Scaled outdoor experimental studies of urban thermal environment in street canyon models with various aspect ratios and thermal storage
Scaled outdoor experimental studies of urban thermal environment in street canyon models with various aspect ratios and thermal storage
复制标题
不同纵横比和蓄热街道峡谷模型中城市热环境的室外规模实验研究
DOI：
10.1016/j.scitotenv.2020.138147
复制
发表时间：
2020-07-15
影响因子：
9.8
通讯作者：
Wang, Kai
中科院分区：
文献类型：
--
作者：
Chen, Guanwen;Wang, Dongyang;Wang, Kai
街道宽高比和城市蓄热在很大程度上决定了城市的热环境。通过2017年夏季广州地区的室外尺度测量，研究了这些因素对城市热环境时空特征的影响。研究了两种类型的街道峡谷模型，即类似于空心混凝土建筑的“空心”模型和由填满沙子的建筑组成的“砂”模型，它们具有更大的储热能力。对于每个模型，考虑三个街道宽高比（建筑高度/街道宽度，H/W = 1,2,3; H = 1.2 m）。观测了不同情况下空气壁表面温度的日变化，并对其特征进行了量化。不同长径比和蓄热量对墙温日平均温度和日温差影响显著。在白天，较宽的街道峡谷（H/W = 1），遮阳面积较少，其温度高于较窄的街道峡谷（H/W = 2,3），因为壁面接收到更多的太阳辐射。在夜间，较宽的街道峡谷由于较强的向上长波辐射和夜间通风而冷却得更快。对于空心模型，H/W = 1的DTR为12.1℃，比H/W = 2,3的DTR分别高1.2℃和2.1℃。与空心模型相比，砂模型的DTR更小，壁面温度变化率更小，这是因为较大的储热量在白天吸收更多的热量，在夜间释放更多的热量。H/W = 1、2、3时空心模型的DTR分别比砂模型大4.5、4.6、3.8℃。对于空心和沙土模型，较宽的街道的日平均温度（0.3-0.6摄氏度）略高于较窄的街道。我们的研究为人为城市结构如何影响城市气候提供了直接证据，并提出了通过优化城市形态和储热来控制室外热环境的可能性。(C) 2020 Elsevier B.V.版权所有
Street aspect ratios and urban thermal storage largely determine the thermal environment in cities. By performing scaled outdoor measurements in summer of 2017 in Guangzhou, China, we investigate these impacts on spatial/temporal characteristics of urban thermal environment which are still unclear so far. Two types of street canyon models are investigated, i.e. the 'hollow' model resembling hollow concrete buildings and the 'sand' model consisting of buildings filled with sand attaining much greater thermal storage. For each model, three street aspect ratios (building height/street width, H/W = 1, 2, 3; H = 1.2 m) are considered.The diurnal variations of air-wall surface temperatures are observed and their characteristics are quantified for various cases. The daily average temperature and daily temperature range (DTR) of wall temperature vary significantly with different aspect ratios and thermal storage. During the daytime, wider street canyon (H/W = 1) with less shading area experiences higher temperature than narrower ones (H/W = 2, 3) as more solar radiation received by wall surfaces. At night, wider street canyon cools down quicker due to stronger upward long wave radiation and night ventilation. For hollow models, H/W = 1 attains DTR of 12.1 degrees C, which is 1.2 and 2.1 degrees C larger than that of H/W = 2, 3. Moreover, the sand models experience smaller DTR and a less changing rate of wall temperature than hollow models because larger thermal storage absorbs more heat in the daytime and releases more at night. DTR of hollow models with H/W = 1, 2, 3 is 4.5, 4.6 and 3.8 degrees C greater than sand models respectively. For both hollow and sand models, wider streets experience a little higher daily average temperature (0.3-0.6 degrees C) than narrower ones. Our study provides direct evidence in how man-made urban structures influence urban climate and also suggests the possibility to control outdoor thermal environment by optimize urban morphology and thermal storage. (C) 2020 Elsevier B.V. All rights reserved.