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Development of design charts for solar cooling systems. Part II: application of the cooling f-chart
07 Alternative
energy sources (solar energy)
parameters generally reported are highlighted and additional parameters have been suggested. Based on this review, a procedure has been proposed, giving the methodology, test conditions and a sample evaluation sheet. This would assist in an unambiguous evaluation of solar dryer performance and facilitate comparing different solar food dryers. 03/00705 A group of improved heat and mass transfer correlations in solar stills Zheng, H. et al. Energy Conversion and Manugrmrnt, 2002, 43, (18), 2469-2478. Based on the analogy of heat and mass transfer and an empirical correlation, a group of improved heat and mass transfer correlations in basin type solar stills is established. In order to validate the correlation group, a multi-stage stacked tray solar still with basin area of 0.665 x 0.650 m2 is constructed of aluminium sheets. By comparison of the calculated results with the measurement results, which were obtained from the steady state simulated experiments and reported in previous literature, it is found that the correlation group developed in this work can provide better predictions for the evaporation rate of basin type solar stills at the wide range of Rayleigh number (3.5 x 10” < Ra ( 2.26 x 107) and temperature (35 < T, < 86°C). 03/00706 Buildin and climate influence on the balance temperature of bu Bldings Karlsson, J. et al. Building and Envirorzmrnt, 2003, 38, (1), 75-8 I. In this paper, the fact that the balance temperature varies for different types of buildings is evaluated and discussed. An explicit method to add useful hourly solar heat to the degree-hour formalism directly from building and climate data is presented. This also leads to a straightforward definition of the solar utilization factor. Results from taking solar energy into account are compared with results from not taking solar energy into account demonstrating large deviations. The formalism is compared with a dynamic building simulation program (DEROB-LTH). The effect on the balance temperature when changing several building parameters is analysed in order to illustrate the errors of using a fixed balance temperature in the degree-hour methods for different buildings. 03/00707 Calculations of light trapping, responsivity, and internal quantum efficiency of In-doped silicon (n) structure Mohamad, W. F. Renewable Energy, 200, 28, (2), 31 l--320. This research intends to investigate a mathematical model for In-doped silicon (n) structure, and calculate the absorbance of the simulated cell, then study the effect of impurity photovoltaic effect on the responsivity and internal quantum efficiency using the Shockley-Read-Hall model. It is found that the internal flux inside the simulated Lambertian cell could be enhanced as much as 25 times as a result of light trapping. Maximum responsivity and internal quantum efficiency of the simulated cell was obtained at a wavelength around 1 urn and 10” cmd3 indium concentration. Near infrared response of the simulated cell is improved due to the enhancements of sub-band gap response by indium doping. To compare the mathematical model with the practical results, few samples of In-doped n-type silicon structures have been fabricated using the thermal vacuum resistive technique. Maximum responsivity and maximum internal %uantu_m efficiency are obtained at ’ indium concentration. The wavelength 0.9-l pm and 3.96 x 10 cm results of the simulated and practical cells agree. 03/00708 Development of design charts for solar cooling systems. Part I: computer simulation for a solar cooling system and development of solar cooling design charts Joudi, K. A. and Abdul-Ghafour, Q. J. Energ! Conversion rrnrl Management, 2003, 44, (2), 313-339. An integrated transient simulation program is developed for simulating the Iraqi solar house cooling system, using TRNSYS as a design tool. The simulation is modelled for other virtual solar cooling systems similar to the Iraqi solar house. A number of computer programs were developed and used in parallel with TRNSYS for developing an integrated program for the complete simulation of a solar cooling system with a lithium bromide-water absorption chiller. The results obtained from the simulation were used to develop a general design procedure for solar cooling systems, presented in a graphical form called the cooling f-chart. Using this design chart simplifies the designer’s task for predicting the long term cooling energy supplied from a solar collector array serving an absorption chilled water system. A correlation was developed from the simulation results for estimating the hot water storage size necessary for the solar cooling system. This was based on minimizing the energy discarded from the vent valve when the solar heated water attains a temperature higher than the boiling temperature.
