Profitability analysis for working fluids in regasification circuit based on closed Rankine cycle

BACKGROUND: The global transition to low-carbon energy requires the development of efficient technologies for utilizing the cold energy of liquefied gases. However, existing solutions are expensive and have low efficiency. Gaps in the improvement of working fluids and Rankine cycle parameters limit the profitability of such systems. This study is aimed at selecting the optimal working fluid and operating conditions ensuring the least payback period and the highest energy efficiency. AIM: To develop of a method for selecting the optimal working fluid and parameters of a closed Rankine cycle for regasification of cryogenic products, ensuring the highest energy efficiency and the least plant payback period. METHODS: 1) Thermodynamic analysis, i.e. simulation of the Rankine cycle using the equations of energy, entropy, and exergy to estimate efficiency and energy losses; 2) Exergetic analysis to determine irreversible losses in system components (heat exchangers, turbine, and pump) and assess their influence on the overall efficiency; 3) Economic modeling to calculate the cost of equipment and operating costs based on empirical dependencies, followed by optimization based on the least payback period; 4) Multi-criteria optimization (Pareto method) to search for trade-off solutions between the plant capacity and capital costs for various working fluids; 5) Comparative analysis to assess the effectiveness of alternative working fluids (methane, oxygen, and organic refrigerants) based on thermodynamic and economic indicators. RESULTS: The study allows to determine the optimal operating parameters of the system, including the choice of the working fluid, temperature conditions, and design features of heat exchangers, contributing to the development of more effective and profitable cryogenic power engineering solutions. CONCLUSION: Methane used as a working fluid in a closed Rankine cycle provides the best performance in terms of power, efficiency, and payback. Further improvement of the system requires optimization of heat exchangers to reduce exergy losses.