On the clear sky model of the ESRA — European Solar Radiation Atlas — with respect to the heliosat method

This paper presents a clear-sky model, which has been developed in the framework of the new digital European Solar Radiation Atlas (ESRA). This ESRA model is described and analysed with the main objective of being used to estimate solar radiation at ground level from satellite images with the Heliosat method. Therefore it is compared to clear-sky models that have already been used in the Heliosat method. The diffuse clear-sky irradiation estimated by this ESRA model and by other models has been also checked against ground measurements, for different ranges of the Linke turbidity factor and solar elevation. The results show that the ESRA model is the best one with respect to robustness and accuracy. The r.m.s. error in the estimation of the hourly diffuse irradiation ranges from 11 Wh m⁻² to 35 Wh m⁻² for diffuse irradiation up to 250 Wh m⁻². The good results obtained with such a model are due to the fact that it takes into account the Linke turbidity factor and the elevation of the site, two factors that influence the incoming solar radiation. In return, it implies the knowledge of these factors at each pixel of the satellite image for the application of the Heliosat method.     

Making full use of the clearness index for parameterizing hourly insolation conditions

An enhanced parameterization of insolation conditions based only on the knowledge of global irradiance is presented. Two limitations associated with the current approach using the clearness index are pointed out: its dependence on solar elevation and its inability to differentiate between different conditions that produce the same global irradiance. Suggestions are provided which could overcome part of these limitations. Arguments are substantiated with solid experimental evidence. It is further shown that noticeable gains in accuracy for the decomposition of global into direct and diffuse irradiance are possible if one makes optimum use of the information available within a global irradiance time series.     

METSTAT—The solar radiation model used in the production of the National Solar Radiation Data Base (NSRDB)

This paper describes selectee aspects of the METSTAT (Meteorological/Statistical) solar radiation model. METSTAT was developed specifically to support the production of the National Solar Radiation Data Base for the United States. The model was used to estimate hourly values of direct normal, diffuse horizontal, and global horizontal solar radiation for those times and locations for which measured data were not available. The input parameters for METSTAT include total and opaque cloud cover, aerosol optical depth, precipitable water vapor, ozone, surface albedo, snow depth, days-since-last-snowfall, atmospheric pressure and present weather. The model employs deterministic algorithms to generate accurate monthly means for each element for each hour and statistical algorithms to simulate the statistical and stochastic characteristics of multiyear solar radiation data sets.     

常用太阳跟踪系统接收辐射量的计算

为了解决太阳跟踪系统接收辐射量的理论计算值与实测值偏差较大的问题,本文从任意斜面上太阳光入射角、天顶角和方位角的计算方法出发,阐述了双轴和斜单轴太阳跟踪系统的入射角和方位角的计算方法。并结合太阳散射辐射各向同性的假设,论述了常用太阳跟踪系统所接受辐射量的计算方法,实现了将水平面观测值转化为跟踪系统的有效接收量。将这种基于实测基础上的理论计算结果和完全实测数据进行对比,结果表明该方法能有效的应用于太阳跟踪系统接收辐射量的预测中。     

Solar Thermal Electricity Generation EURELIOS,the 1 MW(el) Helioelectric Power Plant of the European Communities

The fundamental investigations into atmospherothermic solai chimney power plants and the construction of the pilot plant were commissioned by the Minister of Research and Technology of the Federal Republic of Germany. The work was supervised by the energy research project management department of Kernforschungsanlage Jiilich GmbH (The Jiilich Nuclear Energy Research Establishment).

The basic principles of solar chimney power plants are presented in the form of simple estimates. From the relationships between the physical principles on the one hand and the scale and construction costs on the other, it may be concluded that economical power generation will be possible with large-scale plants designed for up to 400 MW/pk. A number of the design features of the pilot plant in Manzanares are also described.     

