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In a current simulation research reported in Porsche Engineering Journal, Porsche Engineering examined the potential of hydrogen combustion engines. The result’s a high-performance powertrain with emissions on the identical stage as ambient air.
Present work on hydrogen combustion engines worldwide is predominantly being accomplished for business autos with a comparatively low particular output of round 50 kW per liter of displacement. For the passenger automotive sector, that is inadequate, mentioned Vincenzo Bevilacqua, Senior Skilled Engine Simulation at Porsche Engineering.
We now have due to this fact developed a hydrogen combustion engine that goals to match the facility and torque of present high-performance gasoline engines as an idea research. On the identical time, we additionally had the target of reaching low gas consumption and retaining emissions on the identical stage as ambient air. The start line for our research was an present 4.4-liter eight-cylinder gasoline engine—or reasonably, its digital knowledge set, since we performed your complete research just about utilizing engine efficiency simulations.
—Vincenzo Bevilacqua
Modifications to the engine mannequin included a better compression ratio and combustion tailored to hydrogen, however most significantly, a brand new turbocharging system.
For clear combustion of hydrogen, the turbochargers must, on the one hand, present round twice as a lot air mass as they do in gasoline engines. Then again, nonetheless, the decrease exhaust gasoline temperatures end in an absence of vitality for his or her propulsion on the exhaust facet.
—Vincenzo Bevilacqua
This discrepancy can’t be resolved with standard turbochargers. Porsche Engineering has due to this fact examined 4 different, notably highly effective turbocharging ideas, a few of which come from the world of motorsport.
Comparability of turbocharging programs. Parallel turbocharging system consisting of e-turbo and e-compressor know-how with management valves for transient operation (high left); two-stage compression consisting of e-turbo and e-compressor know-how with bypass to decouple the compressor stage (high proper); mono-e turbocharger with inlet information vanes between air filter and compressor inlet (backside left) and mono-e turbocharger with back-to-back compressor and cost air intercooling (backside proper, chosen idea). Supply: Porsche
All programs include a number of electrically assisted turbochargers, a few of them mixed with further management valves within the air system or electrically pushed compressors. Every turbocharging system confirmed particular benefits and drawbacks, mentioned Bevilacqua. The selection of the precise idea is due to this fact extremely depending on the necessities profile of the hydrogen engine in query.
For the engine research involved, the event workforce chosen a turbocharging system with back-to-back compressors. The particular function of this design is the coaxial association of two compressor levels, that are pushed by the turbine or the supporting electrical motor utilizing a standard shaft. The method air flows via the primary compressor, is cooled within the intercooler after which recompressed within the second stage.
With an output of round 440 kW, the hydrogen engine is on par with the unique gasoline unit. With the intention to higher assess the efficiency of the powertrain, Porsche Engineering examined it in a luxury-segment reference car with a comparatively excessive whole weight of two,650 kg on the Nürburgring Nordschleife—albeit fully just about: the drive was carried out utilizing what is called a digital twin, i.e. a computer-based illustration of the true car.
With a lap time of eight minutes and 20 seconds, the car demonstrated excessive potential with regard to driving dynamics. Resulting from its chemical composition, neither hydrocarbons nor carbon monoxide are launched throughout hydrogen combustion, and nor do particulates play a task.
By way of optimizing emissions by the hydrogen engine, the specialists at Porsche Engineering due to this fact focused on NOx. In intensive optimization rounds, they tailored the engine’s working technique for the cleanest doable combustion. Their strategy was to maintain the extent of uncooked emissions low via extraordinarily lean and due to this fact colder combustion, making it doable to dispense with an exhaust aftertreatment system.
Because it turned out, the nitrogen oxide emissions are nicely under the boundaries set by the Euro 7 normal at the moment underneath dialogue and are near zero over your complete engine map.
—Matthias Böger, Specialist Engineer Engine Simulation at Porsche Engineering
Along with its barely measurable emissions, the hydrogen engine presents excessive effectivity within the WLTP measurement cycle in addition to in customer-relevant cycles due to its lean combustion.
We now have thereby fulfilled our self-imposed venture purpose: the event of a clear, economical and sporty hydrogen engine, throughout the board.
—Vincenzo Bevilacqua
The price of a hydrogen powertrain in sequence manufacturing may very well be akin to that of a gasoline engine. Though the turbocharger system and a lot of mechanical elements of the hydrogen engine are extra advanced and due to this fact dearer, there isn’t a want for the exhaust gasoline aftertreatment required for the gasoline engine underneath Euro 7.
The hydrogen engine is unlikely to enter manufacturing in its present type, however that wasn’t the purpose of the venture. As an alternative, the main target was on inspecting the technical potential of the choice drive know-how and increasing the capabilities of present engineering instruments.
The research allowed us to realize helpful insights with regard to the event of high-performance hydrogen engines and add fashions and strategies particularly for hydrogen to our digital simulation methodology. With this know-how, we’re able to effectively deal with future buyer initiatives.
—Vincenzo Bevilacqua
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