Microscale
combustion (“microcombustion”), micro power generation and micropropulsion
Quick
Links
On-line presentations:
Microcombustion
and power generation
Micro
solid oxide fuel cells
Micropropulsion
and gas pumping
Papers:
Ronney, P. D., “Heat-Recirculating Combustors,”
Chapter 10 in Microscale
Combustion and Power Generation (Y. Ju, C. Cadou and K. Maruta, Eds.), Momentum Press LLC, New York,
2015, pp. 287-320.
Chen, C.-H., Ronney, P. D., “Scale and geometry
effects on heat-recirculating combustors,” Combustion Theory and Modelling, Vol. 17, pp. 888 - 905 (2013). (DOI:
10.1080/13647830.2013.812807)
Zeng, P., Wang, K., Ahn, J., Ronney,
P. D., “A self-sustaining thermal transpiration gas pump and SOFC power
generation system,” Proceedings of the Combustion Institute, Vol. 34,
pp. 3327 - 3334 (2013). (DOI: 10.1016/j.proci.2012.06.168)
Chen, C.-H., Ronney, P. D.,
“Three-dimensional Effects in Counterflow Heat-Recirculating Combustors,” Vol.
33, pp. 3285-3291 (2011) (DOI:
10.1016/j.proci.2010.06.081)
Ahn, J., Shao, Z., Ronney, P. D., Haile, S., “A
Thermally Self-Sustaining Miniature Solid Oxide Fuel Cell,” Journal of Fuel
Cell Science and Technology, Nov. 2009. (DOI: 10.1115/1.3081425)
Cho, J.-H., Lee, J., Lin, J., Sanford, L. N., Richards, C. D.,
Richards, R. F., Ahn, J., Ronney, P. D., “Demonstration of an external
combustion micro-heat engine,” Proceedings of the Combustion Institute,
Vol. 32, pp. 3099-3105 (2009). (DOI:
10.1016/j.proci.2008.07.017)
Hyland, P., Lee, J. M., Lin, C. S.,
Ahn, J., Ronney, P. D., “Effect of ammonia treatment on Pt
catalyst used for low temperature reaction,” Proceedings
of the ASME International Mechanical Engineering Congress and Exposition 2007,
Vol. 6: Energy Systems: Analysis, Thermodynamics and Sustainability, pp. 135 –
140 (2008).
Sanford, L. L., Huang, S. Y., Lin, C. S.., Lee, J., Ahn, J., Ronney, P. D., “Plastic Mesoscale Combustors/Heat Exchangers,” Proceedings
of the ASME International Mechanical Engineering Congress and Exposition 2007,
Vol. 6: Energy Systems: Analysis, Thermodynamics and Sustainability, pp. 141 –
145 (2008).
Kuo, C.-H., Ronney, P. D., “Numerical Modeling of Heat Recirculating
Combustors,” Proceedings of the Combustion Institute, Vol. 31, pp. 3277-3284
(2007). (DOI:
10.1016/j.proci.2006.08.082)
Haile, S., Ronney, P. D., Shao, Z.,
“Power generator and method for forming the same,” U. S. Patent No. 7,247,402,
July 24, 2007.
Shao, Z,
Haile, S., Ahn, J., Ronney, P. D., Zhan, Z., Barnett, S. A., “A thermally
self-sustained micro Solid-Oxide Fuel Cell with high power density,” Nature,
Vol. 435, pp. 795-798 (9 June 2005). (DOI: 10.1038/nature03673)
Ronney, P. D., “Analysis of non-adiabatic heat-recirculating
combustors,” Combustion and Flame, Vol 135,
pp. 421-439 (2003). (DOI:
10.1016/j.combustflame.2003.07.003)
Ahn,
J., Eastwood, C., Sitzki, L., Ronney, P. D.,
“Gas-phase and catalytic combustion in heat-recirculating burners,” Proceedings
of the Combustion Institute, Vol. 30, pp.
