Computational Analysis of Heat and Mass Transfer of Impinging Jet onto Different Foods during the Drying Process at Low Reynolds Numbers

Resumo

In the present work, heat and mass transfer from different foods by impinging a slot hot air jet at low Reynolds numbers is numerically researched. Banana and apples are selected as foods due to their trading importance. Low Reynolds numbers are operated as Re = 100, 200 and 300. The diameters of the foods and initial jet height are taken as fixed in all examined situations and the impinging jet is laminar and two-dimensional. The shape of foods is assumed as a cylinder. The distance (D/H) between the cylinder and the slot is taken as another effective parameter of drying process and it is used with the three different distances (D/H = 0.22, 0.25, and 0.33) to search jet effectiveness on heat and mass transfer. A finite volume method is employed to solve governing equations of mass, momentum and energy by means of ANSYS Fluent 17.0 program. There is a good agreement with the numerical and experimental data available in the literature. The heat transfer increments and temperature variations for different Reynolds number values and for varying distance, D/H, and also temperature and mass distributions are researched for both inside the foods. It is obtained that heat and mass transfer enhanced with reducing the distance, D/H, between the jet and the cylinder. In addition, locally, the most effective jet drying is achieved close to the stagnation point on the front face of the foods.