PV新型Trombe墙光电光热性能数值模拟

提出了带有PV的新型Trombe墙结构,建立了二维的光伏玻璃板以及PV-Trombe墙系统的数理模型,获得了系统的温度场、太阳电池的电性能和室内得热。模拟结果表明：根据该文所采用的实测气象数据,在特定的模拟工况下,光伏玻璃板上的光电池部分和无光电池部分的温差最大可达10．58℃；有无PV-Trombe墙房间的温差在3d内最大可达13．22℃；运行7d后每天温度能维持在14℃左右。     

PV-Trombe墙体的试验和数值模拟

提出了带有PV的新型Trombe墙结构,建立了该墙体的理论模型,并进行了该墙体对热箱热环境影响的试验和模拟分析.试验结果表明:带有PV-Trombe墙的测试热箱的室内温度比不带该墙体的对比热箱高6℃,与环境的最大温差可达18℃;由于空气流道的冷却,光电池工作温度较低,日平均发电效率可达10.5%.     

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。     

冬季特朗贝墙内置卷帘对墙体热性能的影响

对大连地区某被动式太阳实验房进行实验研究,通过对玻璃幕墙内壁面温度、夹层内空气温度、特朗贝墙墙体温度等相关参数及室外气象参数等的实测,定量地分析了冬季夜间特朗贝墙采用卷帘保温的效果。并且通过有限空间自然对流换热理论计算分析,提出了更为合理的卷帘安装位置,最后根据围护结构响应因子BER指标,讨论了使用卷帘对提高室内热舒适性的影响。     

热煤炉前墙过热的原因分析和解决办法

从燃烧和传热两个方面分析了热媒炉前墙过热的原因，并根据实际情况提出了解决办法，可为该种炉型的改进提供参考和借鉴     

浊度和池底反射率对太阳池热性能的影响

提出了同时考虑浊度和池底漫反射的太阳池辐射透射模型和热效率模型,计算分析了浊度和池底反射 率对太阳池热性能的综合影响。模拟计算表明,浊度一定时,热性能总是随着池底反射率的增大而降低。计算 还表明,存在一个临界池底反射率,当池底反射率小于临界值时,浊度的增大导致太阳池热性能的下降;当池 底反射率超过临界值时,一定范围内浊度的增加反而有利于太阳池热性能的提高;当池底反射率在临界值附近 时,浊度的变化对太阳池热性能的影响很小。通过模拟计算得出了典型情况下的临界池底反射率,在太阳池的 实际研究和设计中可供参考。     

窗墙比和体形系数对办公建筑能耗的影响

济南地区某公共办公建筑,其围护结构按照高效节能的设计方法进行设计。运用Dest软件对该建筑进行能耗模拟,模拟该建筑的逐时能耗,分析不同体形系数和窗墙比对建筑物能耗的影响,以及两者共同作用下的影响。通过模拟结果得出:窗墙比对夏季负荷的影响要大于对冬季的影响,冬季窗墙比越大,能耗变化率相对较小;而体形系数的不同对建筑物空调能耗的影响变化较小。     

辐射对太阳电池光电输出性能影响的定量研究

该文定量研究电子和质子辐射对太阳电池输出特性的影响。首先,证实作者前期工作得到的太阳电池输出电流-电压（I-V）模型仍适用于高能粒子辐射后的太阳电池;其次,由太阳电池输出电流-电压特征量定义一个等效电阻（Req）。采用最小二乘方曲线拟合方法,找到能够定量描述太阳电池能量转化效率（PCE）与等效电阻（Req）的关系,并且定量解释了经历电子和质子辐照的太阳电池的等效电阻（Req）同辐照剂量的关系。最后,扩展这个模型用于定量描述太阳电池外量子效率（EQE）与入射光子能量（hν）的关系,经拟合验证,该模型与实验数据十分吻合,理论同实验结果的相关系数R大于0.98,平均相对误差（ARE）小于3%。     

中冷技术对涡轮增压柴油机性能影响的研究

对废气涡轮增压中冷柴油机理论循环热效率进行了辨析.应用Matlab语言和Avl Boost软件,对EQ6102D柴油机工作循环进行了建模、编程和模拟计算,并对发动机进行了水冷和空冷2种模式的试验,计算与试验结果均表明中冷技术在提高发动机功率、降低排气温度和抑制NO_x生成方面效果显著,在提高热效率方面效果不明显,深度中冷加上适当增大空燃比,可提高热效率约5%.     

