Energy-exergy analysis and co-optimization of compressed cold air-cooling system for dry cutting machine tools

Compressed cold air-cooling system (CCAS) has been widely employed in dry cutting machine tools to maintain the thermal stability of the cutting space. However, CCAS is an energy-intensive and inefficient thermodynamic system with multi-energy and multi-exergy flows, which poses serious burdens for green manufacturing. To tackle the gap, this research carries out the energy-exergy characteristics analysis and the multi-objective optimization between energy consumption and exergy efficiency for CCAS. Firstly, the energy usage and exergy destruction characteristics for CCAS are analyzed according to the thermodynamic knowledge. Then, the multi-parameter-driven energy consumption and exergy efficiency models are developed, in which the relationships between the thermodynamic parameters and the objective functions are revealed. To obtain a compromise between the high energy use and low thermal energy efficiency, an energy-exergy co-optimization is constructed, and the NSGA-II algorithm combined with the Euclidean technique and TOPSIS decision-making method is adopted to derive the optimal solutions. Finally, a case study is conducted to validate the proposed models. The results show that the relative errors of the proposed energy and exergy models are 1.32% and 1.88%, respectively. The energy consumption is reduced by 10.7%, and the exergy efficiency is improved by 8.9% after optimization. The air compressor consumed the most energy and had the highest exergy destruction. The presented research lays a foundation for exploring the energy-saving potentials and improving the exergy efficiency of CCAS, and provides a theoretical foundation for achieving sustainable manufacturing.