way, also the construction quality has been hard to get a good control.The lightweight building has been developed quickly in recent years, particularly light steel structure building, which has become new building structure pattern to apply and develop currently at home and abroad. Due to having a quick construction speed, the well anti-vibration capability, less foundation expenses, beauty building shape, less building material and steel use, high recycle utilization advantage, the lightweight building extensively is used for kinds of industrial building, the civil building and public building. Especially in some low layers construct with a special request, the advantages of the lightweight constructs is more obvious, for example troops barracks sentry, the soldier barrack and greatly crosses building etc. But the lightweight constructs cannot attain the request of related building energy efficiency standard because the cumulate thermal capability of light weight structure is weak and whole thermal inertia is bad. Some scholars definitely have put forward that the common lightweight construct was unwell used for passive solar building technique.Because of the high cumulate thermal density and the light weight, compared with obvious thermal material (concrete and brick.etc.), the Phase Change Materia(lPCM) will reduce the request of construct and structure strength of building. Be applied to lightweight building fabric, PCM can increase the cumulate thermal capability of lightweight fabric and improves the thermal capability of lightweight constructs, and make the whole thermal inertia index to attain the request of energy efficiency standard. In the meantime it will be one of the effective paths that improve the indoor thermal environment quality in light weight building. Up to now, using PCM in building materials has been limited by many difficulty,such as: lack of the making and characteristic research on PCM appling to the fabric structure material; at the time of satisfying using request, how to make sure the fabric combinative form of easy construction; how to evaluate the effect of PCM using under different conditions, such as phase change material temperature, thickness, insulation thickness and night ventilation in different climate area and incorporating the PCM into the wallboard,lack of design theories research and engineering fulfillment at different weather characteristic region lightweight etc.According to above-mentioned analysis of foreground and existence problem for PCM using in the fabric, combining passive solar house technique the thesis developed the technique application study that utilize PCM to improve the fabric thermal characters and indoor temperature environment in lightweight building:①Build up the non-steady heat conduction mathematics model for phase change fabric, and carry on the numerical analysisHeat conduction of phase change is strong nonlinear mathematics problem; many literatures had already proven that there is no accurate solution for the kind of phase change heat conduction problem through the limited thickness flat panel of fabric. In the meantime the approximate method is more difficult to solve this kind of problem and inapplicable for engineering, but the numerical method is more effective means to handle this problem. The thesis analyzed the heat conduction characteristic for phase change fabric, established the mathematics models of the phase change heat conduction and indoor air heat balance of PCM room, ulteriorly dispersed the equations and carried on the numerical calculation with the limited different method, this work would provide the calculation and analysis means for the design of phase change fabric and building energy efficiency application.②Put up the research of nature convective heat transfer model for phase change fabric passive solar house(Trombe),and carry on the numerical analysisThesis had carried on the simulation researches on the heat transfer and air convective heat exchange in the PCM fabric trombe passive solar building, and builds the mathematic model on the air flow and heat exchange. Adopted the finite difference method to disperse the equations and solved the differential system of equations with the Semi-Implicit iterative Method.It could provide the credible theory and powerful calculative tools for stimulating and forecasting the indoor thermal environment of PCM lightweight fabric passive solar building.③Prepare new-style PCM and complete the structure design for PCM lightweight fabric.We had made the compound PCM of fatty acids and salts by the sol-gel method in this paper, which utilizes the silicon dioxide as the carrier. We had Adopted the PCM grain or plank as the cumulate thermal function layer, and the silicon and calcium fiberboard or lightweight metal plank as the wall structure support layer, and EPS and mineral thermal insulation material.etc.as the thermal insulation function layer, and finally had completed kinds of the cumulate thermal function layer + thermal insulation function layer + structure layer" structure design and making for fabric.④Establish PCM lightweight fabric experiment, carry on the identification for the usefulness of modelRespectively we had constructed the PCM lightweight fabric experiment chambers at Xining region (passive solar building condition in winter), test the inner surface and indoor air temperature in the lightweight fabric chambers, and carried on contrast verification with the calculation results of theories models.⑤Put forward the evaluation indexes for PCM lightweight wall usage effect on the condition of heat insulation and passive solar heatingCombining the characteristic of charging and discharging thermal capability of the PCM lightweight fabric and usage effect, we had established the usage effect evaluation indexes, that is the"Accumulative Excursion for Indoor Air Temperature in One Day—I EX"for passive solar heating on the PCM lightweight building.⑥Combining the passive solar energy technique, optimizing the structure form of PCM lightweight fabricUtilizing the mathematics model certificated, we had carried on the optimization analysis for applying the PCM passive solar technique in Xining zone. Carry on the simulation of many factors with many levels for the influence parameters on the indoor air temperature in the PCM lightweight passive solar building. Finally we had made sure the optimization structure forms of PCM lightweight fabric that could be applicable to the passive solar building in the the northern region of Qinghai and Tibet plateau. The optimization results could be as the passive solar building fabric design project.⑦Engineering designUtilizing the above-mentioned analytical results, we had constructed the PCM lightweight fabric building in Xining and Yushu, and analyzed and test the indoor thermal environment. The results had indicated that PCM can improve the indoor thermal environment quality in light weight building in winter, and improve the thermal capability of lightweight constructs, and attain the preferable effect of energy efficiency .In conclusion, the thesis developed the application study on making use of the PCM fabric to improve the thermal characteristic of fabric and indoor thermal environment in the lightweight passive solar building. Paper established the model of phase change heat transfer and the indoor air temperature thermal equilibrium. Put forward the evaluation index for PCM lightweight wall usage effect in passive solar building. The thesis carried on the scientific and exact analysis to the influence factors of the PCM application. Commanded the PCM apply regulation on the lightweight building fabric, and developed the engineering fulfillment. Parts of conclusions of thesis lay the initial theories foundation for carrying on reasonable design and application of PCM fabric in the lightweight passive solar building building and implementing the preferable economy energy effect.