Operating Strategies of an Industrial R717 Heat Pump Recovering Waste Heat of a Chiller

Process chains within the food industry, in particular dairies, often demand cooling and heating. While chillers serve the required cooling load, high-temperature heat pumps (HTHPs) can cover parts of the heating demand by lifting the waste heat of chillers to temperature levels suitable for process heat supply.
This study analyses an R717-HTHP, which was directly integrated into the refrigerant circuit of the existing R717 chiller at a dairy. A simulation model in Dymola is used to model the system consisting of the chiller, directly integrated HTHP, thermal energy storage (TES) and the cleaning-in-place (CIP) system as the supplied process. Validation with experimental data qualifies the model for further analysis of the system behaviour.
The simulation model is used to study the influence of the operating parameters (e.g. refrigerant subcooling, medium pressure level, heat sink temperatures and cooling capacity) on the efficiency of the system. Based on these findings, increasing the medium pressure is shown to increase the ability to cover peak loads of the CIP system.