Milk Fouling Simulation in a Triple Tube Heat Exchanger

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.