Experimental Investigation of Low-Grade Heat Recovery in a Direct Contact Heat Exchanger: Operational Variable Impact

Experimental Investigation of Low-Grade Heat Recovery in a Direct Contact Heat Exchanger: Operational Variable Impact Kurt Adams, Ph.D. Candidate A. Leon Linton Department of Mechanical, Robotics, and Industrial Engineering Lawrence Technological University Abstract This presentation describes an experimental study of low-grade heat recovery using a three-phase direct contact heat exchanger with R1234yf and water as the working and heat-source fluids in an organic Rankine cycle. Background information on conventional closed-loop heat exchangers and direct-contact heat exchangers is presented, highlighting their operating principles, advantages, limitations, and relevance to low-grade waste heat recovery applications. The experimental test apparatus is described, along with the operational commissioning results obtained. Three experiments and their objectives are discussed, including the effects of refrigerant mass flow rate, water flow rate, water inlet temperature, system pressure, refrigerant charge, and water working height on exergy, heat transfer, and the volumetric heat transfer coefficient. Results are presented in the form of scatter plots with corresponding correlations. Conclusions are provided, including apparatus and experimental limitations, suggested improvements to both, as well as opportunities for future research. This presentation was distilled from the slide deck used in the defense of my dissertation on September 30, 2026. Date: November 6, 2026 Time: 12:30 - 1:30 PM Venue: E159, Engineering Building