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01366 Performance of a solar dryer using hot air from roof-integrated solar collectors for drying herbs and spices
13 Altemative energy supplies (solar energy) 06/01361 Hybrid copper-indium disulfide/polypyrrole photovoltaic structures prepared by electrodeposition Bereznev, S. et al. Solar Energy Materials and Solar Cells, 2005, 87, (1 4), 197 206. Photovoltaic structures on the basis of photoactive polycrystalline CuInS2 (CIS) in combination with electrically conductive polymer polypyrrole (PPy) were prepared using the electrodeposition technique. In order to prepare stable PPy films with a good adherence to the surface of CIS, the appropriate concentrations of reagents, current densities and electrodeposition potentials were selected experimentally. Electrochemical polymerization of pyrrole to PPy on the CIS surface is faster under white light irradiation, and the polymerization starts at a lower potential than in the dark. Significant photovoltage and photocurrent of the fabricated CIS/PPy structures have been observed under standard white light illumination. The best structure showed an open-circuit voltage of 509 mV, a short-circuit current density of 6.45 mA/cm 2, fill-factor 0.47 and photoconversion efficiency of 1.53% under white light illumination of 100 mW/cm 2.
06•01362 systems
Improving the performance of solar desalination
Abdel-Rehim, Z. S. and Lasheen, A. Renewable Energy, 2005, 30, (13), 1955 1971. Two modifications for solar desalination systems are presented. The first modification, using a packed layer that installed in the bottom of the basin to increase the efficiency of the still. A packed layer is formed from glass balls which is considered as simple thermal storage system. The second modification, using rotating shaft installed close to the basin water surface. The target of using the rotating shaft to break the boundary layer of the basin water surface, thus increasing the water vaporization and condensation, the performance of the present solar desalination system may also be increased. The numerical analysis presented the equations of the direct coupling of the selected PV-solar panel, DC-motor and inverter for small PV-system. The characteristics of PV array and the DC-motor are presented for the specific PV DC power. The performance of the two modified solar stills and the conventional one is compared. Three experiments were carried out using the climate conditions of Cairo site, Egypt. Transient temperatures of the two modified solar stills and the conventional one are measured from sunrise to sunset with the same operating parameters. The energy equations that governed the present solar desalination system are presented. Energy absorbed by glass cover, basin water, packed layer and the required power of the rotating shaft are calculated to obtain the water productivity and efficiency of the present systems. The results show that the two modifications enhanced the performance of the solar desalination system. The efficiency of the modified solar desalination system using packed layer thermal energy storage was increased by 5% at May, 6% at June, and 7.5% at July, while it was increased by 2.5% at May, 5% at June, and 5.5% at July for the modified one using rotating shaft and PV-system.
06•01363 Influence of electrolyte in transport and recombination in dye-sensitized solar cells studied by impedance spectroscopy Fabregat-Santiago, F. et al. Solar Energy Materials and Solar Cells, 2005, 87, (1 4), 117 131. The main features of the characteristic impedance spectra of dyesensitized solar cells are described in a wide range of potential conditions: from open to short circuit. An equivalent circuit model has been proposed to describe the parameters of electron transport, recombination, accumulation and other interfacial effects separately. These parameters were determined in the presence of three different electrolytes, both in the dark and under illumination. Shift in the conduction band edge due to the electrolyte composition was monitored in terms of the changes in transport resistance and charge accumulation in TiO2. The interpretation of the curren~potential curve characteristics, fill factor, open-circuit photopotential and efficiency in the different conditions, was correlated with this shift and the features of the recombination resistance.
