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New progresses of solar energy utilization technology
07 Alternative
energy sources (solar energy)
index over Oman. These maps will serve as a much needed reference for design and performance evaluation of solar energy conversion \ystcm\ rn this region.
OWO1290 New method to store heat energy in horizontal solar desalination still Rahim, N. H. A. Ranewcrh/~~ E~c,xI~. 2003. 2X. (3). 419 433. A new approach is proposed to store excess heat energy in horizontal solar desalination stills during daytime for the continuation of the process at night. This technique divides the horizontal still into evaporating and heat storing zones and combines the advantages of shallow and deep stills. The performance of heat storing zone was studied over one year and exhaustive data were collected, analysed and presented. To show the effectiveness of the system, its performance was compared with that of the shallow still. The heat storing capacity of the system during the daytime was found to be an average of 35.7% of the total amount of solar energy entering the system. The efficiency of recovering process, in the form of portable water produced at night, was found to be an average of 47.2% of the total amount of energy stored during the day. Furthermore, this technique does not require any kind of external power for storing and recovering processes.
03/01291 New progresses of solar energy utilization technology Tanaka. T. Tui.ro Enerugi, 2002, 28, (2) 2-6. (In Japanese) A review of the title subject, including solar fuel methanol production from fossil fuels and biomass and hydrogen production and storage technology.
03/01292 Novel external field source by localization of electrons for improvement of solar cells Konig. D. and Ebest, G. So/or Encrgr Matcviuls tmd Solar c‘~ll.s, 2003, 75, (i-4). 335343. For drift field generation IS structures with a fixed positive charge were developed in the 1970s and employed on solar cells. While many papers were published about the positively charged IS structure there has been little interest in a negatively charged IS structure. In comparison to solar cells with back surface field such structures could improve conversion efficiency more significantly. They also open the way to novel-field-effect-supported solar cells on n-type silicon. The paper represents results of the preparation and characterization of the IS structure on Silicon (Si) consisting of a layer compound AIF 11SiOz on Si, a discussion of the phenomena encountered and respective conclusions. 03/01293 Optical fibers for a mini-dish/Stirling system: thermodynamic optimization Jaramillo,
0. A. and Del Rio, J. A. Journcd of’ Phyric.~ D: Applied 2002. 35, (1 I), 1241-1250. A thermodynamic optimization of a solar mini-dish/Stirling system is presented. The solar collector heat losses by convection and radiation arc diminished by using optical fibres to transport concentrated solar energy. An absorber-heater for the solar heat engine was analysed to ensure the reduction of the heat losses using the first law and the second law. Taking into account internal and external irreversibilities for the solar heat engine, the optimal operating temperature and the overall efficiency of the system are established. Pltpics,
UK. The models are now run under variable solar conditions tn ordcrto optimize the dryers and compare their performance. The inputs to the simulation models were Zambian weather conditions and materials. The solar drying simulations arc combined with the cost of the dryer materials and a search technique that finds the dryer dimensions at the minimum drying cost. Optimization gave a shorter collector length for the mixed-mode solar dryer (1.8 m) than for the indirect-mode dryer (3.34 m) of the same grain capacity (90 kg). The drymg cost, annual cost and initial cost of the mixed-mode dryer are lower than those of the indirect-mode although the quantity of dry grain ohtained from the mixed-mode for the whole year is less than for the indirect-mode: the drying costs are 12.76 and 16.05 US%/ton for mlxcd-mode and indit-rclmode dryers. respectively.
Patterns of efficiency and de radation in dye sensitization solar cells measured with Bmaging techniques
03101288
Macht, B. et al. Solnr Energ,~ Mntwids and Solar Crlk. 2002, 73. (2). 163-173. A larger number of dye sensitization solar cells based on cisRu”(LH&(NCS)~ with LHa =2,2’-bipyridyl-4,4’-dicarboxylic acid with an electrolyte consisting of 0.5 M LiI, 50 mM I*. 0.2 M tert-hutyl pyridine in acetonitrile have been studied, using spatially resolved photocurrent imaging techniques. Measurements have been made after preparation and periodically during a longer period of simulated solar light illumination. The observed phenomena have been grouped into five categories. The first one concerns significant inhomogeneities reflecting the TiOz-layer preparation technique used. The second category concerns an inhomogeneous deterioration of the dye sensitization cell during illumination, The third phenomenon involves photodegradation itself, which can be visualized by selectively illuminating the dye sensitization solar cell. Changes observed in the composition of the electrolyte, typically indicated by a bleaching of the iodide/iodine solution were also observed. Finally, the fifth category to be considered deals with a loss of electrolyte and the parallel appearance of gas bubbles in the solar cell. All these phenomena may coexist, being responsible for the overall process of degradation. The different mechanisms are discussed and analysed in an effort to determine parameters critical for increasing efficiency and stability of dye sensitization solar cells.
