太阳墙热特性分析

对改进的特朗勃墙进行热过程分析,采用CFD技术耦合流固传热求解控制方程,研究了该太阳墙的动态热特性及在冬夏季华北典型气象条件的集热、保温、隔热及预热特性。同时,对墙体材料、墙体高度、空气层厚度、通风孔尺寸等敏感因子进行了分析,给出了适宜的墙体材料及构造形式。所得结论将有利于推进太阳能—建筑一体化技术的发展。     

集热蓄热墙保温构造形式优化及适应性分析

将集热蓄热墙物理模型简化,采用数值模拟和实测验证相结合的方法研究不同保温构造形式下墙体的动态集热供热特性。结果表明:外保温构造的集热蓄热墙,其对流供热量受太阳辐照变化敏感,昼间瞬时供热量大,集热效率最高;而采用内保温、无保温时,二者规律相似,墙体蓄热能力强,供热量在时间上分布更为均匀。通过对集热蓄热墙式太阳房室内热环境的模拟计算分析,提出拉萨地区集热蓄热墙宜采用无保温或内保温形式,且可基本满足全天热舒适需求;西宁地区采用外保温形式时,可满足白天时段房间的供暖需求,夜间尚需其他主动采暖配合。     

集成管道生物质蓄热墙设计及热工性能研究

针对传统生物质墙体存在集热蓄热差的热工问题,提出一种以太阳能为热源的集成管道生物质蓄热墙体,通过建立对比实验模型,分别测试墙体系统及室内物理环境参数,研究2种模型存在的热效率差异,并对实验组墙体系统进行供热性能分析。结果表明：所提出的集成管道生物质墙体系统具有良好的集热、蓄热性能;管道流系统循环控制策略应适应当地气象条件以优化系统供热效率;集成管道生物质蓄热墙节能率可达79.3%,经济效益明显,在生物质能与太阳能富集地区具有广泛应用前景。     

应用于日光温室墙体的相变材料热物性优化研究

建立日光温室计算传热模型,以室内空气温度和墙体内表面温度为指标,通过实验方法验证了所建立的传热模型准确性,最后分析相变材料相变温度、相变焓、导热系数、密度等热物性对室内最低温度和相变蓄热率的影响规律,确定被动式相变蓄热墙体和主-被动式相变蓄热墙体的最佳相变材料热物性,阐明了实际应用时相变材料选择原则。研究结果表明,所建立的日光温室传热模型具有较高准确性,可用于日光温室墙体相变材料热物性优化;主-被动式相变蓄热墙体最佳相变材料的相变温度为27 ℃,相变焓为200 kJ/kg,导热系数为0.35 W/（m·K）,密度为440 kg/m³,被动式相变蓄热墙体最佳相变材料的相变温度为26 ℃,相变焓为200 kJ/kg,导热系数为0.35 W/（m·K）,密度为792 kg/m³;最佳相变材料热物性应用时,2种墙体室内最低温度均可达到15.0 ℃,但是被动式相变蓄热墙体的相变蓄热率较主-被动式相变蓄热墙体减小29.5%。本研究可为相变材料在日光温室的高效利用提供参考。     

冬季太阳能相变蓄热通风墙热工性能的数值模拟

在建筑通风墙体中加入相变材料被认为是改善其冬季热工性能的有效方法。相变材料在墙体中可采用分块的方法进行宏观封装，此时材料在熔化过程中产生的自然对流现象十分显著，不能被忽略。该文使用开源计算流体力学框架OpenFOAM下开发的求解器针对被动式相变蓄热通风墙体的热工性能开展了数值研究，以准确模拟相关传热、流动、相变等物理过程。计算结果表明：相变材料蓄热墙能有效降低室内温度波动；相变材料内部的自然对流作用很大程度上影响着材料的熔化与凝固速度，因此材料封装时的长宽比以及分块方式应做出审慎选择。     

太阳能蓄热墙相变蓄热材料的研究进展

综述了国内外关于太阳能蓄热墙相变材料的研究进展.其中包括太阳能相变材料的分类,物理、化学性质等.目前对于一些相变材料缺陷的改进方法,及相变材料在墙体中的应用.     

嵌管式热激活复合墙体综合能量特性全局敏感性研究

针对复合墙体主动保温隔热过程建立动态传热模型,采用全局敏感性方法分析3类12个变量对其综合能量特性的协同影响。结果表明:在热屏障附加作用下,室外气象因子对墙体综合能量特性影响大幅下降,复合墙体适用于所研究的4个气候区/城市;冷/热源温度和房间设定温度影响最为显著,二者在内墙面耗热/冷量、注热/冷量等指标中始终呈现相互制约的关系;低品位能源系统运行时长和墙体导热系数影响次之,前者推荐值不低于冬季6 h/d和夏季8 h/d,后者推荐值为0.50～2.75 W/(m·℃);嵌管间距对墙体内部热堆积影响较大,间距为100～250 mm有利于形成连续热屏障。     

