Solar & Wind Technology最新文献

This research paper is aimed at investigating means for space heating using processes suitable for implementation in areas where the conventional energy resources are scarce. Bearing in mind the low cost of capital investment and utilization possibilities, mainly space heating, we have designed and fabricated a simple solar collector-storage system. The objectives of this research paper are: (1) exploring the possibility of using different materials for the insulated base, the transparent coverings, the collecting plate, box structure, potential candidates for sensible heat storage, etc., (2) to design a suitable medium capacity solar collector-storage unit and (3) to discuss the constructional features of the system under investigation.

Several development projects are described. The most successful are the very small micro hydro generators, the photovoltaic battery lantern and the waterwheel.

The model introduced by Gopinathan to estimate the global radiation on a horizontal surface was evaluated. The model has been modified in order to allow a better estimation of the global radiation in Bahrain. The annual monthly mean of the global radiation was found to be $\text{19.49±5.11}\text{MJ m}{}^{\mathrm{-2}}\text{d}{}^{\mathrm{-1}}$. However, the calculated annual monthly mean of the diffused and direct radiation using other theoretical models were found equal to $\text{5.52±1.13}\text{and}\text{13.95±4.23}\text{MJ m}{}^{\mathrm{-2}}\text{d}{}^{\mathrm{-1}}$ respectively.

An ideal tracker which follows the sun both north-south and east-west is designed and constructed. It is suitable for mounting a linear concentrator, focusing parabolic concentrator or photovoltaic array of aperture area 2 m². The apparatus is built with two axes equational mount and controlled by a microprocessor system. The tracking is carried out by utilizing the astronomical coordinates of the sun. As such the present system gives improved tracking capability over the conventional sensor controlled tracker systems. The performance of the tracking system was studied with photovoltaic array mounted on it and tracking error of less than one degree was achieved. This tracking error can be reduced further by proper software.

A discrete time control algorithm for a solar heating model based on the characteristics path of the fluid element leaving the system is developed. The algorithm is verified on a solar system adopting the hyperbolic partial differntial equations in describing the model. The simulation tests have shown significant improvement of the control performance at the desired outlet load temperature with particular emphasis on the model parameters variations.

Performance evaluation studies of Syltherm-800 (a proprietary heat transfer fluid) and Partherm-290 (a proprietary heat storage salt) are reported based on the data collected for a 1-year operation of solar powered freeze desalination pilot plant (200 m³ capacity), located in Yanbu, Saudi Arabia. In spite of some operational problems, the thermal stability of these heat transfer media has been observed to be good, which ensures their prolonged use in solar power-generation technology.

Rural development policies in India have rarely been designed for women as beneficiaries of development schemes. This is despite the fact that the women in rural communities, especially the very isolated, play a crucial role towards maintaining families at a subsistance level. The economics of womens' contribution in terms of energy, goods and income supplement is not clearly understood and often overlooked by planning authorities. An attempt is being made here to demonstrate the major role played by women in energy usage and expenditure, by quantifying womens' work in terms of household income distribution. The point being made is that womens' work should not be regarded as only drudgery to be eliminated. One should work towards reducing womens' workload by bringing in appropriate technology to ease her work and not eliminate the work itself by importing a substitute. If this is not done we end up getting rid of women as important contributors to society.

A solar driven, high efficiency, compound refrigeration system is considered, made up of two cooperating absorption parts, which use NH₃/H₂O and H₂O/LiBr solutions, respectively. Solar heat is given to the vapour generator of the NH₃/H₂O unit, and the heat produced by the absorber and the condenser of this unit is supplied to the vapour generator of the H₂O/LiBr unit. A method for simulating the operation of the compound system has been developed and applied for predicting the hour by hour performance of the system operating during the typical year in Athens, for which solar radiation and ambient temperature data are available. An optimization study for the compound and the individual cycles has also been made. Very high performance of the system has been predicted. For example, on 21 May, the calculated theoretical coefficient of performance is 219% while the corresponding theoretical values of single H₂O/LiBr and NH₃/H₂O units are 93% and 65% respectively. The corresponding calculated cooling power produced by the system is 543 W/m²-collector. An annual analysis shows that the cooling produced by a NH₃/H₂O unit in Athens is 0.87 GJ/m²-year, while the present compound system gives an impressive increase to 3 GJ/m²-year.