- Email: [email protected]
02902 Solar position algorithm for solar radiationapplications
07 Alternative energy sources (solar energy) of various dimensions of the pond has been carried out. Effects of the pond's water-depth Xw, wind speed V, the sides' X~ and back Xb insulation thicknesses as well as the height C and width W of the outer mirror have been investigated. The influence of the number of glass covers over the pond during the night have also been studied. Comparisons between experimental and theoretical results showed that good agreement has been achieved. Experiments indicated that the pond could provide 88 1 of hot water at a maximum temperature of 60°C at sunset. The pond can retain hot water till 7.00 a.m. next day at a temperature of 47°C: this is suitable for domestic applications.
04•02899 Photocatalytic effect of ZnO on carbon gasification with CO2 for high temperature solar thermochemistry Gokon, N. et al. Solar Energy Materials and Solar Cells, 2003, 80, (3), 335-341. A pbotocatalytic effect of ZnO on carbon gasification with CO2 was studied using a concentrated Xe beam to enhance the gasification rate in solar/chemical energy conversion process. The sample, activated carbon impregnated with ZnO (5 wt%), was heated at 873 K by a Xe beam irradiation with UV (<400 nm). The gasification rate at 873 K increased 2 folds in comparison with the Xe irradiation without UV, but, the difference of the rate of CO evolution decreased with the increasing temperature from 873 to 1073 K. The carbothermal reduction of ZnO ( Z n O + C - ~ Z n + C O ) proceeded at above 950 K, which was demonstrated by XRD analysis and thermodynamic calculation. These results indicate that the photocatalytic effect of ZnO with the UV irradiation enhance the gasification rate of carbon at low temperature (873 K).
There have been many published articles describing solar position algorithms for solar radiation applications. The best uncertainty achieved in most of these articles is greater than ±0.01 ° in calculating the solar zenith and azimuth angles. For some, the algorithm is valid for a limited number of years varying from 15 years to a hundred years. This report is a step by step procedure for implementing an algorithm to calculate the solar zenith and azimuth angles in the period from the year -2000 to 6000, with uncertainties of --0.0003 ° . The algorithm is described in a book written by Jean Meeus in 1998. This report is written in a step by step format to simplify the complicated steps described in the book, with a focus on the sun instead of the planets and stars in general. It also introduces some changes to accommodate for solar radiation applications. The changes include changing the direction of measuring azimuth angles to be measured from north and eastward instead of being measured from south and eastward, and the direction of measuring the observer's geographical longitude to be measured as positive eastward from Greenwich meridian instead of negative. This report also includes the calculation of incidence angle for a surface that is tilted to any horizontal and vertical angle, as described by Iqbals in 1983.
04/02903
04/02904 04/02900 Predicting solar irradiance on inclined surfaces using sky radiance data Li, D. H. W. and Lain, J. C. Energy Conversion and Management, 2004, 45,(11 12), 1771-1783. The availability of more comprehensive solar irradiance data is invaluable for the reduction of cooling load in buildings and for the evaluation of the performance of photovoltaie plants. In many parts of the world, however, the basic solar irradiance data are not always readily available. This paper presents an approach to calculate the solar irradiance on sloped planes by integrating the sky radiance distribution. Sky radiance data recorded from January 1999 to December 2001 in Hong Kong were used to estimate the solar irradiance for the horizontal and four principal vertical surfaces (N, E, S and W). The performance of this approach was assessed against data measured in the same period. Statistical results showed that using sky radiance distributions to predict solar irradiance can give reasonably good agreement with measured data for both horizontal and vertical planes. The prediction approach was also employed to compute the solar irradiance of a 22.3 ° (latitude angle of Hong Kong) inclined south oriented surface. The findings indicated that the method can provide an accurate alternative to determine the amount of solar irradiance on inclined surfaces facing various orientations when sky radiance data are available.
