The diagram illustrates the newly-described reaction that transforms molecules of ketohydroperoxide into acids and carbonyl molecules, after going through intermediate stages. Credit: ACS, Jalan et al. Click to enlarge. Researchers at MIT, with colleagues at the University of Minnesota, have provided evidence and theoretical rate coefficients for new pathways in... Read more →

In-cylinder pressure (on the left) and heat release rate (on the right) as a function of the CAD and ozone concentration injected in the intake of the engine for PRF40. The results show that ozone seeding improves combustion and advances phasing. The same trends were observed for the other fuels... Read more →

The Sandia team has proposed extensions to John Dec’s 1997 model for diesel combustion, represented above. Credit: Musculus et al.; Dec. Click to enlarge. A team at Sandia National Laboratories recently proposed conceptual models for a specific subset of low-temperature combustion regimes: low-load, single-injection, partially premixed compression ignition (PPCI LTC)... Read more →

U Wisc. study explores effects of biodiesel-gasoline blend in diesel engine

One high-efficiency combustion concept under investigation is gasoline compression ignition (GCI)—the use of gasoline-like fuels to deliver very low NOx and PM emissions as well as high efficiency in a diesel compression ignition engine. (Earlier post.) A challenge to be overcome with this approach is the higher resistance to autoignition... Read more →

The LTC research project has three proposed components. Click to enlarge. The University of California Berkeley is partnering with MIT, Lawrence Berkeley, Lawrence Livermore and Sandia National Labs and Ricardo to investigate the the use of partial fuel stratification (PFS) in compression-ignition (CI) engines as well as the combination of... Read more →

Study finds moderate biofuel blends increase benefits of RCCI in light-duty engines

Preliminary results from a new study by a team from Oak Ridge National Laboratory (ORNL) and the University of Wisconsin suggest that the fuel properties of moderate biofuel blends such as E20 and B20 increase the benefits of the use of Reactivity Controlled Compression Ignition (RCCI). RCCI is a Low... Read more →

U. Wisconsin team reports gross indicated thermal efficiency of RCCI operation near 60%

In a paper presented at the 2013 SAE World Congress, a team from the University of Wisconsin reported a gross indicated thermal efficiency of Reactivity Controlled Compression Ignition (RCCI) operation of near 60%, given optimized combustion management and thermodynamic conditions. That 60% gross engine efficiency provides a pathway to meet... Read more →

Simulated fuel economy for 1.8L GDCI Engine and 2.4L GDi baseline engine. GDCI showed a predicted fuel economy improvement of 65%, 28%, and 28% for the FTP City, Highway, and US06 cycles, respectively, for a combined FE improvement of 50%. Source: Sellnau et al. Click to enlarge. At SAE World... Read more →

The effects of gasoline ratio on indicated thermal efficiency of HCII and GDBF modes. Yu et al. Click to enlarge. Researchers at Tsinghua University have compared the combustion and emissions characteristics of two dual-fuel (diesel-gasoline) modes intended to integrate the advantages of both fuels to achieve high thermal efficiency and... Read more →

Diagram of direct injector placement used in the study; future work will use a more parallel alignment of the injectors. Wissink et al. Click to enlarge. By using a new strategy entailing the direct, separate injection of both low- and high-reactivity fuels, researchers at the University of Wisconsin have found... Read more →

KAIST team explores mode transition between low-temperature and conventional combustion in a light-duty diesel

A team at the Korea Advanced Institute of Science and Technology (KAIST) reports on the effect of operating parameters such as rate of exhaust gas recirculation (EGR) change, residual gas, EGR path length, fuel injection pressure and engine speed on the mode transition between low-temperature combustion (LTC) and conventional combustion... Read more →

The effect of increasing levels of fuel stratification on observed pressure. Increased stratification leads to longer combusstion duration, no stratification results in the highest PRR. Krisman et al. Click to enlarge. Researchers from the University of New South Wales (Australia) and Sandia National Laboratories in the US report that ethanol... Read more →

Conceptual model for conventional diesel combustion (CDC), left, and LTC combustion, right, for heavy-duty engines. Source: CRF. Click to enlarge. Researchers at the Combustion Research Facility (CRF) at Sandia National Laboratories are proposing a conceptual model based on findings from their work for low temperature combustion (LTC). The LTC model... Read more →

NSF and DOE form Partnership on Advanced Combustion Engines; goal 25-40% better LDV fuel economy and 55% BTE in heavy-duty engines; $12M in awards for FY 2012-2014

The Directorate for Engineering at the National Science Foundation (NSF) has established a partnership with the Vehicle Technologies Program (VTP) of the US Department of Energy (DOE) to address critical fundamental and applied research challenges associated with advanced combustion engine technologies. The goal of the partnership is to leverage the... Read more →

