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02965 Microprocessor based load voltage regulator for photovoltaic systems
07
Alternative energy sources (solar energy)
porous absorber will enhance heat transfer from the absorber to the airstream. The thermal efficiency of this type of collector is significantly higher than the thermal efficiency of conventional air heaters.
to the plane of the substrate. The films are nearly stoichiometric. The optical absorption spectra are similar to those of smgle crystals. and the high photosensitivity of the films is attrihuted to a grain size enhancement by the Ni-S phase.
Hydrogen production with solar energy 97102963 Olgun, H. Hydrogen Em&y Prog. Xl, Proc. World Hydrogen Energy Conf., 11th. 1996, 1, 633-638. Edited by Veziroglo, T. N. International Association
97102969
for Hydrogen Energy, Coral Gables, Florida. Two methods were used in this study for the production of hydrogencontaining gas. The first method comprised the gasification of furnacepreheated coal particles in a laboratory-scale reactor. The effect of reactor temperature, the amount of water vapour used, and of particle size on the level of gas production were investigated. In the second method, coal particles were preheated by solar energy in the reactor prior to gasification. A stainless steel reactor. which is put in the focus of parabolic reflector, was used in this system. The results for coal were compared with results for graphite and wild reed for different reactor temperatures and the produced gases were chemically analysed.
97102964 ,;;;mance USA
ASHRAE
Methods of testing to determine the thermal of flat plate solar collectors contammg bollmg ANSIIASHRAE,
ASHRAE
Standard 109-1986 (RA 96),
1997, 6pp. Test methods for determining the thermal performance of flat plate solar energy collectors that use boiling fluids for thermal energy transfer are provided. Applies to flat-plate solar collectors in which some of the fluid entering the collector boils and some fraction leaves as a saturated vapour. Methods for conducting tests outdoors under natural solar irradiance and for conducting tests indoors under simulated solar irradiance are supplied and the paper also provides test method and calculation procedures for determining steady-state and quasi-steady-state thermal performance, time and angular response characteristics of solar collectors.
97102965 photovoltaic
Microprocessor systems
based
load voltage
regulator
for
Anis. W. R. and El-Samahy. A. E.-S. M. Energy Convers. Mgmr, 38, (I), 13-20. The paper describes a conventional photovoltaic (PV) system driving a DC load consisting of a PV array, storage battery, a battery voltage regulator (BVR) and a load. According to this arrangement, the load voltage is equal to the battery voltage. The hattery voltage varies according to its state of charge (SOC). Critical loads, such as some communication systems, require a regulated voltage, hence conventional battery voltage variations are not accepted for these applications. The typical solution of this problem is to operate the PV system at a higher voltage and to include a control circuit that introduces passive elements so that the load is operating within the allowed limits. Such a solution leads to power dissipation in the passive elements and this presents power loss. An alternative solution based on a microprocessor that keeps the load voltage at the predetermined level is discussed. The proposed technique avoids the power loss and therefore required PV array size hecomes smaller improving the system economics,
97102966 Modelling a permanent magnet DC motorlcentrifugal pump assembly in a photovoltaic energy system Suehrcke, H. et al. Solar Ener~, 1997, 59, (l-3), 37-42. In a photovoltaic pumping system, direct current (DC) motors and centrifugal pumps operate at variable speed. To analyse the diurnal operation of a pumping system where the solar radiation varies causing variation in the photovoltaic power, the input/output relationship of the motor pump assembly must be determined. Pump similarity laws may be applied to the analysis of centrifugal pump performance for variable speed operation. Modelling equations of the motor pump assembly are derived from single speed pump characteristics and a no-load motor test.
97102967 Modelling, optimisation and performance evaluation of a parabolic trough solar collector steam generation system Kalogirou, S. et al. Solar Energy, 1997, 60, (l), 49-59. This paper presents a parabolic trough collector (PTC) system used for steam generation. PTCs are able to work at high temperatures with a good efficiency. The modelling program developed called PTCDES is used to predict the quantity of steam produced by the system. System performance tests indicate that the modelling program is accurate to within 1.2%. Finally, the theoretical system energy analysis is presented in the form of a Sankey diagram. The analysis shows that only 48.9% of the available solar radiation is used for steam generation. The rest is lost either as collector or thermal losses.
