湿热地区室外动态热环境中二节点模型的验证及修正

快速城镇化和全球变暖使城市室外环境的热不舒适加剧,热安全风险提高。为了解湿热地区室外动态热环境中人体生理量的变化规律,为快速评价室外热环境提供依据,开展了室外人体热反应观测实验。基于实测数据,对二节点模型进行了模拟精度分析和吻合度检验,研究得到了人体在室外受风速、MRT和自身调节的作用下,皮肤温度和体核温度呈现不同的变化规律及二节点模型修正方法。在室外动态热环境中应用二节点模型,需从皮肤、体核调定温度、人体标准模型、肌体启动体温调节的环境温度值及人体与室外环境的对流换热系数4个方面对人体二节点模型进行修正,相关参数和调节过程应写成可赋值的变量或数学表达式,修正后的二节点模型对室外人体热反应预测具有通用性和适用性。     

Study on outdoor thermal environment of apartment block in Shenzhen,China with coupled simulation of convection,radiation and conduction

Shenzhen City in China is developing rapidly now. Correspondingly, deterioration of the outdoor environment in phenomena such as heat island has become a serious problem. This aggravation of the thermal environment has spoiled urban sustainability. In this paper, (1) in order to predict the outdoors thermal environment in summer in an apartment block, unsteady coupled simulation of convection, radiation, and conduction is developed and used. The velocity, temperature, humidity, and MRT in the urban area are obtained from the simulation. In order to estimate the pedestrian level of thermal comfort in the outdoor thermal environment, the spatial distributions of New Standard Effective Temperature (SET¹) is calculated using the above results. (2) The actual situation of the outdoors thermal environment in summer in an apartment block in Shenzhen City is investigated by field measurements. (3) The effect of schemes to improve the outdoor thermal environment in this apartment block, such as changing building shapes, planting arrangements, etc. are examined using this prediction method.     

A design supporting simulation system for predicting and evaluating the cool microclimate creating effect of passive evaporative cooling walls

As a passive cooling strategy to control increased surface temperatures and create cooler urban environments, we have developed a passive evaporative cooling wall (PECW) constructed of pipe-shaped ceramics that possess a capillary force to absorb water up to a level higher than 130 cm. The current paper presents a simulation system to predict and evaluate microclimatic modifying effects of PECWs in urban locations where PECW installation is under consideration at the design stage. This simulation system is composed of a CFD simulation tool and a 3D-CAD-based thermal simulation tool. Simulation methodology of coupling the two simulation tools was developed and described in this paper. Numerical models for simulating surface temperatures and evaporation of PECWs were proposed based on analysis results of experimental data. Validation of the proposed numerical models was confirmed by comparing simulated results with measured data. In order to demonstrate the applicability of the proposed simulation system, a case study was then performed to predict and evaluate the microclimate in a rest station where PECWs were assumed to be installed. Spatial distributions of air temperature, airflow, moisture and surface temperature in the rest station were simulated under a sunny weather condition in the summer of Tokyo. Furthermore, thermal comfort indexes (mean radiant temperature and new standard effective temperature) were used to evaluate thermal comfort in the human activity spaces of the rest station. Simulation results show that this simulation system can provide quantitative predictions and evaluations of microclimatic modifying effects resulting from the application of PECWs.     

A numerical simulation method for analyzing the thermal improvement effect of super-hydrophilic photocatalyst-coated building surfaces with water film on the urban/built environment

As an application of the super-hydrophilicity of a photocatalyst (TiO₂) coating, buildings are cooled by sprinkling water on their external surfaces coated with TiO₂. This is a new cooling technology that was recently developed in Japan. In order to make better use of this cooling system, quantitative prediction and evaluation of the cooling effect on the urban/built environment is required during design. In an attempt to provide a computer-aided simulation tool for supporting the above-mentioned design, we introduce a thermal simulation tool that was developed previously by the authors’ group. The goal of the present study is to develop a numerical model by which to predict the temperature of a TiO₂-coated surface with a water film and integrate the calculation algorithm into the simulation tool. The availability of the proposed model was discussed in the present paper. Various urban districts in downtown Tokyo were selected for a discussion of the availability of the simulation tool in which the proposed model is integrated. Simulations were performed to quantify the thermal improvement effect of the cooling system in terms of surface temperature reduction, mean radiative temperature (MRT), heat island potential (HIP), indoor air temperature, and cooling load reduction.     

