Optimising the tilt angle for solar surfaces using different solar irradiation models in Yazd,Iran

This paper deals with the determination of the optimum tilt angle for south-facing solar surfaces to collect the maximum solar irradiation in Yazd, Iran. In order to increase the accuracy of results, different models are used in this study. The accuracy of the models is compared in terms of the statistical indicators, RMSE and MBE. The results indicate that the Klucher model gives the best results for estimating the solar radiation reaching the solar surfaces. In comparison to the horizontal surface, on average the gain of energy during the year will be 22.82% if a solar surface is installed at yearly optimum tilt angle. For higher efficiency, it is suggested that the solar surface mounts at the seasonal tilt angle. This leads to an increase in the efficiency of the solar surface of more than 8.86% over that of a similar fixed solar surface at the annual tilt angle.     

某高速公路顺层路堑边坡的勘察和优化设计

公路顺层边坡的的稳定与否,对于公路的施工安全和运行安全有着重要的影响。所以对此类边坡特点的分析研究非常重要。首先总结公路顺层路堑边坡的特点,提出了公路顺层路堑边坡的优化设计路线。在此基础上,以连云港某公路边坡为例,按照公路顺层边坡设计思路：在工程地质条件分析的基础上,采用赤平投影分析其破坏模式和极限平衡法计算其稳定性,以及对边坡的主要影响因素进行了敏感性分析,并依据计算结果确定了最优设计坡角。在保证总体边坡稳定的前提下,提出边坡的加固设计方案。结果表明该设计对工程建设有着很强的实用性和系统性。     

Year-round numerical simulation of a parabolic solar collector under Lebanese conditions: Beirut case study

A detailed thermal and optical numerical model is developed to simulate the performance of a small-scale parabolic collector having an evacuated receiver line with selective coating, taking into account different energy balances and interactions with the surrounding. An analytical model is developed to estimate the direct, diffuse and global solar radiation intensities on inclined surfaces. The collector performance model was validated using published experimental data. A year-round dynamic simulation for the collector performance under Beirut climatic conditions was carried out with an economic and environmental analysis. The outlet water temperature could reach a maximum of 114°C in July and 52°C in December by employing a collector of about 6 m² aperture area with 0.01 kg/s water flow rate. The maximum daily thermal energy production is attained in July with 22.267 kWh while January exhibits the lowest thermal energy production with 6.704 kWh per day with a maximum thermal efficiency of 72%.     

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.     

Experimental investigation and analysis of the hybrid solar collector

Hybrid solar collector is a new and innovative technique to harness all the spectrum of sunlight and hence generate a system to harness sunlight. This project deals with the fabrication of a parabolic trough which suits the required design of the solar collector. This project deals with the study of heat transfer across the receiver tube and mode of heat transfer across the hybrid solar collector, to optimise the design, to minimise the losses and maximise the heat and photon transfer to the receiver and power generating unit. Our aim is to study the heat exchange process across tube and to prevent the heating of solar panels from the radiations emitted by the receiver tube when light is focused on it and direct the working of solar collector to a maximum efficient way. We consider the radiation spectrum of sun to be of different waves and utilising each component of it – that is, visible and UV (consisting most of photons) and infrared (consisting of heating radiation) – and try to segregate them with the help of a water jacket and bring the temperature of the PV panels to an optimum condition.     

Prediction of the optimum slope and surface azimuth angles using the Genetic Algorithm

In this paper, the Genetic Algorithm is applied to calculate the optimum slope and surface azimuth angles for solar collectors to receive maximum solar radiation. An area of Iran is selected to verify the results of this algorithm. The optimum angles and the collector input solar energies for these angles are calculated in hourly, daily, monthly, seasonally and yearly bases respectively. Then, the influence of different combinations of solar radiation components on the optimum slope angle and the energy gain is investigated. The results show that the Genetic Algorithm is a useful technique to find the optimum angles specifically when the number of independent parameters is large. The results show that the daily, monthly and yearly optimum surface azimuth angles for receiving the maximum solar energy are zero. Adjusting the collector at the daily optimum slope angle slightly increases the collector input energy compared with the case of monthly optimum slope angle so that the gain of solar energy is almost the same. The results also show that the hourly optimum surface azimuth angle is not zero and mounting the solar collector at the hourly optimum slope and azimuth angles increases the input energy significantly compared with the case of daily optimum angles. It is shown that the optimum slope angles are mostly dependent on the beam solar radiation. Furthermore, the results indicate that the optimum slope angles of solar collector and Photovoltaic panels are almost the same.     

谈调斜工作对采煤方法的重要性

针对现代化倾斜长臂综采工作面采煤工作中出现的刮板输运机偏离工作面正常位置,向工作面两边移动的问题,提出了调斜工作面的应对措施,分析了综采工作面调斜的关键技术参数,优化并确定了调斜开采方案,解决了工作中的诸多难题。     

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。     

Control-oriented model of a solar community with seasonal thermal energy storage: development,calibration and validation

The development of a control-oriented model of a solar community with seasonal storage (the Drake Landing Solar Community) is investigated. The proposed approach, intended to facilitate the development and testing of control strategies and targeting an actual predictive control implementation, is based on grey-box models, and enables the prediction of the system state (temperatures at key locations). This paper discusses the concept of state update procedure (whereby the system state is periodically corrected with measurements), which plays a fundamental role for control purposes. Firstly, the DLSC is presented and both operation and monitoring system are described. Secondly, a simplified model is developed for each sub-system: district and solar loops, short-term (water tanks) and seasonal (borehole) thermal energy storage, and existing operation rules are encoded. Finally, the model is calibrated and validated by using measurements at 10-min intervals over two years of operation (2015–2016, 2016–2017) and accurately predicts the system performance.     

