Multi-objective optimization for a combined heat and power unit with steam ejector at varied boundary: Energy, Economic and Environment (3E) analysis

Combined heat and power (CHP) represents a promising technology for achieving carbon neutrality. To enhance the energy, economic and environment (3E) performance of the ejectors integrated CHP unit, a data-corrected mechanism model was firstly developed. Subsequently, the limitations of different heating modes are analyzed at full production and under production. The maximum heat load of the condenser and availability of exhaust flow are primary concerns for exhaust heating. Extraction flow presents a high-grade heat source, yet it has an adverse effect on the system power output and results in a notable increase in fuel consumption. With a novel marginal heating efficiency, economic, efficiency and environment analysis was conducted, then a global sensitivity index analysis was performed in order to reveal the contribution of each parameter. The profitability of high back pressure heating, steam ejector and extraction heating is increasingly strong, but their impact on efficiency and environment must be considered. Finally, multi-objective optimization is conducted, and the correlations of each target are examined. Selected from the Pareto front, the marginal heating efficiency is 2.52, heating profit is 11424.9 $/h and the emission is 448.1 tCO2/h at full production conditions.