Developing a modified typical meteorological year weather file for Hong Kong taking into account the urban heat island effect

Building energy computer simulation software is a useful tool for achieving sophisticated design and evaluation of the thermal performance of buildings. For successful thermal and energy simulation of buildings, it requires hourly weather data such as dry bulb air temperature, relative humidity, solar radiation, wind speed, etc. Nowadays, an urban city faces a problem of an urban heat island which causes the urban area to have a higher air temperature than the rural region. Since the currently available weather dataset used in building simulation software mainly comes from weather stations located in remote and rural areas, the impact of the urban heat island on thermal and energy performance of buildings may not be effectively reflected. This paper reports an approach to construct a modified typical meteorological weather file, taking into account the urban heat island effect in the summer season. Field measurements have been carried out in the summer months and the corresponding urban heat island intensities were then determined. With a morphing algorithm, an existing typical meteorological year weather file was modified. An office building and a typical residential flat were modeled with a renowned building energy simulation program EnergyPlus. Computer simulations were conducted using the existing and modified typical meteorological year weather files. It was found that there was around a 10% increase in air-conditioning demand caused by the urban heat island effect in both cases. The implications of this and further work will also be discussed in this paper.     

Thermal comfort assessment in semi-outdoor environments: Application to comfort study in stadia

The present study addresses thermal comfort assessment of outdoor and semi-outdoor environments. Two stadium case studies are used to demonstrate the potentiality of the approach that combines wind tunnel data and the calculation of human heat balance due to particular climatic environments. The thermal index PET (physiological equivalent temperature) is used to evaluate the thermal comfort in such complex environments. The specificities of stadium semi-outdoor spaces are summarised and the necessary assumptions made to apply the computation procedure are described. The approach includes assumptions on the thermo-physical phenomena as well as geometric computations. This work benefited from the development of an interactive design tool of built environments (outdoor urban surroundings): EVE (enriched virtual environments). It is a virtual reality platform developed at CSTB to help designers, architects and urban planners to evaluate the various options in competition regarding acoustic, visual, thermal and wind comfort of pedestrian in a particular urban environment.     

校园行道树对夏季室外行人热舒适的 影响研究

道路绿地作为城市绿地的重要组成部分,在缓解城市热岛和改善行人热舒适等方面起着重要作用。通过监测大学校园内7种典型行道树树荫和阳光下的空气温度(T_a)、相对湿度(RH)、风速(V_a)、黑球温度(T_g)和太阳辐射(G)等气象参数以及行道树的叶表面温度(T_(1s),运用通用热气候指数(Universal Thermal Climate Index,UTCI)分析不同行道树对道路空间热环境的影响和行人热舒适的改善效果。结论如下:1)行道树改善道路空间行人热舒适作用明显,对T_a和平均辐射温度(Mean Radiant Temperature,T_(mrt)降低能力最强的树种分别为悬铃木和银杏;2)天空可视因子(Sky View Factor,SVF)是影响道路空间行人热舒适的主要因素;3)T_(1s)与UTCI呈强线性正相关(R~2=0.8083),夏季T_(1s)越高,道路空间行人热舒适度越差。研究结果从室外热舒适评价的角度为行道树设计提供了理论基础和量化指导。     

室外热环境研究中景观水体动态热平衡模型及其数值模拟分析

为解决室外热环境数值模拟研究中水体边界条件设定的问题,借鉴水库和湖泊水温分布的计算方法,并根据室外景观设计中的水体特点,对水面蒸发换热项和对流换热项进行了修正。建立了室外热环境研究中水体温度的动态热平衡模型,编制了水体温度分布的数值计算程序,并使用该程序分析了水面植被遮挡系数、水体深度及水面尺寸等因素对水面温度的影响。数值分析结果表明:1)由于存在蒸发现象,水面温度一般低于空气温度,而当水面有漂浮植被时,水体表面温度会显著降低;2)水体表面温度随水体深度的增加而减少,但当水体深度超过4 m后,影响变得较小;3)水面尺寸对水面温度的影响比较小,只要水体深度设计适当,室外环境中的水体可以获得较低的表面温度。     

Outdoor thermal comfort: Analyzing the impact of urban configurations on the thermal performance of street canyons in the humid subtropical climate of Sydney