160
Fuel and Energy Abstracts
May 2003
03/00709 Development of design charts for solar cooling systems. Part II: application of the cooling f-chart Joudi, K. A. and Abdul-Ghafour, Q. J. Energy Conversion and Management, 2003. 44, (2), 341-355. This work includes the evaluation of the solar contribution in solar cooling systems by the newly developed solar cooling design chart. The effect of collector area and storage volume on the solar fraction is well taken into account in the cooling design charts. The results of several experimental installations are compared with the present cooling fchart predictions. The agreement is very good, which verifies the validity of design predictions by the new cooling flchart. Changing the collector area in a solar cooling system has a similar effect on the solar fraction as that in a solar heating system. Storage volume appears to show an optimum in a solar cooling system with a marked influence on the solar contribution. The cooling f-chart may be used in equation form for design purposes. Design by solar cooling design charts is applicable for different building constructions, solar collector types, length of cooling season, location and meteorological conditions.fchart predictions 03/00710 Modeling the life cycle energy and environmental performance of amorphous silicon BIPV roofing in the US Keoleian, G. A. and Lewis, G. M. Renr~vahlr Enugy, 200, 28, (2), 271 293. Building integrated photovoltaics (BIPV) perform traditional architectural functions of walls and roofs while also generating electricity. The displacement of utility generated electricity and conventional building materials can conserve fossil fuels and have environmental benefits. A life cycle inventory model is presented that characterizes the energy and environmental performance of BIPV systems relative to the conventional grid and displaced building materials. The model is applied to an amorphous silicon PV roofing shingle in different regions across the USA. The electricity production efficiency (electricity output/total primary energy input excluding insolation) for a reference BIPV system (2kW, PV shingle system with a 6% conversion efficiency and 20 year life) ranged from 3.6 in Portland OR to 5.9 in Phoenix, AZ indicating a significant return on energy investment. The reference system had the greatest air pollution prevention benefits in cities with conventional electricity generation mixes dominated by coal and natural gas, not necessarily in cities where the insolation and displaced conventional electricity were greatest. 03/00711 Modeling the luminous efficacy of diffuse solar radiation on inclined surfaces for all sky conditions Robledo, L. and Soler, A. Energ?, Conversion and Management, 2003, 44, (I), 177-189. In the present work, a study was undertaken of the luminous efficacy 01 diffuse solar radiation incident on vertical surfaces facing north, east, south and west for all sky conditions and mean hourly values of diffuse irradiance and diffuse illuminance. Luminous efficacv models were developed, of the type previously obtained for a horizontal surface. assuming that the surface slope will qualitatively influence illuminance and irradiance in the same way. Taking into account that the models obtained show that there is little variation of the luminous efficacy with the independent variables, an approximation to these models has been proposed that considers a constant value for the luminous efficacy of diffuse solar radiation. Statistical assessment shows that this approximation offers reasonable results for north, east and west vertical surfaces. When statistical assessment of the models is performed, it is observed that the values of the statistical indicators largely depend on the possibility for the surface to ‘see’ the solar disk, as determined from geometrical considerations. For both types of models, better values of the statistical indicators are obtained when the surface sees the solar disk than when it does not. 03/00712 Reliability/cost implications of utilizing photovoltaics in small isolated power systems Billinton, R. and Karki, R. Reliahilitv Engineering & .S~~stem &/et\‘. 2003, 79, (I)_ 1 I 16. The rapid growth of renewable energy applications in electric power systems dictates a need to develop comprehensive techniques that can be used to evaluate the economics involved and the reliability of power supply that can be achieved from the utilization of these energy sources. Photovoltaic (PV) arrays have the potential to significantly reduce operating costs in remote small systems that are generally supplied using costly diesel fuel. This paper presents a simulation method that provides objective indicators to help system planners decide on appropriate installation sites, selection of PV arrays or diesel units in capacity expansion and optimum PV penetration levels when utilizing PV energy in small isolated systems. 03/00713 overview Anyanwu, 301~ 312.
