Design and performance assessment of a flat-plate solar milk pasteurizer forarid pastoral areas

Abstract

A solar milk pasteurizer consisting of flat-plate water-heating collector and a 1.5-mm thick stainless steel cylindrical milk vat was designed and tested in an arid pastoral area of northern Kenya.The milk vat had a capacity of 80 L and a 50-mm widehotwaterjacketinsulatedwith38-mmthickfiberglass.Hotwaterproducedby the collector was used for pasteurizing milk. The optimum quantity of milk that could be pasteurized by this device under the study conditions was 40 L, and the average temperature difference between hot water and milk being pasteurized was 8.1 1.4C.Totalbacterialcountsinpasteurizedmilkwerelessthan10 cfu/mLwhile coliformcountswerenegative.Thislow-costsolarmilkpasteurizerisappropriatefor arid pastoral areas without grid electricity, where milk marketing is an important incomesource,andwheremostofthemilkisboiledusingfirewood.