区域建筑冷负荷预测中的朝向因素分析及转换

通过对建筑墙体受太阳辐射得热的特性分析,把墙体所受太阳直射辐射得热量进行等效分解,在此基础上建立了建筑朝向转换规则,并以上海地区2种不同长宽比的实际建筑进行模拟分析,得到实际建筑与转换后建筑的冷负荷对比曲线,模拟结果显示,转换后的虚拟建筑冷负荷与实际建筑冷负荷有很好的吻合,建筑朝向对冷负荷影响的实质即为不同朝向的墙体面积和窗体面积的改变,在预测区域建筑冷负荷时,可以应用转换规则,把区域内建筑转换为同一朝向建筑进行分析,减少了朝向因素对冷负荷的影响。     

带走廊玻璃幕墙建筑的日射负荷计算分析

为带走廊玻璃幕墙建筑中的日光传递过程建立了物理模型,用级数求和的方法对内部房间的日射得热进行了分析,对房间墙体外表面扰量的等效温度和通过幕墙逃逸回外界的辐射量进行了计算.结合不同的建筑实例进行了分析,结果表明,透过幕墙的太阳辐射可能会在内部房间的墙壁外侧形成一个较大的扰量,不能简单地忽略;透过幕墙进入建筑内部的太阳辐射只有一部分会转化为走廊空间的空调负荷,计算时需对此加以分析,否则会时建筑物的节能不利.     

半透明光伏玻璃窗对室内负荷的影响

该文以广州地区办公建筑为例,采用EnergyPlus软件比较研究了光伏薄膜玻璃窗和普通玻璃窗对房间冷负荷的影响,结果表明光伏玻璃窗对建筑节能效果显著,尤其是窗墙比较大的建筑。当窗墙比为0.7时,相比普通玻璃窗,光伏玻璃窗可使室内冷负荷减少50%。该文还研究了光伏窗空气层宽度和通风量对夏季窗户得热的影响,对于小面积光伏窗,适当增大通风通道宽度能降低室内得热;当窗户面积较大时,机械通风可以有效减少高温光伏组件对室内的传热,但通风量不宜超过0.01 m~3/(s m)。     

区域供冷负荷预测模型的建立

随着经济的发展,区域建筑越来越多,如何进行区域冷负荷预测是一个难题。传统的面积负荷指标法不能反映区域负荷的特点,预测结果往往偏大;而由于在区域规划阶段,很多建筑信息和参数都不全,采用软件进行详细的模拟计算也显得不可行。本文根据城市用地分类标准及建筑冷负荷特性将城市建筑进行分类,对每类建筑建立典型建筑模型并确立冷负荷的物理因素、内扰因素和外扰因素,应用DeST(Designer’s Simulation Toolkits)软件对典型建筑模型进行模拟,通过对模拟结果进行适当处理后得到城市建筑动态冷负荷数据库,为区域供冷冷负荷预测提供参考和依据。     

曲面玻璃建筑的日射冷负荷计算

为解决暖通规范及各类手册上冷负荷计算数据有限的困难 ,方便准确地计算球形、半球形及圆筒形玻璃建筑由日射得热引起的空调冷负荷 ,笔者建立了计算上述 3类玻璃建筑各计算时刻日射总得热的数学模型 ,并导出了相应的计算公式。日射总得热包括太阳透射得热和被玻璃吸收的又以辐射与对流方式进入室内的太阳辐射得热 ,计算公式为 :球形玻璃建筑的日射总得热 :Ｑ球 =πＲ2 ( 0 .788Ｉｂ ,ｎ 0 .3 2 9ＩＨ ,Ｄ 1.975ＩＨ ,ｄ)半球形玻璃建筑的日射总得热 :Ｑ半球 =πＲ2 [( 0 .3 94 ｕ)Ｉｂ ,ｎ 0 .0 82ＩＨ ,Ｄ 1.3 17ＩＨ ,ｄ]圆筒形玻璃建筑的…     

