With the rising population, environmental pollution, and social development, potable water is reducing and being contaminated day by day continually. Thus, several researchers have focused their studies on seas and oceans in order to get potable fresh water by desalination of their saltwater. Solar still of basin type is one of the available technologies to purify water because of free solar energy. The computational fluid dynamic CFD model of the solar still can significantly improve means for optimization of the solar still structure because it reduces the need for conducting large amount of experiments. Therefore, the main purpose of this study is presenting a multi-phase, three-dimensional CFD model, which predicts the performance of the solar still without using any experimental measurements, depending on the CFD solar radiation model. Simulated results are compared with experimental values of water and glass cover temperatures and yield of fresh water in climate conditions of Sheben El-Kom, Egypt (latitude 30.5° N and longitude 31.01° E). The simulation results were found to be in acceptable agreement with the experimental measured data. The results indicated that the daily simulated and experimental accumulated productivities of the single-slope solar still were found to be 1.982 and 1.785 L/m2 at a water depth of 2 cm. In addition, the simulated and experimental daily efficiency were around 16.79% and 15.5%, respectively, for the tested water depth.

The optimum geometries of the ejectors, which give maximum efficiency, are numerically predicted and experimentally measured. The numerical investigation is based on flow equations governing turbulent, compressible, two-dimensional, steady, time averaged, and boundary layer equations. These equations are iteratively solved using finite-difference method under the conditions of different flow regimes, which can be divided into several distinctive regions where the methods for estimating the mixing length are different for each flow region. The first region depicts the wall boundary layer, jet shear layer, and secondary and primary potential flows. The second one contains a single region of developing flow. A simple ejector with convergent-divergent primary nozzle was fabricated and experimentally tested. The present theoretical and experimental results are well compared with published data. The results obtained are used to correlate the optimum ejector geometry, pressure ratio, and ejector optimum efficiency as functions of the operation parameters and ejector area ratio. The resultant correlations help us to select the optimum ejector geometry and its corresponding maximum efficiency for particular operating conditions.

The present paper concerns with studying experimentally the mixture of gas-solid (air-coal) flows in a Venturi meter in an attempt to prepare a metering tool for suspended gas-solid mixture flows. The different parameters that affect the gas-solid mixture flows metering process were determined and analyzed. In order to conduct the study, an experimental setup was designed and manufactured in the laboratory of the thermal power engineering in Menoufia University. Furthermore, seven nonstandard (long-throated) geometrical Venturi models with different diameters ratios and throat lengths were selected guided by previous literature and manufactured to be used in the present experimental work. Additionally, the experimental study was performed on the selected models to determine the effect of different Venturi meter geometric models on pressure drop sensitivity, pressure recovery, and to seek a viable method for determining loading ratio for suspended gas-solid flows in the Venturi. The results showed that the coal loading ratio affected greatly and positively both the pressure drop and recovery ratios of air-coal mixture flows in the Venturi. However, inlet and exit geometries of the Venturi had smaller effect on the pressure drop and recovery ratios than the coal loading ratio and particles diameter range. Additionally, decreasing the diameters ratio and increasing the throat length improved the Venturi pressure drop sensitivity to solids loading. Finally, the experimental results helped greatly to analyze the different parameters concerning the air-coal mixture flows in a Venturi meter and provided an insight on the feasibility of using the Venturi as a metering tool for suspended gas-solid mixture flows in a future continuation of the present work.

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The objective of this work is to study the performance of solar water heaters using heat pipes for heat transfer, from absorber plate to water tank, with two different types of working fluids (Ethanol and Acetone) and different numbers of heat pipes. Additionally, a theoretical investigation is conducted to predict the performance of the solar water heaters. These systems have been designed and fabricated with the same dimensions and materials. The hourly variation of the absorber plate temperature, the water storage tank temperature and solar radiation intensity are measured. Accordingly, the stored energy and the efficiency has been calculated. The results showed that, a good agreement has been achieved between the experimental and theoretical results. The operation point of the conventional system begins at the operating start while the operation point of the thermosyphon systems starts when the absorber plates temperatures reaches the boiling point of the working fluid. The maximum water temperatures gained of the forced convection system and thermosyphon system charged with ethanol and acetone were 66 C, 67.8 C, and 64.6 C, respectively while those of theoretical calculations were around 69.2 C, 69 C and 69.3 C, respectively. In addition, the maximum value of the actual efficiency of conventional system was ranged between 47~53% while that of theoretical calculation was between 50~53%. The experimental maximum efficiency of thermosyphon systems was around 55% at the case of installing 14 heat pipes charged with acetone and theoretical efficiency was 55% for same the case. The thermosyphon system gives better performance than forced convection system, because thermosyphon system does not consume electricity. Performance of the thermosyphon system using acetone as working fluid was better than the performance of the thermosyphon system using ethanol and the increase of the heat pipes number improves performance.