Enhanced heat transfer study of thermoelectric generation system based on bidirectional coupling simulation

ABSTRACT

To improve the performance of thermoelectric generator (TEG) for recovering the waste heat of thermaI fluid, a fluid-thermoelectric multiphysics numerical model is developed by using a bidirectional-coupled simulation method. The interaction between the thermal fluid and the TEG system is considered in this method and the numerical model is experimentally validated. Two numerical models of TEG systems with straight fins and corrugated fins are established, respectively. The temperature and potential distributions of the TEG at different inlet velocities and temperatures are analyzed. The results show that the corrugated fins can enhance the convective heat transfer, thereby improving the output characteristics of TEG. The developed model can predict the output characteristics of TEG system accurately. The error between the simulated and experimentally measured open-circuit voltage does not exceed 2.41%. Increasing the inlet air velocity and temperature improves the TEG hot side temperature, thus increasing its output power. Compared with the TEG system with straight fins, the heat transfer coefficient of the thermal fluid in the TEG system with corrugated fins was improved by about 10%. The output power and conversion efficiency were also improved by 18.9% and 0.12%, respectively, at a higher inlet velocity of 5.36 m/s.

KEYWORDS:

• Bidirectional coupling
• corrugated fin
• heat exchanger
• heat transfer
• thermoelectric generator

Nomenclature

Symbol	=
Z	=	Figure of merit values
T	=	Temperature, K
$\underset{\mathit{V}}{\to }$	=	Velocity vector, m·s−1
$\mathit{p}$	=	Pressure, Pa
$\mathit{C}$	=	Specific heat, J·kg−1·K−1
$\underset{J}{\to }$	=	Current density vector, A·m2
D	=	Hydraulic diameter, m
$\mathit{V}$	=	Fluid velocity, m·s−1
L	=	Tube length, m
Vin	=	Inlet velocity, m·s−1
Tin	=	Inlet temperature, K
R	=	Resistance, Ω
Re	=	Reynold number
$\mathit{Q}$	=	Heat flow, W
P	=	Power, W
Abbreviation	=
TEG	=	Thermoelectric generator
HEX	=	Heat exchanger
CFD	=	Computational fluid dynamics
Greek symbols	=
$\mathit{\mu }$	=	Dynamic viscosity, Pa·s
$\mathit{\rho }$	=	Density, kg·m−3
$\mathit{\lambda }$	=	Thermal conductivity, W·m−1·K−1
$\mathit{\alpha }$	=	Seebeck coefficient, V·K−1
${\sigma }^{-1}$	=	Electrical resistivity, Ω·m
$\mathit{\varphi }$	=	Electric potential, V
$\mathit{\eta }$	=	Conversion efficiency
Subscripts	=
f	=	Fluid
s	=	Solid
PN	=	PN-type thermoelectric legs
w	=	wall
h	=	hot side of TEG
c	=	cold side of TEG
eff	=	effective
ref	=	reference
out	=	output

Acknowledgements

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author ([email protected]; Jiangsu University) upon reasonable request.

Future work

In this paper, a steady-state multiphysics field model is solved using the bidirectional coupling method. However, the heat source may be unsteady in many practical applications. Therefore, future work could focus on developing such a transient model based on the bidirectional coupling method.

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [51776090]

Notes on contributors

Jun Wang

Jun Wang received his Ph.D. in 2009, now he is an professor of the School of Automotive and Traffic Engineering at Jiangsu University. His research interests are the energy conversion, storage and management, the emission and control of internal combustion engine. Contribution to this work: Methodology, Study design, Writing-Review and Editing, Supervision, Project administration.

Zhiqiang Huang

Zhiqiang Huang is a master degree candidate in Prof. Jun Wang’s group at Jiangsu University. He received his BS (2020) degree in Energy and Power Engineering at Jiangsu University of Science and Technology. His research interests include the experiment and simulation of heat transfer process of thermoelectric generator. Contribution to this work: Writing-Original draft preparation, Experiment, Simulation calculation, Data curation.

Jin Chai

Jin Chai is a master student in Prof. Jun Wang’s group at Jiangsu University. He received his BS (2020) degree in Mechanical engineering at Tongling University. His research interests include the recovery and utilization of low grade waste heat. Contribution to this work: Resources, Investigation.