新V型内聚光CPC热管式真空管集热器的热性能

基于圆管型复合抛物聚光器(CPC)的研究,由于接受体和CPC反光板之间存在缝隙而造成大量漏光损失,设计了一种可以减少漏光损失和热损的新V型CPC反光板,并综合利用热管式真空管集热器的优越性,开发出一种新V型内聚光CPC热管式真空管集热器。首先给出了其设计结构,并对其进行传热分析,推导出该型集热器的集热效率、总热损系数的计算方法,再进行室外动态性能试验,测定了它的效率曲线,试验结果与理论计算值较符合。     

The influence of PV coverage ratio on thermal and electrical performance of photovoltaic-Trombe wall

This paper presents a novel photovoltaic-Trombe wall (PV-TW). Based on the actual measured weather data in Hefei, a detailed simulation model for PV-TW is presented. The simulation results show that as the coverage ratio increases, the electrical yield and the total efficiency of PV-TW increases, but the indoor temperature and the thermal efficiency of PV-TW decreases. The maximum indoor air temperature difference, corresponding to the lowest and the highest coverage ratio, can reach to 6.8 °C above. In addition, as the coverage ratio increases, the electrical efficiency of photovoltaic cell decreases, but the influence of coverage ratio on electrical efficiency is slight, less than 0.5%.     

Effect of hybrid nanofluids mixture ratio on the performance of a photovoltaic thermal collector

Solar photovoltaic-thermal (PV/T) collectors, are hybrid collectors used to convert solar radiation into usable thermal and electrical energy. Recently, the field of research on PV/T is has focused on improving the efficiency of the PV/T collector by replacing the conventional heat transfer fluids (HTFs) with nanofluids. This article investigates the effect of hybrid nanofluids mixture ratio on the useful energy and overall efficiency of a PV/T collector operating with Al₂O₃-ZnO water nanofluid as the HTF. Experiments to measure the thermophysical properties of the hybrid nanofluids were conducted for various temperatures, volume concentrations, and mixture ratios, furthermore, accurate correlation models were proposed. Metrological data and energy output readings collected from the PV solar farm at Cyprus International University were used to validate our model. The study observed that at the optimum mixture ratio (0.47 of Al₂O₃ in the hybrid), the electrical, thermal, and exergy efficiencies of the PV/T collector are 13.8%, 55.9%, and 15.13% respectively. Also, the cell temperature drops by 21% when the mass flow rate is 0.1 kg/s as compared to when it is 0.01 kg/s. Finally, the study concludes that by using the Al₂O₃-ZnO hybrid nanofluid an overall peak thermal efficiency of 91% can be attained, and this represents a 34% enhancement in the collector's performance when compared to water.     

Shading effects on the winter thermal performance of the Trombe wall air gap: An experimental study in Dalian

There has been little research on the application of shading devices in the air gap of the Trombe wall in China. Experiments on the thermal performance of an advanced Trombe wall with shading in the air gap was conducted in a passive solar house in Dalian. The thermal performance was investigated with regard to the simultaneous temperatures, heat gain and their acquisition of the Trombe wall. By analyzing experimental data, an investigation was carried out on the heat preservation effect by the shading device on a winter night. The theoretical optimum fixed location of the shading in the air gap for minimizing the heat loss was also discussed. Finally, the influence of shading on improving indoor thermal comfort was discussed using the concept of the building envelope response factor (BER) presented earlier by Lukic [The transient house heating condition—the building envelope response factor (BER). Renewable Energy 2003;28(4):523–32].     

Numerical investigation of lobe spacing ratio on performance of forced mixer nozzle

Geometric models of a lobed mixer nozzle with variation of lobe spacing ratios are created and the corresponding flow fields are simulated using a steady Reynolds Averaged Navier–Stokes (RANS) equation with a realizable k‐? turbulence model and standard wall function. According to the numerical simulation results, the spacing ratio has a large influence on the shape of streamwise vortices, but a relatively small effect on the streamwise vorticity field at the lobe exit. Therefore, at the initial part of mixing, a change of spacing ratio has little effect on the thermal mixing efficiency and the total pressure recovery coefficient. In addition, the thermal mixing efficiency increases sharply at the initial part, and near the nozzle exit it approaches some constant. The development of the total pressure recovery coefficient is totally reverse to the thermal mixing efficiency. It falls rapidly at the beginning. Then the rate of descent gradually slows down, and approaches some constant. At the nozzle exit cross‐section, the thermal mixing efficiency ascends and the total pressure recovery efficiency reduces as the spacing ratio increases. Besides, the thrust coefficient has little relationship to the spacing ratio, with a variation smaller than 0.01 when the spacing ratio increases from 4.87 to 0.497. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20363     

