DEVELOPMENT OF NEW EFFECTIVE NUSSELT-REYNOLDS CORRELATIONS FOR AIR-COOLING OF SPHERICAL AND CYLINDRICAL PRODUCTS

An effective study for determining the effective heat transfer coefficients of spherical and cylindrical bodies cooled in air-flow is provided in this paper. In this respect, both experimental and theoretical investigations were conducted. The center temperatures of spherical and cylindrical products, namely figs, tomatoes, pears, cucumbers and grapes, during air-cooling at a temperature of 4-degrees-C and at different flow velocities were measured. In the theoretical case, the effective heat transfer coefficients for spherical and cylindrical products cooled were determined by using the Dincer's models presented here. Using the obtained effective heat transfer coefficients together with some heat transfer coefficients data given in the literature, the diagrams of Nu/Pr1,3 against Re were observed. Then, the following Nu-Re correlations were found as (Nu/Pr1/3) = 1.56Re0.426 and (Nu/Pr1/3) = 0.291Re0.592 for all the spherical and cylindrical products.