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Parameters affecting solar still productivity
07 A/temafive energy sources (solar energy) characteristics had an impact on the greenhouse energy demand and on the amount of solar energy available to the canopy, only for small plants on an almost uncovered floor. 00100402
Numerical model of a building with transparent
insulation Athienitis, A. K. and Ramadan, H. Solar Energy, 1999, 67, (l-3), lOl109. An explicit finite difference simulation model is developed to study the thermal performance of an outdoor test-room with one transparently insulated (TI) wall. The thermal behaviour of the room is examined under different control strategies for the shading device and for air flow through the TI wall to the room. Simulation results indicate significant energy savings with practically no auxiliary heating required on cold sunnv davs in Montreal. However. anorouriate control strategies are ‘req&ed to prevent overheating ‘df t‘he room and discomfort. Air flow through the TI wall and then into the room succeeds in lowering its room surface temperature to less than 31°C and reducing to zero the auxiliarv heating reauired on anv clear dav. Blind contrd is based on severaicriteria: in&ding outside temperature, room-facing surface temperature of TI wall (not to exceed 29°C) and room air temperature not to exceed a certain maximum.
Numerical simulation and sensitivity analysis of lattice passive solar heating walls
W/O0403
Fang, X. Li, Y. Solar Energy, 2000, 69, (I), 55-66. A lattice passive solar heating wall (LPSHW) can remarkably improve the heating performance of passive solar heated buildings. Many parameters affect the thermal performance of the LPSHW so that it is not realistic to scrutinize the- thermal performance of the LPSHW exoerimentallv. This oaner develoos a three-dimensional transient heat transfer mod;1 of the’ CPSHW, b&ed on which a computer simulation program is developed in FORTRAN language. The model predictions igree quite well with experimental data. The program canbe used to simulate and evaluate the transient thermal performance, to analyse the sensitivity and the effect of climate and to optinuze LPSHW structural of oarameters. Hour-bv-hour comouter simulations are run with the progiam to analyse the sdnsitivity of-a variety of parameters of the LPSHW. The calculations are rerun many times with structural parameters changed one at a time so that the effect of the changed structural parameter on the thermal performance of the LPSHW can be assessed. From the sensitivity analysis, the optimum configuration is thus obtained. The comparison between the LPSHW and the Trombe wall is made thereafter. Under the chosen conditions, thermal efficiency is 30.2% for the LPSHW and 22.6% for the Trombe wall.
00/00404 Optical and electrical properties of flashevaporated amorphous CulnSe2 films Sakata, H. Ogawa, H. Sol. Energy Mat. & Sol. Cells, 2000,63, (3), 259265. Amorphous films of CuInSez were deposited on glass substrate by flash evaporation of source materials. The films were found to be p-type se&conductors. The direct optical band-gap energy was obtained to be 1.21-1.41 eV. The film DC conductivitv raneed from 1.2-5.7 S cn-’ at 285 K for different film thickness with &responding activation energy of 55.5-301 meV. From temperature dependence of conductivity, the carrier transport was interpreted to be due to band conduction above 270 K. 0 tical characterization of industrially sputtered nickel-nlcke Poxide solar selective surface
W/W405
Adsten, M. et al. Solar Energy, 2000, 68, (4), 325-328. Tandem absorbers are often used in the design of solar absorbers for photothermal conversion. They consist of a thin coating, selectively absorbing in the wavelength range of the solar spectrum, on a metal substrate. The ootical oerformance of a tandem absorber deoends on the optical constants aid thickness of the absorbing coating anh also on the reflectivity of the underlying metal. A very high solar absorptance is achieved when the coating has a non-uniform composition in the sense that the refractive index is highest closest to the metal substrate and then gradually decreases towards the front surface. This type of composition suppresses coating interference and gives a low front surface reflection if the refractive index at the front surface is low. This paper reports on an optical analysis of a solar absorber with a graded index coating of sputtered nickel-nickel oxide deposited on aluminium. The optical constants have been determined from reflectance, transmittance and ellipsometry data by fitting the data to a two-layer model of the coating. The optical constants of the two layers can be regarded as effective optical constants for the lower and upper part of the graded index coating respectively. It is found that the effective refractive index of the top layer is somewhat lower than for the base layer. The extinction coefficient is higher in the lower part of the coating. Both effective refractive index and extinction coefficient of the base layer increase monotonically with increasing wavelength as for metallic materials. 42
Fuel and Energy Abstracts
January 2001
