Thermo-electrochemical redox flow cycle for continuous conversion of low-grade waste heat to power
Jorrit Bleeker (Student TU Delft)
Stijn Reichert (Student TU Delft)
Joost Veerman (REDstack B.V.)
D.A. Vermaas (TU Delft - ChemE/Transport Phenomena)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Here we assess the route to convert low grade waste heat (< 100 °C) into electricity by leveraging the temperature dependency of redox potentials, similar to the Seebeck effect in semiconductor physics. We use fluid-based redox-active species, which can be easily heated and cooled using heat exchangers. By using a first principles approach, we designed a redox flow battery system with Fe(CN)63−/Fe(CN)64− and I−/I3− chemistry. We evaluate the continuous operation with one flow cell at high temperature and one at low temperature. We show that the most sensitive parameter, the temperature coefficient of the redox reaction, can be controlled via the redox chemistry, the reaction quotient and solvent additives, and we present the highest temperature coefficient for this RFB chemistry. A power density of 0.6 W/m2 and stable operation for 2 h are achieved experimentally. We predict high (close to Carnot) heat-to-power efficiencies if challenges in the heat recuperation and Ohmic resistance are overcome, and the temperature coefficient is further increased.
help_outline