外部气候条件对辐射供冷负荷的影响分析

针对辐射供冷房间冷负荷的计算问题,提出了一种以热平衡为基础、以试算法为辅助的计算方法,充分考虑房间各围护结构的得热类型和传热方式,并依据实际情况建立房间模型,通过对各个围护结构的热平衡方程式联立求解得到房间冷负荷,给出了顶板辐射供冷冷负荷和辐射板温度与室内温度之间的差值关系式。分析和对比数据显示不同地区冷负荷计算公式具有普适性,且室外气候条件中太阳辐射强度比室外温度对冷负荷影响程度更大,总换热系数可以表征辐射板供冷能力的大小。分析结果能为辐射供冷冷负荷计算提供一定的参考价值。     

《建筑物空调负荷计算分析》出版

该书由上海交通大学制冷与低温工程研究所谷波教授撰写 ,由科学出版社出版。该书共分 8章 ,第 1章介绍建筑物空间特性与冷负荷计算步骤 ,从总体上介绍了空调负荷计算 ;第 2章为设计工况 ,所用的数据来自于室外设计条件 ;第 3章介绍蓄热与峰值不同步性和热分层 ,给出了计算制冷装置瞬时的制冷负荷 (实际冷负荷 )的数据和计算程序 ,把这些数据应用到特定的单个得热量 ,便能得到实际制冷负荷 ;第 4章为通过玻璃的太阳辐射得热 ;第 5章为通过围护结构的热湿传递 ;第 6章为渗风与通风 ,其数据是基于ASHRAE对室外空气的渗风和通风品质进行测评…     

太阳辐射对疆北地区住宅能耗影响分析

以乌鲁木齐市某典型住宅建筑为研究对象,采用Sketch Up建立建筑模型,并用Energy Plus模拟计算通过围护结构进入室内的太阳辐射得热量。对比分析室内逐时指标热负荷,表明充分利用太阳辐射,可降低供热负荷;并得出在供热低谷期的中午时段南向房间太阳辐射得热量已大于室内指标热负荷。通过改善墙体保温性能,优化窗墙比,充分利用太阳辐射,可以有效降低疆北地区住宅能耗。     

遮阳对室内热环境的影响

太阳辐射对于建筑夏季空调空间的影响可以通过如下过程阐述：太阳辐射照射到建筑外表面,一部分通过传热造成建筑围护结构内表面温度上升,另一部分则透过透明围护结构进入房间,其中绝大部分热量将被地板、墙壁或室内家具等蓄热体所吸收,导致这些物体表面温度上升,并引起室内气温提高,从而形成空调负荷和开启空调的需求。而外遮阳设施有效地将太阳辐射中的直射辐射挡在了室外,减少了进入建筑的太阳辐射得热,从而降低了空调负荷,实现建筑节能。这部分结论已经为广大科研人员与民众所认可。事实上,遮阳设施的影响还存在于对室内人员热感觉的影响上。     

NM-BIN模型在热湿地区建筑能耗评价中的应用研究

传统的BIN模型在评价建筑全年能耗时是稳态计算,只考虑对温度划分频段,认为太阳辐射负荷与温度成线性关系,精确度较低。为了提高BIN模型在建筑能耗评价中的准确性,主要对目前传统的BIN法进行改进,在对温度划分频段时对含湿量也划分了频段,形成了温湿度频段,并且认为太阳辐射量不与室外温度成线性关系,对太阳辐射所造成的负荷重新进行计算。提出的改进方法可以使温湿度频段划分得更加精确,减小BIN模型进行能耗评价时的误差,通过对透过玻璃窗的日射得热、围护结构不稳定传热、室内散热源的改进,以及对含湿量划分频段,获得New Modified BIN法(简称NM-BIN法)。采用NM-BIN法和Energy Plus对热湿地区建筑能耗进行了能耗模拟,并将模拟结果与建筑实测能耗进行了对比。结果显示,NM-BIN和Energy Plus的模拟结果与建筑实测能耗的相对误差分别为3.92%和1.45%,即NM-BIN和Energy Plus的模拟结果只差2.43%。该结果表明新改进的NM-BIN法具有较好的准确度。由于NM-BIN无需复杂建模,方便手算,因此具有更好的工程实用性。     

Heat transfer modelling on windows and glazing under the exposure of solar radiation