Review of solid adsorption solar refrigerator I: an of the refrigeration cycle E. E. Energ~~ Conversion urld Managunrnt, 2003. 44, (2),
energy sources (solar energy)
parameters generally reported are highlighted and additional parameters have been suggested. Based on this review, a procedure has been proposed, giving the methodology, test conditions and a sample evaluation sheet. This would assist in an unambiguous evaluation of solar dryer performance and facilitate comparing different solar food dryers. 03/00705 A group of improved heat and mass transfer correlations in solar stills Zheng, H. et al. Energy Conversion and Manugrmrnt, 2002, 43, (18), 2469-2478. Based on the analogy of heat and mass transfer and an empirical correlation, a group of improved heat and mass transfer correlations in basin type solar stills is established. In order to validate the correlation group, a multi-stage stacked tray solar still with basin area of 0.665 x 0.650 m2 is constructed of aluminium sheets. By comparison of the calculated results with the measurement results, which were obtained from the steady state simulated experiments and reported in previous literature, it is found that the correlation group developed in this work can provide better predictions for the evaporation rate of basin type solar stills at the wide range of Rayleigh number (3.5 x 10” < Ra ( 2.26 x 107) and temperature (35 < T, < 86°C). 03/00706 Buildin and climate influence on the balance temperature of bu Bldings Karlsson, J. et al. Building and Envirorzmrnt, 2003, 38, (1), 75-8 I. In this paper, the fact that the balance temperature varies for different types of buildings is evaluated and discussed. An explicit method to add useful hourly solar heat to the degree-hour formalism directly from building and climate data is presented. This also leads to a straightforward definition of the solar utilization factor. Results from taking solar energy into account are compared with results from not taking solar energy into account demonstrating large deviations. The formalism is compared with a dynamic building simulation program (DEROB-LTH). The effect on the balance temperature when changing several building parameters is analysed in order to illustrate the errors of using a fixed balance temperature in the degree-hour methods for different buildings. 03/00707 Calculations of light trapping, responsivity, and internal quantum efficiency of In-doped silicon (n) structure Mohamad, W. F. Renewable Energy, 200, 28, (2), 31 l--320. This research intends to investigate a mathematical model for In-doped silicon (n) structure, and calculate the absorbance of the simulated cell, then study the effect of impurity photovoltaic effect on the responsivity and internal quantum efficiency using the Shockley-Read-Hall model. It is found that the internal flux inside the simulated Lambertian cell could be enhanced as much as 25 times as a result of light trapping. Maximum responsivity and internal quantum efficiency of the simulated cell was obtained at a wavelength around 1 urn and 10” cmd3 indium concentration. Near infrared response of the simulated cell is improved due to the enhancements of sub-band gap response by indium doping. To compare the mathematical model with the practical results, few samples of In-doped n-type silicon structures have been fabricated using the thermal vacuum resistive technique. Maximum responsivity and maximum internal %uantu_m efficiency are obtained at ’ indium concentration. The wavelength 0.9-l pm and 3.96 x 10 cm results of the simulated and practical cells agree. 03/00708 Development of design charts for solar cooling systems. Part I: computer simulation for a solar cooling system and development of solar cooling design charts Joudi, K. A. and Abdul-Ghafour, Q. J. Energ! Conversion rrnrl Management, 2003, 44, (2), 313-339. An integrated transient simulation program is developed for simulating the Iraqi solar house cooling system, using TRNSYS as a design tool. The simulation is modelled for other virtual solar cooling systems similar to the Iraqi solar house. A number of computer programs were developed and used in parallel with TRNSYS for developing an integrated program for the complete simulation of a solar cooling system with a lithium bromide-water absorption chiller. The results obtained from the simulation were used to develop a general design procedure for solar cooling systems, presented in a graphical form called the cooling f-chart. Using this design chart simplifies the designer’s task for predicting the long term cooling energy supplied from a solar collector array serving an absorption chilled water system. A correlation was developed from the simulation results for estimating the hot water storage size necessary for the solar cooling system. This was based on minimizing the energy discarded from the vent valve when the solar heated water attains a temperature higher than the boiling temperature.
