Investigations of Energy Savings in Bulk Milk Cooler by Waste Heat Recovery

Abstract

In milk production practices harvested milk is chilled from its initial temperature of 35 °C to 4 °C to arrest the bacterial growth and maintain the quality of milk. Milk chilling equipment used depends on the quantity of milk required to be handled. In small and medium dairy farms and cooperative societies milk is chilled using bulk milk coolers (BMC). Milk chilling process by using BMC is energy intensive process. Increased energy cost concern encouraged an investigation of energy saving by waste heat recovery from bulk milk cooler as one energy conservation alternative. Hot water is used in dairy industry to clean all dairy equipment which is heated separately by using oil and gas as a fuel or electrical energy. This amount of energy required for water heating is saved by recovering and utilizing heat dissipated to the surrounding from BMC. Waste heat is recovered by retrofitting the shell and coil heat exchanger in the BMC system. Experimental investigations are done for water instead of milk which has nearly similar properties. In this paper energy saving potential in 1000 liter capacity bulk milk cooler is investigated for three different water quantities at varying mass flow rate of water through heat recovery heat exchanger (HRHX). It is revealed that there is considerable energy saving potential in bulk milk cooling systems. Significant improvements have been achieved and coefficient of performance (COP) of the system is increased from 3 to 4.8.