A numerical study on the effect of the heat sink as condenser on the performance of passive solar still
A theoretical work is presented to study the effect of using heat sink as condenser on the performance of passive solar still. Single acting solar still facing the south with pure saline water is used in this work. During this study, a heat sink of a tip fin is used as a condenser instead of vertical glass plate of the conventional passive solar still. The theoretical model of the energy balance equations for each component: the basin water, the cover glass, the basin base and the condenser of the solar still were presented. The theoretical model was numerically solved by using MATLAB to assess the temperatures of the various components, the desalinated water productivity, and the system performance. To examine the validity of the model, the numerical results were compared with the available experimental data in the literature. It is found that the numerical results were in close agreement with the experimental data for both the components' temperatures and output productivity. A comparison of the performance of the studied solar still and the conventional solar still is presented. The results showed that the maximum productivity and efficiency of the solar still with heat sink as condenser are 0.8756 kg/m2.hr and 61.72 %, respectively comparing with 0.4305 kg/m2.hr and 30.35% for conventional solar still at the same conditions. Additionally, heat sink as condenser increases also the performance of the solar still compared to conventional solar still.
Performance investigation of low – Concentration photovoltaic systems under hot and arid conditions: Experimental and numerical results
Abstract In this study, a comparative performance analysis was performed between a conventional photovoltaic system and a low-concentration photovoltaic system. Two typical photovoltaic modules and two compound parabolic concentrating photovoltaic systems were examined. A Cooling system was employed to lower the temperature of the solar cells in each of the two configurations. Experimental and numerical investigations of the performance of the two arrangements with and without cooling were presented. Experiments were conducted outdoors at the Egypt-Japan University of Science and Technology, subjected to the hot climate conditions of New Borg El-Arab City, Alexandria, Egypt (Longitude/Latitude: E 029°42′/N 30°55′). A comprehensive system model was established, which comprises an optical model, coupled with thermal and electrical models. The coupled model was developed analytically and solved numerically, using MATLAB software, to assess the overall performance of the two configurations, considering the concentration ratio of the concentrated photovoltaic system to be 2.4X. The results indicated that cooling the solar panels considerably improved the electrical power yield of the photovoltaic systems. By employing cooling, the temperatures of the conventional photovoltaic system and the concentrated photovoltaic system were effectively lowered by approximately 25% and 30%, respectively, resulting in a significant enhancement in the electrical power output of the photovoltaic system by 11% and that of the concentrated photovoltaic system by 15%. Furthermore, the results revealed that the concentrated photovoltaic system outperformed the non-concentrated photovoltaic system, for both non-cooling and cooling cases, by 33% and 52%, respectively. Finally, experimental verification of the numerical results revealed a good agreement for both configurations, with an average error of 4% and 5% for the photovoltaic systems and the concentrated photovoltaic systems, respectively.
Characterization of a tube-in-shell thermosyphon heat exchanger for solar water heating
Performance of a double-wall, natural convection, two-pass, tube-in-shell heat exchanger designed for use in a solar water heating system is measured. The heat exchanger is mounted along the length of a solar water storage tank. Flow of cold water on the shell side of the heat exchanger is driven solely by buoyancy forces. Hot side fluid is pumped. Flow rate, pressure drop and temperature data needed for a semi-empirical model of the heat exchanger are obtained. Performance is measured for forced convection, hot side volumetric flow rates of 0.016, 0.032 and 0.079 l/s. Temperature difference between hot and cold fluid at the inlets is varied from 0 to 75 degC. Measured values include thermosyphon and forced flow rates, temperature differences across the beat exchanger, vertical temperature distribution in the storage tank, and pressure drop due to shear on the thermosyphon side of the heat exchanger. Heat exchanger effectiveness and overall heat transfer area product (UA) are calculated. Thermosyphon mass flow rates are on the order of 0.01 kg/s. Although the low flow rates create thermal stratification of the water storage tank, they restrict energy transfer in the heat exchanger.