High energy density entrainment-based catalytic micro-combustor for portable devices in extreme environmental conditions
Name
lin-elin49-ms-meche-2023-thesis.pdf
Description
Thesis PDF
Size
6.38 MB
Format
Adobe PDF
Checksum (MD5)
0e64ed3ccab9a1b1c88238447b59936b
Author(s)
Lin, Emily
Advisor(s)
Chen, Gang
Date Issued
June 2023
Publisher
Massachusetts Institute of Technology
Abstract
The increasing demand for low-cost, high energy density heat sources has motivated the development of compact and lightweight combustion-based devices. In this work, we first optimized the catalytic bed segmentation scheme to enhance fuel management in a mesoscale parallel-plate combustor. After contextualizing the driving parameters for combustion efficiency, we developed an energy-dense (≈236 MW/m³) entrainment-based catalytic micro-combustor for heating portable systems. The multichannel micro-combustor (coated with Pt/Al₂O₃ catalyst) leverages a copper-nichrome wire to enable quick and localized ohmic preheating durations (2-3 mins). Furthermore, we demonstrated low ignition temperature (108-125°C), which facilitates low energy consumption (~1948 J). In addition, an optimal fuel flow rate (3.09×10⁻⁸ m³/s) was determined via FEM simulations and experiments to enable fuel savings (high fuel conversion) while achieving high heat fluxes by analyzing the reaction kinetics and species transport behavior in the microchannels. Additional FEM studies were performed to optimize the heat transfer between the high thermal mass and combustor at the insulating mica sheet stack interface. Afterwards, through independent testing, we established the micro-combustor’s ability to maintain long-term autothermal combustion at a high saturation wall temperature (585°C), which was attained at short timescales to enable fast heating/cooling cyclability. The successful cyclic heating demonstration of large thermal mass additions (at least 41 times the micro-combustor’s mass), coupled with the combustor’s high energy density, shows promise for device-level implementation for a range of commercial, defense, and energy conversion applications. Finally, a combustor array was assembled and tested in an atmospheric water extractor (AWE) device in harsh environmental conditions, at temperatures ranging from 1.7°C to 43.3°C.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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