POWERTRAIN
HARNESSING HYDROGEN
A new gas injector system design has made it possible to inject hydrogen directly into a vehicle’s combustion chamber
L
ike all internal combustion engines (ICEs), zero-emission hydrogen engines require a mixture formation system for
metering fuel, in this case hydrogen gas. Currently, the most promising approach is a low-pressure direct injection (LP-DI) system, which injects the fuel directly into the engine’s combustion chamber. If injection is only allowed to start after the intake valves has closed, undesirable air displacement can be avoided and torque can be increased by around 20% at the same boost pressure of simple duct injection systems. However, the low density of hydrogen
requires comparatively large opening cross sections to blow the gas into the combustion chamber in the available time window, and presently there are no mass-produced LP-DI injectors that can meet the required specifications in the long-term. Led by Professor Karsten Wittek,
researchers from the Heilbronn University of Applied Sciences are seeking to change this, having developed a novel LP-DI system for gaseous fuels that makes it possible to inject hydrogen directly into the combustion chamber. “Using hydrogen as an energy source
in a vehicle has the advantage over a battery that the vehicle can be refuelled much faster than a battery can be charged,” Wittek says. “The hydrogen fuelled ICE is slightly less efficient than a fuel cell system, but an ICE vehicle is much less complex and less expensive than a fuel cell vehicle, and is the more robust system.” The design is based on an inward
10
www.engineerlive.com
The H2 test engine in which the team tested the new injector system
opening nozzle with a seat seal that is actuated servo-pneumatically and uses the pressure energy of the inflowing fuel gas. The design of the seat geometry in combination with highly wear-resistant ceramic materials guarantees compliance with the demanding service life requirements of various industrial applications, particularly the large engines of heavy commercial vehicles, construction machinery and locomotives. “In those applications where the
average power demand is high, the efficiency gap between the ICE and the fuel cell gets very small,” Wittek explains. “Heavy commercial vehicles are often operated at high power output, thus the fuel cell does not consume significantly less fuel when compared to a hydrogen-fuelled ICE vehicle. Another point is that a hydrogen ICE can easily achieve the lifetime of a present day diesel truck engine without any degradation in power and efficiency over its lifetime. How far fuel cell trucks and battery trucks might achieve this still needs to be found out.”
Although realised as a prototype for
now, extensive tests were completed on the injection nozzle test bench and engine test bench to confirm the system delivered all relevant functional properties. A patent has since been filed for the invention. According to Wittek, now that his team’s hydrogen injection system has undergone a first prototype phase, the next step is to carry out further development in cooperation with an unnamed Tier 1 supplier. Regarding how the system could
be realistically implemented in future, he explains: “Existing diesel engines of on and off-road vehicles could be retrofitted with moderate effort, particularly regarding changes to the engine. The hydrogen tank system is the biggest issue when retrofitting a vehicle. In a truck, the hydrogen storage tanks will be mounted behind the cabin.”
For more information visit
www.hs-heilbronn.de/de/kmh
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
