Advanced Combustion and Alternative Fuels Laboratory
Development of power generation and propulsion systems with an emphasis on advanced combustion modes and alternative fuels for internal combustion engines. CIEES team works with the Advanced Combustion and Alternative Fuels Laboratory on development of alternative carbon-neutral fuels for retrofit of existing internal combustion engines.
Solid Oxide Fuel Cell - Gas Turbine
Dr. Dimitris Assanis, Director of the Advanced Combustion and Alternative Fuels Laboratory
Among various environmentally sustainable solutions for the production of electrical energy, solid oxide fuel cells (SOFCs) can generate electricity with a high conversion efficiency while emitting relatively low emissions of pollutants. This is attributed to the inherent theoretical conversion efficiency advantage of SOFCs, since electricity is generated directly from oxidizing the fuel instead of converting it to electricity by means of combustion. A promising approach to increase electrical conversion efficiency and reduce emissions is the integration of SOFCs with downstream energy conversion devices such as gas turbines and internal combustion engines. In a solid oxide fuel cell – gas turbine energy system, the combustor is used to burn the high-energy anode off-gas from the SOFC to produce extra shaft work for the hybrid system that is converted to electrical power.
Dr. Assanis's team is exploring the feasibility of a realistic SOFC anode off-gas as a potential alternative fuel under SI combustion conditions over a range of compression ratios, as well as to determine the fuel's compositional effects on engine thermodynamics, combustion characteristics, and emissions levels. The experimental results reveal that the conventional spark-ignition engine can be used downstream of a SOFC stack to generate additional power, thus confirming the feasibility of a fuel cell- internal combustion engine hybrid power plant to improve the combined electrical efficiency.
Alternative fuels for internal combustion engines
Advanced Combustion and Alternative Fuels Laboratory Team
The Assanis team is actively studying alternatives to gasoline for internal combustion engines. Natural gas is a gaseous fuel, which has been extensively used and investigated in spark-ignition automotive engines. Combining it with lean combustion has shown the potential to reduce emissions and improve efficiency compared to stoichiometric gasoline engines. The main limitations of lean Natural gas combustion are instability and ignitability. Supplementing Natural gas with Hydrogen is considered a solution to lean Natural gas combustion limitations, and it has been studied extensively. The research has demonstrated that Hydrogen addition accelerates combustion, extends the lean ignition limit, and improves combustion efficiency. The lean ignition limit extension offered by Hydrogen enables increased efficiency and NOx reduction.
Another promising research area is renewable fuels from biomass. Biomass catalytic fast pyrolysis integrated with hydrotreating produces advanced biofuels that could be used as bio-blendstocks to improve the properties of petroleum diesel fuels and enhance their combustion in compression ignition engines. The biofuels produced are rich in naphthenes (cycloalkanes) that could improve cold-weather behavior and reduce the sooting propensity of blended diesel fuels. Dr. Assanis's team research indicates that based on the present surrogate fuel formulation representing a low-oxygenated naphthenic bio-blendstock produced from the fast catalytic pyrolysis, such biofuels have the potential to be a viable drop-in fuel for compression ignition engines at moderate blend ratios without compromising engine performance and impacting exhaust emissions.
Advanced combustion strategies for gasoline engines
A test internal combustion engine
Advanced combustion strategies employing highly dilute and low-temperature combustion modes promise significant improvements in efficiency and emissions of internal combustion engines. For spark-ignited engines, advanced ignition systems, stratified charge operation, and exhaust gas recirculation with enhanced reactivity are some of the most promising near-term solutions for increasing dilution tolerance. Mixture dilution with air and exhaust gas is a key enabler of high thermal efficiency through direct thermodynamic benefits, as well as indirectly by allowing engine boosting and downsizing, higher compression ratios and reducing the need for airflow throttling.
