Transonic Looking at Final Funding Round This Year, Production Deployment of Supercritical Fuel System in 2014; 50-75% Improvement in Engine Fuel Economy
Transonic Combustion, a start-up developing a supercritical fuel injection system that can improve the fuel economy of internal combustion engines by between 50-75% (earlier post), will raise its final round of funding (D round) this year and is targeting production deployment of its TSCi Fuel Injection System by OEMs by 2014, according to Mike Rocke, Transonic’s Vice President Marketing and Business Development. Transonic was exhibiting at the Department of Energy’s ARPA-E Energy Innovation Summit in Washington earlier this week.
Transonic is currently working with four OEMs on evaluating the system, Rocke said: one each in Asia, North America, Europe and the other in the heavy-duty engine sector.
|The TSCi system components. Click to enlarge.
A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. The TSCi Fuel Injection System comprises new fuel injectors that take the fuel charge to a supercritical state just prior to its direct injection at Top Dead Center (TDC) into the cylinder; a next-generation electronic control unit; a high-efficiency fuel pump; and fuel rail (accumulator).
The TSCi injectors can work with a range of fuels (given appropriate software adjustment and control). The company currently is optimizing the system for use in modern high-compression diesel architecture engines, near-term running on gasoline while longer-term utilizing advanced low-carbon fuels.
(Researchers at Syracuse University are working on a method to prepare, inject and combust supercritical diesel fuel. Earlier post.)
|Left: TSCi supercritical injection. Right: Liquid Direct Injection. The view is up through the piston bowl. The TSCi charge is nearly invisible to the eye. Click to enlarge.
The TSCi gasoline fuel charge enters the cylinder at around 400 °C—compared to about 100 °C for a conventional liquid direct injection fuel charge—at precisely Top Dead Center (TDC, 0° crank angle). The supercritical charge facilitates short ignition delay and fast combustion, with the energy released focused just on pushing the piston down. The fast combustion minimizes crevice burn and partial combustion near the cylinder walls, and prevents droplet diffusion burn.
The TSCi system supports more efficient engine operation over the full range of conditions—from stoichiometric air-to-fuel ratios at full power to lean 80:1 air-to-fuel ratios at cruise.
The software control is key to facilitating the extremely fast combustion, enabled by advanced microprocessing technology. The TSCi injection system can also be supplemented by advanced thermal management, exhaust gas recovery, electronic valves, and advanced combustion chamber geometries. (The Syracuse team, for example, is using exhaust gas heat to help bring the fuel to SC states.) Through the use of its software, the TSCi system can optimize the use of any combustion chamber geometry or piston bowl shape.
(As an aside to illustrate the flexibility of the TSCi system and the importance of the software control, Rocke said that during one of their demonstrations to an OEM, the Transonic engineers switched from diesel to gasoline in the fuel supply. Although the switch required some rapid on-the-fly computer keyboard work by an engineer, the engine didn’t miss a beat, according to Rocke.)
Transonic’s testing on a mid-size vehicle on a chassis dynamometer resulted in EPA highway fuel economy of 64 mpg (3.7 L/100km), with city testing being finalized this year, estimated at 47 mpg (5.0 L/100km). As a comparison, the 2010 Prius delivers 51 mpg US (4.6 L/100km) EPA city and 48 mpg (4.9 L/100km) highway. The TSCi system would add about $1,500 to the cost of the vehicle, Rocke said, compared to about a $4,000 delta for a current full hybrid solution.
The Transonic OEM system can be deployed on existing engine architectures with minimal OEM re-configuration, a “relative drop-in” solution.
Although its early work showed significant reductions in engine-out emissions, Transonic will begin more thorough emissions testing on its system this year, according to Rocke.