The quality of outdoor space is becoming increasingly important with the growing rate of urbanization. Visual, acoustic, and thermal balance degradation are all negative impacts associated with outdoor comfort in dense urban fabrics. Urban morphology thus needs assessment and optimization to ensure favorable outdoor thermal comfort (OTC). This study aims to evaluate the thermal performance of streets in residential zones of Liverpool, NSW, Australia, and tries to improve their comfort index (Physiological Equivalent Temperature) to reveal optimum urban configurations. This evaluation is done by investigating the following urban design factors affecting OTC using computational simulation techniques: street orientation, aspect ratio, building typology, and surface coverage. Our findings reveal that street canyon orientation is the most influential factor (46.42%), followed by aspect ratio (30.59%). Among the influential meteorological parameters (air temperature, wind speed, humidity and solar radiation), wind velocity had the most significant impact on the thermal comfort of the outdoor spaces in this coastal region, which typically experiences intense airflow. The results of our analysis can be utilized by multiple stakeholders, allowing them to understand and extract the most vital design factors which contextually influence the thermal comfort of outdoor spaces. Outdoor thermal comfort has a direct effect on the health and wellbeing of occupants of outdoor spaces.     

基于遮阴率的湿热地区慢行道热舒适 特征研究

慢行道设计对景观、空间尺度及与环境的协调都有 相应的要求，各景观构成要素对微气候环境，如太阳辐射遮 挡、温湿度分布及风场都有一定的影响，其中行道树遮阴是影 响慢行道热环境的主要因素。依据遮阴率指标选取典型慢行 道，对其微气候要素进行连续观测，同时向步行和骑行人群发 放问卷调研，获取慢行道的热环境水平及人群的热特征，采用 标准有效温度(SET* )指标结合SPSS软件的回归分析方法对慢 行道的热舒适进行量化评价，得出影响人群的微气候因素偏 好、热舒适区域及出行时的热期望，构建以“遮阴率－热环 境－热期望”的慢行道微气候环境评价策略。最后，以广州市 一处实际室外场地为例，采用ENVI-met 4.0 CFD模拟耦 合RayMan软件的方法，探讨建立在热环境、热舒适量化实 证基础上的慢行道热环境评价方法。     

A simplified method to predict the outdoor thermal environment in residential district

The outdoor thermal environment is very important to pedestrian’s comfort and safety. Under the fast development of urbanization it is essential to develop a quick assessment method to assist design. The present paper introduces a simplified simulation system consisting of convection, conduction and radiation to predict the outdoor thermal environment. A double mesh system for radiation simulation is used to reduce the amount of calculation and storage, meanwhile a thermal response factor method is introduced to calculate the transient heat conduction process. By taking advantage of the thermal response factor method, two kinds of simplified coupling methods are proposed. To validate the simulation system, a filed measurement was carried out and the simulation results are in compliance with the experiment. The simulation results show that the error caused by simplification is acceptable in most conditions, and a lot of coupling calculation amount could be saved.     

VRF空调室外机换热相似模型的研究

应用相似缩小模型代替实际模型研究了室外机与环境空气的换热过程。以某VRF空调系统室外机为原型,选取Gr/Re2为特征数,结合根据能量方程推导出的热源强度比例关系式,阐述了相似模型(几何比例取1∶3)的设计过程。获得了该相似模型换热过程中的速度和温度分布,并与原型的测试结果进行了比较。结果表明二者吻合度较好,验证了相似准则选取的准确性和利用相似模型来研究室外机与环境空气换热的可行性。     

绿化和建筑布局对住宅小区的风热环境影响的数值模拟分析

良好的住宅小区风热环境可以加快室外热量的消散和污染物排放,保证居民的健康和舒适。影响小区风热环境的因素主要有小区布局、建筑形态及下垫面形式等。以青岛市一个实际小区为案例采用数值模拟的方法分析小区冬夏季行人高度的风场及温度场分布,评估设计的合理性,找出小区内风热环境不满足要求的区域。通过调整小区内建筑的布局和改变下垫面形式等方法改进小区的设计,并对改进后的方案进行模拟计算。通过模拟结果的对比发现:1合理布局建筑位置,在小区内形成风道可有效改善风环境;2改变下垫面热物性,提高地面材料的反射率,能够降低地面附近的空气温度和体感温度,改善小区热环境。     

地铁岛式站台空调气流CFD模拟

为给岛式站台的气流组织设计提供依据,评价气流组织设计方案,确定合适的送风温差以优化岛式站台空调系统的设计。建立典型岛式站台的三维几何模型,应用标准湍流模型作为站台气流的物理模型,根据实际测试的站台热湿负荷设定数值模拟的边界条件,应用CFD（计算流体力学）对地铁岛式站台空调系统进行模拟。岛式站台的温度场模拟结果与实际测试的站台温度场吻合较好,表明在合理的简化条件下,采用标准湍流模型的计算流体力学模拟能够较为准确地模拟和预测地铁岛式站台的温度场,可以为岛式站台空调系统的气流组织设计提供依据。     