03/01297 Perceived performance of dayiighting systems: lighting efficacy and agreeableness Fontoynont, M. S&r Energy, 2002. 73. (2). 83 -94. Can daylighting systems be assessed through objective procedures? On one hand, they can be considered as lighting techniques and deserve to be characterized through the same type of parameters: illuminances, uniformity, luminances, colour temperature, colour rendering indices, etc. On the other hand, two major aspects differentiate them from artificial lighting installations. Firstly, the daylight source is variable, requiring a long term approach and an assessment of the duration of the phenomena per day, month or year. Secondly, the brightness of the window cannot be totally disconnected from the content of the view and its agreeableness. This suggests that psychological well-being may be in some cases as important as visual comfort issues. For the window component industry, it appears that a serious concern about the two aspects of windows - i.e. lighting efficacy and agreeableness - should he carefully approached for each design.
Photoelectrochemlcal characterieation of indium nitride and tin nitride in aqueous solutfon
03/01298
03/01294 Optimal process of solar to thermal energy conversion and design of irreversible flat-plate solar collectors Torres-Reyes, E. ct cd.Energy. 2003. 28, (2), 99 -I 13. Thermodynamic optimization based on the first and the second law is developed to determine the optimal performance parameters and to design a solar to thermal energy conversion system. An exergy analysis is presented to determine the optimum outlet temperature of the working fluid and the optimum path flow length of solar collectors with various configurations. The collectors used to heat the air flow during solar-to-thermal energy conversion, are internally arranged in different ways with respect to the absorber plates and heat transfer elements. The exergy balance and the dimensionless exergy relationships are derived by taking into account the irreversibilities produced by the pressure drop in the flow of the working fluid through the collector. Design formulas for different air duct and absorber plate arrangements arc obtained.
03/01295 Optimization of mixed-mode and indirect-mode natural convection solar dryers Simate, I. N. Renewable Energy, 2003, 28, (3), 435453. This paper presents a comparison of optimized mixed-mode and indirect-mode natural convection solar dryers for maize. The mixedmode and indirect-mode solar drying simulation models were validated against results from a laboratory solar dryer with experiments carried out under a solar simulator at the University of Newcastle upon Tyne,
236
Fuel and Energy Abstracts
July 2003
Lindgren,
T. PI al. Solar Energy Materials
and Solttr Celk.
2002. 73. (4).
377-389.
Indium nitride (InN) and tin nitride (SnN,) films were produced with reactive dc. magnetron sputtering technique. The thin film semiconductors were optically and photoelectrochemically characterized and the energetic positions of the two semiconductors’ band edges were determined with respect to the normal hydrogen electrode. The sputtered InN thin film showed an indirect bandgap of 1.4 eV and a direct bandgap of 1.8 eV. The optical spectra of SnN, indicated a bandgap energy of approximately 1.4 eV. All nitride films showed ntype photoresponse in KI (aq) electrolyte at an irradiation Intensity ol 1000 W/m2. The photoelectrochemical characterization indicated that InN and SnN, with a bias of about 400 mV or less can he used for photo-oxidation of water.
03/01299 Relationships between UV (0.290-0.399 m) and broad band solar radiation hourly values in Valencia and Cbrdoba, Spain
Canada, J. et a/. Energy, 2003, 28, (3), 199-217. Data were analysed of hourly UV (0.290-0.385 urn) and broad band, G, irradiation on a horizontal plane measured in Cordoba and Valencia, Spain, during the period January 1996 to December 1998. The mean monthly hourly values of the quotient between UV and total global radiation varied within the interval 4.4-5.6% for Valencia with a mean value of 5%. and in Cordoba they ranged from 3.9 to 4.5% with a mean
energy sources (solar energy)
index over Oman. These maps will serve as a much needed reference for design and performance evaluation of solar energy conversion \ystcm\ rn this region.
