太阳辐射直散分离模型比较研究——以北京地区为例

在建筑能耗模拟与太阳能建筑系统设计中,逐时的太阳直射和散射气象数据是最重要的基本参数。由于中国辐射观测数据的缺失,逐时直射和散射数据很难获得。很多学者对此进行了研究,提出了数十种直散分离模型。采用北京地区2009年—2011年3年太阳总辐射和散射实测数据,选取Erbs模型、Orglill模型、清华大学随机气象模型、宇田川光弘模型、张晴原模型5个代表性的直散分离模型进行计算验证,分析比较了实测数据和计算数据之间的相关系数R、均方根误差RMSE和相对误差RE,得出晴空指数Kt可以作为最主要的影响因子,Erbs模型预测散射的准确率最高,其次为张晴原模型和Orglill and Hollands模型。     

Hybrid models for global solar radiation prediction: a case study

ABSTRACT

This paper presents a comparison between different prediction models for solar radiation application. The present study assessed the performance of multi-layer perceptron (MLP) as well as boosted decision tree, and used a new combinition of these models with linear regression for the prediction of daily global solar irradiation (DGSR). The performance of the studied models was validated using a real dataset measured at the Applied Research Unit for Renewable Energies (URAER) situated in the south of Algeria. Different input combinations have been analysed in order to select the relevant input parameters for DGSR prediction. The results acheived show that the MLP model perfoms better than the others models in terms of statistical indicators: normalised root mean square error (0.033) and R² (97.7%).     

Correlation between global solar radiation and its direct and diffuse components

Work on typical correlations between global solar radiation and its direct and diffuse components is reviewed. Data for diffuse, global horizontal radiation measured at the City University of Hong Kong for the period 1991–1994 are analysed. Three correlations are considered — the diffuse coefficient (K_d) and the clearness index (K_t), the diffuse fraction (K) and K_t, and the direct normal (I_dn) and K_t. A hybrid correlation model based on hourly measured data is proposed for the prediction of hourly direct and diffuse components from the global solar radiation for Hong Kong.     

Comparison of solar radiation data sources for design and performance appraisal of CSP systems in India

The choice of a solar radiation data source is expected to have a significant impact on the predicted performance of a concentrating solar power (CSP) system and consequently on its technical and financial feasibility. In the present study, an attempt has been made to analyse the effect of choice of various solar radiation data sources on the predicted performance of a CSP system at 13 different locations in 5 different climatic zones of India. It was observed that there is significant variation in the amount of annual electricity output obtained for various locations using different solar radiation data sources resulting in variations in levelised cost of electricity. For a 50-MW parabolic trough-based CSP plant located in Jaisalmer, the estimated value of annual electricity output varies from 63 to 124?GWh. For a CSP plant based on the central tower receiver technology, the corresponding range is from 106 to 145?GWh.     

An Analytical Study on global radiation and meteorological parameters for India

ABSTRACT

A study is carried out for global radiation (global horizontal and global tilted radiation) and meteorological parameters (humidity and temperature) recorded for a period of one year (2011) at the National Institute of Solar Energy (NISE), Gwal Pahri (28.42°N, 77.15°E), India. Maximum global horizontal radiation of 7.22?kWh/m² is recorded in the month of June while minimum of 0.91?kWh/m² is observed in February. The highest value of the tilted radiation 7.27?kWh/m² is recorded in March and the lowest value 0.90?kWh/m² is noticed in February. The maximum temperature of 36.5°C and humidity of 87.6% are observed in the months of June and July, respectively. Conversely, minimum temperature of 6.1°C and humidity 21.7% are noticed in the months of January and April, respectively. Furthermore, meteorological parameters have been correlated with global radiation on horizontal and tilted surface. The study is vital for the performance analysis of different solar energy applications.     

Multi-step-ahead forecasting of daily solar radiation components in the Saharan climate

ABSTRACT

Accurate estimation of renewable energy sources plays an important role in their integration into the grid. An unexpected atmospheric change can produce a range of problems related to various solar plant components affecting the electricity generation system. Global solar radiation (GSR) assessment has been increased in the past decade due to its important use in photovoltaic application. In this paper, we propose the use of machine learning-based models for daily global and direct solar radiation forecasting in a semi-arid climate, using a combination set of meteorological parameters on a horizontal surface in the Ghardaïa region. The models are presented and implemented on 3-year measured meteorological data at Applied Research Unit for Renewable Energies (URAER) at Ghardaïa city between 2014 and 2016. The results show that both MLP and RBF models perform well for three-step-ahead forecasting with a slight improvement in MLP models in terms of statistical metrics.     