97102968 cells
MS, (M = W, MO) Photosensitive
thin films for solar
Gourmelona, E. S&r Energ? Materials and Solar Cells, 1997, 46, (2), 115121. As long as the substrates used are each coated with a IO-20 nm Ni layer, photosensitive textured WS2 and MO&, films can be obtained by the techniques of reactive sputtering and sohd state reaction. MS2 (M = W, MO) layers were deposited onto these substrates and then annealed for half an hour at 1073 Kin an argon atmosphere. Textured films crystallized in the 2H-M’S2 structure were obtained, with their C crystallite axes perpendicular
244
Fuel and Energy Abstracts
July 1997
Multi-region
solar cell modeling
Pfleiderer, H. and Bullemer, B. Solar EnerR/ Muteria/.t utrd Solur C‘C~/V, 1997, 46. (I), 17-27. Complications in the understanding of crystalline-silicon p-n solar cells arise from the emitter doping profile. A one-dimensional multi-region method appears as a natural tool to solve the continuity equation for minority carriers in emitter and base, joining the junction on both sides. Analytical analysis can be achieved from this method, which can he further extended to organize full one-dimensional device modelling.
97102970 A new model of very high efficiency silicon solar cell
buried emitter
Bouazzi, A. S. EI al. Solor Enerp Muterials and Solur Cells, 1997, 46, (I). 29-41. A new model of symmetrical silicon solar structure where the emitter i\ buried is presented. Many depletion regions are consequently created in series inside the cell. The photocurrent in this model is computed for AM0 solar spectrum and is compared to the classical p-n junction.
97102971 n-SilSn02 for photoconversion
junctions
based on macroporous
silicon
Cacheta, H. et al. Solar Energy Materials and Solar Cells, 1997, 46, (2), 101-l 14. It is proved that it is possible to form a photovoltaic junction by spraying a thin, transparent, conductive SnOz layer onto macroporous n-type silicon produced by photoelectrochemical etching. The cell reflectivity spectrum is flat and drops to a few percent in the visible and near infrared spectral range. EDX analysis and impedance measurements show that charge separation and current collection occur in the upper part of the pores and in the interpore region, whereas the bottom of the pores only acts as a photon absorber. The active junction area is found to be four times larger than with a mirror-polished substrate. A solar conversion efficiency of IOcS is achieved by a solar cell equipped with just a front ring contact.
97102972
Object-oriented
modeling
of solar heating
systems
Franke, R. Solar Energy, 1997, 60, (3/4), 171-180. The benefit of the object-oriented modelling approach is that it cornhines the convenience of composing system models from universal component models with the advantage of the availability of analytical system descriptions. This study describes its application to solar heating systems. The central solar heating plant with seasonal storage (CSHPSS) in Sara, Sweden is used as an example. An object-oriented system model was developed by using the top-down approach, defining general terminals and abstract base classes first and specialising component models afterwards. System simulation results obtained with the object-oriented simulation environment OmSim are compared with results obtained with the modular simulation environment TRNSYS. Analytical system descriptions are used as the basis for numerical system optimisations.
97102973 system
Opposite
sunspaces
passive
solar
air
heating
Tan, M. Solar Enera, 1997. 60, (314), 127-134. For the provision of passive solar heating in multi-storey huildings, an opposite sunspaces passive solar air heating system has heen developed. The system envisages the natural transfer of the solar energy gained in the southern sunspace of an apartment to the northern glazed space through air ducts placed in the ceiling and floor. The heated air in the southern sunspace rises, enters the air ducts placed in the ceiling and flows through these ducts to the northern glazed space. The displaced air in the southern sunspace is replaced with cooler air flowing from the northern glazed space to the southern sunspace through the air ducts placed in the floor. The application of the system in Ankara Solar House and the Belko Solar Building is described.
97102974 climates
Optimal
sizing
of photovoltaic
systems
in varied
Samimi, J. et al. Solar Energv. 1997, 60, (?), 97-107. Solar modules, especially in the rural and remote areas, are not often utilized economically, because of the lack of solar irradiation and climatological data. Using solar irradiation estimation and cloud cover data interpolation techniques, and incorporating the irradiation dependent efficiency function of the solar cells, the tilt angle of the modules was optimized. The cloud cover data is then used to estimate the expected number of successive cloudy days in each month. This optimization technique has been applied to the varied climates of Iran.