04/02901 Solar photo-catalytic water detoxification of paper mill effluents Sattler, C. et al. Energy, 2004, 29, (5-6), 835-843. To implement solar photo-catalytic water detoxification in industrial processes, problems have to be identified. The effluents from paper mills contain non-biodegradable substances like poly-phenolie polymer lignin. Photo-catalysis is a suitable method to degrade this class of substances. Especially in good solar regions, like Brazil, solar radiation should be ideally used for that process. The German Aerospace Centre and the Federal University of Uberl~ndia-MG, Brazil are cooperating in a project funded by the German International Bureau of the Federal Ministry of Education and Science and CNPq, Brazil to implement solar photo-catalysis in the treatment of paper mill effluents. Therefore, the following tasks are worked on: model compounds for the contaminants have been identified and compared to the real effluents. Different photo-catalysts and oxidizing agents were tested to shape the degradation process for use in an industrial application. Tests were carried out in lamp reactors as well as in solar reactors to determine the influence of the reactor on the degradation. The kinetic of the degradation was also determined. The test results have shown that the non-biodegradable substances can be very effectively degraded by photo-catalytic treatment. Especially in solar reactors like the CPC type reactor, degradation takes place very fast. Total mineralization of the contaminants can be reached. The paper describes the project as well as the test results and will provide an outlook to the implementation of solar photo-catalytic detoxification technology in Brazil.
04•02902 Solar position algorithm for solar radiation applications Reda, I. and Andreas, A. Solar Energy, 2004, 76, (5), 577 589.
410
Fuel and Energy Abstracts
November 2004
Some structures for cascade solar cells
Abrahamyan, Y. A. et al. Solar Energy Materials and Solar Cells', 2003, 80, (4), 451-457. Some versions of new, inexpensive structures of cascade solar cells are presented in this work. Advantages of these structures are described. The suggested structures can be easily realized on the basis of modern technologies.
Sun following system adjustment at the UTFSM
Georgiev, A. et al. Energy Conversion and Management, 2004, 45, (1112), 1795-1806. The 'Evaluacicen Solar' Laboratory of the Technical University Federico Santa Maria (UTFSM) in Valparaiso exists since 1957. Some types of sun following systems using instruments for different types of solar measurements were created during the mentioned period in this Laboratory. A solar tracking unit INTRA was recently installed in the UTFSM. It is considered a modern measuring and registering system for actual measuring of radiation in digital form, easier to store and to process. The action of the sun tracker is autonomous, which makes it a flexible tool to support direct radiation measurements. A special device was designed and constructed to support the measuring instruments. Three Eppley pyrheliometers were mounted on the unit and connected with an automatic registering system. An additional UV measuring sensor will be mounted soon. The realized measurements were compared with the results obtained manually from a K&Z pyrheliometer. The difference between both types of pyrheliometers is very small, which is a good precondition for using the INTRA sun tracker for precise measurements in the future.
04102905 Thermal stratification in vertical mantle heatexchangers with application to solar domestic hot-water systems Knudsen, S. and Furbo, S. Applied Energy, 2004, 78, (3), 257-272. Experimental and numerical investigations of vertical mantle heat exchangers for solar domestic hot-water (SDHW) systems have been carried out. Two different mantle inlet positions are investigated. Experiments based on typical operation conditions are carried out to investigate how the thermal stratification is affected by different positions of the mantle inlet. The heat transfer between the solar collector fluid in the mantle and the domestic water in the tank is analysed by CFD-simulations. Furthermore, side-by-side laboratory tests have been carried out with SDHW systems with different mantle inlet-positions. It is shown that for a high inlet-temperature to the mantle, it is an advantage to have the inlet located at the top and for a low inlet temperature it is an advantage to have the inlet moved down. Marketed tanks have typically the mantle inlet located at the top of the mantle. The side-by-side laboratory tests indicate that it is an advantage to move the inlet down from the top.
04/02906
Two axes sun tracking system with PLC control
Abdallah, S. and Nijmeh, S. Energy Conversion and Management, 2004, 45, (l 1-12), 1931-1939. In this paper, an electromechanical, two axes sun tracking system is designed and constructed. The programming method of control with an open loop system is employed where the programmable logic controller is used to control the motion of the sun tracking surface. An experimental study was performed to investigate the effect of using two axes tracking on the solar energy collected. The collected energy was measured and compared with that on a fixed surface tilted at 32 ° towards the south. The results indicate that the measured collected solar energy on the moving surface was significantly larger than that on a fixed surface. The two axes tracking surface showed a better performance with an increase in the collected energy of up to 41.34% compared with the fixed surface.
