Reduction of Energy Consumed by CO₂ Heat Pump for Raw Milk Cooling System

Abstract

A pre-cooling system for raw milk was developed using a heat pump and an ice builder that employs a natural refrigerant, i.e., CO₂; in addition, tests were conducted to evaluate the energy balance, thermal effi ciency, and other performance parameters of the system. The developed system recovers the waste heat, generated by the formation of ice in the ice builder, in the form of hot water (around 85°C). The hot water can be utilized to wash bulk cooler tanks and milk pipelines. The system was installed by two farmers in Tochigi prefecture. It had a heat exchanger effectiveness of approximately 45-79 %, and its deployment resulted in an annual reduction in energy consumption, running cost, and CO₂ exhaust tonnage of approximately 34-49 %, 19-39 % (90 000-140 000 Yen), and 21-40 %, respectively.