OWO1290 New method to store heat energy in horizontal solar desalination still Rahim, N. H. A. Ranewcrh/~~ E~c,xI~. 2003. 2X. (3). 419 433. A new approach is proposed to store excess heat energy in horizontal solar desalination stills during daytime for the continuation of the process at night. This technique divides the horizontal still into evaporating and heat storing zones and combines the advantages of shallow and deep stills. The performance of heat storing zone was studied over one year and exhaustive data were collected, analysed and presented. To show the effectiveness of the system, its performance was compared with that of the shallow still. The heat storing capacity of the system during the daytime was found to be an average of 35.7% of the total amount of solar energy entering the system. The efficiency of recovering process, in the form of portable water produced at night, was found to be an average of 47.2% of the total amount of energy stored during the day. Furthermore, this technique does not require any kind of external power for storing and recovering processes.
03/01291 New progresses of solar energy utilization technology Tanaka. T. Tui.ro Enerugi, 2002, 28, (2) 2-6. (In Japanese) A review of the title subject, including solar fuel methanol production from fossil fuels and biomass and hydrogen production and storage technology.
03/01292 Novel external field source by localization of electrons for improvement of solar cells Konig. D. and Ebest, G. So/or Encrgr Matcviuls tmd Solar c‘~ll.s, 2003, 75, (i-4). 335343. For drift field generation IS structures with a fixed positive charge were developed in the 1970s and employed on solar cells. While many papers were published about the positively charged IS structure there has been little interest in a negatively charged IS structure. In comparison to solar cells with back surface field such structures could improve conversion efficiency more significantly. They also open the way to novel-field-effect-supported solar cells on n-type silicon. The paper represents results of the preparation and characterization of the IS structure on Silicon (Si) consisting of a layer compound AIF 11SiOz on Si, a discussion of the phenomena encountered and respective conclusions. 03/01293 Optical fibers for a mini-dish/Stirling system: thermodynamic optimization Jaramillo,
0. A. and Del Rio, J. A. Journcd of’ Phyric.~ D: Applied 2002. 35, (1 I), 1241-1250. A thermodynamic optimization of a solar mini-dish/Stirling system is presented. The solar collector heat losses by convection and radiation arc diminished by using optical fibres to transport concentrated solar energy. An absorber-heater for the solar heat engine was analysed to ensure the reduction of the heat losses using the first law and the second law. Taking into account internal and external irreversibilities for the solar heat engine, the optimal operating temperature and the overall efficiency of the system are established. Pltpics,
UK. The models are now run under variable solar conditions tn ordcrto optimize the dryers and compare their performance. The inputs to the simulation models were Zambian weather conditions and materials. The solar drying simulations arc combined with the cost of the dryer materials and a search technique that finds the dryer dimensions at the minimum drying cost. Optimization gave a shorter collector length for the mixed-mode solar dryer (1.8 m) than for the indirect-mode dryer (3.34 m) of the same grain capacity (90 kg). The drymg cost, annual cost and initial cost of the mixed-mode dryer are lower than those of the indirect-mode although the quantity of dry grain ohtained from the mixed-mode for the whole year is less than for the indirect-mode: the drying costs are 12.76 and 16.05 US%/ton for mlxcd-mode and indit-rclmode dryers. respectively.
Patterns of efficiency and de radation in dye sensitization solar cells measured with Bmaging techniques
03101288
Macht, B. et al. Solnr Energ,~ Mntwids and Solar Crlk. 2002, 73. (2). 163-173. A larger number of dye sensitization solar cells based on cisRu”(LH&(NCS)~ with LHa =2,2’-bipyridyl-4,4’-dicarboxylic acid with an electrolyte consisting of 0.5 M LiI, 50 mM I*. 0.2 M tert-hutyl pyridine in acetonitrile have been studied, using spatially resolved photocurrent imaging techniques. Measurements have been made after preparation and periodically during a longer period of simulated solar light illumination. The observed phenomena have been grouped into five categories. The first one concerns significant inhomogeneities reflecting the TiOz-layer preparation technique used. The second category concerns an inhomogeneous deterioration of the dye sensitization cell during illumination, The third phenomenon involves photodegradation itself, which can be visualized by selectively illuminating the dye sensitization solar cell. Changes observed in the composition of the electrolyte, typically indicated by a bleaching of the iodide/iodine solution were also observed. Finally, the fifth category to be considered deals with a loss of electrolyte and the parallel appearance of gas bubbles in the solar cell. All these phenomena may coexist, being responsible for the overall process of degradation. The different mechanisms are discussed and analysed in an effort to determine parameters critical for increasing efficiency and stability of dye sensitization solar cells.
