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.
An experimental work on the performance of solar still incorporating with wind turbine and thermal energy storage unit
The performance of single slope solar still incorporating with a wind turbine by a new coupling technique is investigated experimentally. The coupling technique is based on transferring the output power from the turbine directly to the brackish water in the still basin by utilizing an electrical heater embedded in the still basin. The advantage of this technique is that the turbine power is transmitted directly to the salty water in the basin without any intermediate which affects negatively on the transmitting performance. Moreover, the wind turbine doesn’t require extra land than the land occupied by the still where it can be built on the same area of the stills. The system performance (solar still plus turbine) is also studied in case of utilizing thermal energy storage unit of phase change material (PCM) coupled with the still’s basin base. Moreover, it is studied in case of using black steel wool fibers (BSWF) in the basin. Four cases are studied to determine the influence of wind power on the performance of the solar still; (i) conventional solar still (CSS) (ii) CSS with wind turbine only, (iii) CSS with wind turbine and BSWF saturated with salty water in the basin, and (iv) CSS with a wind turbine and PCM. The performance of the different cases is experimentally evaluated and compared to each other at the same climate conditions of Borg El-Arab City, Alexandria, Egypt (Longitude/ Latitude: E 029°42’/N 30°55’). The findings illustrate that using the turbine increases the still temperatures and yield. BSWF are more effective than PCM in case of CSS but in case of using wind turbine with CSS, PCM is more effective than BSWF. Coupling the wind turbine with CSS rises its yield by around 19.8%, 30.9%, and 20.1% in case of CSS, still with BSWF, and still with PCM, respectively.
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).