严寒地区单体建筑太阳能-相变墙系统蓄热特性研究

利用太阳能对水加热并通入相变墙进行蓄热,对减少严寒地区单体建筑供热能耗有重要意义。以大庆市某单体建筑为例,结合该地区太阳能分布特点及建筑热负荷大小,对适用于该地区的太阳能-相变墙系统进行集热与储热能力计算,并采用CFD方法研究单一工况下该系统的热工变化规律及不同热水参数、换热管规格对相变墙蓄热特性的影响。结果表明：该相变墙热稳定性良好,但受自然对流影响,底部相变材料熔化较慢;管径DN25、入口流速0.3m/s、供水温度310.15K、回水温度309.15K、管间距107mm可使相变材料在4小时内完成蓄热,平均节能率为31.8%。研究结果可望为降低严寒地区建筑供热能耗提供新思路。     

热管置入式墙体在实际建筑中的传热特性研究

该文在热管置入式墙体稳态传热实验和动态传热模拟的基础上,于天津地区搭建实际环境下热管置入式墙体测试系统。该测试系统基于2个相同结构尺寸房间,在其中一间的南外墙上置入热管,测试期间用电暖器维持室内18 ℃。依据测试数据对实际环境下墙体的动态传热特性进行分析。结果表明,相比于普通墙体,热管置入式墙体的内表面温度提升率为3.4%,蓄热能力提高;热管置入式墙体平均延迟时间为11.12 h,比普通墙体滞后约0.50 h;热管置入式墙体平均衰减倍数为89.37,比普通墙体大;测试期间热管置入式墙体节能率为25.9%。     

冷空气幕加侧送方式影响室内热环境的数值模拟——一种新型室内送风方式探索

通过对受热墙体上增设冷空气幕和传统侧送的送风方式进行数值模拟研究,对比分析传统的侧送与受热墙体侧冷空气幕+侧送两种空调方式。探讨靠近受热墙体的冷空气幕对整体房间气流组织、人体舒适度和能量利用系数的影响规律。在特定的环境下(存在传热量较大窗墙的房间),冷空气幕+侧送的方式与传统侧送相比,模拟房间的整体风速较低,房间整体温度分布与置换通风相近,即房间截面的温度随着高度逐渐增加。在送风量相同的条件下,冷空气幕+侧送方式的能量利用系数、预测平均投票(predicted mean vote,PMV)及预测不满意百分率(predicted percent dissatisfied,PPD)值均优于传统侧送方式。     

Thermal performance of adobe structures with domed roofs and moist internal surfaces

The inside air and the mean radiant temperatures of two buildings, one built of brick having a flat roof and the other built of lightweight adobe and having a domed roof, were estimated through a thermal network analysis. The analysis was repeated for both buildings when their ceilings and inside wall surfaces were kept moist and evaporatively cooled. A design day for a hot, arid region was considered for the analysis. It is shown that the temperature of the moist surfaces is reduced appreciably and the floor and the air temperatures are also reduced by their heat transfer to the moist surfaces. When natural ventilation rate is high, the room air does not become uncomfortably humid.With low mean radiant temperature in the moist buildings, thermal comfort can be maintained for the occupants. The total area and the duration when the surfaces are kept moist, along with the natural ventilation rate, can be controlled by the occupants to provide thermal comfort when it is otherwise uncomfortable. The use of a domed roof with a hole in its crown can ensure high ventilation rates at low wind velocities and in buildings which cannot otherwise be sufficiently vented.     

PV/T蒸发屋面传热性能实验研究

提出一种新型的PV/T蒸发屋面被,该屋面除具有防水、美观等基本功能外,还兼作PV/T热泵系统的蒸发器,集发电、制热于一体。通过实验,详细分析夏季工况下PV/T屋面各层的温度分布、空腔中流体的流动特性,并探讨PV/T屋面的设置对建筑外表面温度及建筑得热量的影响。结果表明;夏季热泵系统运行时,PV/T屋面系统中腔体内流体被加热,较普通屋面而言,其原屋面外表面温度降低,最高降低21℃,但夜间时略高于普通屋面1℃,总体而言,PV/T屋面的设置使建筑得热量降低44%。     

A two dimensional thermal network model for a photovoltaic solar wall

A two dimensional thermal network model is proposed to predict the temperature distribution for a section of photovoltaic solar wall installed in an outdoor room laboratory in Concordia University, Montréal, Canada. The photovoltaic solar wall is constructed with a pair of glass coated photovoltaic modules and a polystyrene filled plywood board as back panel. The active solar ventilation through a photovoltaic solar wall is achieved with an exhaust fan fixed in the outdoor room laboratory. The steady state thermal network nodal equations are developed for conjugate heat exchange and heat transport for a section of a photovoltaic solar wall. The matrix solution procedure is adopted for formulation of conductance and heat source matrices for obtaining numerical solution of one dimensional heat conduction and heat transport equations by performing two dimensional thermal network analyses. The temperature distribution is predicted by the model with measurement data obtained from the section of a photovoltaic solar wall. The effect of conduction heat flow and multi-node radiation heat exchange between composite surfaces is useful for predicting a ventilation rate through a solar ventilation system.     

