A Comprehensive Study of a Low-Grade Heat-Driven Cooling and Power System Based on Heat Current Method

Combined cooling and power (CCP) system driven by low-grade heat is promising for improving energy efficiency. This work proposes a CCP system that integrates a regenerative organic Rankine cycle (RORC) and an absorption chiller on both driving and cooling fluid sides. The system is modeled by using the heat current method to fully consider nonlinear heat transfer and heat-work conversion constraints and resolve its behavior accurately. The off-design system simulation is performed next, showing that the fluid inlet temperatures and flow rates of cooling water as well as RORC working fluid strongly affect system performance. The off-design operation even becomes infeasible when parameters deviate from nominal values largely due to limited heat transfer capability of components, highlighting the importance of considering heat transfer constraints via heat current method. Design optimization aiming to minimize the total thermal conductance is also conducted. RORC efficiency increases by 7.9% and decreases by 12.4% after optimization, with the hot fluid inlet temperature increase from 373.15 to 403.15 K and mass flow rate ranges from 10 to 30 kg/s, emphasizing the necessity of balancing system cost and performance.