Showing papers in "Renewable Energy in 1991"

TL;DR: In this paper, a simple theoretical method was developed to estimate the optimum tilt angle of a solar absorber plate of free orientation during any period of time "t" in the year (t = N × day where "N" is an integer).

TL;DR: In this article, a detailed theoretical parametec analysis has been made on corrugated and flat plate solar air heaters of five different configurations, investigating the effects of the air flow velocities (or the air channel depths) on the air temperature increase, the system efficiency and the pressure drop experienced by the flowing air for different air channel lengths and different specific mass flow rates of air.

TL;DR: In this paper, a model based on the modified version of Gaussian distribution function has been proposed to estimate the clear day global radiation, which fits very well on the recorded data which is further exploited to develop a relationship between the ratio of hourly to daily global radiation and day length (time between sunrise to sunset).

TL;DR: In this paper, three towns were chosen as the best locations for wind energy utilization, namely: Laayoune, Tanger and Dakhla, for 5 years' hourly wind data for 17 locations in Morocco.

TL;DR: In this paper, a review and evaluation of the methods of estimating monthly average global solar radiation using bright sunshine hours is presented, along with model validation and comparison techniques and summarizes comparisons of some of the models using the data of various locations.

TL;DR: In this paper, the extinction coefficient of pure water in the wavelength range of 300-2500 nm and the solar spectrum at sea level in the same wavelength range were reconstructed via a computer program.

TL;DR: In this paper, the characteristics of wind regimes and the availability of wind energy resources in Makkah, its outskirts and selected sites on the eastern and western coasts of the Red Sea have been studied.

TL;DR: A complete design and fabrication for a parabolic square-dish solar cooker is presented in this article, which can be used for water distillation as well as cooking in an isolated area.

TL;DR: In this paper, the first experimental results of a study performed on buried pipes for individual house air cooling in summer are presented, which points out different aspects of this cooling technique: general thermal behaviour, air cooling possibility, and influence of different parameters, such as air flow rate, or working management of heat exchanger system.

TL;DR: In this paper, a dynamic model of biogas production systems based on system dynamics methodology is presented, which consists of four coupled nonlinear first-order differential equations, two microbial growth equations and the resulting equation for BiOGAS production, and sensitivity analysis shows that gas production is sensitive to the influent concentration and retention time.

TL;DR: In this paper, a hybrid system using regenerative sources on the island of Fehmarn was constructed by Telefunken systemtechnik with financial support by the Federal Ministry of Research and Technology, the Government of Schleswig-Holstein, the community of Burg and Daimler-Benz.

TL;DR: In this paper, the authors discuss design considerations of small scale wind energy systems and present results from some Australian remote area power supply systems Small scale wind power systems have the potential for considerable improvement in the standard of living of individuals in rural areas in the developing countries.

TL;DR: In this article, the authors examined two electric generator options for use in autonomous wind systems producing asynchronous electric power, including a capacitor-excited squirrel-cage induction generator feeding a battery bank and an induction motor driven centrifugal pump.

TL;DR: In this paper, a multi-purpose solar tunnel dryer was modified to enable operation under tropical weather conditions, and the results showed that compared to natural sun drying, the drying time of cocoa, coffee and coconut could be reduced up to 40%.

TL;DR: In this paper, the match between high technology engineering, high reliability, and simple and effective operation as seen from the user, is investigated and economic analyses are performed to compare different energy systems.

TL;DR: In this article, the influence of ejector configuration and operating conditions on the performance of a R11 vapour jet refrigeration system (VJRS) was investigated. But the authors did not consider the effect of the ejector configurations on the operating conditions.

TL;DR: In this paper, the hourly and monthly energy outputs of three commercial machines (22 kW, 16 kW and 4 kW) having different cut-in wind speed were computed for the years 1978-1981.

TL;DR: In this article, simple models of these vaulted roof buildings are made and tested in a two dimensional low speed wind tunnel for low velocity smoke flows. Flow pattern over and around the models are visualized and photographed.

TL;DR: In this paper, a sensible heat storage unit in the form of a bed, randomly packed with spheres manufactured from a local material (an Egyptian clay), is subject to explicit and implicit constraints.

TL;DR: In this paper, for the first time, values of solar radiation over Jordan as estimated from correlation relations and models were presented, and the agreement with measurements is better than 5% and 1% on monthly and yearly basis respectively.

TL;DR: In this paper, the authors present a research communication aimed at investigating the most appropriate cost effective food preservation technology suitable for implementation with limited financial resources, which can be fabricated using simple tools and relatively cheap and localy available materials by small scale industries.

TL;DR: In this article, an estimation of wind energy available has been carried out from wind speed data recorded over 25 years (1963-1987), as observed in the main meterological stations called synoptical stations of the observation network of the “Agence pour la Securite et la Navigation Aerienne en Afrique” (ASECNA), located in various localities of the Benin Republic (Ex Dahomey), in which the possible applications of this energy for each station are discussed.

TL;DR: In this paper, the accuracy of different methods (power law, logarithmic, log-linear) for extrapolating wind speed at WECS hub height is investigated.

TL;DR: In this article, an experimental saturated solar pond is constructed using magnesium chloride salt, and the temperature and concentration gradients are developed by heating the pond from the bottom and adding powdered salt from the top.

TL;DR: In this paper, 11 years' daily wind speed data at 21 locations in the state of Tamil Nadu, India were analyzed to assess the available wind power potential using Weibull distribution under two different methods.

TL;DR: In this article, correlation equations have been developed to obtain the monthly average of daily global, beam and diffuse solar radiation at Karachi, Pakistan from the fraction of maximum possible sunshine hours.

TL;DR: A field test of the performance of photovoltaic (PV) refrigerator in the Sudan tropical climate is presented in this paper, where the authors show that without having a conventional energy source at one's disposal, the existence of mechanical refrigerators connected to photovolastic panels could present a possible solution to this difficulty.

TL;DR: In this paper, the authors analyzed the wind energy data by using the Weibull distribution and determined scaling and shaping parameters by using least-squares approximation to a straight line.

TL;DR: In this paper, the inclination dependent performance of water-filled heat pipes was investigated both theoretically and experimentally for solar energy applications, and the results showed that the performance of the water filled heat pipes are strongly dependent on the inclination and the heat source temperatures.

TL;DR: In this article, a statistical model developed by Tarpley is applied to estimate solar irradiance over West Germany during November 1986, and daily sums and montly means of global radiation obtained fro 29 stations, uniformly distributed over the studied region are compared with corresponding ground measurements of solar radiation provided by pyranometers.