03/01297 Perceived performance of dayiighting systems: lighting efficacy and agreeableness Fontoynont, M. S&r Energy, 2002. 73. (2). 83 -94. Can daylighting systems be assessed through objective procedures? On one hand, they can be considered as lighting techniques and deserve to be characterized through the same type of parameters: illuminances, uniformity, luminances, colour temperature, colour rendering indices, etc. On the other hand, two major aspects differentiate them from artificial lighting installations. Firstly, the daylight source is variable, requiring a long term approach and an assessment of the duration of the phenomena per day, month or year. Secondly, the brightness of the window cannot be totally disconnected from the content of the view and its agreeableness. This suggests that psychological well-being may be in some cases as important as visual comfort issues. For the window component industry, it appears that a serious concern about the two aspects of windows - i.e. lighting efficacy and agreeableness - should he carefully approached for each design.
Photoelectrochemlcal characterieation of indium nitride and tin nitride in aqueous solutfon
03/01298
03/01294 Optimal process of solar to thermal energy conversion and design of irreversible flat-plate solar collectors Torres-Reyes, E. ct cd.Energy. 2003. 28, (2), 99 -I 13. Thermodynamic optimization based on the first and the second law is developed to determine the optimal performance parameters and to design a solar to thermal energy conversion system. An exergy analysis is presented to determine the optimum outlet temperature of the working fluid and the optimum path flow length of solar collectors with various configurations. The collectors used to heat the air flow during solar-to-thermal energy conversion, are internally arranged in different ways with respect to the absorber plates and heat transfer elements. The exergy balance and the dimensionless exergy relationships are derived by taking into account the irreversibilities produced by the pressure drop in the flow of the working fluid through the collector. Design formulas for different air duct and absorber plate arrangements arc obtained.
03/01295 Optimization of mixed-mode and indirect-mode natural convection solar dryers Simate, I. N. Renewable Energy, 2003, 28, (3), 435453. This paper presents a comparison of optimized mixed-mode and indirect-mode natural convection solar dryers for maize. The mixedmode and indirect-mode solar drying simulation models were validated against results from a laboratory solar dryer with experiments carried out under a solar simulator at the University of Newcastle upon Tyne,
236
Fuel and Energy Abstracts
July 2003
Lindgren,
T. PI al. Solar Energy Materials
and Solttr Celk.
2002. 73. (4).
377-389.
Indium nitride (InN) and tin nitride (SnN,) films were produced with reactive dc. magnetron sputtering technique. The thin film semiconductors were optically and photoelectrochemically characterized and the energetic positions of the two semiconductors’ band edges were determined with respect to the normal hydrogen electrode. The sputtered InN thin film showed an indirect bandgap of 1.4 eV and a direct bandgap of 1.8 eV. The optical spectra of SnN, indicated a bandgap energy of approximately 1.4 eV. All nitride films showed ntype photoresponse in KI (aq) electrolyte at an irradiation Intensity ol 1000 W/m2. The photoelectrochemical characterization indicated that InN and SnN, with a bias of about 400 mV or less can he used for photo-oxidation of water.
03/01299 Relationships between UV (0.290-0.399 m) and broad band solar radiation hourly values in Valencia and Cbrdoba, Spain
Canada, J. et a/. Energy, 2003, 28, (3), 199-217. Data were analysed of hourly UV (0.290-0.385 urn) and broad band, G, irradiation on a horizontal plane measured in Cordoba and Valencia, Spain, during the period January 1996 to December 1998. The mean monthly hourly values of the quotient between UV and total global radiation varied within the interval 4.4-5.6% for Valencia with a mean value of 5%. and in Cordoba they ranged from 3.9 to 4.5% with a mean