南京地区外保温墙体保温层经济厚度分析

Analysis on optimum insulation thickness of external thermal insulation walls in Nanjing zone

针对当前保温材料经济厚度的研究中通常采用的稳态或非稳态传热计算方法存在不精确、未考虑湿传递、太阳辐射等问题,采用以温度和相对湿度为计算驱动势的一维墙体热湿耦合传递模型,以南京典型气象年的逐时气象参数(包括温度、相对湿度、太阳辐射强度)为室外边界条件,恒温恒湿工况为室内边界条件,对南京地区外保温墙体进行了热湿耦合传递模拟.结果表明,在南京地区的环境下,忽略湿传递的影响会对外保温墙体的全年传热量产生约2.74%~ 6.53%的偏差.通过对南京地区外保温墙体常见的3种保温材料进行热湿耦合传递模拟,并使用P1-P2经济学模型,对比分析了膨胀聚苯板(EPS)、聚氨酯泡沫(PU)、挤塑聚苯板(XPS)3种保温材料的外保温墙体的经济性,得出了3种材料的经济厚度分别为69.8、39.8 和49.7 mm,投资回收期聚氨酯泡沫最长,挤塑聚苯板次之,膨胀聚苯板最短.

At present, the calculation methods of steady-state or unsteady-state heat transfer for studying optimum thickness of thermal insulation layers were inaccurate without considering the effects of moisture transfer and solar radiation. A coupled heat and moisture transfer model for one-dimensional walls, with temperature and relative humidity as the driving forces, was used to simulate the heat and moisture transfer situation of the external thermal insulation walls in Nanjing. Hourly meteorological data including temperature, relative humidity and solar radiation intensity of a typical meteorological year in Nanjing was taken as outdoor boundary conditions, while the constant temperature and the humidity were taken as indoor boundary conditions. The results show that neglecting the effect of moisture transfer in Nanjing can result in a deviation of about 2.74% to 6.53% in the annual heat transfer calculation of external thermal insulation walls. The heat and moisture transfer simulation of three kinds of common insulation materials for external thermal insulation walls in Nanjing is carried out. The P1-P2 economic model is used to analyze and compare the economic efficiency of the external thermal insulation wall of three kinds of insulation materials, such as expanded polystyrene (EPS), polyurethane (PU) and extruded polystyrene (XPS). The optimum thicknesses of the three materials are 69.8, 39.8 and 49.7 mm. The payback period of PU is the longest, followed by XPS and EPS.