Advanced thermo-economic scheme and multi-objective optimization for exploiting the waste heat potentiality of marine natural gas engine

Abstract

Abstract Energy crisis and environmental pollution are great challenges to the sustainable development of human society. In response to increasingly stringent emissions regulations, scientists are actively seeking solutions, such as the exploitation of new energy. In recent years, natural gas has attracted wide attention because of its environmental advantages over the traditional diesel engine. In addition, the higher exhaust temperature of natural gas engine gives it a good potential for waste heat recovery, especially in cascade utilization system. To recover the available energy of natural gas engine at multiple temperatures, an integrated system consisting of supercritical carbon dioxide Brayton cycle, double effect absorption refrigeration system and Kalina cycle is established in this study. After verifying the model accuracy of three sub-cycles, we analyze and discuss the influence of major parameters on system performance in detail, as well as carrying out the dynamic response analysis of waste heat recovery system, After the completion of multi-objective optimization, the thermodynamic and economic analysis indicate that the output power increased by 15.33% and the payback period shortened by 25.6%. Therefore, it can conclude that the new scheme is a practicable approach to recover waste heat of natural gas engines.