06•01364 Lauric and myristic acids eutectic mixture as phase change material for low-temperature heating applications KcIc, S. et al. International Journal of Energy Research, 2005, 29, (9), 857 870. Lauric acid (mp: 42.6°C) and myristic acid (mp: 52.2°C) are phase change materials (PCM) having quite high melting points which can limit their use in low-temperature solar applications such as solar space heating and greenhouse heating. However, their melting temperatures can be tailored to appropriate value by preparing a eutectic mixture of lauric acid (LA) and myristic acid (MA). In the present study, the thermal analysis based on differential scanning calorimetry (DSC) technique shows that the mixture of 66.0 wt% LA forms a eutectic mixture having meltin~ temperature of 34.2°C and the latent heat of fusion of 166.8 J g . This study also considers the experimental
establishment of thermal characteristics of the eutectic PCM in a vertical concentric pipe-in-pipe heat storage system. Thermal performance of the PCM was evaluated with respect to the effect of inlet temperature and mass flow rate of the heat transfer fluid on those characteristics during the heat charging and discharging processes. The DSC thermal analysis and the experimental results indicate that the LA-MA eutectic PCM can be potential material for low-temperature solar energy storage applications in terms of its thermo-physical and thermal characteristics.
06/01365 Performance analysis of a double-pass photovoltaic/thermal (PV/T) solar collector with CPC and fins Othman, M. Y. Hj. et al. Renewable Energy, 2005, 30, (13), 2005 2017. The use of PV/T in combination with concentrating reflectors has a potential to significantly increase power production from a given solar cell area. A prototype double-pass photovoltaic-thermal solar air collector with CPC and fins has been designed and fabricated and its performance over a range of operating conditions was studied. The absorber of the hybrid photovoltaic/thermal (PV/T) collector under investigation consists of an array of solar cells for generating electricity, compound parabolic concentrator (CPC) to increase the radiation intensity falling on the solar cells and fins attached to the back side of the absorber plate to improve heat transfer to the flowing air. Energy balance equations have been developed for the various nodes of the system. Both thermal and electrical performance of the collector are presented and discussed.
06/01366 Performance of a solar dryer using hot air from roof-integrated solar collectors for drying herbs and spices Janjai, S. and Tung, P. Renewable Energy, 2005, 30, (14), 2085 2095. A solar dryer for drying herbs and spices using hot air from roofintegrated solar collectors was developed. The dryer is a bin type with a rectangular perforated floor. The bin has a dimension of 1.0 mx2.0 mx0.7 m. Hot air is supplied to the dryer from fibreglass-covered solar collectors, which also function as the roof of a farmhouse. The total area of the solar collectors is 72 m 2. To investigate its performance, the dryer was used to dry four batches of rosella flowers and three batches of lemon-grasses during the year 2002 2003. The dryer can be used to dry 200 kg of rosella flowers and lemon-grasses within 4 and 3 days, respectively. The products being dried in the dryer were completely protected from rains and insects and the dried products are of high quality. The solar air heater has an average daily efficiency of 35% and it performs well both as a solar collector and a roof of a farmhouse.Solar collector
06/01367
Properties of intermediate band materials
Tablero, C. et al. Solar Energy Materials and Solar Cells, 2005, 87, (1 4), 323 331. Intermediate band materials (MIB) have been proposed in previous works as a new kind of photovoltaic materials. These materials are principally characterized by an intermediate partially occupied band, isolated from the valence and conduction bands of the host semiconductor. These materials have a theoretical efficiency greater than that of conventional solar cells because they can absorb photons with a lower energy than the bandgap of the original host semiconductor. However, although the operation of these solar cells has been described, it is necessary to use a method to be able to propose the material that has these properties. In this work, a theoretical study of the electronic and optoelectronic properties using quantum-mechanics calculations is presented. The results confirm that MIB are able to absorb photons of lower energy than the host semiconductor.
