Performance of a dairy heat exchanger declines as milk fouling deposits on the heating surface. It causes an increased resistance to heat flow thereby the milk outlet temperature decreases with increasing fouling thicknesses. Various models have been suggested for the prediction of fouling thickness and milk outlet temperature in a heat exchanger. The present paper describes an improved simulation model for the accurate estimation of fouling thickness and milk outlet temperature. Local fouling factor in terms of the Biot number is used in the work undertaken. Fouling thickness and milk outlet temperature are predicted as a function of time and over the entire length of the heat exchanger. Right from the beginning fouling occurred to a greater extent towards the outlet and with the progress of time the rate of increase of the fouling thickness decreased. The milk outlet temperature decreased with the time as the fouling increased. (c) 2006 Elsevier Ltd. All rights reserved.