01661 Simulation and optimization of a LiBr solar absorption cooling system with evacuated tube collectors

01661 Simulation and optimization of a LiBr solar absorption cooling system with evacuated tube collectors

07 Altemative energy sources (solar energy) 05/01658 PV for buildings. Benefits and experiences with amorphous silicon in BIPV applications Maurus, H...

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07 Altemative energy sources (solar energy) 05/01658 PV for buildings. Benefits and experiences with amorphous silicon in BIPV applications Maurus, H. et al. Refocus, 2004, 5, (6), 22-27. Thin-film technology based on amorphous silicon (a-Si) offers a range of attractive features that are ideally suited for building-integrated photovoltaic installations (BIPV). Solar modules may be assembled to customer-specific BIPV elements for roofs and facades, and thus may combine various functions, namely electricity generation, thermal insulation, shading, and even satisfy aspects of architectural design. Compared to other PV technologies, a-Si modules show only a minor reduction in power output at elevated temperatures, and in efficiency at lower light levels, and thus offer superior energy yields per peak power.

05•01659 Radiometric pulse and thermal imaging methods for the detection of physical defects in solar cells and Si wafers in a production environment Ewan, E.D. et al. Solar Energy Materials and Solar Cells, 2004, 82, (3), 467-480. Steady-state infrared imaging and time-dependent radiometric pulse methods were used to identify certain characteristics and defects of silicon wafers, solar cells and photovoltaic solar modules. The application of the no contact, time-dependent radiometric pulse method has been demonstrated for the detection of cracked or fractured solar cells and its potential for the detection of wafer or cell thickness variation identified. The sensitivity of this method to thermophysical variations shows promise also for the detection of electrically poor bonds.

05•01660 Recent advances of high-efficiency single crystalline silicon solar cells in processing technologies and substrate materials Zhao, J. Solar Energy Materials and Solar Cells, 2004, 82, (1-2), 53-64. Single crystalline silicon solar cells have demonstrated high-energy conversion efficiencies up to 24.7% in a laboratory environment. One of the recent trends in high-efficiency silicon solar cells is to fabricate these ceils on different silicon substrates. Some silicon wafer suppliers are also involved in such development. Another recent trend is the increased production of high-efficiency silicon cells, some of them with low-cost structures. This paper will discuss the progress at the University of New South Wales, and these trends in other organizations.

05•01661 Simulation and optimization of a LiBr solar absorption cooling system with evacuated tube collectors Assilzadeh, F. et al. Renewable Energy, 2005, 30, (8), 1143-1159. Solar radiation is a clean form of energy, which is required for almost all natural processes on earth. Solar-powered air-conditioning has many advantages when compared to a conventional electrical system. This paper presents a solar cooling system that has been designed for Malaysia and similar tropical regions using evacuated tube solar collectors and LiBr absorption unit. The modeling and simulation of the absorption solar cooling system is carried out with TRNSYS program. The typical meteorological year file containing the weather parameters for Malaysia is used to simulate the system. The results presented show that the system is in phase with the weather, i.e. the cooling demand is large during periods that the solar radiation is high. In order to achieve continuous operation and increase the reliability of the system, a 0.8 m 3 hot water storage tank is essential. The optimum system for Mala~sia's climate for a 3.5 kW (1 refrigeration ton) system consists of 35 m ~ evacuated tubes solar collector sloped at 20 °.

05•01662 Solar glass with industrial porous SiO2 antireflection coating: measurements of photovoltaic module properties improvement and modelling of yearly energy yield gain Ballif, C. et al. Solar Energy Materials and Solar Cells, 2004, 82, (3), 331-344. An industrial sol-gel process to coat solar glass with a porous SiO2 antireflection (AR) layer has been recently developed. This paper presents the first detailed study obtained on sets of commercial multicrystalline silicon solar cells encapsulated with patterned low-iron glasses, with or without this A R coating. Measurements under standard test conditions (STC) show a current gain of 2.65% with the A R glass, whereas an additional current gain is obtained at high light incidence angle. Based on the mini-module results and on the outdoor monitoring of test modules to evaluate temperature effects, simulations were performed to asses the yearly photovoltaic energy yield gain at different locations. A significant energy yield increase of 3.4-3.7% is expected with the new A R glass.

05•01663 Solar powered induction motor-driven water pump operating on a desert well, simulation and field tests Daud, A.-K. and Mahmoud, M. M. Renewable Energy, 2005, 30, (5), 701-714.


