Hydrogen as a fuel for internal combustion engines

Hydrogen as a fuel for internal combustion engines Contents: Introduction External mixture formation for hydrogen operated engines Experimental engine for hydrogen in Stralsund Internal mixture formation for hydrogen Summary

Introduction production of hydrogen by electrolysis (electrical energy only from renewable energies) substitution of fossil sources of energy reduction of emissions : CO2, CO, HC spark ignition and self ignition is possible external and internal mixture formation ist possible high laminar burning velocity wide ignition limits (in air) specific mixture formation and combustion for hydrogen safety systems are necessary

Characteristics of hydrogen hydrogen petrol min. ignition energy mj 0,02 0,24 in air ignition limits in air Vol-% 4-75 1 8 laminar burning velocity (st.) cm/s ca. 190 ca. 40 stoichiometric mixture in air Vol-% 29.53 1.76 heating value of the mixture (st.) kj/m 3 3,240 3,835

Hydrogen operated engines - Current state of development - current state till now: gaseous hydrogen is used in engines liquid hydrogen is used only for storage purposes - low temperatures cause problems with the material of valves, pipes, pumps, etc. internal mixture formation until now only in laboratory experiments spark ignition of hydrogen is without big problems, only water deposits on spark plugs during cold start are problematic self ignition until now only in laboratory experiments external mixture formation is ready for serial production

Hydrogen operated Otto engines - Current state of development - intensive research and development for hydrogen operated Otto engines started in Germany in the 1970 s most important German automobile manufacturers with self-developed engines are : o BMW (750hL, 12-cylinder Otto engine, V H =5,4 dm 3, P=150 kw) o Daimler-Benz 1985-1988 (MB310 Truck, 4-cylinder Otto-engine, V H =2,3 dm 3, P=75 kw) o MAN (SL202 Bus, 6-cylinder Otto engine, V H =12 dm 3, P=140 kw)

Cars with H 2 -Otto engine Fig. : BMW 750 hl (Photo : BMW AG) Fig. : 6-cylinder Otto-engine for Hydrogen on the testbed (Photo : BMW AG) Fig. : MAN-Bus with H 2 -Otto engine (Photo : MAN AG)

External mixture formation for combustion engines external mixture formation single-point mixture formation multi-point mixture formation naturally aspirated engine mixture-charged engine naturally aspirated engine air-charged engine gas mixer single point injection sequential multipoint injection

Hydrogen as fuel for Otto engines - Problems of mixture formation - self-ignition of the mixture during the intake stroke by : hot spots in the cylinder head hot exhaust gases glowing oil particles in the combusion chamber backfiring into the intake pipes during the intake stroke abnormal combustion (knocking problems) NO X -emissions low power output in comparison with petrol

Measures for the elimination of the problems use of lean mixtures (λ 1,8) decreasing of the combustion temperatures (prevents NO X -emission and self ignition) cooling of hot spots in the cylinder head (prevents selfignition) increasing of the ignition energy (prevents selfignition and abnormal combustion ) but it decreases the power output avoidance of hydrogen accumulation in the intake manifold (prevents backfiring)

Requirements to the mixture formation unit supply to the engine with lean mixtures at λ 1,8 sequential multi-point injection for each cylinder only at the intake stroke prevention of leakages in the injectors

External mixture formation for hydrogen Fig.: cross-section through the cylinder head of a BMW twofuel engine with intake manifold (left); gasoline injection valve (top); hydrogen injection valve (bottom) Picture: BMW

External mixture formation for hydrogen Fig.: cross-section of the hydrogen engine with fuel injection valve MAN H2866 UH 6-cylinder-4-stroke cycle 12 litres, 140 kw Picture: MAN

Experimental car of type Ford Escort

Storage unit for hydrogen state of aggregation : gas volume : 2 x 60 dm 3 max. pressure : 200 bar max. capacity : 24 m 3 NTP material : steel wrapped with fibres (Aramid)

Safety system two solenoid valves close the main hydrogen pipe in case : if one of three gas sensors detects hydrogen if a mechanical shock is detected by a special sensor if voltage is not present if the crankshaft does not turn

Gas detection system Fig.: sensor for H 2 over the driver seat Fig.: sensor for H 2 over the storage unit

Experimental engine at FH Stralsund Project : modification of a series-produced engine for the use of hydrogen; 1996/1997 manufacturer : Ford type : 4 cylinder - 4 stroke Otto engine dispacement : 1,400 cm 3 compression ratio : 9.5 : 1 ignition timing : 10 BTDC used air / fuel ratio λ : 1.8 3.0 max. power : 18 kw (n = 3,900 min -1 ); (previously 55 kw with petrol)

Hydrogen gas system in the experimental car

Mixture formation unit for the experimental engine at FH Stralsund Fig.: mixtur formation unit for hydrogen Fig.: hydrogen injector

Mixture formation unit for the experimental engine at FH Stralsund Fig.: hydrogen injector Fig.: H 2 -control valve

Mixture formation unit for the experimental engine at FH Stralsund Fig.: H 2 -experimental engine Fig.: inlet pressure switch

Experimental engine at FH Stralsund Project : modification of a series-produced engine for the use of hydrogen; 2001/2002/2003 - new free progammable engine control unit MOTEC M4 - adaptation of new and additional sensors : engine temperature, intake air temperature, camshaft position - adaption of wide band lambda sensor Bosch LSM 11 - engine fine tuning (dynamometer Bosch FLA 206) - emission analysis (Horiba EXSA 1500) - combustion pressure indication and work process of the engine

