DEVELOPMENT OF NEW CORRELATIONS FOR FORCED-CONVECTION HEAT-TRANSFER DURING COOLING OF PRODUCTS

This paper presents the new, simple but powerful effective Nusselt-Reynolds correlations for estimating the effective convective heat transfer coefficients of spherical and cylindrical products cooled in water and air flows. In this respect, both experimental and theoretical works were obtained. In the experimental case, several spherical and cylindrical products, namely, tomatoes, pears and cucumbers were cooled in water and air flow and their centre temperature variations were measured. In the theoretical case, the effective convective heat transfer coefficients for the individual spherical and cylindrical products were determined using the centre temperature data in the present approach including Dincer's models. Therefore, the new Nusselt-Reynolds correlations were developed using the effective convective heat transfer coefficient values and a general diagram of Nu/Pr-1/3 against Reynolds number was drawn. This study indicates that the present effective Nu-Re correlations are capable of estimating the effective convective heat transfer coefficients of any spherical and cylindrical shaped products exposed to water and air cooling in practical applications in a simple and accurate manner.