VC-21A-C063 - Quantitative Review of the State-of-the-Art of Conventional and Alternative HVAC&R Technologies

The Heating, Ventilation, Air Conditioning, and Refrigeration (HVAC&R) industry has heavily relied on vapor compression cycles since the early part of the 20th century. However, due to environmental concerns and advances in both material and thermal sciences, non-vapor compression technologies have gained attention as potential alternatives to conventional HVAC&R systems. Non-vapor compression technologies also termed not-in-kind technologies, include solid-state refrigeration technologies, thermally-driven cycles, gaseous cycles, chemical heat pumping, membrane heat pumping technologies, and desiccant systems among others. In 2014, the U.S. Department of Energy’s Building Technology Office (BTO) released a report that compared several non-vapor compression technologies and quantified the potential energy savings. Since then, other researchers have reviewed not-in-kind technologies and compared them with vapor compression systems. However, no direct comparison with the current state-of-the-art equipment and forthcoming standards is available in the literature. To this end, this paper addresses three major aspects: (i) assessing the current state-of-the-art to identify key advancements in conventional and novel HVAC&R technologies; (ii) defining suitable figures-of-merit to compare the different technologies from a thermodynamic standpoint as well as technology readiness; (iii) creating a roadmap for the development of novel HVAC&R technologies.