光电型总日射表性能的初步研究

对光电型总日射表与ＰＳＰ型总日射表进行了对比测试。在带有圆柱形余弦修正器时光电型总日射表的灵敏度尚佳。在太阳高度角小型３５°、没有温度补偿或将传感器与二次仪表做成一体时其误差较大     

Optimal sizing of a solar–biogas-based cooking system for a cluster of villages

Energy supplies particularly in remote and far-flung rural areas are in pathetic situation. Leave aside other needs, most of the rural communities still use wood as a source of energy for cooking. Burning of wood is not only an inefficient method, but also hazardousness for the person working on the stove. People have been working for cleaner and efficient means of cooking for decades. Solar cooker- and biogas-based cook stoves are two of the successfully implemented technologies in this area. Although solar cooker requires no maintenance, the initial investment is quite high for a cluster of villages. In addition to this, the intermittency involved in solar energy makes this an unreliable source.

In this paper, a cluster of villages of Narendra Nagar block of Tehri Garhwal district of Uttarakhand, India, has been studied in terms of their thermal requirements. The potential of solar energy and biomass energy has been estimated. An integrated solar–biogas system has been proposed to satisfy this cooking demand. To obtain the optimal sizes of solar cooker and biogas generator, MATLAB codes have been developed. It was found that this system is more economical and much reliable than the other two cases.     

新型便携式太阳总辐射仪的研制

介绍了新型便携式太阳总辐射仪的设计与实现方法。它可实现瞬时太阳辐照度和一天至一周内太阳辐照度的测量与显示,同时还可实现现场环境温度的测量与显示。它由一个超低功耗智能型带１２位Ａ／Ｄ转换器和传感器宏编程语言解释程序的信号处理器和ＭＡＸＩＭ低功耗集成电路与硅太阳电池及半导体温度传感器组成。通过对实测结果的分析,该仪器令人满意。     

太阳辐射强度和温度对增强型冷却塔换热性能影响的研究

太阳能增强型自然通风冷却塔(SENDDCT)作为一种新型空气冷却系统,可利用太阳能提高自然通风冷却塔的效率。利用FLUENT软件建立太阳能增强型冷却塔的三维模型,研究太阳辐射强度和环境温度对其性能的影响;同时设计并搭建太阳能增强型冷却塔的实验系统,在实际天气条件下研究太阳辐射强度对其换热性能的影响。模拟结果表明太阳辐射强度一定时,通过换热器的空气流速以及换热率都会随着环境温度升高而降低。太阳辐射强度为500 W时,环境温度由10℃升到40℃,换热率由1.106 kW下降到0.281 kW。实验结果表明有辐射时冷却塔入口处的平均空气温度要比无辐射时的高5℃;实验期间无辐射时的平均换热率为0.682 kW,有辐射时的平均换热率为0.794 kW,即利用太阳能将平均换热率提高了0.112 kW。     

A comparison of estimated and measured values of solar radiation in Elazi , Turkey

In this study, variation of global solar radiation reaching the Elazi region at hourly and monthly average daily periods was examined measuring daily global solar radiation between April 1994 and March 1995 by a Kipp–Zonen pyranometer. Taking the measured values as reference, the statistical performance of the three equations used in estimating the monthly average global solar radiation was investigated. Secondly, it was shown that ‘bright sunshine hours/daylength’ and its standard derivation could be used to estimate the monthly daily ‘solar radiation/extraterrestrial radiation’ by applying the maximum likelihood quadratic fit method to the data taken from the state Meteorological Office in Elazi between 1983–1994.     

Performance test of a box‐type solar cooker: effect of load on the second figure of merit

In this paper thermal performance test experiments for first figure of merit (without load) and second figure of merit (with load) of a box‐type solar cooker were conducted as per Bureau of Indian Standards. The values of second figure of merit (F₂) were determined for different loads of water and the results show that F₂ depends on the quantity of water loaded in a solar cooker. Therefore, it is recommended that the performance test method should specify the amount of water which is to be taken. Copyright © 1999 John Wiley & Sons, Ltd.     

A truncated pyramid non-tracking type multipurpose domestic solar cooker/hot water system

For impressive dissemination of the solar thermal gazettes, it is imperative to keep on changing the device design features so as to cater to the different demands of diverse section of the society. Domestic solar hot water systems are not suitable for cooking and the capacity of domestic solar box type cookers for water heating is very low. We report truncated pyramid geometry based multipurpose solar device which could be used for domestic cooking as well as water heating. The device is designed, fabricated and tested. Cooking tests approved by Bureau of Indian Standards were performed in different seasons and the device was found to meet the requirement stipulated on two figures of merit. The performance of the design was also evaluated as a hot water system and the maximum efficiency was found to be 54%. The day-time and average night-time heat-loss coefficients were found to be 5.7 W/°C m² and, 3.74 W/C m², respectively, which are comparable to those of flat-plate collector based solar hot water systems. A simple economic analysis illustrate that this kind of multi-purpose design could be financially viable and physically useful.     

