A new method of predicting the time-variability of product heat load during food cooling — Part 1: Theoretical considerations

Abstract A new method has been developed to predict the way in which the heat load placed upon a refrigeration system by cooling food products varies with time. This information is important to refrigeration system designers and plant operators as capital and running costs may depend strongly upon the heat load sustained by the system. The new method utilises ordinary differential equation models of both chilling and phase change processes and requires only one parameter in addition to those required by existing freezing and chilling time prediction methods. The new method has been tested against finite difference (FD) calculations under a wide range of conditions for those product shapes to which FD methods may be applied. It was found to predict the product heat load to within 10% of the FD estimate for all test cases, except at the very start and at the end of the cooling process. The method requires much fewer computational resources than FD, and is capable of extension to shapes not easily handled by FD methods.