Improvements of truck fuel economy using mechanical regenerative braking
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Conference paper
- Relation: Paper presented at SAE 2010 Commercial Vehicle Engineering Congress, Illinois, USA : 5th-6th October 2010
- Full Text:
- Description: Improvements of truck fuel economy are being considered using a flywheel energy storage system concept. This system reduces the amount of mechanical energy needed by the thermal engine by recovering the vehicle kinetic energy during braking and then assisting torque requirements. The mechanical system has an overall efficiency over a full regenerative cycle of about 70%, about twice the efficiency of battery-based hybrids rated at about 36%. The technology may improve the vehicle fuel economy and hence reduced CO2 emissions by more than 30% over driving cycles characterized by: frequent engine start/stop, vehicle acceleration, brief cruising, deceleration and stop. The paper uses engine and vehicle simulations to compute: first the fuel benefits of the technology applied to passenger cars, then the extension of the technology to deal with heavy duty vehicles.
Design of the 690 and 420 touring car racing engines
- Authors: Boretti, Alberto
- Date: 2009
- Type: Text , Conference paper
- Relation: Paper presented at Non-Conference Specific Technical Papers - 2009, Warrendale, Pennsylvania, USA :
- Full Text: false
- Description: The paper presents design data and indicated, brake and mean effective pressure results for two successful racing engines developed by FIAT Auto Corse for touring car applications, namely the 690 2.5 liters V6 engine powering the Alfa Romeo 155 car developed for the 1996 International Touring Car (ITC) Championship and the 420 2.0 liters in-line 4 engine powering the Alfa Romeo 156 car developed for the 1998 Campionato Italiano Superturismo. In their first year of life, the sophisticated 690 engine was delivering 500 HP with a revolution limiter of 12000 rpm, while the more conservative 420 engine was delivering 310 HP with a revolution limiter of 8500 rpm. Brake mean effective pressures of these naturally aspirated engines were very close to the maximum achievable values for the racing engine technology of the late nineties, and certainly still a good reference point for development of new racing engines. Geometrical and operating parameters of these engines are provided in detail, as well as similarity rules for derivation of new engines.
Comparison of fuel economies of high efficiency diesel and hydrogen engines powering a compact car with a flywheel based kinetic energy recovery systems
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 35, no. 16 (2010), p. 8417-8424
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- Description: Coupling of small turbocharged high efficiency diesel engines with flywheel based kinetic energy recovery systems is the best option now available to reduce fuel energy usage and reduce green house gas (GHG) emissions. The paper describes engine and vehicle models to generate engine brake specific fuel consumption maps and compute vehicle fuel economies over driving cycles, and applies these models to evaluate the benefits of a H2ICEs developed with the direct injection jet ignition engine concept to further reduce the fuel energy usage of a compact car equipped with a with a flywheel based kinetic energy recovery systems. The car equipped with a 1.2 L TDI Diesel engine and KERS consumes 25 g/km of fuel producing 79.2 g/km of CO2 using 1.09 MJ/km of fuel energy. These CO2 and fuel energy values are more than 10% better than those of today's best hybrid electric vehicle. The car equipped with a 1.6 L DI-JI H2ICE engine consumes 8.3 g/km of fuel, corresponding to only 0.99 MJ/km of fuel energy. © 2010
Improvements of vehicle fuel economy using mechanical regenerative braking
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Conference paper
- Relation: Paper presented at SAE 2010 Annual Brake Colloquium And Engineering Display, Phoenix, USA : 10th-13th October 2010
- Full Text:
- Description: Improvements of fuel economy of passenger cars and light and heavy duty trucks are being considered using a flywheel energy storage system concept to reduce the amount of mechanical energy produced by the thermal engine recovering the vehicle kinetic energy during braking and then assisting torque requirements. The mechanical system has an overall efficiency over a full regenerative cycle of about 70%, about twice the efficiency of battery-based hybrids rated at about 36%. The technology may improve the vehicle fuel economy and hence reduced CO2 emissions by more than 30% over driving cycles characterized by frequent engine start/stop, and vehicle acceleration, brief cruising, deceleration and stop.
