Numerical simulation and experimental investigation of air cooling system using thermoelectric cooling system

Journal of Thermal Analysis and Calorimetry - Efficient air-conditioning inside the cars is a challenge in automobile industry. Thermoelectric is one of the new methods for air cooling. It has many...     

Comparison of quasi-steady-state and unsteady-state formulations in a freeze dryer modeling

An unsteady-state model is developed for primary and secondary stages of freeze drying process of skim milk. The results are compared with those obtained from a quasi-steady-state (QSS) formulation. The QSS formulation is not valid where the applied heat load is high. The applied heat load affects on the drying time the most compared to other parameters like chamber pressure and the radiation surface temperature.     

Synthesis of SnO<Subscript>2</Subscript> nanopowders by a sol-gel process using propanol-isopropanol mixture

A simple sol-gel process is proposed for synthesizing SnO₂ nanopowders utilizing normal propanol and isopropanol mixture instead of just using normal alcohols such as ethanol, propanol or butanol for Sol preparation. No surfactant was used in this Sol preparation process. The structure of sol is studied by FT-IR-ATR technique. On altering propanol to isopropanol ratio, three different nanopowders were obtained. X-ray powder diffraction, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction pattern (SAED) and BET techniques were used to characterize prepared powders. Results show that smaller grain size was obtained via altering alcohols ratio. In addition, Merck commercial SnO₂ powder was also used as a reference material for comparing purposes; because it has nanometer scale (ca. 60 nm). HRTEM images show that obtained nanopowders were polycrystalline and their average diameters fall into the range of 6–80 nm. Finally, the effect of alkoxide ligand size through sol-gel synthesis on product particle size is discussed.