04•02899 Photocatalytic effect of ZnO on carbon gasification with CO2 for high temperature solar thermochemistry Gokon, N. et al. Solar Energy Materials and Solar Cells, 2003, 80, (3), 335-341. A pbotocatalytic effect of ZnO on carbon gasification with CO2 was studied using a concentrated Xe beam to enhance the gasification rate in solar/chemical energy conversion process. The sample, activated carbon impregnated with ZnO (5 wt%), was heated at 873 K by a Xe beam irradiation with UV (<400 nm). The gasification rate at 873 K increased 2 folds in comparison with the Xe irradiation without UV, but, the difference of the rate of CO evolution decreased with the increasing temperature from 873 to 1073 K. The carbothermal reduction of ZnO ( Z n O + C - ~ Z n + C O ) proceeded at above 950 K, which was demonstrated by XRD analysis and thermodynamic calculation. These results indicate that the photocatalytic effect of ZnO with the UV irradiation enhance the gasification rate of carbon at low temperature (873 K).
There have been many published articles describing solar position algorithms for solar radiation applications. The best uncertainty achieved in most of these articles is greater than ±0.01 ° in calculating the solar zenith and azimuth angles. For some, the algorithm is valid for a limited number of years varying from 15 years to a hundred years. This report is a step by step procedure for implementing an algorithm to calculate the solar zenith and azimuth angles in the period from the year -2000 to 6000, with uncertainties of --0.0003 ° . The algorithm is described in a book written by Jean Meeus in 1998. This report is written in a step by step format to simplify the complicated steps described in the book, with a focus on the sun instead of the planets and stars in general. It also introduces some changes to accommodate for solar radiation applications. The changes include changing the direction of measuring azimuth angles to be measured from north and eastward instead of being measured from south and eastward, and the direction of measuring the observer's geographical longitude to be measured as positive eastward from Greenwich meridian instead of negative. This report also includes the calculation of incidence angle for a surface that is tilted to any horizontal and vertical angle, as described by Iqbals in 1983.
04/02903
04/02904 04/02900 Predicting solar irradiance on inclined surfaces using sky radiance data Li, D. H. W. and Lain, J. C. Energy Conversion and Management, 2004, 45,(11 12), 1771-1783. The availability of more comprehensive solar irradiance data is invaluable for the reduction of cooling load in buildings and for the evaluation of the performance of photovoltaie plants. In many parts of the world, however, the basic solar irradiance data are not always readily available. This paper presents an approach to calculate the solar irradiance on sloped planes by integrating the sky radiance distribution. Sky radiance data recorded from January 1999 to December 2001 in Hong Kong were used to estimate the solar irradiance for the horizontal and four principal vertical surfaces (N, E, S and W). The performance of this approach was assessed against data measured in the same period. Statistical results showed that using sky radiance distributions to predict solar irradiance can give reasonably good agreement with measured data for both horizontal and vertical planes. The prediction approach was also employed to compute the solar irradiance of a 22.3 ° (latitude angle of Hong Kong) inclined south oriented surface. The findings indicated that the method can provide an accurate alternative to determine the amount of solar irradiance on inclined surfaces facing various orientations when sky radiance data are available.
