Performance Evaluation of On-farm Raw Milk Cooling System

This experiment was conducted with an aim to evaluate novel on-farm raw milk cooling system (OFMC). The system consisted of plate cooler, cooling cum storage tank and thermal storage tank. Conventional bulk milk cooling system was considered as control (CMC). The raw milk cooling systems were evaluated for overall heat transfer co-efficient, rate of cooling, coefficient of performance, total energy consumption and total cost of raw milk cooling. Raw milk cooling in OFMC was completed within 30 min whereas CMC took more than 2h to cool raw milk to 4°C. For OFMC, the U value of plate cooler when milk cooled to 4°C was 872.03 W/m2 °C. The average overall heat transfer coefficient of cooling cum storage tank for milk cooling in the evening and morning were 359.0 W/(m2 °C) and 350.2 W/(m2 °C) respectively. The average U value for thermal storage was 121.65 W/m2°C. The COP of the OFMC ranged from 3.97 to 2.36 during day time ice formation and 4.34 to 2.47 during night time ice formation. The average COP of the system was higher during night time compared to day time. When cost of electricity considered at ₹ 9.7 per kWh, cooling cost per litre of milk for OFMC and CMC were ₹ 0.2939 and ₹ 0.3589, respectively. The energy consumed in CMC was higher than the OFMC. Such on-farm raw milk cooling system can be a better option than conventional bulk milk coolers.