Due to the effect of solar radiation on windows and glazing system the evaluation of heat flow is of primary importance in modeling the thermal performance within building interiors to account thermal comfort and overall energy consumption of a building. In this context the optical properties of window glazing are measured to determine the percentage absorption of incident solar radiation. An experimental study was performed in a room to measure the glazing surface temperature due to the global radiation on it. The corresponding window plane global radiation and horizontal global radiation were measured outside for simulation. Mathematical models have been developed to simulate the window plane solar radiation and corresponding glazing surface temperature aiming at validating the measured values. The thermal model is concerned with laminar heat transfer for natural and forced convection process according to the ambient conditions. The estimated errors between experimental and simulated values of window plane radiation and glazing temperature are shown to be within ±5%. Using the developed thermal model the heat flow inside the room through windows is determined. Thus overall heat transfer coefficient of glazing (U-factor) and the Solar Heat Gain (SHG) of building interior have been predicted from the simulation.     

A simple model for assessing the energy performance of windows

A simple model for the annual energy balance of the window taking solar radiation and heat losses into consideration has been further developed and analysed. Hourly meteorological data for the solar irradiation and the outside temperature are used together with the optical and thermal performance of the window to evaluate the net energy heat flow through a window. The model renders a very simple way to compare different advanced windows in different geographical locations, orientations and buildings using basically only the balance temperature as building input. The energy balance and the cost efficiency for several glazing combinations are evaluated for buildings with different balance temperatures in a typical mid-Swedish climate. This model has a potential to be used for energy rating of windows.     

Comparison between PCM filled glass windows and absorbing gas filled windows

From the thermal point of view, windows represent the weak link between the internal and external ambients of a room. In cold climates, they are responsible for 10–25% of the heat lost from the heated ambient to the external atmosphere. In hot climates, the excessive solar radiation entering the internal ambient through the windows leads to increasing the cooling load of the refrigeration system. The use of absorbing gases filling the gap between glass sheets appears to be an alternative solution for thermally insulated glass windows. The other options one may incorporate filling materials such as silica aerogel or a PCM. In this work, a comparison between the thermal efficiency of two glass windows one filled with an absorbing gas and the other with a PCM and exposed to solar radiation in a hot climate is done. To model double glass window filled with infrared absorbing gases, a CW real gas model is used. A radiative convective conductive model and a radiative conductive model were investigated. Three mixtures of gases were used; a strongly absorbing gas mixture, an intermediate absorbing gas mixture and a transparent to infrared radiation mixture. To model the double glass window filled with a PCM, a relatively simple and effective radiation conduction one dimensional formulation is used. Heat transfer through the window is calculated and the total heat gain coefficients are compared and discussed.     

Prediction of solar heat gain of double skin facade windows

A linear model involving the solar heat gain coefficient and U value is often used to calculate the solar heat gain of traditional windows; however, it is not known if such linear model is applicable to double skin facades, which is typically featured by ventilated cavity and often with blinds inside. This paper reports on an experimental investigation into the relation between the two coefficients and the energy gain by a double skin facade without blinds. A small-scale solar calorimeter was constructed to measure the energy gain of a double skin facade window about 1.1 m high. Four tests with solar radiation intensity ranging from 205 to 793 W/m² showed that the energy gain can be represented by such linear model. The solar heat gain coefficient can be determined from the data fitting process with more accuracy than the U value, which, being a minor determinant of the heat flow in the presence of the solar radiation, may require more data for reasonable accuracy. The advantage of this linear model lies in its simplicity, which makes it easy to incorporate into present building energy simulation tools.     

夏热冬冷地区居住建筑房间得热量分布及节能方向

采用多层板壁热力系统的反应系数法分析计算了典型气象条件下4个典型房间各围护结构的逐时传热量及其在房间得热量中所占比例。结果显示,在夏季典型气候条件下,单位面积围护结构对房间得热量的影响从大到小依次为外窗太阳辐射、外窗传热、屋顶传热、东西墙传热、南墙传热;白天由太阳辐射引起的得热量一直是房间得热量的主要部分;随着西向窗墙面积比的增大,西窗逐时传热得热量和辐射得热量呈线性显著增加;在夏热冬冷地区,必须提高窗户的遮阳性能,并降低窗户的传热系数,适当控制南向窗户面积,严格控制东西向窗墙面积比,建议西向窗墙面积比不大于0.2。     

Optimization of the form of a building on an oval base

The aim of this work is to analyze the possibility of optimizing an abstract, symmetrical with respect to the north–south axis form of a building with vertical walls and windows, and constant volume and height. The external south partitions of the building are walls with whole windowpanes. The heat losses through walls, floors, roof and the gain of solar radiation through transparent partitions with respect to their direct correlation with the shape of building form are next taken into consideration. The gain of solar energy for the north part of the building have been disregarded.     

