Refrigerant Selection and Cycle Design for Industrial Heat Pump Applications exemplified for Distillation Processes

Mechanical compression heat pumps are indispensable to facilitate the transition from thermally driven processes to renewable energy by electrification, upgrading low-temperature waste heat to recycle it at a higher temperature level. However, the implementation of such heat pumps up to date encounters limitations, due to equipment limitations and a lack of tools for the design of process concepts for the application of high-temperature heat pumps. The optimal design of heat pumps relies heavily on the selection of an appropriate refrigerant, as the thermodynamic properties significantly affect the heat pump cycle design and performance. While existing methods are capable of identifying thermodynamically beneficial refrigerants, they do not directly account for practical constraints such as limitations on the compressor discharge temperature, compression ratio, and vacuum operation. The current study proposes a fast-screening approach for arbitrary heat pump applications, considering a large set of established refrigerants. The method automatically assesses the performance of the refrigerants for a specified set of heat sink and source, adjusting the heat pump design with an optional internal heat exchanger in case of necessary superheating prior to compression. The approach is illustrated for the evaluation of heat pump-assisted distillation processes.