Comparison of Different Evaporator Topologies for Industrial Heat Pumps

Abstract

Reducing the energy consumption associated with industrial process heating is one of the crucial steps toward building a green and climate-neutral Europe, as the thermal energy demand of industry accounts for a significant portion of the total primary energy consumption and carbon emissions of this sector. In this regard, waste heat utilization using high-temperature heat pump systems is one of the most promising solutions to increase industrial energy efficiency. To efficiently recover and convert the available waste heat, the performance of the individual heat pump components, in particular the heat exchangers, is key. This paper reports a comparison between two different evaporator concepts considered for high-temperature heat pump systems, namely the shell and tube and the falling film evaporator. Four key characteristics of the two evaporator concepts are analyzed and compared: the overall heat transfer coefficient, the induced pressure losses, the footprint, and the required refrigerant charge. The results indicate that the falling film evaporator features a higher overall heat transfer coefficient and enables approximately a 77% reduction of the required working fluid charge with respect to the shell and tube evaporator.