Conventional combined heating and power (CHP) systems often suffer from suboptimal thermal integration and limited exergy utilization, resulting in low overall energy efficiency and significant carbon emissions. To address these challenges, this study proposes a novel high-efficiency CHP system based on the synergistic integration of a solid oxide fuel cell (SOFC) and a lithium bromide (LiBr) absorption heat pump. The architecture is specifically designed to maximize cascaded energy recovery and enhance comprehensive thermodynamic and economic performance.

A comprehensive steady-state model encompassing thermodynamic and economic analysis was developed to evaluate the system behavior. In the proposed configuration, unreacted fuel in the SOFC anode exhaust is combusted using oxy-fuel technology, yielding a CO₂-concentrated flue gas suitable for carbon capture while simultaneously upgrading waste heat quality. The high-temperature flue gas is then recovered through an advanced cascaded heat exchanger network, sequentially enabling cathode air preheating, endothermic methane reforming, and high-pressure steam generation. This steam serves as the thermal driving source for the LiBr absorption heat pump to meet heating demands. A detailed parametric sensitivity analysis was conducted to investigate the effects of the steam-to-carbon ratio, SOFC operating temperature, and fuel utilization factor on key performance indicators.

Simulation results show that increasing the steam-to-carbon ratio monotonically reduces both SOFC electrical efficiency and overall thermal energy utilization efficiency, whereas the coefficient of performance (COP) of the absorption heat pump remains stable at approximately 1.72. Higher SOFC operating temperatures significantly improve electrochemical kinetics and flue gas quality, thereby enhancing both electrical and thermal performance. A clear trade-off is observed with fuel utilization: higher fuel utilization factor increases electrical output but diminishes the availability of high-grade heat for downstream recovery. Under optimized conditions (with the steam-to-carbon ratio of 2, temperature of 1 000 ℃, and fuel utilization ratio of 0.85), the system achieves an electrical efficiency of 52%, an exergy efficiency of 56.6%, and an overall thermal energy utilization efficiency of 100.54% (defined on the basis of the fuel’s lower heating value, including all recovered thermal energy). Compared to a conventional natural gas-fired CHP benchmark, the proposed system improves the thermal utilization efficiency by 20%, and increases the exergy efficiency by 2.6%. Economic evaluation yields a levelized cost of exergy of 0.102 6 dollars/(kW·h) and a dynamic payback period of 8 years under current industrial energy pricing.

This coupled system significantly improves the energy utilization efficiency and comprehensive performance through the optimization of the energy cascade utilization mode. It demonstrates substantial economic feasibility and potential for engineering applications. The identified influence mechanisms of key parameters provide a theoretical foundation for the optimal design and operational control of such systems.