A critical review on waste heat recovery utilization with special focus on Organic Rankine Cycle applications

In the recent era of development, energy consumption increased many folds. While tapping this energy from various resources, almost half of this energy is dumped back into the environment causing adverse environmental imbalance. This can be mitigated by the recovery and utilization of waste heat which will also lead to the conservation of fossil fuel. In the present study, various waste heat recovery (WHR) technologies are explored and a state-of-the-art review is conducted with a particular focus on Organic Rankine Cycle (ORC). It is concluded that ORC technology is a reliable and promising solution. In the present study research challenges associated with the selection of ORC working fluid are evaluated and described. It is found that zeotropic mixtures could be good alternatives because of their temperature glide reducing the irreversibility of the system. The research is conducted on different configurations of ORC such as Regenerative cycle, CO2 transcritical power cycle (CTPC), and cascade ORC system. It is explored from the literature that the high thermal decomposition temperature of carbon dioxide reduces the irreversibility in CTPC systems. Multi-grade waste heat is efficiently recovered by the Cascade-Organic Rankine Cycle (C-ORC). Technical challenges in the application of Phase Change Material (PCM) into WHR and utilization of WHR in adsorption cooling and Hybrid vehicle is critically reviewed to identify the potential knowledge gap between the present status and futuristic research. The study also discussed the present Indian scenario of WHR utilization for ORC applications.