Abstract
In this study, a novel trigeneration system is proposed as an idea for future research based on the industrial waste heat recovery operated steam generator for process heat, and produces both power and refrigeration simultaneously with stack gases, using ammonia-water mixture as the working fluid. An extensive review of various energy and exergy based approach used in the analysis of different cogeneration and trigeneration cycles is reported. Energy and exergy efficiencies have been defined, and computational analysis is performed to investigate the effects of exhaust gas inlet temperature and gas composition on first law efficiency, electrical/thermal energy ratio and exergy efficiency of an industrial waste heat recovery based trigeneration system. The variation in specific heat with exhaust gas composition and temperature is accounted in the analysis for further discussion. The first law (energy) efficiency increases while electrical/thermal energy ratio and exergy efficiency decrease with increasing exhaust gas inlet temperature. Exergy efficiency significantly varies with gas composition and oxygen content of the exhaust gas. Approximating the exhaust gas as air and the air standard analysis leads to either underestimation or overestimation of proposed trigeneration cycle from the point of view of exergy analysis. The present analysis will provide a convenient and practical tool for engineers and researchers dealing with the energy efficiency improvements in a sustainable manner.