DYNAMICS AND CONTROL OF SOLAR MILK PASTEURIZATION PROCESSES

Abstract

Milk pasteurization process consumes a large amount of energy, using solar energy for pasteurization process reduces the required conventional energy. The study is conducted to utilizethe solar energy as a thermal source for pasteurizing the milk. The system was powered bythe solar thermal andphotovoltaicand an auxiliary source was used when the solar energy is insufficient. The thermal system was comprised of solar parabolic dish, energy conversion subsystem, and heat exchanger.The solar dish wasequipped with dual axis sun tracking device. The study was represented control strategy of the system to maximize the utility of the solar energy, and to ensure that the milk has pasteurized efficiently. In addition, the work is concerned to analysis of thermodynamic behavior of the system. The system was able to pasteurize about 260 ml of milk at 72 ˚C in average time about 108 secondsdepended on the solar radiation. The average hourly productivity of solar pasteurized milk was about 8 liters. The results indicated that the tracking device was led to increase of the cumulative daily heat gain by approximately 59 %. The solar energy usage was about 20 % at radiation value less than 400 W/m2, while it was 100 % at radiation value larger than 800 W/m2.The overall thermal efficiency was about 41 %. The solar technique may be saving about 75 % of the costs of energy of conventional pasteurization.Analysis of the chemical tests of the pasteurized milk showed good results. Keywords: Solar Energy Applications, Milk Pasteurization, Solar Milk Pasteurization, Control of Solar Energy Systems.