Simulation of continuous thermally regenerative electrochemical flow cycle and coupled with photovoltaic/thermal system.

Thermally regenerative electrochemical cycle (TREC) is an efficient, clean and feasible low-temperature thermoelectric conversion technology. Coupling it with flow battery (FB) can not only achieve continuous operation, but also can be used to realize the heat energy recovery of the photovoltaic/thermal (PV/T) system. In this paper, a continuous TREC-FB system including two charging-free cells is proposed for outputting power at both high and low temperatures. An electrochemical-thermodynamic coupling algebraic model is established to explore the effects of electrolyte flow rate, temperature difference and design parameters of heat exchanger on the power density (P TREC) and thermoelectric efficiency (η ele,TREC) of the TREC-FB. Experimental study on TREC-FB is carried out for model validation. The results show that P TREC is determined by the temperature difference and the electrolyte flow rate, which contribute to enhanced voltage and mass transfer, respectively. For specific heat source scenarios, the η ele,TREC is mainly affected by the flow rate, followed by the heat transfer area A H , and finally is the flow channel height and the thermal conductivity of the heat exchanger. Moreover, for the continuous TREC-FB-PV/T coupled system, the energy conversion efficiency reaches an average of 11 % within one day by optimizing the designed temperature difference. [Display omitted] • Flow battery is combined with charging-free TREC for operating continuously. • An algebraic model of continuously operated TREC-FB is established. • Effects of operating parameters on system performance are analyzed. • Experimental study of continuous TREC-FB is conducted for model validation. • The continuous TREC-FB is coupled with PV/T system to realize waste heat recovery. [ABSTRACT FROM AUTHOR]