04/02901 Solar photo-catalytic water detoxification of paper mill effluents Sattler, C. et al. Energy, 2004, 29, (5-6), 835-843. To implement solar photo-catalytic water detoxification in industrial processes, problems have to be identified. The effluents from paper mills contain non-biodegradable substances like poly-phenolie polymer lignin. Photo-catalysis is a suitable method to degrade this class of substances. Especially in good solar regions, like Brazil, solar radiation should be ideally used for that process. The German Aerospace Centre and the Federal University of Uberl~ndia-MG, Brazil are cooperating in a project funded by the German International Bureau of the Federal Ministry of Education and Science and CNPq, Brazil to implement solar photo-catalysis in the treatment of paper mill effluents. Therefore, the following tasks are worked on: model compounds for the contaminants have been identified and compared to the real effluents. Different photo-catalysts and oxidizing agents were tested to shape the degradation process for use in an industrial application. Tests were carried out in lamp reactors as well as in solar reactors to determine the influence of the reactor on the degradation. The kinetic of the degradation was also determined. The test results have shown that the non-biodegradable substances can be very effectively degraded by photo-catalytic treatment. Especially in solar reactors like the CPC type reactor, degradation takes place very fast. Total mineralization of the contaminants can be reached. The paper describes the project as well as the test results and will provide an outlook to the implementation of solar photo-catalytic detoxification technology in Brazil.
04•02902 Solar position algorithm for solar radiation applications Reda, I. and Andreas, A. Solar Energy, 2004, 76, (5), 577 589.
410
Fuel and Energy Abstracts
November 2004
Some structures for cascade solar cells
Abrahamyan, Y. A. et al. Solar Energy Materials and Solar Cells', 2003, 80, (4), 451-457. Some versions of new, inexpensive structures of cascade solar cells are presented in this work. Advantages of these structures are described. The suggested structures can be easily realized on the basis of modern technologies.
Sun following system adjustment at the UTFSM
Georgiev, A. et al. Energy Conversion and Management, 2004, 45, (1112), 1795-1806. The 'Evaluacicen Solar' Laboratory of the Technical University Federico Santa Maria (UTFSM) in Valparaiso exists since 1957. Some types of sun following systems using instruments for different types of solar measurements were created during the mentioned period in this Laboratory. A solar tracking unit INTRA was recently installed in the UTFSM. It is considered a modern measuring and registering system for actual measuring of radiation in digital form, easier to store and to process. The action of the sun tracker is autonomous, which makes it a flexible tool to support direct radiation measurements. A special device was designed and constructed to support the measuring instruments. Three Eppley pyrheliometers were mounted on the unit and connected with an automatic registering system. An additional UV measuring sensor will be mounted soon. The realized measurements were compared with the results obtained manually from a K&Z pyrheliometer. The difference between both types of pyrheliometers is very small, which is a good precondition for using the INTRA sun tracker for precise measurements in the future.
04102905 Thermal stratification in vertical mantle heatexchangers with application to solar domestic hot-water systems Knudsen, S. and Furbo, S. Applied Energy, 2004, 78, (3), 257-272. Experimental and numerical investigations of vertical mantle heat exchangers for solar domestic hot-water (SDHW) systems have been carried out. Two different mantle inlet positions are investigated. Experiments based on typical operation conditions are carried out to investigate how the thermal stratification is affected by different positions of the mantle inlet. The heat transfer between the solar collector fluid in the mantle and the domestic water in the tank is analysed by CFD-simulations. Furthermore, side-by-side laboratory tests have been carried out with SDHW systems with different mantle inlet-positions. It is shown that for a high inlet-temperature to the mantle, it is an advantage to have the inlet located at the top and for a low inlet temperature it is an advantage to have the inlet moved down. Marketed tanks have typically the mantle inlet located at the top of the mantle. The side-by-side laboratory tests indicate that it is an advantage to move the inlet down from the top.
04/02906
Two axes sun tracking system with PLC control
Abdallah, S. and Nijmeh, S. Energy Conversion and Management, 2004, 45, (l 1-12), 1931-1939. In this paper, an electromechanical, two axes sun tracking system is designed and constructed. The programming method of control with an open loop system is employed where the programmable logic controller is used to control the motion of the sun tracking surface. An experimental study was performed to investigate the effect of using two axes tracking on the solar energy collected. The collected energy was measured and compared with that on a fixed surface tilted at 32 ° towards the south. The results indicate that the measured collected solar energy on the moving surface was significantly larger than that on a fixed surface. The two axes tracking surface showed a better performance with an increase in the collected energy of up to 41.34% compared with the fixed surface.