A prototype receiver for medium temperature conversion of solar radiation to heat

2011 ◽  
Vol 225 (8) ◽  
pp. 1111-1119 ◽  
Author(s):  
V Stefanović ◽  
M Bojić ◽  
S Pavlović ◽  
N Apostolović ◽  
I Nikolić ◽  
...  
Keyword(s):  
Solar Radiation ◽  
High Efficiency ◽  
Electric Energy ◽  
Glass Tube ◽  
Diffuse Radiation ◽  
Long Distance ◽  
Medium Temperature ◽  
Circular Arcs ◽  
Thermal Measurements ◽  
Solar Receiver

In this article, a solar receiver prototype (marked as P2CC, parabolic-and-circular collector) is described for medium temperature conversion of solar radiation in heat. The investigated concentrator has a tubular receiver and two identical reflectors, one from each side of the tubular receiver. The tubular receiver is a concentric tube consisting of a metal tube (absorber) inside the glass tube. Each reflector curve is defined using three curves where one curve is parabola and two curves are circular arcs. The demonstrated prototype has the reception angle of 110° at concentration ratio CR = 1.38, with the significant reception of diffuse radiation. The hydraulic measurements reveal the pressure drop up to 200 Pa. Thermal measurements discover the high efficiency of the P2CC of up to 75 per cent. The prototype application would mean significant savings of electric energy which is now used for preparation of warm water, and in central and long-distance heating systems.

scholarly journals New Control Scheme for Solar Power Systems under Varying Solar Radiation and Partial Shading Conditions

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1359
Author(s):  
Anindya-Sundar Jana ◽  
Hwa-Dong Liu ◽  
Shiue-Der Lu ◽  
Chang-Hua Lin
Keyword(s):  
Solar Radiation ◽  
Power Systems ◽  
High Efficiency ◽  
Rapid Change ◽  
Maximum Power ◽  
Maximum Power Point ◽  
Partial Shading ◽  
Detection Scheme ◽  
Threshold Control ◽  
Power Point

The traditional perturbation and observation (P&O) maximum power point tracking (MPPT) algorithm of a structure is simple and low-cost. However, the P&O algorithm is prone to divergence under solar radiation when the latter varies rapidly and the P&O algorithm cannot track the maximum power point (MPP) under partial shading conditions (PSCs). This study proposes an algorithm from the P&O algorithm combined with the solar radiation value detection scheme, where the solar radiation value detection is based on the solar photovoltaic (SPV) module equivalent conductance threshold control (CTC). While the proposed algorithm can immediately judge solar radiation, it also has suitable control strategies to achieve the high efficiency of MPPT especially for the rapid change in solar radiation and PSCs. In the actual test of the proposed algorithm and the P&O algorithm, the MPPT efficiency of the proposed algorithm could reach 99% under solar radiation, which varies rapidly, and under PSCs. However, in the P&O algorithm, the MPPT efficiency was 96% under solar radiation, which varies rapidly, while the MPPT efficiency was only 80% under PSCs. Furthermore, in verifying the experimental results, the proposed algorithm’s performance was higher than the P&O algorithm.

Thermal comfort analysis of a high-speed train cabin considering the solar radiation effects

2019 ◽  
Vol 29 (8) ◽  
pp. 1101-1117
Author(s):  
Lin Yang ◽  
Xiangdong Li ◽  
Jiyuan Tu
Keyword(s):  
Solar Radiation ◽  
Thermal Comfort ◽  
High Speed ◽  
Radiation Effects ◽  
Numerical Study ◽  
Thermal Conditions ◽  
Long Distance ◽  
High Speed Rail ◽  
Hot Weather ◽  
Cabin Environment

Due to the fast development of high-speed rail (HSR) around the world, high-speed trains (HSTs) are becoming a strong competitor against airliners in terms of long-distance travel. Compared with airliner cabins, HST cabins have much larger window sizes. When the big windows provide better lighting and view of the scenery, they also have significant effects on the thermal conditions in the cabins due to the solar radiation through them. This study presents a numerical study on the solar radiation on the thermal comfort in a typical HST cabin. The effect of solar radiation was discussed in terms of airflow pattern, temperature distribution and thermal comfort indices. Parametric studies with seven different daytime hours were carried out. The effect of using the roller curtain was also studied. The overall cabin air temperature, especially near passengers, was found to have significantly increased by solar radiation. Passengers sitting next to windows were recorded to have an obvious thermal comfort variation at different hours of the day. To improve the passengers’ comfort and reduce energy consumption during hot weather, the use of a curtain could effectively reduce the solar radiation effect in the cabin environment.