基于遗传算法的钢结构优化设计及相应软件开发

针对结构优化问题的强离散性和遗传算法求解离散变量优化问题的有效性,将遗传算法应用于钢结构优化问题的求解。针对简单遗传算法的早熟缺陷进行了改进,并将改进后的遗传算法应用于钢结构的优化设计中。基于改进遗传算法和《钢结构设计规范》(GB50017—2003)开发了钢结构优化设计工具箱。算例表明,软件具有简单、快速、有效等优点。     

Overall cooling efficiency of a solar desiccant plant powered by direct-flow vacuum-tube collectors: simulation and experimental results

Using solar thermal energy is an interesting option for heat-driven air conditioning, e.g. desiccant cooling. In this article, the autonomous operations of a solar desiccant cooling plant powered by direct-flow vacuum-tube collectors are investigated. A model of the solar installation and the desiccant air handling unit is presented and implemented in the SPARK simulation environment and then it is validated experimentally. The overall cooling efficiency of the system is evaluated using simulation for humid and moderately humid climates and the effect of increasing the regeneration temperature on the cooling capacity, the overall cooling efficiency is studied and finally the overall efficiency of the collectors is calculated for the studied cases.     

集中太阳能水箱和集热器总采光面积探讨

就太阳能保证率的含义提出了日用热水量保证率和温度保证率理论,推导出太阳能集热水箱的两种计算公式,通过理论推导与研究确定了最经济且要充分利用太阳能时集热水箱的计算公式,从而简化了集热面积计算。     

Design and fabrication of the passive solar still using blue metal stone

In this paper, an attempt has been made to find out the effect of blue metal stone on heat transfer coefficient for a passive single-slope distillation system in summer climatic conditions. The experiments have been conducted on a south facing, single slope, solar still of 10° inclination of condensing cover, in summer climatic conditions for 24?h on 5 different days for three different sizes of blue metal stone from 6 to 20?mm and this is finally compared by using the basin without any absorbing material. The thermal efficiency is calculated by using the energy balance equation.     

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%).     

某变电站边坡加固方案及稳定性分析

通过某变电站边坡工程地质条件分析,确定了边坡破坏的影响因素以及破坏方式,并为该边坡的加固工程选择了合理的加固方案,采用PCSTABL4(边坡稳定性分析)程序分段计算了边坡加固后的稳定性,结果表明,采用的加固方案对边坡的治理是可行的,边坡的稳定性得到了较大的提高。     

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.     

某建筑用花岗岩矿边坡稳定性分析及最优边坡角研究

本文以某建筑用花岗岩矿边坡为研究对象,根据矿山开采现状、工程地质条件选取边坡稳定性计算剖面,通过三轴压缩强度试验获取岩体的物理力学参数,采用M-P法和Bishop在自重+地下水+爆破震动荷载工况计算现状边坡及设计边坡的稳定性系数,最终边坡角以向下取1°和2°进行优化。计算结果显示：该矿现状边坡局部稳定性系数为不满足要求,该矿采场边坡整体边坡角可从47°优化成47.5°,优化后稳定性系数满足要求。     

某住宅楼基础及边坡支护结构设计

结合长沙市某住宅楼基础的设计方案,介绍了护坡桩的设计方法,并在现有边坡边界条件不变的情况下,用住宅楼的部分基础承重桩支护边坡,达到一桩两用的效果,具有参考价值。     

Experimental investigation of the solar cooker during sunshine and off-sunshine hours using the thermal energy storage unit based on a parabolic trough collector

A solar cooker based on a parabolic trough collector with thermal energy storage (TES) was investigated. In this experimental set-up, solar radiations were focused on the absorber tube and the collected heat was transferred to the solar cooker by natural circulation (thermosiphon) of the working fluid. The water and thermal oil (engine oil) were used separately as working fluids. Acetanilide was used as the TES material in the solar cooker. In day time, the phase change material (PCM) stored heat as well as transferred it to the cooking pot. In evening time, the stored energy by PCM was used to cook the food. The cooking process was carried out with different foods and with variation in the quantity of food. It was found that the temperature of thermal oil was 10–24°C higher than water as the working fluid. The system was able to cook the food twice a day and the rate of evening cooking was higher as compared with noon cooking. Using thermal oil as the working fluid, the quantity of heat stored by PCM was increased by an amount of 19.45–30.38% as compared with water.     

Correlation between natural slope angle and rock mass strength rating in the Betic Cordillera,Granada, Spain

This study proposes a method to determine zones gentler or steeper than the equilibrium slope angle based on rock mass strength (RMS) and to regionalize the parameters. The method was developed using GIS and applied to rock masses of the Alpujarride Complex (Granada, Spain). 41% of the natural slopes studied have angles lower than the equilibrium due to dissolution processes and the presence of alluvial or colluvial deposits, while 28% of those slopes have angles higher than the equilibrium due to rapid erosion in tectonically active zones. Cross correlation analysis between maps showing degrees of slope equilibrium and landslide inventories suggest that long-term geomorphic changes have induced slope angles higher than the equilibrium which are associated with rock falls and rock slides.