A SIMPLE-MODEL FOR ESTIMATION OF THE FILM COEFFICIENTS DURING COOLING OF CERTAIN SPHERICAL FOODSTUFFS WITH WATER

In this study, a method was proposed and tested for the determination of the convective heat transfer coefficients during cooling of the spherical foodstuffs by means of a water flow in the pool. Experiments were performed in a cold water pool at temperatures of 0.8, 1 and 1.2-degrees-C, and at a flow velocity of 0.05 m/s. The product temperatures at the center, semi-radial distance and surface were measured and then the experimental convective heat transfer coefficients were obtained by using the proposed model which was the function of dimensionless temperature and the Biot and Fourier numbers. The semitheoretical convective heat transfer coefficients were also calculated by Vliet and Leppert's correlation. Furthermore, the experimental and semi-theoretical coefficients were plotted against time at different water temperatures for two products.