高温集热管真空寿命预测研究

针对高温真空集热管真空老化性能展开真空度预测和寿命评价研究。模拟电站高温集热管运行环境，在400℃进行热循环模拟和热损测试，在450℃进行过热加速循环试验。结果表明：集热管封离后，室温条件下其内初始真空度达4.7×10^-4Pa，在400和450℃经过400次循环后，管内真空度分别为5×10^-3Pa和6×10^-2Pa。室温状态下集热管在吸收涂层法向发射比为0.08，真空度为10^-3Pa时，400℃下热损为216 W/m，显示出良好的热性能。拟合结果表明在400℃条件下集热管使用寿命满足25年要求。     

夏季大空间屋顶节能喷淋器的实验研究

针对大空间建筑模型进行喷淋效果实验,通过实验得到以下结论:由于Low-E玻璃材料在夏季具有较强的温室效应,未喷淋时,屋顶内表面平均温度为56.8℃,与环境平均温差为21.9℃,增加了空调的能耗。彩钢板屋顶具有较好的保温性能,未喷淋时,屋顶内表面平均温度为40.6℃,模型内部空间平均温度为38.9℃,该温度远低于Low-E玻璃模型温度,能耗比Low-E玻璃模型小。喷淋时,Low-E内层温度比外层温度低约5.4℃;彩钢板内外层温度在喷淋时两者相差不大,仅为0.5℃,喷淋对Low-E玻璃屋顶空调节能意义明显。     

Solar thermal modelling of a non-airconditioned building: Evaluation of overall heat flux

This paper presents an investigation of the thermal behaviour of a non-airconditioned building with walls/roof being exposed to periodic solar radiation and atmospheric air while the inside air temperature is controlled by an isothermal mass, window and door in the walls of the room. The effects of air ventilation and infiltration, the heat capacities of the isothermal storage mass inside air and walls/roof, heat loss into the ground, and the presence/absence of the window/door have been incorporated in the realistic time dependent periodic heat transfer analysis to evaluate the overall heat flux coming into the room and the inside air temperature. A numerical computer model using typical weather data for Delhi has been made to appreciate the analytical results quantitatively. It is found that the heat fluxes through different walls have different magnitudes and phase lags w.r.t. the corresponding solair temperatures. The overall heat flux coming into the room as well as the room air temperature are sensitive functions of the number of air changes per hour, closing/opening of the window and the door ventilation. The effects of the heat capacity of the isothermal mass and the basement ground are found to reduce the inside air temperature swing and the presence of a window is found to increase the inside air temperature even when the window area is much smaller than the wall/roof area. The model presented would be an aid to a building architect for good thermal design of non-airconditioned buildings.     

夏热冬冷地区"双层皮"玻璃幕墙节能技术研究

玻璃幕墙是影响到建筑能耗的关键部位。本文分析了传统玻璃幕墙的弊端;通过玻璃幕墙的耗能计算公式说明影响玻璃幕墙耗能的相关因素;阐述了适合夏热冬冷地区的节能型玻璃幕墙—“双层皮”玻璃幕墙的构造和节能原理;通过实验验证了“双层皮”玻璃幕墙比传统的“单层皮”玻璃幕墙具有更佳的热工性能,其节能效果与通风和遮阳构造设计等有关。     

高效双通道型Trombe墙冬季热性能分析

针对传统Trombe墙冬季供热效率不高、夏季过热等问题,提出一种高效双通道型Trombe墙系统,对该系统在冬季时的热性能和采暖效果进行实验研究。结果表明,高效双通道型Trombe墙热效率是传统Trombe墙的1.6~3.4倍,室内温度相比于传统Trombe墙可升高0.7~5.7 ℃。其中,当总通道厚度为0.5 m,外通道为0.2 m,隔热板形状为凹凸板时热效率最高为31%,此时室内温度可达21.7 ℃。此外,在实验研究基础上建立高效双通道型Trombe墙的传热模型,并验证其准确性。     

Thermal performance of a non-air-conditioned building with PCCM thermal storage wall

This paper presents a time-dependent periodic heat transfer analysis of a non-air-conditioned building having a south-facing wall of phase-changing component material (PCCM). A rectangular room (6 × 5 × 4 m) based on the ground is considered. The effects of heat transfer through walls and roof, heat conduction to the basement ground and furnishings, heat gain through window and heat loss due to air ventilation have been incorporated in the periodic time-dependent heat transfer analysis. The time-dependent heat flux through the PCCM south-facing wall has been obtained by defining the effective thermal properties of the PCCM for a conduction process with no phase change. Numerical calculations are made for a typical mild winter day (7 March 1979) at New Delhi for heat flux entering through the wall and inside air temperature. Further, a PCCM wall of smaller thickness is more desirable, in comparison to an ordinary masonry concrete wall, for providing efficient thermal energy storage as well as excellent thermal comfort in buildings.