基于太阳辐射模拟的外遮阳优化设计

为解决在这种复杂建筑体型和朝向条件下的外遮阳优化,通过夏季太阳辐射量模拟分析了不同遮阳形式的遮阳效果,指出选择固定外遮阳效果不佳的立面采用可调节外遮阳,达到了节能率和经济性兼顾的效果。     

Evaluation of global luminous efficacy models for Florianópolis,Brazil

Several global luminous efficacy models have been tested with daylight-measured data obtained for Florianópolis, Southern Brazil. The models have been used with their original coefficients, given by the authors and also with local coefficients obtained when the models were optimized with the data measured in Florianópolis. The evaluation of the different models has been carried out considering three sky categories, according to a higher or lower presence of clouds.     

室外气温与太阳辐射的随动性关系研究

室外气温与太阳辐射强度之间存在某种随动关系,以中国南方13个典型城市气象数据为依据,通过回归分析方法,得到了太阳辐射与地表温度的动态拟合关系及地气温差随时间变化的动态拟合关系,各拟合公式相关系数R2均在0.97以上,说明拟合结果能显著的反映数据点的变化规律,进而建立了室外气温与太阳辐射强度的随动性关系。结果表明:高原地区,太阳辐射是室外气温与时间的一次函数;平原地区,太阳辐射是室外气温与时间的对数函数。对建筑冷负荷计算提供简便的方法,同时,也为太阳辐射强度与建筑冷负荷的随动性关系及太阳能空调的适宜性研究提供科学依据。     

Simplified correlations of global,direct and diffuse luminous efficacy on horizontal and vertical surfaces

A simple calculation method to calculate the mean hourly global, direct and diffuse illuminance on horizontal and vertical surfaces for all sky, clear sky, intermediate and overcast sky conditions, initially developed for Arcavacata di Rende (Italy), was compared with experimental data obtained at Geneva (Switzerland), Vaulx-en-Velin (France), Bratislava (Slovakia) and Osaka (Japan). The method is based on the use of constant luminous efficacies, adopted also for the vertical surfaces. In spite of its simplicity, the method furnishes reasonably good predictions, in comparison with a more complex reference calculation method and can be proposed as a simplified tool for design purposes.     

Performance assessment of empirical models for prediction of daily and monthly average global solar radiation: the case study of Ibadan,Nigeria

In this study, the performance assessment of empirical models for modelling global solar radiation in Ibadan is presented. The empirical models are derived from the three basic models: Angstrom–Prescott model, Garcia model and Hargreaves–Sammani model. The data used in the analysis consist of daily average global solar radiation, daily average sunshine hours, daily average maximum temperature and daily average minimum temperature collected over a period of nine years (2000–2008). Regression constants are determined for each of the model for each months of the year. The study reveals that Garcia Quadratic model puts up the best overall performance. The model can predict the daily average global solar irradiation with Mean Absolute Error of 1.86?MJ?m^?2?day^?1, Root Mean Square Error of 2.7?MJ?m^?2?day^?1, Mean Absolute Percentage Error 9.34% and Coefficient of Determination (R²) of 0.68.     

建筑节能分析太阳总辐射模型研究综述

太阳辐射是建筑节能分析的重要基础气象参数,实测数据远远不能满足需求,理论计算是目前获取辐射数据的主要途径。将常用水平面太阳总辐射模型归纳为气象参数、空间插值和基于DEM三类,详述了各自的原理和计算方法。对三类模型在建筑节能分析中的适用性进行了分析,展望了建筑节能分析用太阳辐射模型的发展趋势:气象参数模型与DEM模型的融合。     

Performance analysis on improved efficiency in a hybrid solar still and solar heater

ABSTRACT

This paper deals with solar still. Today fresh water demand is increasing continuously, because of the industrial development, intensified agriculture, improvement of standard of life and increase in the world population. Only about 3% of the world water is potable and this is not evenly distributed on the earth. On deserts and islands, underground water is not readily available and the cost of shipping to other places is high, it is worthwhile to consider producing potable water from saline water using solar energy that is in abundant in deserts. The efficiency of the solar still can be increased by increasing the evaporation rate and by minimising the convective and radioactive losses in still. The evaporation rate can be increased effectively by coating the still base with photocatalyst materials or by pre-heating the inlet water of still. The easily available GAC is one of the best photocatalyst materials suitable for the solar still for enhancing the evaporation rate. Solar-still technology is a renewable and efficient technology for pre-heating the inlet water to solar still. Hence the combination of GAC coating and solar-still technology can increase the evaporation rate and efficiency of solar still.     

