Energy, Exergy, Economic, Environment Analysis and Multiobjective Optimization of the Organic Rankine Cycle...

The rapid growth of data centers has led to substantial energy consumption and associated environmental concerns, highlighting the need for efficient waste heat recovery and sustainable energy supply. In this study, an integrated system driven by geothermal energy is proposed for the power supply and waste heat recovery of data centers. The system integrates an organic Rankine cycle with an absorption heat transformer to achieve cascade utilization of thermal energy and enhanced recovery of low-grade waste heat. A comprehensive energy, exergy, economic, environment analysis is conducted to evaluate the system performance. Furthermore, a multiobjective optimization framework based on the nondominated sorting genetic algorithm II is developed to simultaneously maximize net power output and energy recovery efficiency while minimizing annual cost and lifecycle greenhouse gas (GHG) emissions. Exergy analysis and comprehensive performance assessment are conducted to identify the irreversibility and quantitatively assess the advantage of the proposed system in economic and environmental aspects. The results indicate that the proposed system can achieve a net power output of 1690.44 kW and an energy recovery efficiency of 56.90% under optimal conditions, with an annual cost of 886.67 kUSD and lifecycle GHG emissions of 1083.31 ton CO_2‑eq. Compared with conventional systems without waste heat recovery, the proposed configuration reduces the annual cost and GHG emissions by 11.11% and 37.69%, respectively, while achieving significant improvements over grid-powered scenarios. Exergy analysis reveals that, to balance thermodynamic, economic, and environmental performance, the system sacrifices part of its thermodynamic efficiency, which leads to increased thermal mismatches during heat transfer, and the primary irreversibility is contributed by the ORC evaporator and condenser, accounting for over 65% of total exergy destruction.