A new Wind Atlas to support the expansion of the Italian wind power fleet

As a contribution to national strategic energy planning, recent developments in meteorological modeling and wind generation technologies have improved the representation of the spatio-temporal features of wind. This paper describes an updated Italian Wind Atlas (Atlante EOLico ItaliANo [AEOLIAN]) released in the early 2000s. The objective of AEOLIAN is to guide future wind generation to accord with ambitious European greenhouse gas emission targets set for 2030 and 2050. AEOLIAN is the result of a collaboration effort between Ricerca sul Sistema Energetico (RSE) SpA and the National Center for Atmospheric Research (NCAR), which jointly developed a novel approach combining high-resolution numerical weather modeling with the Analog Ensemble (AnEn) statistical technique. This paper uses dynamical model runs with hourly output for 1990–2019 with 4 km horizontal grid spacing. For 2015–2019, an inner grid nest with 1.33 km horizontal grid spacing is used. The AnEn is then employed to temporally extend the 5 years of high-resolution runs back through 1990–2014 to create a 30-year dataset for Italy and surrounding marine areas. A thorough verification is carried out using 104 observational stations homogeneously distributed throughout the territory. Compared with other state-of-the-art products, AEOLIAN provides enhanced accuracy over complex terrain thanks to higher horizontal resolution and the assimilation of observational wind data over the domain, which result in a reduction of model bias on complex terrain and a better reconstruction of the wind distributions. Finally, a new WebGIS interface ( https://atlanteeolico.rse-web.it/ ) to explore AEOLIAN data is described.     

A procedure to select working fluids for Solar Organic Rankine Cycles (ORCs)

The selection of working fluid and working conditions of the Organic Rankine Cycle (ORC) has a great effect on the system operation, and its energy efficiency and impact on the environment. The main purpose of this study is to develop a procedure to compare capabilities of working fluids when they are employed in solar Rankine cycles with similar working conditions. The Refprop 8.0 database with 117 organic fluids has been considered as the reference in this study. A procedure to compare ORC working fluids based on their molecular components, temperature–entropy diagram and fluid effects on the thermal efficiency, net power generated, vapor expansion ratio, and exergy efficiency of the Rankine cycle has been proposed. Fluids with the best cycle performance have been recognized in two different temperature levels within two different categories of fluids: refrigerants and non-refrigerants. Based on categories of solar collectors, 11 fluids have been suggested to be employed in solar ORCs that use low or medium temperature solar collectors. Collector efficiency improvement and use of the regenerative ORC instead of the basic cycle reduce irreversibility of a solar ORC. Calculation results show that for selected fluids, the theoretical limits for irreversibility reduction and exergy efficiency enhancement through collector efficiency improvement are 35% and 5% respectively, when the collector efficiency increases from 70% to 100%. The effect of regeneration on the exergy efficiency of the cycle is fluid dependent while the effect of collector efficiency improvement on the exergy efficiency of the cycle is nearly independent of fluid type. At the two temperature levels studied, higher molecular complexity results in more effective regenerative cycles except for Cyclohydrocarbons.     

Performance of S-CO_2 Brayton Cycle and Organic Rankine Cycle(ORC) Combined System Considering the Diurnal Distribution of Solar Radiation

This paper researches the performance of a novel supercritical carbon dioxide(S-CO_2) Brayton cycle and organic Rankine cycle(ORC) combined system with a theoretical solar radiation diurnal distribution. The new system supplies all solar energy to a S-CO_2 Brayton cycle heater, where heat releasing from the S-CO_2 cooler is stored in the thermal storage system which is supplied to the ORC. Therefore, solar energy is kept at a high temperature, while at the same time the thermal storage system temperature is low. This paper builds a simple solar radiation diurnal distribution model. The maximum continuous working time, mass of thermal storage material, and parameter variations of the two cycles are simulated with the solar radiation diurnal distribution model. 10 organic fluids and 5 representative thermal storage materials are compared in this paper, with the mass and volume of these materials being shown. The longer the continuous working time is, the lower the system thermal efficiency is. The maximum continuous working time can reach 19.1 hours if the system provides a constant power output. At the same time, the system efficiency can be kept above 38% for most fluids.     

Solar hydrogen energy: The European–Maghreb connection. A new way of excellence for a sustainable energy development

The global sustainability is a key word of the future energy system for human beings. It should be friendly to our earth. Hydrogen energy is a critical resource to sustainable energy development. Over the coming decades, rapid economic growth will necessitate expanded and diversified energy supplies. This study is proposed to illustrate the attention to the opportunities and possibilities of connecting the energy consumer in North Mediterranean countries, to the reservoir of the Great Sahara of North Africa using hydrogen as a solar energy carrier. It also discusses cooperation between North Africa and north sides of the Mediterranean that has been going on for a long time, in oil and natural gas industry, and why cannot be done in solar hydrogen energy industry, which will reduce pollution and will last forever. Clearly, North Africa is a major bilateral partner with the Europe and the people of the two shares of the Mediterranean will be work together and to built strategic relationships for many decades. In the future, North Africa countries are well-positioned to play a greater role in the Europe clean energy equation. Demographically, interregional migration due to economic concerns will decline. Now, there are good chances to start such cooperation for the benefits of all partners.     