06/01368 Prospects of solar water heating for textile industry in Pakistan Muneer, T. et al. Renewable and Sustainable Energy Reviews, 2005, 10, (1), 1 23. Energy is the prime source of human activities in all sectors of life. Traditionally fossil fuel has been the prime source of energy. However, there are two major concerns regarding fossil fuels, i.e. their rapid depletion and their contribution towards growing global warming. It is being widely realized that for sustainable development presently used energy mediums such as fossil fuel and nuclear power have to be quickly replaced by renewable energy sources. The latter are sustainable and have the potential to meet present and future projected global energy demands without inflicting any environmental impacts. Pakistan is amongst the most prominent cotton producing countries in the world. The affluent availability of local cotton has lead to a wellestablished textile sector in Pakistan. A large proportion of its cotton products go into export. Being a successful candidate in international textile market Pakistani textile industry is continuously seeking modern and high-tech facilities to improve quality of its products. The biggest challenge Pakistani textile industry is facing today is how to cut down its environmental burdens to cope with the international standards on the issue. Water heating system as required for dying process is one of
Fuel and Energy Abstracts
May 2006
203
06•01362 systems
Improving the performance of solar desalination
Abdel-Rehim, Z. S. and Lasheen, A. Renewable Energy, 2005, 30, (13), 1955 1971. Two modifications for solar desalination systems are presented. The first modification, using a packed layer that installed in the bottom of the basin to increase the efficiency of the still. A packed layer is formed from glass balls which is considered as simple thermal storage system. The second modification, using rotating shaft installed close to the basin water surface. The target of using the rotating shaft to break the boundary layer of the basin water surface, thus increasing the water vaporization and condensation, the performance of the present solar desalination system may also be increased. The numerical analysis presented the equations of the direct coupling of the selected PV-solar panel, DC-motor and inverter for small PV-system. The characteristics of PV array and the DC-motor are presented for the specific PV DC power. The performance of the two modified solar stills and the conventional one is compared. Three experiments were carried out using the climate conditions of Cairo site, Egypt. Transient temperatures of the two modified solar stills and the conventional one are measured from sunrise to sunset with the same operating parameters. The energy equations that governed the present solar desalination system are presented. Energy absorbed by glass cover, basin water, packed layer and the required power of the rotating shaft are calculated to obtain the water productivity and efficiency of the present systems. The results show that the two modifications enhanced the performance of the solar desalination system. The efficiency of the modified solar desalination system using packed layer thermal energy storage was increased by 5% at May, 6% at June, and 7.5% at July, while it was increased by 2.5% at May, 5% at June, and 5.5% at July for the modified one using rotating shaft and PV-system.
06•01363 Influence of electrolyte in transport and recombination in dye-sensitized solar cells studied by impedance spectroscopy Fabregat-Santiago, F. et al. Solar Energy Materials and Solar Cells, 2005, 87, (1 4), 117 131. The main features of the characteristic impedance spectra of dyesensitized solar cells are described in a wide range of potential conditions: from open to short circuit. An equivalent circuit model has been proposed to describe the parameters of electron transport, recombination, accumulation and other interfacial effects separately. These parameters were determined in the presence of three different electrolytes, both in the dark and under illumination. Shift in the conduction band edge due to the electrolyte composition was monitored in terms of the changes in transport resistance and charge accumulation in TiO2. The interpretation of the curren~potential curve characteristics, fill factor, open-circuit photopotential and efficiency in the different conditions, was correlated with this shift and the features of the recombination resistance.
06•01364 Lauric and myristic acids eutectic mixture as phase change material for low-temperature heating applications KcIc, S. et al. International Journal of Energy Research, 2005, 29, (9), 857 870. Lauric acid (mp: 42.6°C) and myristic acid (mp: 52.2°C) are phase change materials (PCM) having quite high melting points which can limit their use in low-temperature solar applications such as solar space heating and greenhouse heating. However, their melting temperatures can be tailored to appropriate value by preparing a eutectic mixture of lauric acid (LA) and myristic acid (MA). In the present study, the thermal analysis based on differential scanning calorimetry (DSC) technique shows that the mixture of 66.0 wt% LA forms a eutectic mixture having meltin~ temperature of 34.2°C and the latent heat of fusion of 166.8 J g . This study also considers the experimental
establishment of thermal characteristics of the eutectic PCM in a vertical concentric pipe-in-pipe heat storage system. Thermal performance of the PCM was evaluated with respect to the effect of inlet temperature and mass flow rate of the heat transfer fluid on those characteristics during the heat charging and discharging processes. The DSC thermal analysis and the experimental results indicate that the LA-MA eutectic PCM can be potential material for low-temperature solar energy storage applications in terms of its thermo-physical and thermal characteristics.
