Review of enhancement for ocean thermal energy conversion system

Ocean thermal energy conversion (OTEC) is a renewable energy source that uses differences in ocean water temperature between warm surface and cold depth to generate electricity. It is an essential link in the carbon neutrality chain and one of the rising sectors of the ocean energy. This paper provides an overview of studies on closed thermodynamic cycles and the numerous difficulties that OTEC technology faces. A description of the thermodynamic cycles incorporating mixed or pure working fluids, as well as the implications of different working fluids on cycle efficiency were also studied. Changes in condensing and evaporating temperatures induced by variations in heat resources affect the efficiency of cycles with pure working fluids. Several strategies, such as intermediate extraction regeneration and heat recovery of ammonia-depleted solution can increase the thermal efficiency with mixed working fluids. In addition, the impact of the ejector on the cycle's performance is examined. Finally, the efficiency-improving strategies are described and summarized. Thermodynamic efficiency can increase using suitable working fluids and taking steps to maximize the rate of ocean thermal energy. To establish which approach is the most effective, different methods have been evaluated and compared under identical operating conditions.