Design and development of efficient multipurpose domestic solar cookers/dryers

A truncated pyramid-type solar cooker is designed, fabricated and tested. The truncated pyramid geometry concentrates the incident light radiations towards the bottom and the glazing glass surface on the top facilitates the trapping of energy inside the cooker. One of the salient features of the proposed design is to completely eradicate the need for tracking the sun during cooking, as tracking of sun does not yield better performance. During testing, the highest plate stagnation temperature, under no-load condition, approached 140 °C and under full-load condition, water temperature inside the cooker reached 98.6 °C in 70 min. Two figures of merit, F₁ and F₂, were calculated and their values were 0.117° C m²/W and 0.467 °C l, respectively, meeting the standards prescribed by the Bureau of Indian Standards for solar box-type cookers. Minor modifications in design are recommended to achieve higher temperatures and reduce cooking times. The design also allows trays to be retained for use as a household dryer.     

PV/T太阳能光伏光热系统关键参数影响特性研究

利用PV/T太阳能光伏光热系统实验平台针对空气质量流量、太阳辐照强度、环境温度和大气降尘 4种影响系统性能的关键工况参数进行了实验研究。结果表明:在实验设定的流量范围内,PV/T系统的光热和光电效率都随着空气质量流量增大而稳步上升;太阳辐照强度增大时,系统输出电功率随之增大,光热效率变化较小,光电效率有一定程度的降低;环境温度在一定范围内时,系统的输出电功率和集热效率都随着环境温度的增大而增大,而当环境温度超过一定值后,系统的光伏模块受面板温度升高的影响光电转换效率呈下降趋势;随着积尘密度的增大,玻璃盖板的透射率减小,一个月的积尘量会导致系统光电效率和输出电功率分别下降17.84%和18.25%,若以光电效率衰减20%为界限,清洁周期为5周左右。     

光伏电站输出功率影响因素分析

光伏发电系统的发电量取决于太阳辐照强度和温度等因素,其输出功率的变化具有间歇性和不可控性,大规模的光伏并网应用将对大电网的稳定运行造成冲击。光储联合应用将有助于降低光伏电源的负面影响,为了协调配置光伏系统与储能系统,需要深入了解光伏发电系统的输出特性。首先分析了大规模光伏发电系统并网应用对电网带来的影响,进而介绍了光伏发电原理和影响光伏组件输出的因素;然后依托某100 kWp光伏电站的实际历史运行数据,基于统计学方法,从气象因素如日类型、太阳辐射强度和温度等影响光伏出力的角度,对光伏发电系统的输出特性作了定性、定量的分析,从而归纳了光伏输出特性,最后据此提出了光伏电站输出功率的评价指标。     

不同环境温度与负荷条件下燃气轮机联合循环热电联产特性分析

为研究环境温度、热电负荷条件对联合循环热电联产全工况性能的影响,采用模块化建模方法对系统各部件建模,利用各部件参数的相互关系将各模型耦合得到联合循环热电联产模型,通过对比分析各环境温度下的机组特性得出结论:满负荷时,随环境温度的变化联合循环热效率存在最佳值,主要与凝汽器压力变化规律有关,凝汽器压力在环境温度Ta=8℃时变化规律发生转变,联合循环效率在该温度下出现最佳值;变负荷运行时,底循环性能在高、中间和低负荷区域内的最佳环境温度不同;供热工况下,分析了热电联产机组不同评价指标下的最优供热方式,其中以经济效率作为热电联产评价指标时,在任何热负荷下都建议高电负荷运行。     

聚光太阳灶用金属相变贮能装置的研究

研究了聚光太阳灶用高温金属相变贮能装置。贮能材料为铝基或锌基合金。当太阳辐射强度为1.3kW/m~2时,在面积为2m~2的聚光灶上该贮能装置可加热到650℃—700℃,贮能装置可将4kg水煮沸。     

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%。     

A Method of Estimating Monthly Global Radiation for Singapore

The design of solar systems and the determination of cooling and heating load of buildings require information on global radiation in addition to other meteorological data. In this study, equations have been developed for the clearness index K_T , which is the ratio of monthly average daily values of global radiation to that of extraterrestrial radiation on a horizontal surface, as a function of the ratio of monthly average daily values of sunshine hours and day length. The extraterrestrial radiation and the day length can be calculated from Eqs. (5) and (3) respectively. The sunshine hours can be obtained from the meteorological station of Singapore. A reasonable estimate of monthly average daily global radiation can be obtained from these equations.