Improved Accuracy Models For Hourly Diffuse Solar Radiation

2005 ◽  
Vol 128 (1) ◽  
pp. 104-117 ◽  
Author(s):  
T. Muneer ◽  
S. Munawwar
Keyword(s):  
Solar Radiation ◽  
Regression Models ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Evaluation Procedure ◽  
Accuracy Score ◽  
Error Statistics ◽  
Diffuse Solar Radiation ◽  
Energy Applications ◽  
Extensive Evaluation

Solar energy applications require readily available, site-oriented, and long-term solar data. However, the frequent unavailability of diffuse irradiation, in contrast to its need, has led to the evolution of various regression models to predict it from the more commonly available data. Estimating the diffuse component from global radiation is one such technique. The present work focuses on improvement in the accuracy of the models for predicting horizontal diffuse irradiation using hourly solar radiation database from nine sites across the globe. The influence of sunshine fraction, cloud cover, and air mass on estimation of diffuse radiation is investigated. Inclusion of these along with hourly clearness index, leads to the development of a series of models for each site. Estimated values of hourly diffuse radiation are compared with measured values in terms of error statistics and indicators like, R2, mean bias deviation, root mean square deviation, skewness, and kurtosis. A new method called “the accuracy score system” is devised to assess the effect on accuracy with subsequent addition of each parameter and increase in complexity of equation. After an extensive evaluation procedure, extricate but adequate models are recommended as optimum for each of the nine sites. These models were found to be site dependent but the model types were fairly consistent for neighboring stations or locations with similar climates. Also, this study reveals a significant improvement from the conventional k-kt regression models to the presently proposed models.

Innovative Volumetric Solar Receiver Micro-Design Based on Numerical Predictions

2015 ◽  
Author(s):  
Raffaele Capuano ◽  
Thomas Fend ◽  
Bernhard Hoffschmidt ◽  
Robert Pitz-Paal
Keyword(s):  
Solar Radiation ◽  
Energy Demand ◽  
Large Scale ◽  
Solar Power ◽  
Numerical Models ◽  
Numerical Predictions ◽  
Proper Design ◽  
Global Increase ◽  
Solar Power Tower ◽  
Solar Receiver

Due to the continuous global increase in energy demand, Concentrated Solar Power (CSP) represents an excellent alternative, or add-on to existing systems for the production of energy on a large scale. In some of these systems, the Solar Power Tower plants (SPT), the conversion of solar radiation into heat occurs in certain components defined as solar receivers, placed in correspondence of the focus of the reflected sunlight. In a particular type of solar receivers, defined as volumetric, the use of porous materials is foreseen. These receivers are characterized by a porous structure called absorber. The latter, hit by the reflected solar radiation, transfers the heat to the evolving fluid, generally air subject to natural convection. The proper design of these elements is essential in order to achieve high efficiencies, making such structures extremely beneficial for the overall performances of the energy production process. In the following study, a parametric analysis and an optimized characterization of the structure have been performed with the use of self-developed numerical models. The knowledge and results gained through this study have been used to define an optimization path in order to improve the absorber microstructure, starting from the current in-house state-of-the-art technology until obtaining a new advanced geometry.

Comparative analysis of straight grate machines and combined facilities grate-tubetype kiln-cooler for selection technologies of pellets production

2021 ◽  
Vol 77 (8) ◽  
pp. 957-968
Author(s):  
A. A. Butkarev ◽  
E. A. Butkareva
Keyword(s):  
Comparative Analysis ◽  
Iron Ore ◽  
High Efficiency ◽  
Electric Energy ◽  
Iron Ore Pellets ◽  
Electric Energy Consumption ◽  
Ore Pellets ◽  
Type Selection ◽  
Cost Of Energy ◽  
Selection Of

At present, mainly straight grate machines (SGM) and combined facilities grate-tube-type kiln-cooler (GKC) are used for heat-strengthening induration of iron ore pellets. Their total share in the produced iron ore pellets in the world accounts for 93%, of which SGM takes 60% and GKC – 33%, which speaks about high efficiency of both methods of induration. At the same time, when making decision on construction a pelletizing plant, a question of selection of most effective technology of iron ore pellets production by SGM and GKC often arises. Results of comparative analysis of efficiency of technologies of iron ore pellets production by SGM and GKC presented. Features of various ore types pellets induration considered as well as possibilities of ensuring the required quality of finished pellets at application for induration SGM and GKC. Data on maximum productivity of the considered induration facilities, amount of dust, fines formation, emissions of harmful substances into environment and electric energy consumption presented. Importance of a possibility of accounting of fuel type selection, of heat expenses for heat treatment, of expenses for maintenance, capital and operation costs were noted. It was shown that choice of a particular variant of technology should be done at the stage of elaboration feasibility study accounting existing experience of facilities running, availability of fuel types, cost of energy resources, climate zone and assembling solutions.