Analysis of design of pure ethanol engines
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Conference paper
- Relation: Paper presented at International Powertrains, Fuels & Lubricants Meeting 2010, Rio De Janeiro, Brazil : 5th-7th May 2010 p. 1-13
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- Description: Ethanol, unlike petroleum, is a renewable resource that can be produced from agricultural feed stocks. Ethanol fuel is widely used by flex-fuel light vehicles in Brazil and as oxygenate to gasoline in the United States. Ethanol can be blended with gasoline in varying quantities up to pure ethanol (E100), and most modern gasoline engines well operate with mixtures of 10% ethanol (E10). E100 consumption in an engine is higher than for gasoline since the energy per unit volume of ethanol is lower than for gasoline. The higher octane number of ethanol may possibly allow increased power output and better fuel economy of pure ethanol engines vs. flexi-fuel engines. High compression ratio ethanol only vehicles possibly will have fuel efficiency equal to or greater than current gasoline engines. The paper explores the impact some advanced technologies, namely downsizing, turbo charging, liquid charge cooling, high pressure direct injection, variable valve actuation may have on performance and emission of a pure ethanol engine. Results of simulations are described in details providing guidelines for development of new dedicated engines.
The lean burn direct injection jet ignition gas engine
- Authors: Boretti, Alberto , Watson, Harry
- Date: 2009
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 34, no. 18 (2009), p. 7835-7841
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- Reviewed:
- Description: This paper presents a new in-cylinder mixture preparation and ignition system for various fuels including hydrogen, methane and propane. The system comprises a centrally located direct injection (DI) injector and a jet ignition (JI) device for combustion of the main chamber (MC) mixture. The fuel is injected in the MC with a new generation, fast actuating, high pressure, high flow rate DI injector capable of injection shaping and multiple events. This injector produces a bulk, lean stratified mixture. The JI system uses a second DI injector to inject a small amount of fuel in a small pre-chamber (PC). In the spark ignition (SI) version, a spark plug then ignites a slightly rich mixture. In the auto ignition version, a DI injector injects a small amount of higher pressure fuel in the small PC having a hot glow plug (GP) surface, and the fuel auto ignites in the hot air or when in contact with the hot surface. Either way the MC mixture is then bulk ignited through multiple jets of hot reacting gases. Bulk ignition of the lean, jet controlled, stratified MC mixture resulting from coupling DI with JI makes it possible to burn MC mixtures with fuel to air equivalence ratios reducing almost to zero for a throttle-less control of load diesel-like and high efficiencies over almost the full range of loads. © 2009 Professor T. Nejat Veziroglu.
Fuel cycle CO2-e targets of renewable hydrogen as a realistic transportation fuel in Australia
- Authors: Boretti, Alberto
- Date: 2011
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 35, no. 5 (2011), p. 3290-3301
- Full Text: false
- Reviewed:
- Description: The claim of catastrophic man made climate change or global warming through anthropogenic CO2 has presently focused the interest on the tailpipe emissions of CO2 per km, with recent legislations obsessively targeting these emissions of CO2 with defectively implemented procedures. With a variety of different propulsion solutions (electric, hybrid electric, hybrid mechanic, conventional) and different fuels (Diesel, Petrol, alternative fossil, alternative renewable) available in the near future, a more comprehensive approach based on the full fuel cycle, and eventually also the full life cycle of the vehicle appear to be necessary. The paper is a contribution to trigger further improvement to currently implemented procedures. The paper discusses the CO2 emission data in the present form, some simple but effective measures to improve the accuracy of the data collection procedure, and propose results of fuel cycle CO2-e analysis of vehicles with electric and thermal engines having different fuels. Vehicles with advanced internal combustion engines and power trains fuelled with Diesel may reach CO2-e values of 100 g/km in Australia. Use of bio-ethanol in these vehicles may deliver in Australia a significant reduction of CO2-e emissions to values below 36 g/km. Emission factors for Victoria are presently 1.23 kg CO2-e/kWh for the purchased electricity and vehicles powered by electric motors will need a significant reduction of this indirect CO2-e emission to become competitive. Values below 0.5 kg CO2-e/kWh are needed to make electric cars competitive with Diesel cars while values below 0.1 kg CO2-e/kWh are needed to make electric cars competitive with bio-ethanol cars. Compared with all these alternatives, renewable hydrogen may possibly compete with Diesel when produced with renewable energy sources and made available at the pump for less than 0.1 kg CO2-e/MJ of fuel energy, and with bio-ethanol if produced and distributed at a cost below 0.02 kg CO2-e/MJ of fuel energy.
