Multi-objective optimization of heat exchange network and thermodynamic cycles integrated system for cooling and power cogeneration

Thermodynamic cycles and heat exchange of process streams are effective waste heat recovery technologies, and their cooperation will make the use of energy more diversely and efficiently. To this end, a novel integrated system including compression-absorption cascade refrigeration system (CACRS), organic Rankine cycle (ORC) and heat exchanger network (HEN) is presented for cooling and power cogeneration and simultaneously performing the heat exchange of process streams. To achieve the optimal design of the integrated system, a thermoeconomic multi-objective optimization model is developed for balancing the economic and thermodynamic objectives, along with optimizing the operating conditions and configuration structure simultaneously. Two cases in different application scenarios are studied. Compared with the literature, the economic cost and exergy destroy are reduced by 1.6% and 31.5%, respectively, demonstrating the superiority of the proposed method in improving energy efficiency and reducing energy losses. Furthermore, the conflicting relationship between economic and thermodynamic objectives is verified and the trade-off solution with both favorable economic and thermodynamic performances is determined for both cases. Compared with the optimal solutions with solo objective of economy and exergy, the exergy destroy and economic cost of the trade-off solution for case 1 are decreased by 315 kW and 50,063$/y, and for case 2 the decrease are 750 kW and 112,678 $/y, respectively.

Automated summary

Thermodynamic cycles and heat exchange technologies play important roles in waste heat recovery, and their cooperation can improve energy efficiency. By developing an integrated system and a multi-objective optimization model, it is possible to achieve a balance between economic and thermodynamic objectives, resulting in favorable economic and thermodynamic performances.