97102975 tion system
Optimization
of solar pond electrical
power genera-
Khalil, R. A. H. ef al. Energ) Covers. Mgmr, 1997, 38, (8) 787-798. The potential of using a solar pond for the generation of electricity in Jordan was investigated. A solar pond power plant model is presented to simulate and optimize such a system under the Jordanian climatic
Alternative energy sources (solar energy)
porous absorber will enhance heat transfer from the absorber to the airstream. The thermal efficiency of this type of collector is significantly higher than the thermal efficiency of conventional air heaters.
to the plane of the substrate. The films are nearly stoichiometric. The optical absorption spectra are similar to those of smgle crystals. and the high photosensitivity of the films is attrihuted to a grain size enhancement by the Ni-S phase.
Hydrogen production with solar energy 97102963 Olgun, H. Hydrogen Em&y Prog. Xl, Proc. World Hydrogen Energy Conf., 11th. 1996, 1, 633-638. Edited by Veziroglo, T. N. International Association
97102969
for Hydrogen Energy, Coral Gables, Florida. Two methods were used in this study for the production of hydrogencontaining gas. The first method comprised the gasification of furnacepreheated coal particles in a laboratory-scale reactor. The effect of reactor temperature, the amount of water vapour used, and of particle size on the level of gas production were investigated. In the second method, coal particles were preheated by solar energy in the reactor prior to gasification. A stainless steel reactor. which is put in the focus of parabolic reflector, was used in this system. The results for coal were compared with results for graphite and wild reed for different reactor temperatures and the produced gases were chemically analysed.
97102964 ,;;;mance USA
ASHRAE
Methods of testing to determine the thermal of flat plate solar collectors contammg bollmg ANSIIASHRAE,
ASHRAE
Standard 109-1986 (RA 96),
1997, 6pp. Test methods for determining the thermal performance of flat plate solar energy collectors that use boiling fluids for thermal energy transfer are provided. Applies to flat-plate solar collectors in which some of the fluid entering the collector boils and some fraction leaves as a saturated vapour. Methods for conducting tests outdoors under natural solar irradiance and for conducting tests indoors under simulated solar irradiance are supplied and the paper also provides test method and calculation procedures for determining steady-state and quasi-steady-state thermal performance, time and angular response characteristics of solar collectors.
97102965 photovoltaic
Microprocessor systems
based
load voltage
regulator
for
Anis. W. R. and El-Samahy. A. E.-S. M. Energy Convers. Mgmr, 38, (I), 13-20. The paper describes a conventional photovoltaic (PV) system driving a DC load consisting of a PV array, storage battery, a battery voltage regulator (BVR) and a load. According to this arrangement, the load voltage is equal to the battery voltage. The hattery voltage varies according to its state of charge (SOC). Critical loads, such as some communication systems, require a regulated voltage, hence conventional battery voltage variations are not accepted for these applications. The typical solution of this problem is to operate the PV system at a higher voltage and to include a control circuit that introduces passive elements so that the load is operating within the allowed limits. Such a solution leads to power dissipation in the passive elements and this presents power loss. An alternative solution based on a microprocessor that keeps the load voltage at the predetermined level is discussed. The proposed technique avoids the power loss and therefore required PV array size hecomes smaller improving the system economics,
97102966 Modelling a permanent magnet DC motorlcentrifugal pump assembly in a photovoltaic energy system Suehrcke, H. et al. Solar Ener~, 1997, 59, (l-3), 37-42. In a photovoltaic pumping system, direct current (DC) motors and centrifugal pumps operate at variable speed. To analyse the diurnal operation of a pumping system where the solar radiation varies causing variation in the photovoltaic power, the input/output relationship of the motor pump assembly must be determined. Pump similarity laws may be applied to the analysis of centrifugal pump performance for variable speed operation. Modelling equations of the motor pump assembly are derived from single speed pump characteristics and a no-load motor test.
97102967 Modelling, optimisation and performance evaluation of a parabolic trough solar collector steam generation system Kalogirou, S. et al. Solar Energy, 1997, 60, (l), 49-59. This paper presents a parabolic trough collector (PTC) system used for steam generation. PTCs are able to work at high temperatures with a good efficiency. The modelling program developed called PTCDES is used to predict the quantity of steam produced by the system. System performance tests indicate that the modelling program is accurate to within 1.2%. Finally, the theoretical system energy analysis is presented in the form of a Sankey diagram. The analysis shows that only 48.9% of the available solar radiation is used for steam generation. The rest is lost either as collector or thermal losses.
