相变木塑围护结构热工性能实验与数值模拟

为对相变木塑围护结构的热工性能进行研究,以相变木塑复合构件为基础制成缩尺实验箱,对箱内温度实时监测,采用辐射蓄热、对流放热的方式对相变木塑复合构件的热工性能进行了测试,得出:相变木塑墙体比普通木塑墙体有更理想的室温调节能力,光照的不足对墙体蓄、放热能力影响很大,相变木塑墙体在阴天光照条件下相比于晴天温控能力大大降低.为对相变木塑围护结构的热工性能进行改善,建立相变传热物理模型及数学模型,利用MATLAB软件进行室内温度、相变内墙与室内空气对流换热量、相变内墙表面温度的数值模拟,得出:提高材料导热系数及增大墙体对流换热强度均能改善相变木塑墙体的热工特性,随着导热系数的增加,夜间室内平均温度由15.2℃升至15.7℃,同时对流换热量和内墙温度增加,但增加幅度十分有限,随着对流换热强度的增加,夜间室内平均温度由15.2℃升至16.3℃,同时夜间相变墙体表面对流换热量显著增加,增加幅度明显,所以提高对流换热强度更具热工性能的改善潜力.

Experiment and Numerical Simulation of the Thermal Performance of Phase Change Wood-Plastic Envelopes

The reduced scale experimental box was made based on the phase change wood-plastic component to study the thermal performance of the phase change wood-plastic envelope. During the experiment,the inside temperature was monitored and the thermal performance was tested by the method of radiant heat storage and convective heat release. Some conclusions were drawn that the phase change wood-plastic wall had more ideal room temperature adjustment ability compared with the normal woodplastic wall. Insufficient light had a great influence on the heat storage capacity of the wall,and the temperature control capability on cloudy days could be significantly reduced. The physical models and mathematical models of phase change heat transfer were built to improve the thermal performance of the phase change wood-plastic envelope,and the numerical simulation of the indoor air temperature,the convection heat transfer between the phase change interior walls and the indoor air,and the phase change interior wall surface temperature were performed using MATLAB. Results show that both improving thermal conductivity and increasing the convective heat transfer coefficient can improve the thermal performance. Nighttime average indoor temperature can rise from 15. 2 ℃ to 15. 7 ℃ with the increase of the thermal conductivity,and the interior wall surface temperature and the convection heat transfer canalso rise; however,the rate of increase is small. Nighttime average indoor temperature can rise from 15. 2℃ to 16. 3 ℃ with the increase of the convective heat transfer intensity,the interior wall surface temperature and the convection heat transfer can also rise,and the rate of increase is larger; therefore,the latter has a greater potential for the improvement of the thermal performance.