06/01365 Performance analysis of a double-pass photovoltaic/thermal (PV/T) solar collector with CPC and fins Othman, M. Y. Hj. et al. Renewable Energy, 2005, 30, (13), 2005 2017. The use of PV/T in combination with concentrating reflectors has a potential to significantly increase power production from a given solar cell area. A prototype double-pass photovoltaic-thermal solar air collector with CPC and fins has been designed and fabricated and its performance over a range of operating conditions was studied. The absorber of the hybrid photovoltaic/thermal (PV/T) collector under investigation consists of an array of solar cells for generating electricity, compound parabolic concentrator (CPC) to increase the radiation intensity falling on the solar cells and fins attached to the back side of the absorber plate to improve heat transfer to the flowing air. Energy balance equations have been developed for the various nodes of the system. Both thermal and electrical performance of the collector are presented and discussed.
06/01366 Performance of a solar dryer using hot air from roof-integrated solar collectors for drying herbs and spices Janjai, S. and Tung, P. Renewable Energy, 2005, 30, (14), 2085 2095. A solar dryer for drying herbs and spices using hot air from roofintegrated solar collectors was developed. The dryer is a bin type with a rectangular perforated floor. The bin has a dimension of 1.0 mx2.0 mx0.7 m. Hot air is supplied to the dryer from fibreglass-covered solar collectors, which also function as the roof of a farmhouse. The total area of the solar collectors is 72 m 2. To investigate its performance, the dryer was used to dry four batches of rosella flowers and three batches of lemon-grasses during the year 2002 2003. The dryer can be used to dry 200 kg of rosella flowers and lemon-grasses within 4 and 3 days, respectively. The products being dried in the dryer were completely protected from rains and insects and the dried products are of high quality. The solar air heater has an average daily efficiency of 35% and it performs well both as a solar collector and a roof of a farmhouse.Solar collector
06/01367
Properties of intermediate band materials
Tablero, C. et al. Solar Energy Materials and Solar Cells, 2005, 87, (1 4), 323 331. Intermediate band materials (MIB) have been proposed in previous works as a new kind of photovoltaic materials. These materials are principally characterized by an intermediate partially occupied band, isolated from the valence and conduction bands of the host semiconductor. These materials have a theoretical efficiency greater than that of conventional solar cells because they can absorb photons with a lower energy than the bandgap of the original host semiconductor. However, although the operation of these solar cells has been described, it is necessary to use a method to be able to propose the material that has these properties. In this work, a theoretical study of the electronic and optoelectronic properties using quantum-mechanics calculations is presented. The results confirm that MIB are able to absorb photons of lower energy than the host semiconductor.
06/01368 Prospects of solar water heating for textile industry in Pakistan Muneer, T. et al. Renewable and Sustainable Energy Reviews, 2005, 10, (1), 1 23. Energy is the prime source of human activities in all sectors of life. Traditionally fossil fuel has been the prime source of energy. However, there are two major concerns regarding fossil fuels, i.e. their rapid depletion and their contribution towards growing global warming. It is being widely realized that for sustainable development presently used energy mediums such as fossil fuel and nuclear power have to be quickly replaced by renewable energy sources. The latter are sustainable and have the potential to meet present and future projected global energy demands without inflicting any environmental impacts. Pakistan is amongst the most prominent cotton producing countries in the world. The affluent availability of local cotton has lead to a wellestablished textile sector in Pakistan. A large proportion of its cotton products go into export. Being a successful candidate in international textile market Pakistani textile industry is continuously seeking modern and high-tech facilities to improve quality of its products. The biggest challenge Pakistani textile industry is facing today is how to cut down its environmental burdens to cope with the international standards on the issue. Water heating system as required for dying process is one of
Fuel and Energy Abstracts
May 2006
203