Dr. Assanis's team works on strategies based on controlled auto-ignition driven by chemical kinetics, such as homogeneous charge compression ignition, that have demonstrated great efficiency benefits. Controlled auto-ignition driven by chemical kinetics considerably extends the lean operating limit while still maintaining fast combustion. The reduced residence time, in addition to the inherently lower combustion temperatures, further reduces efficiency losses due to heat transfer. The advanced combustion strategies revealed potential improvements in net thermal efficiency up to 30%, with an additional 12.5% possible.
Z. N. Ran, J. Longtin, and D. Assanis, "Investigating anode off-gas under spark-ignition combustion for SOFC-ICE hybrid systems," International Journal of Engine Research, vol. 23, no. 5, pp. 830-845, May 2022, Art no. 14680874211016987, doi: 10.1177/14680874211016987.
Z. N. Ran, R. R. Hadlich, R. N. Yang, D. C. Dayton, O. D. Mante, and D. Assanis, "Experimental investigation of naphthenic biofuel surrogate combustion in a compression ignition engine," Fuel, vol. 312, Mar 2022, Art no. 122868, doi: 10.1016/j.fuel.2021.122868.
I. Nikiforakis, Z. N. Ran, M. Sprengel, J. Brackett, G. Babbit, and D. Assanis, "Investigating realistic anode off-gas combustion in SOFC/ICE hybrid systems: mini review and experimental evaluation," International Journal of Engine Research, vol. 23, no. 5, pp. 876-892, May 2022, doi: 10.1177/14680874211058324.
J. P. Longtin, J. Brittelli, D. Assanis, C. R. Page, and S. Bergese, "THE COREVENT 2020: AN OPEN-SOURCE, RAPID DESIGN-BUILD-TEST EMERGENCY VENTILATOR DEVELOPED FOR COVID-19," Technology and Innovation, vol. 22, no. 2, pp. 199-217, Mar 2022, doi: 10.21300/22.2.2021.9.
M. Koraiem and D. Assanis, "Wood stove combustion modeling and simulation: Technical review and recommendations," International Communications in Heat and Mass Transfer, vol. 127, Oct 2021, Art no. 105423, doi: 10.1016/j.icheatmasstransfer.2021.105423.
E. A. Ortiz-Soto, G. A. Lavoie, M. S. Wooldridge, and D. N. Assanis, "Thermodynamic efficiency assessment of gasoline spark ignition and compression ignition operating strategies using a new multi-mode combustion model for engine system simulations," International Journal of Engine Research, vol. 20, no. 3, pp. 304-326, Mar 2019, doi: 10.1177/1468087417752195.
P. S. Shingne, J. Sterniak, D. N. Assanis, C. Borgnakke, and J. B. Martz, "Thermodynamic model for homogeneous charge compression ignition combustion with recompression valve events and direct injection: Part IICombustion model and evaluation against transient experiments," International Journal of Engine Research, vol. 18, no. 7, pp. 677-700, Sep 2017, doi: 10.1177/1468087416665052.
P. S. Shingne, R. J. Middleton, D. N. Assanis, C. Borgnakke, and J. B. Martz, "A thermodynamic model for homogeneous charge compression ignition combustion with recompression valve events and direct injection: Part I Adiabatic core ignition model," International Journal of Engine Research, vol. 18, no. 7, pp. 657-676, Sep 2017, doi: 10.1177/1468087416664635.
A. Sofianopoulos, D. N. Assanis, and S. Mamalis, "Effects of Hydrogen Addition on Automotive Lean-Burn Natural Gas Engines: Critical Review," Journal of Energy Engineering, vol. 142, no. 2, Jun 2016, Art no. E4015010, doi: 10.1061/(asce)ey.1943-7897.0000319.
A. A. Salvi, J. Hoard, D. Styles, and D. Assanis, "In Situ Thermophysical Properties of an Evolving Carbon Nanoparticle Based Deposit Layer Utilizing a Novel Infrared and Optical Methodology," Journal of Energy Resources Technology-Transactions of the Asme, vol. 138, no. 5, Sep 2016, Art no. 052207, doi: 10.1115/1.4032942.