Dr. Mahdi Shahbhakti
Assistant Professor, Mechanical Engineering-Engineering Mechanics
The US Department of Transportation’s National Highway Traffic
Safety Administration (NHTSA) requires the vehicle corporate
average fuel economy to be increased by 53% (from 15.1 to
23.2 km/l) for light duty vehicles from 2016 to 2025. In
addition, the new US Environmental Protection Agency (EPA)
emission standards (Tier III and LEV III) regulate that
emissions of Nitrogen Oxides and Non- Methane Organic Gas
(NOx+NMOG) reduces from current 99.2 mg/km to 18.6 mg/km in
2025 on fleet average for light duty vehicles. Thus, there is
now a high demand for engine technologies with low fuel
consumption and low NOx emissions.
research is centered on developing advanced fuel-efficient
combustion engines that promise a significant reduction in
low NOx and particulate matters (PM) and greenhouse gas
emissions. Low temperature combustion (LTC) engines are an
emerging technology that combines characteristics of
spark-ignited and diesel engines. Similar to spark-ignited
engines the fuel-air charge is mostly premixed in LTC, and
similar to diesel engines the mixture is ignited through
compression ignition. These characteristics, combined with the
use of lean mixtures allow LTC to achieve high efficiency and
NOx emissions and PM.
A dual-fuel reactivity controlled compression ignition (RCCI) concept is beneficial to other modes of LTC engines such as Homogeneous Charge Compression Ignition (HCCI) or Premixed Charge Compression Ignition (PCCI) due to the existence of precise means for controlling the heat release rate and combustion phasing. In the RCCI strategy two fuels with different reactivity (auto-ignition characteristics) are blended inside the combustion chamber. Combustion phasing is controlled by the relative ratios of these two fuels and the combustion duration is controlled by spatial stratification between the two fuels. Our project is centered on developing an optimized RCCI engine combustion. Proper operation of RCCI engines requires an in-depth understanding of the interactions between fluid flows, turbulent mixing and chemical kinetics. Computational Fluid Dynamics (CFD) models need to be developed to provide the required understanding. The CFD models are used to investigate the performance and emission characteristics of RCCI engines. Furthermore the CFD models are used to consider the effects of different fuels with different reactivity for a given operating condition. Dr. Shahbhakti and his group's study primarily focuses on development and analysis of advanced combustion models of RCCI engines understanding of the key processes controlling RCCI engine combustion.
This research is done as part of Michigan Tech’s Advanced Power Systems Research Center (APSRC), and Dr. Shahbhakti and Dr. Jeffrey Naber are the principal investigators. The RCCI research study has been done in collaborative efforts with University of Wisconsin-Madison Engine Research Center (ERC), thus advanced methods of RCCI controls can be developed.
For more information, please visit Dr. Shahbhakti's website.