Multi-objective optimization and comprehensive performance analysis of a novel reverse absorption heat pump for blackwater waste heat recovery

To address the challenge of inefficient recovery of the substantial low/medium-grade waste heat in the coal gasification process, this study proposed the application of novel absorption heat pump technology in the black water flash heat recovery system. This system resolves the inability of conventional heat pumps to generate steam through an inverse heating process. A comprehensive performance assessment encompassing energy, exergy, exergoeconomic, environmental, and exergoenvironmental (5E) aspects was conducted for a novel reverse absorption heat pump system. Subsequently, a Pareto-based multi-objective optimization utilizing a genetic algorithm was implemented, with the dual objectives of minimizing variable operating costs and maximizing steam production. The influence of seven key operating parameters, including black water flow rate and condensation temperature, was systematically examined. This analysis reveals the synergistic effects resulting from parameter coupling under multi-parameter interactive effects. The thermodynamic results show that the optimized system achieves a total energy efficiency of 92.60%. Economically, the levelized cost of heat was reduced to 0.20 $/kWh, and the payback period was shortened to 4 years. From an environmental standpoint, the exergoenvironmental factor of the core component decreased by 20.2%. This study provides a new perspective for efficient industrial waste heat recovery under complex operating conditions.