Experimental evaluation of the wind convection heat transfer on the glass cover of the single‐slope solar still

Abstract

Accurate evaluation of the wind convection heat transfer coefficient (hw) for solar‐based systems is essential, especially for solar desalination systems. Thermal behavior and productivity of solar stills are highly affected by the external heat loss through the glass cover. This paper describes a new experimental approach to estimate the hw on the glass cover of the conventional single‐slope solar distiller (CSS). Indoor experiments have been conducted under steady‐state conditions for a wind speed between 0 and 3 m/s. The hw has been evaluated through an energy balance performed on the distiller's glass cover. The results showed that increasing the wind speed increases the hw (from 5.64 to 31.57 W/m2 K) and enhances the distillation rate (from 5.28 to 7.61 mL/min). A new relationship for the hw was proposed for the CSS and compared with the experimental data available in the literature. The comparison shows that the obtained results are close to the data from solar systems, with a deviation ranging from 27.4% to 37%. However, a significant deviation was obtained with earlier models derived from flat plates (from 29.5% to 59%).

Solar Photovoltaic Cooker with No Electronics or Battery

“…insulating material of an effective conductivity k in ∼ = 0.2 W mK ; this is larger than usual because of the relatively tight wrapping, the non-continuous covering and no external impervious cover. Taking into account a spherical external geometry, Figure 7 also accepts moderate wind convection and radiation to the environment, this sums up a heat transfer coefficient h outside ∼ = 12 W m 2 K , according to Rahmadi [58]. The radial conductance of the sphere shell is…”