Local fuel/air equivalence ratio versus temperature. Supercritical dieseline combustion “navigates between the Scylla and Charybdis” of soot and NOx. Source: George Anitescu. Click to enlarge. A team from Syracuse University and the National Institute of Standards and Technology (NIST) is exploring the use of supercritical (SC) dieseline (a diesel-gasoline blend)... Read more →

Transonic demonstrates supercritical gasoline operation under low load, medium load, and high speed low load conditions; simulated vehicle fuel economy of 48.8 mpg

Engineers at Transonic Combustion, a start-up developing a fuel efficient supercritical (SC) fuel injection and combustion system—Transonic Combustion, or TSCi (earlier post)—have demonstrated the TSCi process using gasoline fuel at low load without EGR, medium load with EGR, and high speed low load with EGR. They presented these latest results... Read more →

U. Wisc, GM team extends operation range for gasoline direct-injection compression-ignition using triple-pulse injection

Researchers from the University of Wisconsin-Madison and General Motors have extended the operation range for a light-duty diesel engine operating on gasoline using extended controllability of the injection process via a triple-pulse injection strategy. (Earlier post.) In a paper presented at SAE 2012 World Congress, the team reported the use... Read more →

Conceptual difference between PPCI injection and combustion (left) and MPCI injection and combustion. Wang et al. Click to enlarge. In a project funded by the joint research program between General Motors and Tsinghua University, a team from Tsinghua is developing a different approach to gasoline direct injection compression ignition (GDICI)... Read more →

Engine test results with one of the five injectors for 1500rpm-2bar IMEP, 1500 rpm-3bar IMEP, and 1500 rpm-6bar IMEP. Sellnau et al. Click to enlarge. In 2010, The US Department of Energy (DOE) selected Delphi, along with partners Hyundai America Technical Center, Inc (HATCI); Wisconsin Engine Research Consultants (WERC); and... Read more →

NSF Early Career Award supports investigation of technique to measure temperature of low-temperature combustion reactions

David Rothamer, an assistant professor of mechanical engineering at the University of Wisconsin-Madison, recently received a $405,000 National Science Foundation 2011 Faculty Early Career Development Award (CAREER) to investigate a new technique using nanoparticle thermographic phosphors for measuring the temperature of a low-temperature combustion reaction through the entire process. For... Read more →

PM from conventional diesel, PCCI and RCCI combustion. Prikhodko et al. Click to enlarge. Researchers at Oak Ridge National Laboratory are investigating the characteristics of and control techniques for particulate matter (PM) emissions generated by the Reactivity Controlled Compression Ignition (RCCI) combustion technique. RCCI is a promising combustion technique utilizing... Read more →

Optimized fuel properties with regard to different emissions Janssen et al. Click to enlarge. Tailor-made fuels from biomass have the potential to reduce emissions of criteria pollutants as well as greenhouse gases significantly in low temperature diesel combustion, according to a new open access study by a team from the... Read more →

US DOE awards more than $175M to 40 projects for advanced vehicle research and development

The US Department of Energy will award more than $175 million over the next three to five years to accelerate the development and deployment of a range of advanced vehicle technologies. The funding will support 40 projects across 15 states and will help improve the fuel efficiency of next generation... Read more →

UW-Madison Hybrid Vehicle Team working with Engine Research Center to apply dual-fuel RCCI engines in series and parallel hybrids

The University of Wisconsin-Madison Hybrid Vehicle Team will work with the UW-Madison Engine Research Center to test implementations of Reactivity Controlled Compression Ignition (RCCI) engines being developed by UW mechanical engineering professor Rolf Reitz and his colleagues. RCCI is a dual-fuel compression-ignition engine low-temperature combustion (LTC) strategy that uses in-cylinder... Read more →

BCG comparison of the CO2 reduction potential and cost of different technologies. Source: BCG. Click to enlarge. Conventional automotive technologies have significant emission-reduction potential, according to a draft of the Boston Consulting Group’s (BCG) latest report on automotive propulsion, Powering Autos to 2020. Advanced combustion technologies alone could reduce CO2... Read more →

(Part 2 of a series on low-temperature combustion) In contrast to conventional diesel combustion, the highest temperature for RCCI combustion in center of chamber (adiabatic core). The high temperature in conventional diesel combustion is next to the piston bowl surface. Source: Rolf Reitz. Click to enlarge. Researchers at the University... Read more →

(Part 1 of a series) Low Temperature Combustion (LTC) strategies offer the potential to enable high-efficiency and low-emission operation. Source: Gurpreet Singh, DOE. Click to enlarge. Many near-term (<10 years) efforts of industry and academia in developing more efficient, low-emitting engines are being applied to Low Temperature Combustion (LTC) strategies.... Read more →