Sensitivity of freezing time estimation methods to heat transfer coefficient error

Numerous semi-analytical/empirical methods for predicting food freezing times have been proposed, all of which require knowledge of the surface heat transfer coefficient. The empirical nature of the surface heat transfer coefficient can introduce significant error in the freezing time calculation. Therefore, a sensitivity analysis was performed on various freezing time estimation methods to determine the impact of errors in the heat transfer coefficient upon the calculated freezing times. A condition number was defined which allows for the quantification of the error in the calculated freezing time due to error in the heat transfer coefficient. Condition numbers were determined for 12 freezing time estimation methods. Seven freezing time estimation methods applicable to regularly shaped food items were found to attenuate errors in the heat transfer coefficient, thus resulting in smaller errors in calculated freezing time. Furthermore, for Biot number greater than 1, four equivalent heat transfer dimensionality methods for irregularly shaped food items were also found to attenuate errors in the heat transfer coefficient.