Estimation of time variable heat transfer coefficients in frozen foods during storage

Abstract

Many investigators have studied heat transfer coefficients in foods during freezing, but little work has been done on the estimation of surface heat transfer coefficients in frozen foods during storage. This paper investigates a method for the estimation of time variable surface heat transfer coefficients in frozen foods during storage. This method is unique in that it allows for the estimation of surface heat transfer coefficients as a function of time and in that the procedure incorporates temperature dependent thermal properties. The estimation method is based on the sequential-regularization solution which involves the minimization of a least squares function containing calculated and experimental temperatures. Certain parameters inherent in this method were first determined using simulated data. Experimental temperature measurements were then obtained using the Karlsruhe Test Substance (Gutschmidt, 1960), a methylcellulose material commonly used in food freezing studies. Estimations of the surface heat transfer coefficient from this data varied with changes in the surface and ambient conditions; the estimated values ranged from 6 to 12 W/m 2 °C.