SBIR-STTR Award

The Department of Energy is interested in reducing Americas petroleum consumption to provide greater freedom of mobility, energy security, lower costs and reduced impact on the environment. Dilute-burn gasoline engines are considered one of the most attractive solutions to developing more energy efficient and environmentally friendly highway vehicles; however, ignition instability associated with dilute mixtures prevents wide-spread application1. For this grant, a novel low-energy and cost effective nanosecond pulsed ignition system based on technology that has been shown to reliably ignite dilute mixtures2 while reducing electrode wear will be developed from TRL5 to TRL6, enabling a significant leap in the performance of next generation of fuel efficient vehicles. In dilute-burn gasoline engines, dilution with air or with exhaust gas recirculation allows for improved fuel efficiency and reduced emissions by limiting thermal losses, but it also reduces the engines peak power. This lost power can be recovered through turbocharging, but the combination of dilution and intake pressure boost makes ignition increasingly difficult. Traditional ignition methods can ignite this mixture if the ignition energy is significantly increased, but this causes unacceptable electrode wear. Low-energy nanosecond pulses enable stable dilute-burn ignition without accelerated ignition system fatigue. Low-energy nanosecond pulses will be used to produce a non-thermal plasma, which uses less power and is much more effective compared with the thermal or quasi-thermal plasmas that are commonly generated by alternative advanced ignition techniques3. Traditional thermal ignition systems heat a zone of combustible mixture to a temperature where radicals are thermally generated and produce rapid chemical reactions that generate heat faster than heat transfer can cool the zone, resulting in ignition. This technique, used for over 100 years, has limitations in dilute mixtures because thermally generating radicals is inefficient and slow and excess air in lean mixtures cools the ignition zone more quickly. In non-thermal plasma radicals are produced directly, which is more than 50 times more efficient4, and therefore less energy is needed to generate heat more quickly and the mixture can be leaner. During Phase I, a production intent design of a low-energy nanosecond pulsed ignition system for enabling stable dilute ignition will be developed and tested in a single-cylinder gasoline direct injected engine to measure the effectiveness under dilute and high-pressure conditions. For Phase II, existing relationships with engine testing facilities and original equipment manufacturers will allow quick access to expertise and experience with engine experts to optimize the system. Early versions of the technology have been demonstrated in engine applications in multiple labs, including Sandia National Labs Combustion Research facility2 and Argonne National Lab5. The technology can be applied to all spark-ignition engines and is fuel agnostic, enabling increased fuel efficiency and reduced emissions in gasoline, natural gas, ethanol, hydrogen, propane, and methanol cars, trucks, and generators.

The Department of Energy’s mission includes reducing America’s petroleum consumption to provide greater freedom of mobility, energy security, lower costs and reduced impact on the environment. There are more than 22,000 deaths/year attributed to NOx and particulates1. The worst offender of the in the U.S. is highway vehicles, which produce 11.6 billion lbs. of NOx, 400 million lbs. of particulates, and cost around $400 billion in fuel each year2. Diluteburn engines are an attractive solution to developing more energy efficient and environmentally friendly passenger vehicles; however, ignition instability associated with dilute mixtures prevents widespread application3. A U.S. made, lowenergy nonthermal plasma ignition system demonstrated in Phase I to enable diluteburn engines will have a major impact and could result in a reduction in NOx emissions over 50% and fuel savings up to $80 billion/year in the U.S., while impacting more than 10,000 lives and reducing CO2 emissions. The system also has the potential to extend spark plug lifetime, which is critical when evaluating advanced ignition techniques and is the focus of this Phase II grant. A novel lowenergy nanosecond pulsed ignition system was advanced from TRL5 to TRL6 during the Phase I grant, and was shown to reliably ignite dilute mixtures. The system developed in Phase II will provide a solution to two critical problems for both heavyduty natural gas and gasoline engine manufacturers (e.g. Ford, Caterpillar, etc.), improving both fuel economy and extending spark plug lifetime, which will accelerate the adoption timeline of a product that would enable a significant leap in the performance of next generation of fuel efficient vehicles. The system demonstrated in Phase I will be developed to deliver increased voltage and repetition rates to increase diluteburn stability, and a control system based on a feedback loop will be developed to avoid spark breakdown. This will be the first time that a control system has been developed for a nanosecond pulsed ignition system to avoid spark breakdown and minimize energy delivered to the spark plug while optimizing combustion performance, and it is expected to reduce spark plug service intervals by more than a factor of two compared to highenergy thermal ignition systems. This is especially critical for applications such as stationary power generation where taking an engine out of service to change spark plugs every 16 weeks costs over $10K/hour. During Phase II, existing relationships with engine research facilities and engine manufacturers will provide additional financial support, expertise and experience to develop and optimize the ignition system to meet market needs. The preproduction prototype developed during Phase II will be licensed to ignition system Tier 1 suppliers in Phase III for manufacture and use in spark ignition engines.

Keywords:
Vehicles, Energy Efficient, Environmentally Friendly, LeanBurn Engine, Ignition, Nonthermal Plasma, Nanosecond Pulsed Power, Dilute Combustion, Transient Plasma, Plasma Assisted Combustion