Solar cooling system using concentrating collectors for office buildings: A case study for Greece

On a European level there is intense research activity to broaden the applications of solar thermal systems beyond their established domains (hot water, space heating support) and to foster their participation in the energy maps of the EU-Member States. Concentrated Solar Thermal (CST) systems are expected to play a key role in this effort, especially for achieving the medium and high temperatures needed, for electricity generation, for industrial applications but also for hybridized solar heating/cooling and desalination applications.This paper presents a proposal for implementation of a CST system in the building sector, based on a research carried out in the Laboratory of Environmental and Energy Efficient Design of Buildings and Settlements at the University of Thrace. Specifically, an integrated solar cooling system using parabolic trough solar collectors and double-effect chiller is discussed, used to cover the cooling needs of typical office building in Greece.As it was shown, the use of concentrating solar collectors leads to significantly higher output temperatures that can enable the use of two stage absorption chillers with a higher COP. Alternatively, when low or medium temperature heat is required, the use of CST systems takes less space to cope with it than traditional flat plate collectors. The combination of these parameters can contribute to removing key barriers associated with the broader diffusion of solar cooling technology, enhancing the potential to become more competitive to the conventional air conditioning technologies.     

Sensitivity analysis for thermocline thermal storage tank design

Concentrated solar power coupled with thermal energy storage is a promising approach for providing the world with clean, renewable, sustainable and cost-competitive power on a large scale. Thermocline thermal energy storage has been proposed as an efficient and cost-competitive alternative to the traditional two-tank design. The thermocline thickness is directly linked to the efficiency of the storage tank. Sensitivity analysis is thus applied to a model of the thermocline thickness to identify the parameters that influence it the most. Results indicate that the tank height along with the thermophysical properties of the solid filler material influence the tank efficiency the most, with fluid properties and having a secondary effect.     

Recent Developments in Integrated Solar Combined Cycle Power Plants

Global concern for depleting fossil fuel reserves have been compelling for evolving power generation options using renewable energy sources. The solar energy happens to be a potential source for running the power plants among renewable energy sources. Integrated Solar Combined Cycle(ISCC) power plants have gained popularity among the thermal power plants. Traditional ISCC power plants use Direct Steam Generation(DSG) approach. However, with the DSG method, the ISCC plant’s overall thermal effici...     

Making concentrated solar power competitive with coal: The costs of a European feed-in tariff

The European Union has yet to determine how exactly to reach its greenhouse gas emissions targets for the future. One potential answer involves large-scale development of concentrated solar power (CSP) in the North African region, transmitting the power to Europe. CSP is a relatively young and little utilized technology and is expensive when compared to other methods of generation. Feasibility studies have shown it is possible to generate enough power from CSP plants in Africa to spearhead the EUs climate goals. However, the costs of such a project are less well known. Currently, CSP must compete with low cost coal-fired electricity plants, severely hindering development. We examine the possible investment costs required for North African CSP levelized electricity cost to equal those of coal-fired plants and the potential subsidy costs needed to encourage growth until the technologies reach price parity. We also examine the sensitivity of investment and subsidies to changes in key factors. We find that estimates of subsidy amounts are reasonable for the EU and that sensitivity to such factors as perceived risk and learning rates would enable policy-makers to positively influence the cost of subsidies and time required for CSP to be competitive with coal.     

Study of hot air generator with quasi-uniform temperature using concentrated solar radiation: Influence of the shape parameters

The non-uniformity of the air temperatures and the slow flow rate at the plane collector exit constitute the main cause of the limitations of the solar drying systems. In order to obtain an uniform and a variable flow rate for different uses, a hot air generator using concentrated solar radiation is proposed. To improve the thermal efficiency of the generator, a study of the influence of different shape parameters is realized. The generator is simulated in the laboratory while investigating the flow induced by a circular disc heated uniformly by Joule effect at constant temperature. This disc is placed at the entrance of an open ended vertical cylinder of a larger diameter. Thermal radiation emitted by the hot disc heats the cylinder wall. The heating of the fluid at the cylinder-inlet generates a thermosiphon flow around the one created by the hot disc. The comparison of the velocity and the temperature profiles of the resulting flow permits to determine the influence of the cylinder height, the vertical source-cylinder spacing and the radius ratio, on the resulting flow at the system exit. Thus, a judicious choice of the shape parameters entails an improvement of the flow rate as well as the thermal flux absorbed by the air and a good homogenization of the air temperature at the generator exit.     

Decomposition of Ozone in Highly Concentrated Aqueous Solutions Under semi-Commercial Conditions

The use of ozone in the treatment of drinking water in the form of a highly concentrated aqueous solution yields technological advantages compared with the traditional use of ozone in its gaseous state. However, for a comparative calculation of profitability, it is essential to know the ozone decomposition rate in the water solution in question. The present paper reports for the first time investigations with respect to this question under semi-commercial conditions and compares the results with laboratory tests made at another place.     

蓝晶石精矿烧结样品中SiO_2成分相的存在形式

通过对蓝晶石精矿烧结样品的X射线衍射分析（XRD）和扫描电境（SEM）研究,发现蓝晶石转化成莫来石过程中分解出的SiO2存在形式与蓝晶石的较大的体积膨胀效应及原料的原始成分密切相关;并且,形成的方石英相含量多少及其结晶程度的高低与蓝晶石的快速分解阶段相对应,是蓝晶石精矿快速分解和膨胀温度（区间）的指示剂。     

硫酸装置干吸工序技术改造实践

在硫酸装置干吸工序改造中,引用了带阳极保护管壳式浓硫酸冷却器,高强度的填料塔,对填料,填料支承,除沫器及一些辅助设备进行了改造,改造后技术指标良好,设备运行平稳。     

On the application of concentrated solution theory to the forced convective flow of excess supporting electrolyte

A recent model for electrolysis with forced convection in a channel and an excess of dilute supporting electrolyte is extended using concentrated solution theory. Mean Spherical Approximation theory is used to calculate the necessary Onsager coefficients and ionic activities. Using asymptotic methods, we demonstrate the surprising similarities between the leading order equations for the dilute and concentrated theories. In addition, in deriving the extension, certain omissions in the original work are highlighted: an oversight in the Butler-Volmer law used in the original work is corrected, and the systematic use of similarity-like variables in electrochemical problems that do not have a similarity solution along the entire length of the diffusion layer adjacent to an electrode is demonstrated. This helps to explain the manner in which the solutions for the anode and cathode boundary layers and the bulk region decouple from each other at limiting current, enabling a much simpler solution strategy.     

氯霉素废水的处理

本试验对氯霉素废水的处理分浓废水和淡废水两个部分，浓度水采 烧法处理，淡废水采用还原一氧化二级物化法处理。结果都能达到国家和上海市的排放标准，且工业上可行，投资上节省。