Does the use of Solar Home Systems (SHS) contribute to climate protection?

The paper addresses planners and decision-makers in the field of international development cooperation and also institutions concerned with the impacts of project- and technology promotion. The primary aim of the dissemination of Solar Home Systems (SHS) in off grid areas in developing countries is to improve the living conditions of the population in a cost–effective manner. A large-scale dissemination is essential both for significant contributions to development and for climate effectiveness. However, the contribution of SHS to climate protection is disputed. This analysis presents the most important parameters affecting the contribution of SHS to climate protection and quantifies the influence of those parameters. The case considered presupposes the commercial dissemination of SHS. Greenhouse gas (GHG) emissions are affected by the marketing decisions of the supplier of SHS. With regard to the impact on GHG emissions, a comparison is made between traditional lighting with petroleum lamps and the use of dry cell batteries to operate small devices (baseline case) on the one hand and SHSs on the other. The comparison shows GHG savings of around 9 tonnes of CO₂ equivalent GHG emissions within a 20-year period of use of one single 50 Wp SHS compared with the baseline case. The result is robust with respect to variations in GHG-affecting variables. Petroleum consumption and dry cell batteries dominate GHG emissions balances to such an extent that scarcely any importance can be attached to GHG emissions from the transportation and manufacture of SHS. Therefore, it is permissible to use simplified GHG inventories which ignore the GHG emissions arising from the transportation and manufacture of SHS. Therefore the conclusion is, if SHS are commercially disseminated and used cost efficiently to substitute kerosene and dry cell batteries they reduce GHG emissions effectively. In that case SHS can make a significant contribution to climate protection by the dissemination of large numbers.     

医用直线加速器辐射环境影响评价方法的探讨

文章针对直线加速器辐射环境影响评价方法进行探讨.已建且投入运行的直线加速器采取现场监测进行评价;拟建的直线加速器主要评价其机房设计的合理性,评价方法有类比法和屏蔽计算法.     

Research on new method of electron beam candle melting used for removal of P from molten Si

Abstract

A new method, electron beam candle melting (EBCM), is proposed for the removal of P in molten Si, to produce high quality material such as solar grade silicon for photovoltaic applications. EBCM is designed to overcome the shortcomings of electron beam melting while utilising the high saturated pressure of P in molten Si to effect refining. The experimental result showed that it could remove P from Si effectively; in addition, the energy utilisation ratio was experimentally proved to be high. The evaporation coefficient of P removal is in a reasonable region and comparable with the theoretical value, which indicates that EBCM is a feasible method for the removal of P in molten Si in low power.     

Solar and geothermal heating and cooling of the European Centre for Public Law building in Greece

The European Centre for Public Law in Legraina near Athens in Greece is heated and cooled by a combined solar and geothermal system. The main components of the system are a saline groundwater supplying well, water storage tank for 6 h autonomy, inverter for regulating geothermal flow, heat exchanger, two electrical water source heat pumps placed in cascade, fan coils, air handling units, as well as solar air collectors for air preheating in winter. In addition, hot water is supplied to the building hostel by solar water heaters. Monitoring of the energy system during heating showed excellent energy efficiency and performance.     

太阳能总辐射仿真软件的设计及其实地测量验证

依据太阳能辐射的相关理论，采用VB语言设计了基于任意地理位置的太阳能总辐射仿真软件，通过对徐州地区太阳能总辐射的实地测量研究，证实了该软件的有效性，对于指导各地区太阳能的利用具有一定的实际意义。     

Background to requirements for the prevention of brittle fracture in the European standards for unfired pressure vessels (prEN 13445) and metallic industrial piping (prEN 13480)

Following a brief historical introduction to brittle fracture prevention for pressure vessel applications in various countries, the derivation of the toughness requirements of the European pressure vessel code are described. The background to the specification with respect to yield strength range and the treatment of sub-size Charpy is presented. It is concluded that whilst the European requirements do represent a compromise of various national codes, their correct application will lead to fracture safe pressure vessels.     

