Determination of Convective Heat Transfer Coefficient During Cooling of an Individual Strawberry Fruit Using Different Methods

Abstract

The convective heat transfer coefficient was determined for an individual strawberry fruit, considered as a sphere, using experimental data of the temperature inside the fruit during its cooling. The position of the thermocouple within the fruit was not determined during the experiment and, therefore, is unknown. Two methods were used in the calculations: analytical and numerical ones. In the analytical method, the summation was approximated for only one term. In the numerical solution, several optimizations processes were accomplished by using the inverse method, considering different positions for the temperature sensor. The real position of the thermocouple within the sphere equivalent to the fruit was determined through analyses of the chi-squares of the optimizations. In these optimization processes, the diffusion equation was solved through the finite volume method by using a fully implicit formulation. The results obtained by the two methods are very close. The obtained result for convective heat transfer coefficient by numerical simulation, given by hH = 12.2 W m-2 K-1, is coherent with the value found through analytical solution, and the difference between them is only 2.9%.
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