Evaluation of a novel environmentally friendly cascade combined cooling and power system integrated with LNG regasification and desalination unit

In this study, a comprehensive thermo-economic performance analysis is conducted on a newly developed cascade combined cooling and power system that utilizes the cold energy of liquefied natural gas, integrated with seawater desalination. The proposed system generates electricity through a gas turbine cycle, an organic Rankine cycle equipped with a recuperator, and a power generation unit using LNG as the working fluid. Additionally, gas expansion within the turbine, combined with the integration of an evaporator, yields a cooling output of 943.1 kW. The system demonstrates an energy efficiency of 72.97 %, an exergy efficiency of 48.79 %, total exergy destruction of 3694 kW, a total cost rate of $4569.04/h, and a unit exergy cost of $201.4/GJ. For single-generation and combined cooling and power modes, the energy efficiencies are evaluated at 48.36 % and 55.84 %, respectively. Second-law analysis reveals that the gas turbine and fuel burner are responsible for the highest exergy destruction, contributing 74 % and 54.3 % of the total, respectively. To mitigate system irreversibilities, three key parameters were examined: combustion air flow rate, air temperature before the gas turbine, and the working fluid pressure in the ORC. The analysis indicates that increasing the combustion air temperature to 1000 °C enhances energy efficiency to 76.6 %, exergy efficiency to 53 %, and gas turbine power output to 7581 kW. Moreover, increasing the combustion air flow rate to 12 kg/s results in an improvement in energy efficiency to 77 %, an increase in exergy efficiency to 52 %, and a reduction in the unit exergy cost to $189.13/GJ.