Graphite Electrodes for Hydrogen Production by Acid Electrolysis

2020 ◽  
Vol 1012 ◽  
pp. 158-163
Author(s):  
Oliveira Marilei de Fátima ◽  
Mazur Viviane Teleginski ◽  
Virtuozo Fernanda ◽  
Junior Valter Anzolin de Souza
Keyword(s):  
Hydrogen Production ◽  
Fossil Fuels ◽  
High Efficiency ◽  
Low Cost ◽  
Electric Energy ◽  
Gas Production ◽  
Hydrogen Fuel Cells ◽  
Graphite Electrodes ◽  
Alkaline Electrolysis ◽  
Selection Of

Nowadays, humanity has become aware of the consequences that the use of fossil fuels entails, and the latest developments in the energy sector are leading to a diversification of energy resources. In this context, researching on alternative forms of producing electric energy is being conducted. At the transportation level, a possible solution for this matter may lie in hydrogen fuel cells. The electrolysis of water is one of the possible processes for hydrogen production, but the reaction to break the water molecule requires a great amount of energy and this is precisely the biggest issue involving this process. In this work, low cost electrodes of 254 stainless steel and electrolytic graphite were used for hydrogen production, allowing high efficiency and reduced oxidation during the process. The selection of these materials allows to obtain a high corrosion resistance electrolytic pair, by replacing the high cost platinum electrode usually employed in the alkaline electrolysis process. The formic acid of biomass origin was used as an electrolyte. It was observed that the developed reactor have no energy losses through heat and it was possible to obtain approximately 82% conversion efficiency in the gas production process.

scholarly journals Evaluation of Solar Radiation Transposition Models for Passive Energy Management and Building Integrated Photovoltaics

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 702 ◽  
Author(s):  
Carlos Toledo ◽  
Ana Maria Gracia Amillo ◽  
Giorgio Bardizza ◽  
Jose Abad ◽  
Antonio Urbina
Keyword(s):  
Solar Radiation ◽  
Horizontal Plane ◽  
Architectural Design ◽  
Operating Conditions ◽  
Geographical Information ◽  
Medium Temperature ◽  
Building Integrated Photovoltaics ◽  
Wide Range ◽  
Radiation Modelling ◽  
Winter Time

Incident solar radiation modelling has become of vital importance not only in architectural design considerations, but also in the estimation of the energy production of photovoltaic systems. This is particularly true in the case of buildings with integrated photovoltaics (PV) systems having a wide range of orientations and inclinations defined by the skin of the building. Since solar radiation data at the plane of interest is hardly ever available, this study presents the analysis of two of the most representative transposition models used to obtain the in-plane irradiance using as input data the global and diffuse irradiation on the horizontal plane, which can be obtained by satellite-based models or ground measurements. Both transposition models are validated with experimental measurements taken in Murcia (southeast of Spain) and datasets provided by the photovoltaic geographical information system (PVGIS) and the National Renewable Energy Laboratory (NREL) for vertical surfaces facing the four cardinal points. For the validation, the mean bias deviation, root mean square error and forecasted skill were used as indicators. Results show that the error rate decreases slightly for clear days. Better results are also obtained by dismissing data with low solar elevation angles so as to avoid shadowing effects from the surroundings in the early and late hours of the day, which affects mainly the performance of the transposition models for west and east surfaces. The results highlight the potential of equator-facing façades in winter time when the received irradiation can be twice as much as the one collected by the horizontal plane. It is also noteworthy that the operating conditions of all façades are mainly low irradiance and medium temperature at these locations.

Conceptual Design of Sulfur-Iodine Hydrogen Production Cycle of Korea Institute of Energy Research

2008 ◽  
Author(s):  
Wonchul Cho ◽  
Kikwang Bae ◽  
Chusik Park ◽  
Changhee Kim ◽  
Kyoungsoo Kang
Keyword(s):  
Nuclear Power ◽  
Membrane Reactor ◽  
High Efficiency ◽  
Electric Energy ◽  
Extractive Distillation ◽  
Production Cycle ◽  
Thermochemical Cycle ◽  
Energy Research ◽  
Energy Agency ◽  
Production Of Hydrogen

The Sulfur-Iodine thermochemical cycle offers a promising approach to the high efficiency production of hydrogen from nuclear power. Several SI cycles have been proposed by several research group. General Atomic (GA) studied I2 separation by extractive distillation using H3PO4. RWTH introduced the concept of reactive distillation. In this process, HIx stream coming from the Bunsen reaction is fed to the column. And HIx is distillated and decomposed at the same time to obtain hydrogen. Korea Institute of Energy Research (KIER) and Japan Atomic Energy Agency (JAEA) concentrate HIx using electro-dialysis cell and concentrated HIx is fed to the column to produce HI vapor, which is decomposed to produce hydrogen. HI was separated from HIx solution by an extractive distillation using H3PO4. However, a large amount of electric energy was required to recycle H3PO4. Most of SI processes have difficulties producing hydrogen because it has excess iodine in HI decomposition Section. SI cycle with electrodialysis cell uses membrane reactor to separate H2 and HIx. The current state of the membrane technology is not compatible with the process needs. This study examined several cases of flowsheets to overcome the problems mentioned above. The flowsheets were revised by adding the iodine separator and excluding membrane reactor. The thermal efficiency of SI process was analyzed using the revised flowsheet.

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