Waste heat recovery has become a critical research area in the quest for
improving automotive energy efficiency. Internal combustion engines lose a large
amount of their energy as heat through exhaust gases. Thermoelectric generation
technology presents a promising approach to capturing and converting this waste
heat into useful electrical energy. In this work, a theoretical study on the
application of thermoelectric generators (TEGs) for battery charging by
converting waste heat from internal combustion engine exhaust into usable
electrical energy is proposed. A prototype system incorporating TEG modules was
designed focusing on the minimization of back pressure; flow of exhaust gas is
ensured through a circular internal cross-section. Thermal simulations were
performed using Ansys Workbench, and computational fluid dynamics (CFD) analysis
was conducted to quantify the back pressure. Two heat exchanger materials,
aluminum and copper alloys, were evaluated for their heat transfer performance.
The results indicate that copper achieves superior heat transfer, with hot-side
temperatures approximately 8.6% to 23.9% higher than aluminum. However, aluminum
remains a viable alternative due to its lightweight and cost-effectiveness. With
the cold side being maintained at 91°C to simulate realistic engine coolant
conditions, the experiment shows that a series-parallel configuration of six TEG
modules (three in series × two in parallel) can effectively generate the
necessary voltage (13–15 V) and current (3.5–7 A) to charge a 12-V automotive
battery. CFD analysis confirmed that the circular internal geometry produces low
back pressure, with pressure drops of 28 Pa, 63 Pa, and 168 Pa for inlet
velocities of 25 m/s, 40 m/s, and 70 m/s, respectively. This research
underscores the potential of TEG-based battery charging systems in enhancing
energy efficiency, though further development is required for real-world
automotive integration. Future work could focus on on-vehicle testing,
optimizing thermoelectric materials, and integrating advanced cooling mechanisms
and maximum power point tracking controllers to improve overall system
viability.