Solar energy in Andalusia (Spain): present state and prospects for the future

The unsustainability of the present production–consumption energy model highlights the finite nature of conventional energy resources, as well as the environmental degradation inherent in such a model. Today's environmental policies are largely devoted to fostering the development and implementation in Europe of renewable energy technologies. This paper analyses the present and future situation of renewable energy resources in Andalusia in the south of Spain, and more specifically, of solar energy with an average potential radiation of 4.6±0.3 kW h/m² per day. In Andalusia energy policies are generally implemented through regional development plans such as the Plan Energético de Andalucía (PLEAN)¹ and the Programa Andaluz de Promoción de Energías Renovables (PROSOL).² The principle objective of the latter programme is to implement and increase high-temperature solar thermal energy to 100 MW in 2006, even raising it to 230 MW in 2010. Regarding low-temperature solar thermal energy installations, there are plans to increase the quantity of m²/1000 installed per inhabitant from the present figure of 14 to a total of 142. Regarding individual installations of solar photovoltaic energy, the present aim is to cover 20.4% of the national objectives and 15% in installations connected to the electricity network. The geographic location of Andalusia in the south of Spain signifies that it is in a key position to play an important strategic role in the implementation of renewable energy technology in Europe, as well as providing sufficient energy for its own needs and even exporting such projects to other countries.     

On the Development of the Solar Photovoltaic and Thermal (PVT) Collector

The solar photovoltaic and thermal (PVT) collector is a device which converts solar energy into thermal and electrical energies simultaneously. The PVT collector can be used whenever both electricity and hot water are required, for example, for domestic uses. It is a known fact that the efficiency of the solar (photovoltaic) cells decreases as operating temperatures increase. Therefore, a better and a more efficient use of these cells, calls for cooling the cells. One method for doing that is to use a heat exchange system, which cools the cells by means of a heat absorbing medium, such as water, flowing in pipes. The heat removed from the cells results in hot water. Another advantage of the PVT collector is its higher overall efficiency per unit area and lower packaging costs due to its compact design. In this paper a theoretical analysis of the PVT collector using a simulation model is presented. In this model the PVT collector is divided into a matrix of ``small' PVT collector units, each one consisting of several layers. The energy balance of each ``small' PVT collector unit is studied by analysis of the energies entering and leaving each one of its layers. Later, the process is applied to the PVT collector itself. A PVT collector was designed and constructed and putthru a series of experiments under varying load conditions, insolation levels and other climatological conditions.     

Zur Simulation der Globalstrahlung(On the Simulation of Global Radiation)

Die in Simulationsanlagen für die Globalstrahlung vorhandene spektrale Verteilung der Strahlung wird in der Praxis immer von der der Globalstrahlung abweichen. Wenn in solchen Anlagen die Bestrahlungsstärke auf den Wert der für Prüfzwecke vorgeschlagenen Globalbe-strahlungsstärke eingestellt wird, ergeben sich Wirkungen bei bestrahlten Objekten, die von denen bei Bestrahlung mit Globalstrahlung abweichen.

Für diese Tests ist daher die Bestrahlung so einzustellen, daβ die “wirksame” Bestrahlungs-stärke in der Anlage ebenso groβ ist, wie die “wirksame” Globalbestrahlungstärke. Diese “wirksamen” Bestrahlungsstärken hängen immer von der relativen spektralen Wirkungsfunktion (relative spektrale Empfindlichkeit) des bestrahlten Objektes ab.

Am Beispiel einer Simulationsanlage mit Xenon-Lampen für Tests an Si-Solarelementen werden die notwendigen Berechnungen vorgeführt.

Equipment for the use of solar radiation must be tested under defined conditions, where the absolute irradiance and its spectral distribution, and the solid angle of the incident radiation are of importance.

In praxis the spectral distribution of the incident radiation differs from the prescribed function. Then the effect of the radiation differs from that received by the prescribed radiation for equal irradiance.

For exact test results it is necessary to irradiate the equipment to be tested (solar cell, solar collectors) with an “effective” irradiance, which is equivalent to the effective prescribed irradiation. This effective irradiance depends on the spectral distribution of the radiation used for the test, the prescribed spectral distribution, the relative spectral responsivity of the test object and the prescribed absolute irradiance.

The necessary calculations for the effective irradiance are shown as an example for a test equipment with Xenon-lamps for Si-solar cells.