Review of innovative approaches of thermo-mechanical refrigeration systems using low grade heat

Abstract

Cooling and refrigeration systems consume around 17% of the world-wide electricity. Enhancing the performance of these systems, using renewable energy resources and waste heat recovered from industrial processes, will lead to reduced fossil fuel consumption. Improvements of these systems using eco-friendly working fluids are of equal importance. Both options contribute to the minimization of the emissions of greenhouse gases and ozone depletion substances. In this paper, a detailed and comprehensive review of the innovative and improvement approaches of the thermo-mechanical refrigeration (TMR) systems is introduced and analyzed. The reviewed TMR systems include ejector-driven, organic Rankine cycle-driven, and the new novel isobaric heat-engine driven refrigeration systems. The features and limitations of each approach and system have been detailed and discussed. The improvement approaches found in literature were achieved by improving the performance of conventional systems via optimizing the operating conditions, selection of promising working fluids, introducing new integration configurations of two cycles or more, or via replacing the mechanical compression process with improved thermo-mechanical compression process. The review revealed that there is a lack in the experimental validation, especially for the innovative proposed systems. Also, simplicity and flexibility (in operating conditions, heat sources, and outputs) are major features of the TMR systems compared to the other thermal-driven cooling technologies. However, further improvements including higher coeffecient of performance (COP) and lower cost are still major challenges for TMR systems compared to the conventional vapor-compression refrigeration systems.