Application of Solar Absorption Refrigeration in Milk Pasteurization

Abstract

Pasteurization coupled with refrigeration makes milk safe for human consumption and also extends the shelf-life of the milk. In a milk processing plant, hot water is used as heating medium and chilled water as cooling medium .In milk pasteurization heating and cooling process of milk was integrated by using plate heat exchangers known as regeneration section which saves 82.36% energy. Refrigeration plant for milk processing contributes approx. 30 % of total electricity load. This electricity load can be reduced by using vapor absorption refrigeration system (VARS) which requires heat input in the form of hot water. In the present study the VARS uses 1, 1, 1 tetrafluroethane (R134a) as refrigerant and n,n-dimethyl formamide (DMF) as absorbent. The COP of the system was obtained between 0.48 to 0.71 and refrigeration capacity varied from 0.69 kW to 2 kW. The absorption refrigeration system requires 1.4kW of hot water per kW of refrigeration capacity. Thus the integration of solar energy with absorption refrigeration plays important role in energy optimization and sustainable development in milk processing industry.