EFFECTIVE HEAT-TRANSFER COEFFICIENTS FOR INDIVIDUAL SPHERICAL PRODUCTS DURING HYDROCOOLING

A correlation was developed that may be used to estimate the heat-transfer coefficients for the individual spherically shaped products in the batches containing 5, 10, 15, and 20 kg of product exposed to cooling at temperatures of 0.5, 1, and 1.5 degrees, respectively. Two different food commodities (tomatoes and pears) were evaluated using four different batch weights for each individual product. Temperatures at the centers of the individual products were measured in order to obtain the temperature distributions. A regression analysis was applied to these temperature distributions in the exponential form using the least-squares method in order to obtain the cooling process parameters, namely the cooling coefficients and the lag factors. Also, the thermal properties (thermal conductivity and thermal diffusivity) of the products were estimated. By combining the cooling coefficient and the thermal properties in the present model, the heat-transfer coefficients for the individual products were determined easily and accurately.