2463-2472 (2005). (DOI:
10.1016/j.proci.2004.08.265)
Posthill, J., Reddy, A., Siivola, E., Krueger, G., Mantini,
M., Thomas, P., Venkatasubramanian, R., Ochoa, F.,
Ronney, P. D., “Portable power sources using combustion of butane and thermoelectrics,” 24th International Conference on Thermoelectrics (ICT), pp. 520 – 523 (2005). (DOI:
10.1109/ICT.2005.1520000)
Maruta,
K., Takeda, K., Ahn, J., Borer, K., Sitzki, L,
Ronney, P. D., Deutchman, O., “Extinction Limits of
Catalytic Combustion in Microchannels,” Proceedings
of the Combustion Institute, Vol. 29, pp. 957-963 (2002). (DOI: 10.1016/S1540-7489(02)80121-3)
Weinberg,
F. J., Rowe, D. M., Min, G., Ronney, P. D., “On thermoelectric power conversion
from heat re-circulating combustion systems,” Proceedings of the Combustion
Institute, Vol. 29, pp. 941-947 (2002). (DOI: 10.1016/S1540-7489(02)80119-5)
Pictures
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3D meso-scale
burner (4x larger than final design size of microscale
burner) |
Experimental apparatus for
testing 3D meso-scale burner |
3-turn, 3D microscale
burner built using EFAB (3 mm tall)
(partially folded) |
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2D meso-scale
burner (3x larger than final design size of microscale
burner) |
Experimental apparatus for
testing 2D meso-scale burner |
3-turn, 3D microscale
burner built using EFAB (3 mm tall)
(before folding) |
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Narrative
description
It
is well known that the use of combustion processes for electrical power
generation provides enormous advantages over batteries in terms of energy
storage per unit mass and in terms of power generation per unit volume, even
when the conversion efficiency in the combustion process from thermal energy to
electrical energy is taken into account. For example, hydrocarbon fuels provide
an energy storage density between 40 and 50 MJ/kg, whereas even modern lithium
ion batteries commonly used in laptop computers provide only 0.4 MJ/kg. Thus,
even at only 5% conversion efficiency from thermal to electrical energy,
hydrocarbon fuels provide about 5 times higher energy storage density than
batteries. For this reason automotive and aviation vehicles employ internal
combustion engines for prime moving and electrical power generation almost
entirely to the exclusion of batteries, even in vehicles whose mass may be less
than 1 kg or more than 105 kg. In the past few years, many research
groups from around the world have begun to develop devices called Micro
Electro-Mechanical Systems, or “MEMS,” typically borrowing technologies
originally developed for microelectronic devices. Recently much attention has
been focused on the application of MEMS devices to the production of electrical
power, so-called “Power MEMS” devices,
typically in applications where batteries are currently used.
Many
groups involved in Power MEMS are investigating scaled-down versions of
well-established macro-scale combustion devices (internal combustion engines,
gas turbines, pulsed combustors, etc.) There are numerous difficulties with
this approach, for example the fact that flames extinguish due to heat losses
if the dimension of the combustion chamber is too small, i.e. “microcombustion”
is more difficult than “macrocombustion.” Furthermore,
even if flame quenching does not occur, heat and friction losses become
increasingly important at smaller scales since the heat release due to
combustion and thus power output scales with the volume of the engine whereas
the heat and friction losses scale with the surface area.
For
these reasons we have developed two Power MEMS system concepts based on the
integration of the following four technologies:
•
Microcombustion, heat transfer and
thermal management using a two-dimensional or three-dimensional toroidal “Swiss Roll” counterflow heat exchanger and
combustor.
• Power
generation using thermoelectric elements or a single-chamber solid oxide fuel
cell
• To pump the gaseous reactants through the combustor and
(optionally) generate thrust with no moving parts, a catalytic
combustion driven thermal transpiration pump.
These
approaches have the following advantages over “traditional” approaches to
micropower generation:
• No moving parts, thus no
friction losses
•
Reduction
of heat loss effects, thus minimizing flame quenching problems and
minimizing efficiency losses.
•
Monolithic
construction, requiring at most one simple mechanical assembly step
(for the electrochemical fabrication technique.)
•
Ability
to use hydrocarbon fuels, unlike some Power MEMS concepts
which require hazardous, low-energy-per-unit-storage-volume fuels such as
hydrogen, or fuels derived from solid rocket propellants.
The
goal of these projects is to produce practical working devices using a
combination of experimental examination of scaled-up model microcombustion,
power generation and propulsion devices, numerical modeling of macro- and
micro-scale devices, and micro-scale fabrication using the aforementioned
techniques.