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.
Experimental investigation on the impact of thermal energy storage on the solar still performance coupled with PV module via new integration
Abstract An experimental investigation is performed on the impact of utilizing a thermal energy storage of phase change material (PCM) on the performance of single acting solar still coupled with photovoltaic module (PV) by new integration. The integration of the PV with the still is based on installing directly the PV module over the still condenser where the PV uses the same solar still space. Installing the PV over the still transmits the reflected solar energy from the PV to the saline water in the still basin and the PV output power is also transmitted directly to the saline water. The impact of integrating PCM with the still basin on the still performance is studied for the conventional solar still (CSS) and modified still (CSS + PV) and for forced air cooling (FAC) of the modified still condenser (PCM + CSS + PV). Additionally, the impact of using PV as only a reflector on the still performance is illustrated. The findings indicate that integrating the PV with the CSS increases its productivity by 9%. Using PCM unit with the still coupled with PV increases their daily yield by about 11.7% while using FAC with (CSS + PV + PCM) rises this daily yield by 19.4%. Using PV as a reflector with CSS rises its productivity by 3.5% and lower its production cost compared to CSS. Moreover, the positive impact of the FAC or PCM on the still performance increases with increasing the PV power where using PCM with (CSS + PV) increases its efficiency by about 20%. Using FAC with the system (CSS + PCM and PV) reduces its freshwater yield cost and increases its efficiency.
A Study of the Changes Over Time in State Anxiety in a Computer-Assisted Instructional Program
The purposes of this study were to analyze (1) the changes over time in the state anxiety level of children in a computer-assisted program of reading instruction and in classroom reading instruction, (2) the changes in state anxiety patterns as related to gender, achievement level, and ethnicity, and (3) the difference in anxiety levels of the students while in computer-assisted reading instruction and classroom reading instruction.