Reverse electrodialysis heat engine with helium-gap diffusion distillation: Energy efficiency analysis

Abstract

The depletion of energy resources poses a significant threat to the development of human society. Specifically, a considerable amount of low-grade heat (LGH), typically below 100 °C, is currently being wasted. However, efficient utilization of this LGH can relieve energy shortages and reduce carbon dioxide emissions. To address this challenge, reverse electrodialysis heat engine (REDHE) which can efficiently convert LGH into electricity has emerged as a promising technology in recent years. Extensive efforts have been dedicated to exploring more suitable thermal distillation technologies for enhancing the performance of REDHE. This paper introduces a novel REDHE that incorporates helium-gap diffusion distillation (HGDD) as the thermal separation (TS) unit. The HGDD device is highly compact and efficient, operating at a normal atmospheric pressure, which aligns with the operational conditions of the reverse electrodialysis (RED) unit. A validated mathematical model is employed to analyze the impacts of various operating and structural parameters on the REDHE performance. The results indicate that maintaining a moderate molality of the cold stream, elevating the inlet temperatures of hot and cold streams, lengthening hot- and cold-stream channels, and minimizing the thickness of helium gaps contribute to improving the REDHE performance. Especially, a maximum energy conversion efficiency of 2.96% is achieved by the REDHE when decreasing the thickness of helium gaps to 3 mm and increasing the length of stream channels to 5 m.

Keywords

helium-gap diffusion distillation (HGDD) / reverse electrodialysis (RED) / heat engine / low-grade heat (LGH)

References

[1] Forman C, Muritala I K, Pardemann R. . Estimating the global waste heat potential. Renewable & Sustainable Energy Reviews, 2016, 57: 1568–1579

[2] Lin Y, Chong C H, Ma L. . Quantification of waste heat potential in China: A top-down societal waste heat accounting model. energy, 2022, 261: 125194

[3] Kang S, Li J, Wang Z. . Salinity gradient energy capture for power production by reverse electrodialysis experiment in thermal desalination plants. Journal of Power Sources, 2022, 519: 230806

[4] Wu X, Zhang Y, Zhu X. . Experimental performance of a low-grade heat driven hydrogen production system by coupling the reverse electrodialysis and air gap diffusion distillation methods. Energy Conversion and Management, 2024, 301: 117994

[5] Luo X, Cao X, Mo Y. . Power generation by coupling reverse electrodialysis and ammonium bicarbonate: Implication for recovery of waste heat. Electrochemistry Communications, 2012, 19: 25–28

[6] Giacalone F, Vassallo F, Scargiali F. . The first operating thermolytic reverse electrodialysis heat engine. Journal of Membrane Science, 2020, 595: 117522

[7] Long R, Li B, Liu Z. . Hybrid membrane distillation-reverse electrodialysis electricity generation system to harvest low-grade thermal energy. Journal of Membrane Science, 2017, 525: 107–115

[8] Micari M, Cipollina A, Giacalone F. . Towards the first proof of the concept of a reverse electrodialysis−membrane distillation heat engine. Desalination, 2019, 453: 77–88

[9] Tamburini A, Tedesco M, Cipollina A. . Reverse electrodialysis heat engine for sustainable power production. Applied Energy, 2017, 206: 1334–1353

[10] Hu J, Xu S, Wu X. . Theoretical simulation and evaluation for the performance of the hybrid multi-effect distillation—Reverse electrodialysis power generation system. Desalination, 2018, 443: 172–183

[11] Palenzuela P, Micari M, Ortega-Delgado B. . Performance analysis of a RED-MED salinity gradient heat engine. Energies, 2018, 11(12): 3385

[12] Ortega-Delgado B, Giacalone F, Catrini P. . Reverse electrodialysis heat engine with multi-effect distillation: Exergy analysis and perspectives. Energy Conversion and Management, 2019, 194: 140–159

[13] Ortega-Delgado B, Giacalone F, Cipollina A. . Boosting the performance of a reverse electrodialysis—Multi-effect distillation heat engine by novel solutions and operating conditions. Applied Energy, 2019, 253: 113489

[14] Olkis C, Santori G, Brandani S. An adsorption reverse electrodialysis system for the generation of electricity from low-grade heat. Applied Energy, 2018, 231: 222–234

[15] Olkis C, Brandani S, Santori G. Adsorption reverse electrodialysis driven by power plant waste heat to generate electricity and provide cooling. International Journal of Energy Research, 2021, 45(2): 1971–1987

[16] Liu Z, Lu D, Bai Y. . Energy and exergy analysis of heat to salinity gradient power conversion in reverse electrodialysis heat engine. Energy Conversion and Management, 2022, 252: 115068

[17] Liu Z, Lu D, Guo H. . Experimental study and prospect analysis of LiBr-H₂O reverse electrodialysis heat engine. Applied Energy, 2023, 350: 121791

[18] Hu J, Sun Y, Zhang J. . Experimental performance comparison of helium-gap diffusion distillation and air-gap diffusion distillation. Energy Conversion and Management, 2022, 273: 116427

[19] Hu J, Xu S, Wu X. . Exergy analysis for the multi-effect distillation—Reverse electrodialysis heat engine. Desalination, 2019, 467: 158–169

[20] Abu-Zeid M A E R, Zhang L, Jin W Y. . Improving the performance of the air gap membrane distillation process by using a supplementary vacuum pump. Desalination, 2016, 384: 31–42

