DEPOSIT FORMATION ON HEAT-EXCHANGER SURFACES DURING HEATING OF MILK UNDER INFLUENCE OF ULTRASONICS

The existing milk heating model apparatus was modified by inserting an ultrasonic oscillator (35 kHz, 80 W) with the dimensions of a circula r heat exchange element in the place of one element. The ultrasonic in fluence was investigated under different operating conditions (system pressure in the channel 25-125 kPa, flow velocity 0,2-0,5 m/s). Only a t the heated surface immediately facing the oscillator (distance 2 mm) a remarkable reduction - but no total exclusion - of deposit formatio n could be observed. None of the other heating elements was exhibiting any deposit reduction effect by the ultrasonic sound waves. The effec tive radius of the ultrasonic field has to be estimated to 3-5 mm. Obi ously, the application of ultrasonics is not an appropriate measure fo r avoiding the fouling of milk heat exchangers.