Coupling of a KERS powertrain and a 4 Litre gasoline engine for improved fuel economy in a full size car
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Conference paper
- Relation: Paper presented at SAE 2010 Powertrains Fuels & Lubricants Meeting, San Diego, USA : 25th-27th October 2010
- Full Text:
- Description: Improvements of vehicle fuel economy are being considered using a mechanically driven flywheel to reduce the amount of mechanical energy produced by the thermal engine recovering the vehicle kinetic energy during braking. A mechanical system having an overall efficiency over a full regenerative cycle of about 70%, about twice the efficiency of battery-based hybrids, is coupled to a naturally aspirated gasoline engine powering a full size sedan. Results of chassis dynamometer experiments and engine and vehicle simulations are used to evaluate the fuel benefits introducing a kinetic energy recovery system and downsizing of the engine. Preliminary results running the new European driving cycle (NEDC) show KERS may reduce fuel consumption by 25% without downsizing, and 33% with downsizing of the 4 litre engine to 3.3 litres.
Stoichiometric H2ICEs with water injection
- Authors: Boretti, Alberto
- Date: 2011
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 36, no. 7 (2011), p. 4469-4473
- Full Text: false
- Reviewed:
- Description: For the most part, gasoline engines operate close to stoichiometry because of the high power density and the easy after treatment through the very well established three-way catalytic converter technology. The lean burn gasoline engine suffers major disadvantages for the after treatment still requiring aggressive research and development to meet future emission standards more than for the lower power density compensated by the better fuel conversion efficiency running lean. Hydrogen engines are usually run ultra-lean to avoid abnormal combustion phenomena and possibly to avoid the emission of nitrogen oxides without the difficult non-stoichiometric after treatment. While the ultra-lean combustion of hydrogen may reduce the formation of NOx within the cylinder but makes the power density very low, the only lean combustion of hydrogen requires after treatment for NOx reduction. The suppression of abnormal combustion in hydrogen engines has been a challenge for the three regimes of abnormal combustion, knock (auto ignition of the end gas region), pre-ignition (uncontrolled ignition induced by a hot spot prior of the spark ignition) and backfire (premature ignition during the intake stroke, which could be seen as an early form of pre-ignition). Direct injection and jet ignition coupled to port water injection are used here to avoid the occurrence of all these abnormal combustion phenomena as well as to control the temperature of gases to turbine in a turbocharged stoichiometric hydrogen engine. © 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Coupling of a KERS power train and a downsized 1.2TDI diesel or a 1.6TDI-JI H2 engine for improved fuel economies in a compact car
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Conference paper
- Relation: Paper presented at SAE 2010 Powertrains Fuels & Lubricants Meeting, San Diego, USA : 25th-27th October 2010
- Full Text:
- Description: Recovery of braking energy during driving cycles is the most effective option to improve fuel economy and reduce green house gas (GHG) emissions. Hybrid electric vehicles suffer the disadvantages of the four efficiency reducing transformations in each regenerative braking cycle. Flywheel kinetic energy recovery systems (KERS) may boost this efficiency up to almost double values of about 70% avoiding all four of the efficiency reducing transformations from one form of energy to another and keeping the vehicle's energy in the same form as when the vehicle starts braking when the vehicle is back up to speed. With reference to the baseline configuration with a 1.6 liters engine and no recovery of kinetic energy, introduction of KERS reduces the fuel usage to 3.16 liters per 100 km, corresponding to 82.4 g of CO2 per km. The 1.6 liters Turbo Direct Injection (TDI) Diesel engine without KERS uses 1.37 MJ per km of fuel energy, reducing with KERS to 1.13 MJ per km. Downsizing the engine to 1.2 liters as permitted by the torque assistance by KERS, the fuel consumption is further reduced to 3.04 liters per 100 km, corresponding to 79.2 g of CO2 per km and 1.09 MJ per km of fuel energy. These CO2 and fuel usage values are 11% and 13% better than those of today’s highest fuel economy hybrid electric vehicle. The car equipped with a 1.6 liter Turbo Direct Injection Jet Ignition (TDI-JI) H2ICE engine finally consumes 8.3 g per km of fuel, corresponding to only 0.99 MJ per km of fuel energy.