[21] Lawal D, Abdul Azeem M, Khalifa A. . Performance improvement of an air gap membrane distillation process with rotating fan. Applied Thermal Engineering, 2022, 204: 117964

[22] Andrés-Mañas J A, Ruiz-Aguirre A, Acién F G. . Performance increase of membrane distillation pilot scale modules operating in vacuum-enhanced air-gap configuration. Desalination, 2020, 475: 114202

[23] Shahu V T, Thombre S B. Air gap membrane distillation: A review. Journal of Renewable and Sustainable Energy, 2019, 11(4): 045901

[24] Khalifa A, Lawal D, Antar M. . Experimental and theoretical investigation on water desalination using air gap membrane distillation. Desalination, 2015, 376: 94–108

[25] Veerman J, Saakes M, Metz S J. . Reverse electrodialysis: Performance of a stack with 50 cells on the mixing of sea and river water. Journal of Membrane Science, 2009, 327(1–2): 136–144

[26] Güler E, Elizen R, Vermaas D A. . Performance-determining membrane properties in reverse electrodialysis. Journal of Membrane Science, 2013, 446: 266–276

[27] Hu J, Xu S, Wu X. . Experimental investigation on the performance of series control multi-stage reverse electrodialysis. Energy Conversion and Management, 2020, 204: 112284

[28] Hu J, Xu S, Wu X. . Multi-stage reverse electrodialysis: Strategies to harvest salinity gradient energy. Energy Conversion and Management, 2019, 183: 803–815

[29] BatchelorG K. An Introduction to Fluid Dynamics. New York: Cambridge University Press, 2000

[30] Xu S, Xu L, Wu X. . Air-gap diffusion distillation: Theory and experiment. Desalination, 2019, 467: 64–78

[31] Lagarias J C, Reeds J A, Wright M H. . Convergence properties of the Nelder–Mead simplex method in low dimensions. SIAM Journal on Optimization, 1998, 9(1): 112–147

[32] Cui W Z, Ji Z Y, Tumba K. . Response of salinity gradient power generation to inflow mode and temperature difference by reverse electrodialysis. Journal of Environmental Management, 2022, 303: 114124

[33] Zhang W, Yan H, Wang Q. . An extended Teorell-Meyer-Sievers theory for membrane potential under non-isothermal conditions. Journal of Membrane Science, 2022, 643: 120073

[34] Bevacqua M, Tamburini A, Papapetrou M. . Reverse electrodialysis with NH₄HCO₃-water systems for heat-to-power conversion. Energy, 2017, 137: 1293–1307

[35] Giacalone F, Vassallo F, Griffin L. . Thermolytic reverse electrodialysis heat engine: Model development, integration and performance analysis. Energy Conversion and Management, 2019, 189: 1–13

[36] Liu Z, Lu D, Dong Y. . Performance improvement of LiBr-H₂O reverse electrodialysis unit for heat to power conversion with finite solution flowrate and large concentration change. Energy Conversion and Management, 2022, 270: 116263

[37] Jiang D, Zhang N, He G. . Sandwich-structured covalent organic framework membranes for selective sodium ion transport. Desalination, 2023, 567: 116988

Acknowledgements

Financial support was sponsored by the Fundamental Research Program of Shanxi Province, China (No. 20210302123095) and China Postdoctoral Science Foundation (No. 2021M702418).

Electronic Supplementary Material

Supplementary material is available in the online version of this article at https:/doi.org/10.1007/s11708-024-0947-3 and is accessible for authorized users.

Competing Interests

The authors declare that they have no competing interests.

Notations

Abbreviations
AEM	Anion-exchange membrane
AGMD	Air-gap membrane distillation
CEM	Cation-exchange membrane
HC	High-concentration
HGDD	Helium-gap diffusion distillation
IEMs	Ion-exchange membranes
LC	Low-concentration
LGH	Low-grade heat
MD	Membrane distillation
MED	Multi-effect distillation
MSRED	Multi-stage reverse electrodialysis
RED	Reverse electrodialysis
REDHE	Reverse electrodialysis heat engine
SGE	Salinity gradient energy
TDEG	Thermal-driven electrochemical generator
TS	Thermal separation
Variables
B	Width, m
C	Concentration of solution, mol·m−3
Cp	Specific heat of salt solution, J·kg−1·K−1
I	Current, A
Jv	Mass flux of the vapor diffusion in the gap, kg·m−2·s−1
L	Length, m
ṁ	Mass flowrate, kg·s−1
m	Molality, mol·kg−1
MNaCl	The relative molecular mass of NaCl
N	Number of gaps in HGDD
Ncell	Number of cells in a RED stack
P	Output power, kW or pressure, Pa
Q	Total LGH consumption by HGDD, kW
α	Permselectivity of both ion-exchange membranes
γ	Water latent heat of evaporation, kJ·kg−1 or mean ion activity coefficient
δ	Thickness of solution compartments, m
δc	Thickness of gap, m
ΔP	Pressure drops, Pa
η	Energy conversion efficiency
ηpump	Efficiency of pump
Φ	Specific volume, m3·kg−1
Superscripts and subscripts
af	Water-vapor-partial pressure at the gap and condensate-water-film interface
b	Brackish solution
c/cold	Cold-stream channel or helium gaps
h	Hot-stream channel
ha	Water-vapor-partial pressure at the gap and porous-medium interface
in	Inlet flow
out	Outlet flow

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