基于室外气象信息的CFD室内环境模拟

在使用计算流体动力学（CFD）设计室内环境时，一些包含外墙的房间的热边界条件较难给定，因为外墙的内壁面除了要受到室内热源和气流的影响外很大程度上还要受到室外气象条件的影响。本文提出一种基于室外气象信息的CFD边界条件给定方式，针对一个包含外墙的办公室算例进行模拟，计算结果表明外墙内壁面的温度和热流密度分布很不均匀，但通过本文提出的模拟方法只需根据室外气象信息来给定外墙外壁面的热边界条件，就可以获得比较准确的外墙内壁面的温度和热流密度分布以及室内环境的温度分布信息，便于研究与设计人员使用。     

Improvement of urban thermal environment by managing heat discharge sources and surface modification in Tokyo

This paper analyzes the implications of anthropogenic heat discharges into the urban thermal environment of Tokyo. Heat discharges by the representative office, commercial and residential buildings were simulated with the help of the DOE-2 building energy simulation model. The approach used in this paper also takes into account the heat storage within building structures. The geographical information system based technique was used to estimate the heat discharge distribution all over Tokyo. The mesoscale analyses of the urban climate were carried out with a model that was based on the Colorado State University Mesoscale Model. The improvements in the urban thermal environment via the various measures were analyzed for two types of scenarios, namely, scenarios related to the management of heat discharge sources and urban surface modifications. The maximum improvement in average temperature for daytime was found to be 0.47°C (at noon) as a result of greening the areas around the buildings of Tokyo. Similarly, the maximum improvement in average temperature for the evening was found to be 0.11°C by discharging all heat to the ground.     

基于室外热舒适的寒地教学组团形态设计策略

立足寒地城乡地域特征,修正室外热舒适预测指标,分析寒地高校教学楼组团形态对室外热舒适的影响并提出 优化设计策略,改善寒地室外热舒适性能。基于寒地校园热环境实测数据修正室外热舒适预测指标,通过模拟实验提 出基于室外热舒适的组团形态设计策略。当D/H=2.50 时,教学楼组团室外热舒适和空间感受较好;L 型围合式和三 面围合式是兼顾室外热舒适、节能和空间需求的较优组团形式。室外热舒适评价指标需结合地域特征进行修正,设计 者可通过优化教学楼组团形态改善寒地高校室外热舒适水平。     

A new approach to compute heat transfer of ground-coupled envelope in building thermal simulation software

This study presents a new approach to compute the heat transfer of ground-coupled envelope quickly and correctly which is suitable for implementation into building thermal simulation software. The heat transfer process is decomposed into three processes which are controlled by ground-coupled envelope surface temperature, outdoor ground surface temperature and the temperature difference of ground-coupled envelope surfaces. The three processes are computed by computing one-dimensional Equivalent Slab, simplifying outdoor temperature as harmonic and computing one-dimensional Extra Partition Wall. Validation indicates that the heat flux of ground-coupled envelope surface computed by the new approach is very close to that computed by Finite Difference Method (FDM) under unsteady boundary conditions. The computing time is much less than that with FDM.     

太阳能供暖系统室内地下储热水箱的散热规律

针对太阳能地下储热水箱布置位置的不同,利用Fluent程序对太阳能储热水箱散热进行数值模拟和计算,得出在不同工况下,储热水箱周围土壤的温度场分布。同时,建立地下储热水箱的物理模型和数学模型,分析地下储热水箱的换热特性,并结合实际工程,验证其地下储水箱全年散热量和储能量,获得水箱顶板损失量与总散热量关系。计算结果表明,在相同工况下,冬季室外储水箱能量的散失量远高于室内,室内地下储水箱顶部散热量减少,因此该方式可以用来抵消这部分能量所需的集热器面积的减少,提高储热水箱的储热效率以及减少用户投资。     

Development of a method to predict the heat island potential using remote sensing and GIS data

Most studies directed to urban climate simulation have been carried out under the assumption that an urban canopy layer is a sublayer comprised of various roughnesses, and as a consequence, difficulties have arisen in obtaining a suitable heat balance for such a layer. This paper, therefore, focuses on investigating the surface temperature distributions of all urban surfaces via a new index based on sensible heat flux, named the heat island potential (HIP), which can be employed in urban development planning to evaluate the urban thermal environment. Simulation results following the use of HIP are verified by side-looking airborne multi-spectral scanner (MSS) and geographic information system (GIS) data; thereby enabling elucidation of these thermal effects on the atmosphere. In addition, a heat balance algorithm is developed which simulates urban surfaces such that construction of urban thermal images is possible.