Bioenergetics: Open Access

Abstract

Key Principles of the REHOS Cycle

Johan Enslin

The REHOS (acronym for "Regenerative Heat of Solution") cycle consist basically of an Absorption Heat Transformer (AHT)-Hybrid heat pump, coupled fully regeneratively to an ORC to produce power. Three key principles govern the high efficiency.
The 3 key principles of the extremely high efficiency of the REHOS cycle are explained as: 1. The utilization of an absorption heat transformer type of heat pump as primary sub-cycle to guarantee a very large thermal energy utilization with exceptionally small electrical component for heat pumping. 2. Maximizing the isobaric temperature gliding in the zeotropic medium used in the heat exchangers of the heat pump, allowing it a calculated COP=1.0 with a very high % of the energy required for heat pumping coming from thermal input, with the electrical component at least 2 orders of magnitude smaller that the heat flow. 3. Combining the thermally powered heat pump and power generating ORC fully regeneratively, allowing all ORC-reject heat to be used to offset the heat requirement for the heat pump from an external heat source.
This paper also show the recent developments in thermally powered heat pumps (AHT's) achieving COP's gradually increasing from the turn of the century to 2018 with values like 0.5 optimized to 0.8 during 2014-17 with major increases with the development of high temperature Compressor/Absorption Heat Transformers (CAHT) by authors like Nordtvedt, Borgas and Jensen.