DESIGN AND TESTING OF A SMALL-SCALE INDIRECT TYPE ULTRA-HIGH TEMPERATURE (UHT) MILK STERILIZER

A small scab ultra high temperature (UHT) sterilizer suitable for rura l tropical cooperatives was designed and tested. An indirect tubular t ype UHT sterilizer is better suited to small scale operation and low i nvestment cost. A triple tube heat exchanger (TTHE) was designed for h eating milk from 95 to 145 degrees C in the annulus sf the triple tube using steam in the innermost and the outermost tubes. The holding sec tion was designed to provide 4.3 s residence time to reduce B. Stearot hermophilus by 8 log cycles. The cooling section was designed to cool milk from 145 to 95 degrees C by using water. An iterative procedure w as followed to develop software to handle design calculations. Heating holding, and cooling sections were found to be of 3, 0.6 and 3.1 m le ngth. The set up was tested with milk for determination of heat transf er coefficients.