Vehicle driving cycle performance of the spark-less di-ji hydrogen engine
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 35, no. 10 (2010), p. 4702-4714
- Full Text:
- Reviewed:
- Description: The paper describes coupled CFD combustion simulations and CAE engine performance computations to describe the operation over the full range of load and speed of an always lean burn, Direct Injection Jet Ignition (DI-JI) hydrogen engine. Jet ignition pre-chambers and direct injection are enablers of high efficiencies and load control by quantity of fuel injected. Towards the end of the compression stroke, a small quantity of hydrogen is injected within the spark-less pre-chamber of the DI-JI engine, where it mixes with the air entering from the main chamber and auto-ignites because of the high temperature of the hot glow plug. Then, jets of partially combusted hot gases enter the main chamber igniting there in the bulk, over multiple ignition points, lean stratified mixtures of air and fuel. Engine maps of brake specific fuel consumption vs. speed and brake mean effective pressure are computed first. CAE vehicle simulations are finally performed evaluating the fuel consumption over emission cycles of a vehicle equipped with this engine. © 2010 Professor T. Nejat Veziroglu.
- Description: The paper describes coupled CFD combustion simulations and CAE engine performance computations to describe the operation over the full range of load and speed of an always lean burn, Direct Injection Jet Ignition (DI-JI) hydrogen engine. Jet ignition pre-chambers and direct injection are enablers of high efficiencies and load control by quantity of fuel injected. Towards the end of the compression stroke, a small quantity of hydrogen is injected within the spark-less pre-chamber of the DI-JI engine, where it mixes with the air entering from the main chamber and auto-ignites because of the high temperature of the hot glow plug. Then, jets of partially combusted hot gases enter the main chamber igniting there in the bulk, over multiple ignition points, lean stratified mixtures of air and fuel. Engine maps of brake specific fuel consumption vs. speed and brake mean effective pressure are computed first. CAE vehicle simulations are finally performed evaluating the fuel consumption over emission cycles of a vehicle equipped with this engine. © 2010 Professor T. Nejat Veziroglu.
Computational analysis of the lean-burn direct-injection jet ignition hydrogen engine
- Authors: Boretti, Alberto , Watson, Harry , Tempia, A.
- Date: 2010
- Type: Text , Journal article
- Relation: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering Vol. 224, no. 2 (2010), p. 261-269
- Full Text:
- Reviewed:
- Description: This paper presents a new in-cylinder mixture preparation and ignition system for various gaseous fuels including hydrogen. The system consists of a centrally located direct-injection (DI) injector and a jet ignition (JI) device for combustion of the main chamber (MC) mixture. The fuel is injected in the MC with a new-generation fast-actuating high-pressure high-flowrate DI injector capable of injection shaping and multiple events. This injector produces a bulk lean stratified mixture. The JI system uses a second DI injector to inject a small amount of fuel in a small pre-chamber (PC). A spark plug then ignites a slightly rich mixture. The MC mixture is then bulk ignited through multiple jets of hot reacting gases. Bulk ignition and combustion of the lean jet-controlled stratified MC mixture resulting from coupling DI with JI makes it possible to burn MC mixtures with fuel-to-air equivalence ratios reducing almost to zero for a throttle less control of load diesel-like and high efficiencies over almost the full range of loads. Computations are performed with hydrogen as the PC and MC fuel.
