Numerical Analysis and Optimization of a Continuous‐Flow pH ‐ TRC for Steady‐State Low‐Grade Waste Heat Recovery

The recovery of low‐grade waste heat remains a critical challenge in global energy management, with efficient energy conversion technologies still in their infancy. pH‐sensitive thermally regenerative cells (pH‐TRCs) offer a promising solution by harnessing temperature‐induced pH gradients within carbonate electrolytes to drive electrochemical power generation. However, existing research has mainly focused on short‐term, batch‐mode characterizations, leaving the electrochemical dynamics under practical continuous‐flow conditions unclear. In this study, a two‐dimensional transient multiphysics model is developed to couple fluid dynamics, multicomponent ion transport, carbonate–bicarbonate buffer chemistry, and electrode kinetics for simulating the discharge performance of a continuous‐flow pH‐TRC. The model is validated against experimental data, achieving average relative deviations of 3.36% for voltage and 4.87% for power density. Simulation results reveal a transition from initial polarization to a stable steady state, where the cell delivers a current density of 18.8 A m ⁻² and a power density of 1.61 W m ⁻² . Parametric analysis indicates that elevating the operating temperature from 283 to 373 K enhances ion transport and reaction kinetics, boosting power density from 0.72 to 3.96 W m ⁻² . These findings provide essential theoretical insights and design criteria for advancing continuous‐flow pH‐TRCs toward scalable low‐grade heat recovery applications.