Integrated CO2 refrigeration and heat pump system for a dairy plant: Energy analysis and potential for cold thermal energy storage

Abstract

Dairy processing is considered very energy-intensive due to significant thermal demands for both cooling and heating at different temperature levels. Conventional dairy plants have separate systems for supplying the various thermal loads, such as refrigeration systems for the cold side of the process and boilers for the heating requirements. In a previous study, a fully integrated CO2 heat pump/refrigeration system installed in a dairy plant in central Norway was presented and theoretically evaluated. Recommendations for increasing the energy efficiency at the plant were suggested. This paper continues that work by analysing data collected by the recently installed energy data acquisition system at the dairy. The thermal energy demands on the hot and cold sides of the dairy process were monitored to increase the knowledge of the overall thermal requirements and distribution of load in various periods. Based on the analysed data from the plant, a concept for installing a latent cold thermal energy storage (CTES) into the refrigeration system to reduce the peak loads from process cooling is described. The results of this study will be used as a basis for the decision-making process concerning the installation of a CTES system at the dairy.