Performance rating of glass windows and glass windows with films in aspect of thermal comfort and heat transmission

This article is about a study on glass window and glass window with film of different types in aspect of thermal comfort and heat transmission. Different types of glass window, clear glass, tinted glass, reflective glass, double pane glass, and low-e glass were investigated. Films with different spectral optical properties were then adhered to the glass windows of different types and studied. The analysis was done based on the outside design weather condition which selected from 12 years of Bangkok meteorological data. Predicted percentage of dissatisfied (PPD) was selected as the thermal comfort index. The relative heat gain (RHG) based on local weather condition was selected as the heat transmission index. The PPD can be subdivided into the PPD due to surface temperature effect and the PPD due to solar radiation effect. The analysis indicated that, for most of the glass windows considered except the reflective glasses, the values of PPD due to solar radiation effect were much larger than the values of PPD due to surface temperature effect. And the most discomfort condition occurred when using a clear glass as window. Adhered films to the glass windows caused the PPD due to surface temperature effect increase and cause the PPD due to solar radiation effect decrease. It was also found that the PPD values due to solar radiation effect for glass windows and glass windows with films were varied linearly with the total transmittance of glass windows and glass windows with films. The PPD values due to surface temperature effect were varied with the total absorptance of glass windows and glass windows with films in an almost linear fashion. The heat transmission index, RHG, based on chosen design weather condition can be subdivided into the RHG due to conduction effect and RHG due to solar radiation effect. The analysis indicated that the values of RHG due to solar radiation effect were larger than the values of RHG due to conduction effect for all glass windows and glass windows with films considered in this study. Adhered film to the glass windows resulted in lowering the relative heat gain due to solar radiation in the amount corresponding to the film properties. But the film had very few effect on the relative heat gain due to conduction. The relative heat gain values were varied linearly with the total transmittances of the glass windows and glass windows with films. The relative heat gain values were also varied inversely with the absorptances of glass windows and glass windows with films in a linear fashion.     

低辐射节能玻璃窗最佳镀膜位置的选择

将Low-E中空玻璃窗划分为单框双玻璃和单框三玻璃,利用WINDOW6.1软件建立单框双玻、单框三玻系统在不同镀膜位置和数量时的模型,并计算两种系统的传热系数、太阳得热系数、遮阳系数、可见光透射比和内表面温度等参数,分析以上参数对窗户能耗的影响,确定单框双玻窗和单框三玻窗玻璃系统的最佳镀膜位置。     

Sunlit fraction of vertical slant windowpanes

When evaluating the instantaneous rate of solar heat gain through a window, it is essential to know the shaded area, if any, of the glazing. This is a typical standard drill, which is frequently carried out for conventional windows, which have the glass panes parallel to the building exterior wall. Sometimes, and for architectural or other reasons, the glass may be fixed in a vertical but horizontally rotated position; i.e. non-parallel to the wall. This may help to rationalize the energy requirements for air conditioning. The objective of this paper is to establish a systematic method to calculate the sunlit, and hence the shaded, fraction of slant-glass area. The presented analysis takes into account all of the numerous variables involved in the problem; namely, location, date, time of the day, wall orientation, rotation of glass relative to the wall, and geometrical characteristics of the window. The calculation procedure is casted in a general computer program which can be readily and unlimitedly used for any set of conditions. Some sample results are presented.     

炎热地区夏季窗户的热过程研究

以重庆地区为例，探讨了炎热地区夏季南向和西向窗户的太阳辐射得热问题。认为辐射得热是导致室内热环境恶化的首要原因，西向铝合金双玻窗的辐射得热高达520W／m^2，而基于室内外温差的热流最大也不超过50W／m^2；对于南向窗，太阳直射对室内热环境影响相对较小，天空散射与环境反射是窗户得热的主要来源。对炎热地区的窗户节能而言，有效控制辐射得热、采用遮阳装置是问题的关键。