97102968 cells
MS, (M = W, MO) Photosensitive
thin films for solar
Gourmelona, E. S&r Energ? Materials and Solar Cells, 1997, 46, (2), 115121. As long as the substrates used are each coated with a IO-20 nm Ni layer, photosensitive textured WS2 and MO&, films can be obtained by the techniques of reactive sputtering and sohd state reaction. MS2 (M = W, MO) layers were deposited onto these substrates and then annealed for half an hour at 1073 Kin an argon atmosphere. Textured films crystallized in the 2H-M’S2 structure were obtained, with their C crystallite axes perpendicular
244
Fuel and Energy Abstracts
July 1997
Multi-region
solar cell modeling
Pfleiderer, H. and Bullemer, B. Solar EnerR/ Muteria/.t utrd Solur C‘C~/V, 1997, 46. (I), 17-27. Complications in the understanding of crystalline-silicon p-n solar cells arise from the emitter doping profile. A one-dimensional multi-region method appears as a natural tool to solve the continuity equation for minority carriers in emitter and base, joining the junction on both sides. Analytical analysis can be achieved from this method, which can he further extended to organize full one-dimensional device modelling.
97102970 A new model of very high efficiency silicon solar cell
buried emitter
Bouazzi, A. S. EI al. Solor Enerp Muterials and Solur Cells, 1997, 46, (I). 29-41. A new model of symmetrical silicon solar structure where the emitter i\ buried is presented. Many depletion regions are consequently created in series inside the cell. The photocurrent in this model is computed for AM0 solar spectrum and is compared to the classical p-n junction.
97102971 n-SilSn02 for photoconversion
junctions
based on macroporous
silicon
Cacheta, H. et al. Solar Energy Materials and Solar Cells, 1997, 46, (2), 101-l 14. It is proved that it is possible to form a photovoltaic junction by spraying a thin, transparent, conductive SnOz layer onto macroporous n-type silicon produced by photoelectrochemical etching. The cell reflectivity spectrum is flat and drops to a few percent in the visible and near infrared spectral range. EDX analysis and impedance measurements show that charge separation and current collection occur in the upper part of the pores and in the interpore region, whereas the bottom of the pores only acts as a photon absorber. The active junction area is found to be four times larger than with a mirror-polished substrate. A solar conversion efficiency of IOcS is achieved by a solar cell equipped with just a front ring contact.
97102972
Object-oriented
modeling
of solar heating
systems
Franke, R. Solar Energy, 1997, 60, (3/4), 171-180. The benefit of the object-oriented modelling approach is that it cornhines the convenience of composing system models from universal component models with the advantage of the availability of analytical system descriptions. This study describes its application to solar heating systems. The central solar heating plant with seasonal storage (CSHPSS) in Sara, Sweden is used as an example. An object-oriented system model was developed by using the top-down approach, defining general terminals and abstract base classes first and specialising component models afterwards. System simulation results obtained with the object-oriented simulation environment OmSim are compared with results obtained with the modular simulation environment TRNSYS. Analytical system descriptions are used as the basis for numerical system optimisations.
97102973 system
Opposite
sunspaces
passive
solar
air
heating
Tan, M. Solar Enera, 1997. 60, (314), 127-134. For the provision of passive solar heating in multi-storey huildings, an opposite sunspaces passive solar air heating system has heen developed. The system envisages the natural transfer of the solar energy gained in the southern sunspace of an apartment to the northern glazed space through air ducts placed in the ceiling and floor. The heated air in the southern sunspace rises, enters the air ducts placed in the ceiling and flows through these ducts to the northern glazed space. The displaced air in the southern sunspace is replaced with cooler air flowing from the northern glazed space to the southern sunspace through the air ducts placed in the floor. The application of the system in Ankara Solar House and the Belko Solar Building is described.
97102974 climates
Optimal
sizing
of photovoltaic
systems
in varied
Samimi, J. et al. Solar Energv. 1997, 60, (?), 97-107. Solar modules, especially in the rural and remote areas, are not often utilized economically, because of the lack of solar irradiation and climatological data. Using solar irradiation estimation and cloud cover data interpolation techniques, and incorporating the irradiation dependent efficiency function of the solar cells, the tilt angle of the modules was optimized. The cloud cover data is then used to estimate the expected number of successive cloudy days in each month. This optimization technique has been applied to the varied climates of Iran.
97102975 tion system
Optimization
of solar pond electrical
power genera-
Khalil, R. A. H. ef al. Energ) Covers. Mgmr, 1997, 38, (8) 787-798. The potential of using a solar pond for the generation of electricity in Jordan was investigated. A solar pond power plant model is presented to simulate and optimize such a system under the Jordanian climatic