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Thermoelectric (TE) waste heat recovery has attracted significant attention over the past decades, owing to its direct heat-to-electricity conversion capability and reliable operation. However, methods for application-specific, system-level TE design have not been thoroughly investigated. This work provides detailed design optimization strategies and exergy analysis for TE waste heat recovery systems. To this end, we propose the use of TE system equipped on the exhaust of a gas turbine power plant for exhaust waste heat recovery and use it as a case study. A numerical tool has been developed to solve the coupled charge and heat current equations with temperature-dependent material properties and convective heat transfer at the interfaces with the exhaust gases at the hot side and with the ambient air at the heat sink side. Our calculations show that at the optimum design with 50% fill factor and 6 mm leg thickness made of state-of-the-art Bi2Te3 alloys, the proposed system can reach power output of 10.5 kW for the TE system attached on a 2 m-long, 0.5 × 0.5 m2-area exhaust duct with system efficiency of 5% and material cost per power of 0.23 $/W. Our extensive exergy analysis reveals that only 1% of the exergy content of the exhaust gas is exploited in this heat recovery process and the exergy efficiency of the TE system can reach 8% with improvement potential of 85%.
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This content will become publicly available on July 15, 2026
Energy and Exergy Analyses of Power Generation Cycles Using Powdered Iron as a Fuel Source
Abstract As the effects of climate change become a greater threat, the need for a viable source of sustainable energy grows daily. Iron powder has been proposed as a potential alternative to conventional fossil fuels. Pulverized iron can be burned similarly to coal. Unlike coal, however, iron combustion does not create CO2 as a by-product. It also produces a negligible amount of NOx. Iron is also abundant in the Earth's crust, has a low explosion range, possesses a competitive energy density to hydrocarbons, and reacts well with oxygen. Finally, the iron oxide produced during combustion can be collected and reduced back to iron, creating a fully sustainable process. In this analysis, different power generation cycles were analyzed to maximize the energy and exergy efficiencies as well as the work output per unit mass of iron. It was found that the power cycle that maximized both the energy and exergy efficiencies as well as the work output per unit mass of input iron was a combined power cycle, where the topping cycle was a gas turbine cycle with one-stage compression and expansion and the bottoming cycle was a steam turbine cycle with two-stage expansion and reheat. This brought the theoretical energy efficiency to 59.87%, the theoretical exergy efficiency to 65.37%, and the theoretical work output per unit mass of iron to 4422 kJ/kg. The energy efficiency decreased to 56.81% when auxiliary devices were considered.
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- Award ID(s):
- 2324411
- PAR ID:
- 10657869
- Editor(s):
- Metghalchi, Hameed
- Publisher / Repository:
- ASME
- Date Published:
- Journal Name:
- ASME Open Journal of Engineering
- Volume:
- 4
- ISSN:
- 2770-3495
- Subject(s) / Keyword(s):
- Keywords: alternative energy sources, alternative propulsion/energy storage systems, clean energy, climate change, combined cycle, combustion, energy efficiency, energy storage, energy storage systems, exergy, fuel combustion, fuels and combustion, mechanical engineering
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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