新型相变坡屋顶隔热结构传热分析

Analysis of heat transfer in the heat insulation structure of new phase-change roofs

建立相变与普通坡屋顶结构的三维物理模型与数学模型,分析在夏季室外综合温度作用下的热工特性,得到从初始阶段过渡到稳定阶段时间内上、下表面的平均温度逐时分布曲线,以及稳定阶段下表面的平均温度及平均热流密度24h逐时分布曲线.结果表明:相变屋顶下表面平均温度及平均热流密度波动的幅值比普通坡屋顶分别降低92.2%和92.3%,添加相变材料可以提高坡屋顶结构的热惰性及隔热性能,加强坡屋顶对夏季室外气温波动的衰减能力,使坡屋顶下表面的平均温度及平均热流密度的逐时分布更加平缓,并维持在相对较低的水平,从而提高室内的热舒适度和降低空调恒温模式下的制冷能耗.

The three-dimensional physical and mathematical models of phase change roof and common roof which were two different sloping roof structures were established, and the thermal performance of them under summer outside air comprehensive temperature was analyzed, the hourly distribution of top and bottom surface average temperature from initial stage to steady stage and 24-hour hourly distribution of average temperature and average heat flux of bottom surface in steady stage were also got. Research result showed: The fluctuation amplitude of bottom surface average temperature and bottom surface average heat flux of phase change roof decreased by 92.2% and 92.3% respectively compared to that of common roof, addition of phase change material could observably improve- thermal inertia and heat insulation performance of sloping roof structures, strengthen attenuation capacity of sloping roof to atmospheric temperature fluctuation, make the hourly distribution of average temperature and average heat flux of roof bottom surface more gradual and relatively lower, accordingly improve indoor- thermal comfort and reduce the cooling energy consumption of air-conditioning under the constant temperature mode effectively.