Experimental engine at FH Stralsund Project : modification of a series-produced engine for the use of hydrogen; 2001/2002/2003 Results after optimization max. power : 31 kw (n = 5000 min -1 ); (previously 55 kw with petrol) efficiency η e : max. 0,39 ignition timing : 0-18 BTDC used air / fuel ratio λ : 1.8 2.0

Engine Control Unit

Sensors for combustion pressure indication and work process of the engine TC CPS Fig.: crank angle sensor TC Fig.:cylinder pressure sensor CPS with spark plug adaptor and thermocouples TC for intake air and exhaust gas temperature

Pressure cycle in cylinder p(φ) at different ignition timings, n=2000 min -1, TP=40%, λ=1,8 (ZZP=IT) (TP=throttle position)

Knocking problems p(φ) at different ignition timings, n=2000 min -1, TP=40%, λ=1,8 (ZZP=IT) (TP=throttle position)

Efficiency and torque M d (ΙΤ), η e (IT) at different ignition timings, n=2000 min -1, TP=40%, λ=1,8, (ZZP=IT) (TP=throttle position)

Temperature and NO X -emissions T proc (λ), Τ ex (λ), NO X (λ) at different air-fuel-ratios, n=2000 min -1,M d =30 Nm, IT=5 BTDC

Torque throttle position Torque M d at different engine speed and throttle position (DK=TP=throttle position)

Efficiency Efficiency η e at different engine speed and throttle position (DK=TP=throttle position)

Power air fuel ratio at WOT T proc (λ), Τ ex (λ), NO X (λ) at different air-fuel-ratios, n=2000 min -1,M d =30 Nm, IT=5 BTDC, WOT=Wide Open Throttle

Project: internal mixture formation for hydrogen - main responsible persons: Prof. Dr.-Ing. W. Beckmann Dipl.-Ing. J. Bröcker - carried out from 1996-2001 at FH Stralsund - engineering and design of a high pressure hydrogen injector - numerical simulation of the injection - testing the injector in a combustion chamber with constant volume

Internal mixture formation for combustion engines internal mixture formation naturally aspirated engine charged engine exhaust turbocharger mechanical charger high-pressure injection common-rail unit injection system injection pump

Testbed: constant-volume combustion chamber A Data acquisition system MUSYCS B Servo amplifier C Exhaust-gas analyzer D Needle lift sensor E Servo valve F Hydraulic system G Injection valve H Combustion chamber J Hydrogen system K Air system and nitrogen purge system

Testbed : combustion chamber with constant volume for internal mixture formation Research project at FH Stralsund: Prof. Dr.-Ing. W. Beckmann, Dipl.-Ing. J. Bröcker

Combustion chamber with constant volume for internal mixture formation Indices : S N p u,t u (u) - ambient conditions h uh2,ρ H2(L),p H2(L),T H2(L) (L) - conditions in the gas pipe (Bk) - cond. in the comb. chamber Conditions 1 = intake air conditions Conditions 2 = process conditions V = const. cond. 1 p Air(Bk) T Air(Bk) ρ Air(Bk) m Air(Bk) cond. 2 p (Bk) =f(t) T (Bk) =f(t) m (Bk) =f(t) m Ex-gas(Bk) Research project at FH Stralsund: Prof. Dr.-Ing. W. Beckmann, Dipl.-Ing. J. Bröcker

Behaviour of the high pressure injector 1- Triggertime of servo valve (signal for hi or low pressure of control oil in injection valve) 1.1- Signal voltage corresponding to servo piston stroke (+/- 5V = +/- 50% piston stroke) 2- Nozzle opening time 2.1- Nozzle closed 2.2- Nozzle full open A- Time delay from start signal to start of pressure drop in control oil pipe (2,38 ms) B- Time delay from start signal to full open nozzle (5,13 ms) to attend for injection timing of engine Research project at FH Stralsund: Prof. Dr.-Ing. W. Beckmann, Dipl.-Ing. J. Bröcker

Combustion process in the constant volume combustion chamber valve closed open ZZP-ignition start of combustion Test conditions: - Settings for air and fuel masses for λ = 1 - Gas (H 2 ) pressure in main pipe: p = 157 bar - Seal oil pressure: p = 148 bar - Injection time: t = 13,2 ms - Theoretical injected hydrogen mass: m = 40,25 mg - Ignition timing setting: End of Injection Research project at FH Stralsund: Prof. Dr.-Ing. W. Beckmann, Dipl.-Ing. J. Bröcker

Influence of the air-fuel-ratio to the combustion pressure profil Test conditions: - Gas pressure: p = 157 bar - Injection time: t = 9,54 ms - Ignition timing: 2 ms before end of injection λ settings : 2; 2,5; 3; 3,5 Nozzle body: 8 x 0,345 with rod seal Research project at FH Stralsund: Prof. Dr.-Ing. W. Beckmann, Dipl.-Ing. J. Bröcker

Influence of the ignition timing to the combustion pressure profil Test conditions: - λ setting : 2 - Gas pressure: p = 157 bar - Injection time: t = 9,54 ms - Ignition timing referring to end of injection: 0 ms; -2 ms; -4 ms; -6 ms; -8 ms Nozzle body: 8 x 0,345 with rod seal Research project at FH Stralsund: Prof. Dr.-Ing. W. Beckmann, Dipl.-Ing. J. Bröcker

NO X -emissions of different hydrogen engine types Picture: Hydrogen as an energy carrier ; Winter, Nitsch; 1988

Emissions of a hydrogen engine Engine: MAN H 2866 UH Picture: MAN

Summary internal combustion engines for hydrogen from some manufacturers are ready to go into production state of development is the engine with external mixture formation and spark ignition lower power output compared to petrol engines is the disadvantage further developments with internal mixture formation and supercharged engines for more power output is possible improved hydrogen storage systems are necessary building up a hydrogen infrastructure is necessary