Milk Fouling Simulation in a Triple Tube Heat Exchanger

Abstract

Milk fouling in heat exchanger causing an increased resistance to heat transfer and reduced performance is a
common phenomenon during milk processing at Ultra-High-Temperature (UHT). A mathematical model was
formulated for triple tube heat exchanger using hydrodynamics and heat balance concept. The model was
simulated using a numerical technique based on the method of characteristics. Modified Euler’s technique was
used to solve differential equations using a computer programme. The model predicted with time both the
fouling behaviour and bulk milk temperature along the length of the heat exchanger. At an early period of
operation, uniform fouling deposit occurred throughout the length of the heat exchanger due to constant heat
exchanger wall temperature. The equilibrium value of fouling deposit was found to be 0.84 mm for the inside
tube and 0.61 mm for the middle tube. The fouling thickness was stabilized after about 50 min. The bulk milk
temperature at the end of simulation was found to be 148 ºC. The results can be used to develop a control
system to get target product temperature and optimal operating strategies.