空气分级比对同轴分级燃烧室性能参数的影响

为掌握同轴分级燃烧室性能参数随空气分级比(主燃级空气流量的比值)的变化规律,以某同轴分级燃烧室为研究对象,数值分析了空气分级比对燃烧室的燃烧效率、总压损失、出口温度分布、污染物排放和绝热壁面最高温度的影响。结果表明：空气分级比主要会改变角涡位置的燃烧温度和高温烟气的停留时间;随着空气分级比的升高,燃烧室总压损失、出口温度分布系数、NO_x排放、绝热壁面最高温度逐渐升高,但燃烧效率、CO污染物排放、径向温度分布系数对空气分级比不敏感;在同轴分级燃烧室设计中,在保证燃烧稳定的前提下可采用较小的空气分级比以实现燃烧室高效、低阻、低污染燃烧。     

An experimental and mathematical study of efforts of a novel photovoltaic‐Trombe wall on a test room

A novel photovoltaic‐Trombe wall (PV‐TW) is proposed and investigated experimentally and theoretically in this paper. The PV‐TW was installed at the south‐facing external wall of an environmental chamber that carried two identical test rooms. Both of the test rooms have a double window of the same size. One test room was installed with the PV‐TW (known as the PV‐TW room), and the other without PV‐TW (known as the reference room). The influence of the PV‐TW on the thermal environment of the test room was investigated under different operating conditions. The experimental results show the dual benefits of the PV‐TW system: improving the room thermal condition and at the same time generating electricity. Compared with the reference room, the maximum indoor temperature was found to be 5–7°C higher in winter, and the daily electrical output reached about 0.3 kWh with a PV cell area of 0.72 m². Also, a detailed model is given to evaluate the performance of PV‐TW theoretically, and the PV‐TW room is simulated under one certain operating condition. The simulated and measured air temperatures of PV‐TW room are found to be in good agreement. Copyright © 2007 John Wiley & Sons, Ltd.     

多孔太阳墙式太阳能房间与普通房间热舒适性分析

通过对某多孔太阳墙式太阳能房间和普通房间的数值模拟,分析太阳墙板内空气的受热过程及流动情况,同时系统地比较两种建筑在工作区范围内的热舒适性。与普通采暖房间相比,在有多孔太阳墙送风的情况下,可将室外空气由-3℃加热到21℃,空气流动速度由0.1m/s提高到0.31m/s,提供44.6m3/h的新风量,一定程度上解决了冬季开窗换气所引起的室内热负荷及采暖负荷,论证了多孔太阳墙可使室内热舒适性明显增强的结论。     

The dependence of thermosyphonic system performance on collector aspect ratio

The dependence of a standard thermosyphonic solar system's performance on collector aspect (length to width) ratio is investigated. Numerical simulation of the system's characteristics is conducted for systems with the same overall collector area but three aspect ratios. In all cases, spacing between collector tubes was kept constant to eliminate fin efficiency considerations. The systems were simulated for typical summer and winter days. Results of the investigation reveal that overall performance characteristics (like bulk efficiency or average tank temperature) as well as stratification in the tank and flow rates depend only slightly on the aspect ratio. The practical conclusion is that only economical considerations and not energetical ones should be applied in designing the aspect ratio of a thermosyphonic solar system.     

涂层导热系数变化对换热器传热的影响

采用换热器效能法,对不同种类换热器进行校核计算.研究换热工质为气气、气液、液液时,不同种类换热器的换热性能随涂层导热系数的变化趋势.结果表明,各种换热器的总传热系数皆随涂层导热系数的增加而增大,且在不同低温侧流体雷诺数下增加程度不同,雷诺数越大,增加程度越大.设定涂层厚度为200.000 μm,涂层导热热阻所占比例随着...     

Analysis of thermal and electrical performance of semi-transparent photovoltaic (PV) module

Building-integrated PhotoVoltaic (BIPV) is one of the most fascinating PV application technologies these days. To apply PV modules in buildings, various factors should be considered, such as the installation angle and orientation of PV module, shading, and temperature. The temperature of PV modules that are attached to building surfaces especially is one of the most important factors, as it affects both the electrical efficiency of a PV module and the energy load in a building. This study investigates the electrical and thermal performance of a semi-transparent PV module that was designed as a glazing component. The study evaluates the effects of the PV module's thermal characteristics on its electrical generation performance. The experiment was performed under both Standard Test Condition (STC) and outdoor conditions. The results showed that the power decreased about 0.48% (in STC with the exception of the temperature condition) and 0.52%(in outdoor conditions, under 500 W/m²) per the 1 °C increase of the PV module temperature. It was also found that the property of the glass used for the module affected the PV module temperature followed by its electrical performance.