160
Fuel and Energy Abstracts
May 2003
03/00709 Development of design charts for solar cooling systems. Part II: application of the cooling f-chart Joudi, K. A. and Abdul-Ghafour, Q. J. Energy Conversion and Management, 2003. 44, (2), 341-355. This work includes the evaluation of the solar contribution in solar cooling systems by the newly developed solar cooling design chart. The effect of collector area and storage volume on the solar fraction is well taken into account in the cooling design charts. The results of several experimental installations are compared with the present cooling fchart predictions. The agreement is very good, which verifies the validity of design predictions by the new cooling flchart. Changing the collector area in a solar cooling system has a similar effect on the solar fraction as that in a solar heating system. Storage volume appears to show an optimum in a solar cooling system with a marked influence on the solar contribution. The cooling f-chart may be used in equation form for design purposes. Design by solar cooling design charts is applicable for different building constructions, solar collector types, length of cooling season, location and meteorological conditions.fchart predictions 03/00710 Modeling the life cycle energy and environmental performance of amorphous silicon BIPV roofing in the US Keoleian, G. A. and Lewis, G. M. Renr~vahlr Enugy, 200, 28, (2), 271 293. Building integrated photovoltaics (BIPV) perform traditional architectural functions of walls and roofs while also generating electricity. The displacement of utility generated electricity and conventional building materials can conserve fossil fuels and have environmental benefits. A life cycle inventory model is presented that characterizes the energy and environmental performance of BIPV systems relative to the conventional grid and displaced building materials. The model is applied to an amorphous silicon PV roofing shingle in different regions across the USA. The electricity production efficiency (electricity output/total primary energy input excluding insolation) for a reference BIPV system (2kW, PV shingle system with a 6% conversion efficiency and 20 year life) ranged from 3.6 in Portland OR to 5.9 in Phoenix, AZ indicating a significant return on energy investment. The reference system had the greatest air pollution prevention benefits in cities with conventional electricity generation mixes dominated by coal and natural gas, not necessarily in cities where the insolation and displaced conventional electricity were greatest. 03/00711 Modeling the luminous efficacy of diffuse solar radiation on inclined surfaces for all sky conditions Robledo, L. and Soler, A. Energ?, Conversion and Management, 2003, 44, (I), 177-189. In the present work, a study was undertaken of the luminous efficacy 01 diffuse solar radiation incident on vertical surfaces facing north, east, south and west for all sky conditions and mean hourly values of diffuse irradiance and diffuse illuminance. Luminous efficacv models were developed, of the type previously obtained for a horizontal surface. assuming that the surface slope will qualitatively influence illuminance and irradiance in the same way. Taking into account that the models obtained show that there is little variation of the luminous efficacy with the independent variables, an approximation to these models has been proposed that considers a constant value for the luminous efficacy of diffuse solar radiation. Statistical assessment shows that this approximation offers reasonable results for north, east and west vertical surfaces. When statistical assessment of the models is performed, it is observed that the values of the statistical indicators largely depend on the possibility for the surface to ‘see’ the solar disk, as determined from geometrical considerations. For both types of models, better values of the statistical indicators are obtained when the surface sees the solar disk than when it does not. 03/00712 Reliability/cost implications of utilizing photovoltaics in small isolated power systems Billinton, R. and Karki, R. Reliahilitv Engineering & .S~~stem &/et\‘. 2003, 79, (I)_ 1 I 16. The rapid growth of renewable energy applications in electric power systems dictates a need to develop comprehensive techniques that can be used to evaluate the economics involved and the reliability of power supply that can be achieved from the utilization of these energy sources. Photovoltaic (PV) arrays have the potential to significantly reduce operating costs in remote small systems that are generally supplied using costly diesel fuel. This paper presents a simulation method that provides objective indicators to help system planners decide on appropriate installation sites, selection of PV arrays or diesel units in capacity expansion and optimum PV penetration levels when utilizing PV energy in small isolated systems. 03/00713 overview Anyanwu, 301~ 312.
Review of solid adsorption solar refrigerator I: an of the refrigeration cycle E. E. Energ~~ Conversion urld Managunrnt, 2003. 44, (2),