Evaluation of Fourier - Reynolds Correlation for Estimation of Precooling Parameters of Pomegranate

Temperature management is an important subject in maintaining the quality of horticultural products after harvest. One of the methods in suitable control of temperature, is precooling, that is conducted before storing of the product which increases shelf life and storage time the fruits. On the other hand, estimation of cooling parameters (half and seven-eighths cooling times) need precise sensors and is time consuming in precooling operations. In this research, airflow velocities as an effective factor in cooling at three levels of 0.5, 1, and 1.3 m s-1 was considered. Parameters including lag factor, cooling coefficiency and half and seven-eighths cooling times were calculated based on recorded data of the temperature sensors. Finally, using the dimensionless numbers, Fourier and Reynolds, the estimation of regression models obtained for cooling times and compared with experimental data. With increasing airflow velocity, cooling times decreased and convective heat transfer coefficient was enhanced up to 58.46%. The overall results showed that for sphere shaped products like pomegranate, using Fo-Re correlation, cooling times are estimated with suitable precision (maximum error for half and seven-eighths cooling times 11.46 and 10.83, respectively) and without using complex equations.