混凝土箱形输水桥日照温度场及温度应力研究

分析了箱形输水桥产生日照温差及温度应力的原因,借助有限元软件ANSYS对某输水桥日照温差及温度应力进行有效的仿真模拟,计算结果表明：箱形输水桥的日照温差分布比较复杂,从箱形桥身的温度分布来看,顶板温度变化最剧烈,腹板次之,底板最小,温差近似为二次曲线分布。日照温差作用下混凝土箱形输水桥桥身内无论沿纵向和横向都将产生可观的温度应力,其值已超过混凝土的抗拉设计强度。所以,在箱形输水桥身结构设计中对日照温差作用下的温度应力必须予以重视,在设计中应配置适当的温度钢筋。     

太阳辐射作用下钢管温度场分析

基于ASHRAE晴空模型和热分析有限元理论,研究了太阳辐射作用下钢管温度场的日变化过程及温度场的分布规律.对影响钢管温度场的参数,包括太阳辐射吸收率、地面辐射反射率、钢管尺寸和钢管的空间方位进行了参数分析,研究了太阳辐射作用下各个参数对钢管温度场的影响规律.基于太阳辐射时程有限元分析和稳态热分析理论,提出了太阳辐射作用下钢管的温度场简化计算模型,并通过算例验证了简化计算模型,可为今后空间钢结构温度场和温度应力研究和设计提供借鉴和参考.     

太阳辐射引起建筑群温升的探讨

介绍了建筑群温度变化的数学模型,模拟了济南某小区在四种不同工况下太阳辐射引起的建筑群的温升情况,比较了建筑密度、下垫面材料、风速对建筑群温升的影响,结果表明,改变下垫面材料和增强自然通风可改善城市热岛效应。     

建筑环境设计模拟分析软件DeST第4讲建筑热过程中的太阳辐射相关模型

太阳辐射是影响建筑热状况的重要外扰，在建筑热过程分析时，必须加以准确的考虑。太阳辐射可以被不透明建筑围护结构表面吸收，也可以直接透过建筑的半透明围护结构进入室内，这就需要解决两个问题：有多少太阳辐射量能够到达建筑的表面；到达半透明围护结构表面的太阳辐射有多少能够穿过半透明围护结构直接进入室内。详细介绍了DeST在建筑动态热过程分析中，与建筑表面吸收太阳辐射情况密切相关的建筑表面阴影计算方法和散射辐射的考虑方法，并对半透明围护结构的辐射透过模型与传热模型进行了细致分析。     

Fast computer graphics techniques for calculating direct solar radiation on complex building surfaces

Direct solar radiation has a major influence on a building's thermal behaviour. Current simulation engines are not up to the challenge of accurately modelling solar gains for buildings with complex or curved geometry and buildings sited in dense urban areas. Accurate thermal performance prediction for buildings in early stages of design is hindered by excessive computation time and incompatibility between architectural models and building energy simulation software. This paper proposes using a combination of modern computer graphics rendering techniques and parametric B-spline interpolation methods to quickly and accurately calculate solar gains over a full year based on sparse data with a continuous interpolation method. These new procedures accommodate complex building geometries and intricate shadow patterns and can accelerate shading calculations by several orders of magnitude. Faster calculations allow studies to be made at the early stages of design when modifications can have the greatest impact on a building's thermal behaviour.     

Experimental and simulation analysis of thermal behavior of large-span roof system under solar radiation

The large-span metal roof systems can produce a significant nonuniform temperature effect under solar radiation, leading to potential safety hazards. An experiment is conducted to study the nonuniform thermal behavior of a small-scale continuous welded stainless steel roof (CWSSR) system under solar radiation. The small-scale CWSSR system considered different roof slopes and sunward side and nightside. The efficiency of the numerical analysis of the thermal behavior of the roof slab is verified in comparison with the experimental results. Based on the numerical and experimental results, the thermal effect of a full-scale CWSSR system is studied under different orientations, wind speeds, and atmospheric temperature. Through the analysis of research results, the nonuniform thermal features of the CWSSR system are significant and cannot be overlooked. The temperature difference between the sunward side and nightside roof slab is positively correlated with the roof slope. The thermal behavior of the CWSSR system is greatly influenced by wind speeds but is less affected by orientations and atmospheric temperature.     

RTK-GPS在广州新电视塔变形监测中的应用研究

高耸结构在强风、地震和温度变化作用下,容易产生过大的变形,从而危及结构安全。日照变形是超高层结构常见的变形形式之一,是评价结构健康状况的重要参数,在施工和运营阶段均需进行变形监测。本文以在建的广州新电视塔(塔高610m)为研究背景,利用RTK-GPS测量技术和高精度全站仪对其施工进行了全程日照变形监测。分析表明,当一天内的环境温度变化较大时,塔体的水平位移明显增大;随着电视塔高度的增加,塔体变形也相应增大;核心筒和钢结构的位移变形趋势基本一致等。观测结果验证了监测方案的合理性,对超高层建筑施工安全、施工验收和相应规范的改进具有重要的参考指导作用。