00100406 Optimization of operational and design parameters of plane reflector-tilted flat plate solar collector svstems Hbssein, H. M. S. Energy, 2000, 25, (6), 529-542. Due to the increased interest in the utilization of solar energy, it is essential to enhance the energy collection of solar energy devices. In this paoer. a theoretical analvsis of the instantaneous. dailv and vearlv enh&emknt in solar energy collection of a tilted fla
Optimization of solar district heating systems: seasonal storage, heat pumps, and cogeneration 00100407
Lindenberger, D. et al. Energy, 2000, 25, (7), 591-608. The dynamic energy, emission, and cost optimization model deeco is further developed and applied to the analysis of solar district heating systems with seasonal storage in a pilot project of the Bavarian Research Foundation. The optimum integration of condensing boilers, compression and absorption heat pumps, and cogeneration of heat and power is computed for 100 well insulated housing units with an annual total heat demand of 616 MWh. Collector areas between I and 2.5 m2 per MWh heat demand and water storage volumes between 1.2 and 4.2 m3 per m2 collector area satisfy between 32 and 95 per cent of the total heat demand by solar thermal heat. Compared with a reference case with individual condensing boilers and electricity taken from the public grid, selected scenarios achieve (non-renewable primary) energy savings between 15 and 35% associated with cost increases between -20% and 140%; cogeneration turns out to be quite attractive from an economical point of view. With cogeneration and a solar contribution to the heat supply of 80%. emission reductions of COz-equivalents by 33%, SO2 by 20%, and NO. by 22% can be achieved at cost increases of 120%. Fossil fuel savings of more than 40% are possible if electricity is produced from non-fossil energy sources. 00100406 Parameters affecting solar still productivity Safwat Nafey, A. et al. Energy Convers. Manage.,2000, 41, (IS), 17971809. In this work, investigation of the main parameters affecting solar still performance under the weather conditions of the Suez Gulf area is considered. Four solar still units are designed and constructed to ooerate under the same weather conditions with different design pirameters. A general equation is developed to predict the daily productivity of a single sloped solar still. The developed equation ielates the- dependeni and independent variables which contiol the daily productivity. This equation could be used to predict the daily productivity with a reasonable confidence level (maximum error +5%).
Passivation and gettering of defective crystalline silicon solar cell Lin, A. et al. Sol. Energy Mar. & Sol. Cells, 2000, 62, (l-2), 149-155.
00100409
Different polycrystalline silicon and single-crystalline silicon with dislocationa w& used for passivation and-gettiring processes. These materials have defects and more impurity in the crystal. The dominant increase of electronic oerformance was found for wafers with more defects by using a different casting method. The wafers of single crystalline silicon with dislocations also have higher increase of efficiency of cell in comparison with that wafer without dislocations during oxide passivation processes used. POCl3 was used for gettering processes. Single-crystal wafer with or without dislocations was used for comparison of gettering. 00100410 Performance of a new solid adsorption ice maker with solar energy regeneration Ferreira Leite, A. P. and Daguenet, M. Energy Comers. Manage., 2000, 41, (15), 1625-1647. A predictive model for an adsorption solar cooling system using the activated carbon-methanol pair and its numerical simulation are presented. This model accounts for instantaneous heat and mass transfers in each one of the machine components along a characteristic average day for each month. The solar powered ice maker consists of the following basic components: a reactor containing an adsorptive bed coupled to a static solar collector covered by transparent insulation material (TIM), a condenser and an evaporator. A uniform pressure model for the reactor is considered. The bed’s radial temperature distribution is determined by means of a one-dimensional numerical method based on a finite difference technique. The machine’s performance is evaluated according to meteorological data valid for the hottest six months in Joso Pessoa (7”8’S, 34”5O’WG), whose climate is typically hot and humid. The results are compared with those
Numerical model of a building with transparent
insulation Athienitis, A. K. and Ramadan, H. Solar Energy, 1999, 67, (l-3), lOl109. An explicit finite difference simulation model is developed to study the thermal performance of an outdoor test-room with one transparently insulated (TI) wall. The thermal behaviour of the room is examined under different control strategies for the shading device and for air flow through the TI wall to the room. Simulation results indicate significant energy savings with practically no auxiliary heating required on cold sunnv davs in Montreal. However. anorouriate control strategies are ‘req&ed to prevent overheating ‘df t‘he room and discomfort. Air flow through the TI wall and then into the room succeeds in lowering its room surface temperature to less than 31°C and reducing to zero the auxiliarv heating reauired on anv clear dav. Blind contrd is based on severaicriteria: in&ding outside temperature, room-facing surface temperature of TI wall (not to exceed 29°C) and room air temperature not to exceed a certain maximum.
