An improved cluster thermal time constant(CTTC) and surface thermal time constant(STTC) numerical model was introduced,which took into account the effect of vegetation coverage and modified the expression of net longw...An improved cluster thermal time constant(CTTC) and surface thermal time constant(STTC) numerical model was introduced,which took into account the effect of vegetation coverage and modified the expression of net longwave radiation of the canyon layer.In the case study the model was used to calculate the air temperature variation at downtown of Tianjin City.The relative error between the calculated and measured air temperatures was less than 3%.The tendency of air temperature variation was predicted when the building aspect ratio,vegetation rate,and wind speed changed respectively.It is demonstrated that when the aspect ratio of a building with south-north orientation increased,the heat island intensity at day time was mitigated;however,it became worse after sunset.The vegetation coverage rate and wind speed both had negative relationship with the urban heat island intensity.展开更多
根据建筑群热时间常数(Cluster Thermal Time Constant,CTTC)模型,分别对黑白屋顶吸收辐射所引起的不同温升效果进行了模拟计算。结果显示:(1)屋顶对天空的长波辐射引起的温降远小于屋顶吸收辐射所引起的温升;(2)不同吸收率的黑白屋顶...根据建筑群热时间常数(Cluster Thermal Time Constant,CTTC)模型,分别对黑白屋顶吸收辐射所引起的不同温升效果进行了模拟计算。结果显示:(1)屋顶对天空的长波辐射引起的温降远小于屋顶吸收辐射所引起的温升;(2)不同吸收率的黑白屋顶的温升效果差异比较明显。本文的研究表明:"白屋顶"计划对降低城市热岛效应确有一定程度的作用。展开更多
文摘An improved cluster thermal time constant(CTTC) and surface thermal time constant(STTC) numerical model was introduced,which took into account the effect of vegetation coverage and modified the expression of net longwave radiation of the canyon layer.In the case study the model was used to calculate the air temperature variation at downtown of Tianjin City.The relative error between the calculated and measured air temperatures was less than 3%.The tendency of air temperature variation was predicted when the building aspect ratio,vegetation rate,and wind speed changed respectively.It is demonstrated that when the aspect ratio of a building with south-north orientation increased,the heat island intensity at day time was mitigated;however,it became worse after sunset.The vegetation coverage rate and wind speed both had negative relationship with the urban heat island intensity.
文摘根据建筑群热时间常数(Cluster Thermal Time Constant,CTTC)模型,分别对黑白屋顶吸收辐射所引起的不同温升效果进行了模拟计算。结果显示:(1)屋顶对天空的长波辐射引起的温降远小于屋顶吸收辐射所引起的温升;(2)不同吸收率的黑白屋顶的温升效果差异比较明显。本文的研究表明:"白屋顶"计划对降低城市热岛效应确有一定程度的作用。
