Modelling the cooling phase of heat sterilization processes, using heat transfer coefficients

Publisher Website
Google Scholar
Abstract
Summary: A mathematical model based on finite differences was presented, which improved the accuracy of current modelling techniques during the cooling period for conduction heating foods undergoing thermal processing. The surface heat transfer coefficient between can and cooling fluid was incorporated into the finite difference equations, with a value of 600 W m−2 K−1 chosen from literature and confirmed by calculations from surface temperature measurements and a correlation of the form Nu = f(GrxPr)n.Experimental results were obtained for a cylinder of Sylgard 184 elastomer (length 62mm, diameter 57mm) and a polypropylene block (26x91x141 mm). At the end of cooling the heat transfer coefficient model predicted a centre temperature just 2.5°C above the measured value for polypropylene, and for Sylgard 184 this difference was 2.7°C.This model will improve both real‐time process control via the ‘derived‐value’ technique, and the use of controlled pressure cooling with less damage to containers. Optimization of quality factors will also be improved with increased knowledge of in‐container temperatures.