- Description: 2003007508
Modelling auto ignition of hydrogen in a jet ignition pre-chamber
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 35, no. 8 (2010), p. 3881-3890
- Full Text:
- Reviewed:
- Description: Spark-less jet ignition pre-chambers are enablers of high efficiencies and load control by quantity of fuel injected when coupled with direct injection of main chamber fuel, thus permitting always lean burn bulk stratified combustion. Towards the end of the compression stroke, a small quantity of hydrogen is injected within the pre-chamber, where it mixes with the air entering from the main chamber. Combustion of the air and fuel mixture then starts within the pre-chamber because of the high temperature of the hot glow plug, and then jets of partially combusted hot gases enter the main chamber igniting there in the bulk, over multiple ignition points, lean stratified mixtures of air and fuel. The paper describes the operation of the spark-less jet ignition pre-chamber coupling CFD and CAE engine simulations to allow component selection and engine performance evaluation. © 2010 Professor T. Nejat Veziroglu.
Experimental and computational analysis of the combustion evolution in direct-injection spark-controlled jet ignition engines fuelled with gaseous fuels
- Authors: Boretti, Alberto , Paudel, R. , Tempia, A.
- Date: 2010
- Type: Text , Journal article
- Relation: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering Vol. 224, no. 9 (2010), p. 1241-1261
- Full Text:
- Reviewed:
- Description: Jet ignition and direct fuel injection are potential enablers of higher-efficiency, cleaner internal combustion engines (ICEs), where very lean mixtures of gaseous fuels could be burned with pollutants formation below Euro 6 levels, efficiencies approaching 50 per cent full load, and small efficiency penalties operating part load. The lean-burn direct-injection (DI) jet ignition ICE uses a fuel injection and mixture ignition system consisting of one main-chamber DI fuel injector and one small jet ignition pre-chamber per engine cylinder. The jet ignition pre-chamber is connected to the main chamber through calibrated orifices and accommodates a second DI fuel injector. In the spark plug version, the jet ignition pre-chamber includes a spark plug which ignites the slightly rich pre-chamber mixture which then, in turn, bulk ignites the ultra-lean stratified main-chamber mixture through the multiple jets of hot reacting gases entering the in-cylinder volume. The paper uses coupled computer-aided engineering and computational fluid dynamics (CFD) simulations to provide better details of the operation of the jet ignition pre-chamber (analysed so far with downstream experiments or stand-alone CFD simulations), thus resulting in a better understanding of the complex interactions between chemistry and turbulence that govern the pre-chamber flow and combustion.
Improvements of vehicle fuel economy using mechanical regenerative braking
- Authors: Boretti, Alberto
- Date: 2011
- Type: Text , Journal article
- Relation: International Journal of Vehicle Design Vol. 55, no. 1 (2011), p. 35-48
- Full Text: false
- Reviewed:
- Description: The paper presents a mixed theoretical and experimental evaluation of the improvements in fuel economy that follow the introduction of a mechanical Kinetic Energy Recovery System (KERS) on a full size passenger car. This system, made up of a high speed storage flywheel and a Constant Variable Transmission (CVT), has a full regenerative cycle overall efficiency about twice the efficiency of battery-based hybrids. With reference to the baseline configuration having a 4L gasoline engine, adoption of a KERS may reduce the fuel consumption covering the NEDC by 25% without downsizing, and by 33% downsizing the engine to 3.3L. Copyright © 2011 Inderscience Enterprises Ltd.