Numerical simulation and sensitivity analysis of lattice passive solar heating walls
W/O0403
Fang, X. Li, Y. Solar Energy, 2000, 69, (I), 55-66. A lattice passive solar heating wall (LPSHW) can remarkably improve the heating performance of passive solar heated buildings. Many parameters affect the thermal performance of the LPSHW so that it is not realistic to scrutinize the- thermal performance of the LPSHW exoerimentallv. This oaner develoos a three-dimensional transient heat transfer mod;1 of the’ CPSHW, b&ed on which a computer simulation program is developed in FORTRAN language. The model predictions igree quite well with experimental data. The program canbe used to simulate and evaluate the transient thermal performance, to analyse the sensitivity and the effect of climate and to optinuze LPSHW structural of oarameters. Hour-bv-hour comouter simulations are run with the progiam to analyse the sdnsitivity of-a variety of parameters of the LPSHW. The calculations are rerun many times with structural parameters changed one at a time so that the effect of the changed structural parameter on the thermal performance of the LPSHW can be assessed. From the sensitivity analysis, the optimum configuration is thus obtained. The comparison between the LPSHW and the Trombe wall is made thereafter. Under the chosen conditions, thermal efficiency is 30.2% for the LPSHW and 22.6% for the Trombe wall.
00/00404 Optical and electrical properties of flashevaporated amorphous CulnSe2 films Sakata, H. Ogawa, H. Sol. Energy Mat. & Sol. Cells, 2000,63, (3), 259265. Amorphous films of CuInSez were deposited on glass substrate by flash evaporation of source materials. The films were found to be p-type se&conductors. The direct optical band-gap energy was obtained to be 1.21-1.41 eV. The film DC conductivitv raneed from 1.2-5.7 S cn-’ at 285 K for different film thickness with &responding activation energy of 55.5-301 meV. From temperature dependence of conductivity, the carrier transport was interpreted to be due to band conduction above 270 K. 0 tical characterization of industrially sputtered nickel-nlcke Poxide solar selective surface
W/W405
Adsten, M. et al. Solar Energy, 2000, 68, (4), 325-328. Tandem absorbers are often used in the design of solar absorbers for photothermal conversion. They consist of a thin coating, selectively absorbing in the wavelength range of the solar spectrum, on a metal substrate. The ootical oerformance of a tandem absorber deoends on the optical constants aid thickness of the absorbing coating anh also on the reflectivity of the underlying metal. A very high solar absorptance is achieved when the coating has a non-uniform composition in the sense that the refractive index is highest closest to the metal substrate and then gradually decreases towards the front surface. This type of composition suppresses coating interference and gives a low front surface reflection if the refractive index at the front surface is low. This paper reports on an optical analysis of a solar absorber with a graded index coating of sputtered nickel-nickel oxide deposited on aluminium. The optical constants have been determined from reflectance, transmittance and ellipsometry data by fitting the data to a two-layer model of the coating. The optical constants of the two layers can be regarded as effective optical constants for the lower and upper part of the graded index coating respectively. It is found that the effective refractive index of the top layer is somewhat lower than for the base layer. The extinction coefficient is higher in the lower part of the coating. Both effective refractive index and extinction coefficient of the base layer increase monotonically with increasing wavelength as for metallic materials. 42
Fuel and Energy Abstracts
January 2001
00100406 Optimization of operational and design parameters of plane reflector-tilted flat plate solar collector svstems Hbssein, H. M. S. Energy, 2000, 25, (6), 529-542. Due to the increased interest in the utilization of solar energy, it is essential to enhance the energy collection of solar energy devices. In this paoer. a theoretical analvsis of the instantaneous. dailv and vearlv enh&emknt in solar energy collection of a tilted fla