Fuel and Energy Abstracts

July 2005

A photovoltaic-powered water pumping system, employing an induction motor pump, capable of supplying a daily average of 50 m 3 at 37-m head has been developed. The system was installed on a desert well in Jordan, where: the average solar radiation amount to 5.5 kW h/3/day, to provide the Bedouins living in the well area with drinking water. A mathematical model to enable testing the system performance by computer simulation was developed. This model allows the representation of motor torque in function of speed (and slip) at different supply frequencies, as well as the flow rate and efficiency of the system in function of supply frequency and pumping head. Prior to its installation on the desert well, the system performance, in accordance with frequency and head, was thoroughly tested in the laboratory. As illustrated in this paper, simulation and laboratory testing results are well matched. At constant pumping head, the flow rate is proportional to the supply frequency of the motor. At constant flow rate, the pumping head is proportional to the supply frequency squared only in the range below the peak efficiency of the pump. For higher flow rate values, a special algorithm based on the experimental results could be developed. Higher system efficiency is achievable at higher frequency. It is advisable to operate the motor pump at the nominal frequency, flow rate and head corresponding to maximum efficiency. Long-term field testing of the system shows that it is reliable and has an overall efficiency exceeding 3%, which is comparable to the highest efficiencies reported elsewhere for solar powered pumps.


Solar-hydrogen energy system for Saudi Arabia

Almogren, S. and Nejat Veziroglu, T. N. T. International Journal of Hydrogen Energy, 2004, 29, (11), 1181-1190. A model for solar-hydrogen energy system for Saudi Arabia has been developed by obtaining relationships for and between main energy and energy-related parameters. The parameters' magnitude and trends with and without hydrogen introduction have been investigated over a period of time. The results indicate that the oil resources of Saudi Arabia would not be enough to meet the domestic and export markets starting in three to four decades. The results also show that adopting the solar-hydrogen energy system would extend the availability of oil resources, reduce pollution, and establish a permanent energy system for Saudi Arabia. They also indicate that Saudi Arabia could become an exporter of hydrogen forever.

05101665 Sustainable production of solar electricity with particular reference to the Indian economy Muneer, T. et al. Renewable and Sustainable Energy Reviews, 2005, 9, (5), 444-473. Fossil fuel reserves are diminishing rapidly across the world, intensifying the stress on existing reserves day-by-day due to increased demand. Not only that, fossil fuels, presently contributing to 80% of world primary energy, are inflicting enormous impacts on environment. Climatic changes driven by human activities, in particular the production of greenhouse gas emissions, directly impact the environment. Energy sector has a key role in this regard since energy during its production, distribution and consumption is responsible for producing environmentally harmful substances. A secure and accessible supply of energy is thus very crucial for the sustainability of modern societies. There is an urgent need for a quicker switch over of energy systems from conventional to renewables that are sustainable and can meet the present and projected world energy demand. Solar power is one of the most promising renewables. It is reliable and less vulnerable to changes in seasonal weather patterns. Hydrogen, in the capacity of energy vector, is expected to be the optimum solution for intermittency and storage of energy produced by renewables. Thus, coupled with hydrogen as an energy carrier, solar energy has a large potential to become the fuel of the future. The present study is aimed to explore such potential for India in 2025. India is expected to have a high growth rate in energy demand over the coming years due to its huge population and rapid economic development. By the year 2020, the country's demand for commercial energy is expected to increase by a factor of 2.5. Presently, more than 90% of the energy demand is met by fossil fuels, in spite of the fact that India has limited fossil fuel resources as compared to global reserves. By the year 2020, India, presently the world's sixth largest energy consumer, is expected to meet 75% of its oil and gas needs by imports. Being an energy deficient country, it has not been able to keep up with demand, leading to power shortages and supply interruptions. The growing gap between the demand and supply of energy, and environmental externalities associated with fossil fuel require immediate and substantial increases in electric power generation and transmission capacities, and exploitation of new avenues of energy supply that are more stable and environment friendly. The geographic location of India makes it a strong candidate for harnessing solar energy. Thus, solar PV is a potential technology to meet India's future energy demand and its associated environmental challenges. The present work proposes solar hydrogen based energy network to meet the future energy demand for the major cities of India in a sustainable way. In the proposed energy network, solar PV produced electricity is to be utilized to meet the