The lean burn direct-injection jet-ignition turbocharged liquid phase LPG engine
- Authors: Boretti, Alberto , Watson, Harry
- Date: 2009
- Type: Text , Conference paper
- Relation: Paper presented at 15th Asia Pacific Automotive Engineering Conference (APAC-15), Hanoi, Vietnam : 26th - 28th October 2009
- Full Text: false
Key drivers and challenges for environmentally friendly vehicles and industry and research institutions collaboration to develop and promote alternative fuels
- Authors: Boretti, Alberto
- Date: 2009
- Type: Text , Conference paper
- Relation: Paper presented at 4th Environmentally Friendly Vehicles (EFV) Conference, New Dehli, India : 23rd - 24th November 2009
- Full Text: false
The lean burn direct-injection jet-ignition flexi gas fuel LPG/CNG engine
- Authors: Boretti, Alberto , Watson, Harry
- Date: 2009
- Type: Text , Conference paper
- Relation: Paper presented at 2009 SAE Power trains, Fuels and Lubricants Meeting, San Antonio, Texas : 2nd - 4th November 2009
- Full Text:
- Description: This paper explores through engine simulations the use of LPG and CNG gas fuels in a 1.5-liter Spark Ignition (SI) four-cylinder gasoline engine with double over head camshafts, four valves per cylinder equipped with a novel mixture preparation and ignition system comprising centrally located Direct Injection (DI) injector and Jet Ignition (JI) nozzles. With DI technology, the fuel may be introduced within the cylinder after completion of the valve events. DI of fuel reduces the embedded air displacement effects of gaseous fuels and lowers the charge temperature. DI also allows lean stratified bulk combustion with enhanced rate of combustion and reduced heat transfer to the cylinder walls creating a bulk lean stratified mixture. Bulk combustion is started by a Jet Ignition (JI) system introducing in the main chamber multiple jets of reacting gases for enhanced rate of combustion, initiating main chamber burning in multiple regions with reduced sensitivity to mixture state and composition. Coupling of JI and DI allows the development of a lean burn engine making possible operation up to main chamber overall fuel-to-air equivalence ratios reducing almost to zero and throttle-less load control by quantity of fuel injected as in the diesel engine. Results are presented in terms of maps of brake specific fuel consumption (BSFC) and efficiency and maximum power densities. Load variations are obtained by varying the air to fuel equivalence ratio from \gl\me1 up to \gl\me6.6. Maximum power densities running \gl\me1 are 80 hp/liter (60 kW/liter) with CNG and almost 90 hp/liter (67 kW/liter) with LPG. BSFCs are as low as 200 and 190 g/kWh and brake efficiencies are up to 39 and 37% respectively with LPG and CNG running lean \gl\me1.65. Low BSFCs and high brake efficiencies are possible from 25 to 100% of engine load.
Performances of a turbocharged E100 engine with direct injection and variable valve actuation
- Authors: Boretti, Alberto
- Date: 2010
- Type: Text , Conference paper
- Relation: Paper presented at SAE 2010 Powertrains Fuels & Lubricants Meeting, San Diego, USA : 25th-27th October 2010
- Full Text:
- Description: Current flexi fuel gasoline and ethanol engines have brake efficiencies generally lower than a dedicated gasoline engines because of the constraints to accommodate a variable mixture of the two fuels. Considering ethanol has a few advantages with reference to gasoline, namely the higher octane number and the larger heat of vaporization, the paper explores the potentials of dedicated pure ethanol engines using the most advanced techniques available for gasoline engines, specifically direct injection, turbo charging and variable valve actuation. Computations are performed with state-of-the-art, well validated, engine and vehicle performance simulations packages, generally accepted to produce accurate results targeting major trends in engine developments. The higher compression ratio and the higher boost permitted by ethanol allows larger top brake efficiencies than gasoline, while variable valve actuation produces small penalties in efficiency changing the load. Finally, small, high power density, turbo charged, direct injection, variable valve actuation load controlled engines are proved to operate very efficiently over driving cycles.
Direct injection of hydrogen, oxygen and water in a novel two stroke engine
- Authors: Boretti, Alberto , Osman, Azmi , Aris, Ishak
- Date: 2011
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 36, no. 16 (2011), p. 10100-10106
- Full Text: false
- Reviewed:
- Description: This short communication proposes novel two stroke engine burning hydrogen in oxygen in presence of large amounts of steam as residual gases. This engine has a bowl-in-piston combustion chamber, exhaust valves only and it uses direct injection of hydrogen, oxygen and water. Diesel-like compression ignition combustion is achieved by injecting the oxygen and the hydrogen in the surrounding steam close to a continuously operated glow plug. The operation of the engine is simulated by commercial softwares. The water injection enables acceptable metal temperatures and reduced heat losses. First computational results show brake efficiencies above 55% achieved with mass of water injected about twice the mass of oxygen and hydrogen mixture and operation with a significant amount of exhaust gas recirculation. It seems reasonable to guess efficiencies of the fully optimised and developed engine approaching the 60% mark, 20% higher than those of the state-of-the-art H 2ICEs designed for operation with air using the spark-ignition engine concept as well as of those projected for Diesel engines operating with exhaust energy recovery. Worth of mention is also the much higher power density following the two stroke operation. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.