Optimization of solar district heating systems: seasonal storage, heat pumps, and cogeneration 00100407
Lindenberger, D. et al. Energy, 2000, 25, (7), 591-608. The dynamic energy, emission, and cost optimization model deeco is further developed and applied to the analysis of solar district heating systems with seasonal storage in a pilot project of the Bavarian Research Foundation. The optimum integration of condensing boilers, compression and absorption heat pumps, and cogeneration of heat and power is computed for 100 well insulated housing units with an annual total heat demand of 616 MWh. Collector areas between I and 2.5 m2 per MWh heat demand and water storage volumes between 1.2 and 4.2 m3 per m2 collector area satisfy between 32 and 95 per cent of the total heat demand by solar thermal heat. Compared with a reference case with individual condensing boilers and electricity taken from the public grid, selected scenarios achieve (non-renewable primary) energy savings between 15 and 35% associated with cost increases between -20% and 140%; cogeneration turns out to be quite attractive from an economical point of view. With cogeneration and a solar contribution to the heat supply of 80%. emission reductions of COz-equivalents by 33%, SO2 by 20%, and NO. by 22% can be achieved at cost increases of 120%. Fossil fuel savings of more than 40% are possible if electricity is produced from non-fossil energy sources. 00100406 Parameters affecting solar still productivity Safwat Nafey, A. et al. Energy Convers. Manage.,2000, 41, (IS), 17971809. In this work, investigation of the main parameters affecting solar still performance under the weather conditions of the Suez Gulf area is considered. Four solar still units are designed and constructed to ooerate under the same weather conditions with different design pirameters. A general equation is developed to predict the daily productivity of a single sloped solar still. The developed equation ielates the- dependeni and independent variables which contiol the daily productivity. This equation could be used to predict the daily productivity with a reasonable confidence level (maximum error +5%).
Passivation and gettering of defective crystalline silicon solar cell Lin, A. et al. Sol. Energy Mar. & Sol. Cells, 2000, 62, (l-2), 149-155.
00100409
Different polycrystalline silicon and single-crystalline silicon with dislocationa w& used for passivation and-gettiring processes. These materials have defects and more impurity in the crystal. The dominant increase of electronic oerformance was found for wafers with more defects by using a different casting method. The wafers of single crystalline silicon with dislocations also have higher increase of efficiency of cell in comparison with that wafer without dislocations during oxide passivation processes used. POCl3 was used for gettering processes. Single-crystal wafer with or without dislocations was used for comparison of gettering. 00100410 Performance of a new solid adsorption ice maker with solar energy regeneration Ferreira Leite, A. P. and Daguenet, M. Energy Comers. Manage., 2000, 41, (15), 1625-1647. A predictive model for an adsorption solar cooling system using the activated carbon-methanol pair and its numerical simulation are presented. This model accounts for instantaneous heat and mass transfers in each one of the machine components along a characteristic average day for each month. The solar powered ice maker consists of the following basic components: a reactor containing an adsorptive bed coupled to a static solar collector covered by transparent insulation material (TIM), a condenser and an evaporator. A uniform pressure model for the reactor is considered. The bed’s radial temperature distribution is determined by means of a one-dimensional numerical method based on a finite difference technique. The machine’s performance is evaluated according to meteorological data valid for the hottest six months in Joso Pessoa (7”8’S, 34”5O’WG), whose climate is typically hot and humid. The results are compared with those