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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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:
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:
Downsizing and Turbo Charging (TC) and Direct Injection (DI) may be combined with Variable Valve Actuation (VVA) to better deal with the challenges of fuel economy enhancement. VVA may control the load without throttle; control the valve directly and quickly; optimize combustion, produce large volumetric efficiency. Benefits lower fuel consumption, lower emissions and better performance and fun to drive. The paper presents an engine model of a 1.6 litre TDI VVA engine specifically designed to run pure ethanol, with computed engine maps for brake specific fuel consumption and efficiency. The paper also presents driving cycle results obtained with a vehicle model for a passenger car powered by this engine and a traditional naturally aspirated gasoline engine. Preliminary results of the VVA system coupled with downsizing, turbo charging and Direct Injection permits significant driving cycle fuel economies.
Description:
Downsizing and Turbo Charging (TC) and Direct Injection (DI) may be combined with Variable Valve Actuation (VVA) to better deal with the challenges of fuel economy enhancement. VVA may control the load without throttle; control the valve directly and quickly; optimize combustion, produce large volumetric efficiency. Benefits lower fuel consumption, lower emissions and better performance and fun to drive. The paper presents an engine model of a 1.6 litre TDI VVA engine specifically designed to run pure ethanol, with computed engine maps for brake specific fuel consumption and efficiency. The paper also presents driving cycle results obtained with a vehicle model for a passenger car powered by this engine and a traditional naturally aspirated gasoline engine. Preliminary results of the VVA system coupled with downsizing, turbo charging and Direct Injection permits significant driving cycle fuel economies.
Experimental and computational analysis of the combustion evolution in direct-injection spark-controlled jet ignition engines fuelled with gaseous fuels
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.
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.
Description:
Jet ignition and direct fuel injection are potential enablers of higher efficiency, cleaner Internal Combustion Engines (ICE). Very lean mixtures of gaseous fuels could be burned with pollutants formation below Euro 6 levels (in the ultra-lean mode), efficiencies approaching 50% full load and small efficiency penalties when operating part load. The lean burn Direct Injection Jet Ignition (DI-JI) ICE uses a fuel injection and mixture ignition system comprising one main chamber direct fuel injector and one small size 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 direct fuel injector. In the spark plug version, the jet ignition pre-chamber includes a spark plug that ignites the slightly rich pre-chamber mixture that then bulk ignites the ultra lean, stratified main chamber mixture through multiple jets of hot reacting gases entering the in-cylinder. This paper uses coupled CAE and CFD simulations to provide better details of the operation of the jet ignition pre-chamber. They have been analysed so far with downstream experiments or standalone CFD simulations, enabling a better understanding of the complex interactions between chemistry and turbulence that governs the pre-chamber flow and combustion. CAE simulations are performed for a production 11 litre, in-line six, 24 valve Diesel Truck engine. It is turbo charged, with inter cooler and cooled Exhaust Gas Recirculation (EGR). It is modified to fit the jet ignition pre-chamber and run propane fuel by replacing the Diesel fuel injector with a direct injector for the LPG fuel plus reducing the compression ratio and changing the piston shape. Operation full load with same air-to-fuel equivalence ratio
Description:
Jet ignition and direct fuel injection are potential enablers of higher efficiency, cleaner Internal Combustion Engines (ICE). Very lean mixtures of gaseous fuels could be burned with pollutants formation below Euro 6 levels (in the ultra-lean mode), efficiencies approaching 50% full load and small efficiency penalties when operating part load. The lean burn Direct Injection Jet Ignition (DI-JI) ICE uses a fuel injection and mixture ignition system comprising one main chamber direct fuel injector and one small size 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 direct fuel injector. In the spark plug version, the jet ignition pre-chamber includes a spark plug that ignites the slightly rich pre-chamber mixture that then bulk ignites the ultra lean, stratified main chamber mixture through multiple jets of hot reacting gases entering the in-cylinder. This paper uses coupled CAE and CFD simulations to provide better details of the operation of the jet ignition pre-chamber. They have been analysed so far with downstream experiments or standalone CFD simulations, enabling a better understanding of the complex interactions between chemistry and turbulence that governs the pre-chamber flow and combustion. CAE simulations are performed for a production 11 litre, in-line six, 24 valve Diesel Truck engine. It is turbo charged, with inter cooler and cooled Exhaust Gas Recirculation (EGR). It is modified to fit the jet ignition pre-chamber and run propane fuel by replacing the Diesel fuel injector with a direct injector for the LPG fuel plus reducing the compression ratio and changing the piston shape. Operation full load with same air-to-fuel equivalence ratio
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.
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.