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Technical Paper

Improvements of Vehicle Fuel Economy Using Mechanical Regenerative Braking

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.
Journal Article

Improving the Efficiency of LPG Compression Ignition Engines for Passenger Cars through Waste Heat Recovery

The turbocharged direct injection lean burn Diesel engine is the most efficient now in production for transport applications with full load brake efficiencies up to 40 to 45% and reduced penalties in brake efficiencies reducing the load by the quantity of fuel injected. The secrets of this engine's performances are the high compression ratio and the lean bulk combustion mostly diffusion controlled in addition to the partial recovery of the exhaust energy to boost the charging efficiency. The major downfalls of this engine are the carbon dioxide emissions and the depletion of fossil fuels using fossil diesel, the energy security issues of using foreign fossil fuels in general, and finally the difficulty to meet future emission standards for soot, smoke, nitrogen oxides, carbon oxide and unburned hydrocarbons for the combustion of the fuel injected in liquid state and the lack of maturity the lean after treatment system.
Technical Paper

Improving the Efficiency of Turbocharged Spark Ignition Engines for Passenger Cars through Waste Heat Recovery

The turbocharged direct injection stoichiometric spark ignition gasoline engine has less than Diesel full load brake engine thermal efficiencies and much larger than Diesel penalties in brake engine thermal efficiencies reducing the load by throttling. This engine has however a much better power density, and therefore may operate at much higher BMEP values over driving cycles reducing the fuel economy penalty of the vehicle. This engine also has the advantage of the very well developed three way catalytic converter after treatment to meet future emission regulations. In these engines the efficiency may be improved recovering the waste heat, but this recovery may have ultimately impacts on both the in cylinder fuel conversion efficiency and the efficiency of the after treatment.
Technical Paper

KERS Braking for 2014 F1 Cars

Small, high power density turbocharged engines coupled to kinetic energy recovery systems are one of the key areas of development for both passenger and racing cars. In passenger cars, the KERS may reduce the amount of thermal energy needed to reaccelerate the car following a deceleration recovering part of the braking energy. This translates in a first, significant fuel energy saving. Also considering the KERS torque boost increasing the total torque available to accelerate the car, large engines working at very low brake mean effective pressures and efficiencies over driving cycles may also be replaced by small higher power density engines working at much higher brake mean effective pressures and therefore much higher part load efficiencies. In racing cars, the coupling of small engines to KERS may improve the perception of racing being more environmentally friendly. The KERS is more a performance boost than a fuel saving device, permitting about same lap times with smaller engines.
Technical Paper

Modeling of Engine and Vehicle for a Compact Car with a Flywheel Based Kinetic Energy Recovery Systems and a High Efficiency Small Diesel Engine

Recovery of kinetic energy during driving cycles is the most effective option to improve fuel economy and reduce green house gas (GHG) emissions. Flywheel kinetic energy recovery systems (KERS) may boost this efficiency up to values of about 70%. An engine and vehicle model is developed to simulate the fuel economy of a compact car equipped with a TDI diesel engine and a KERS. Introduction of KERS reduces the fuel used by the 1.6L TDI engine to 3.16 liters per 100 km, corresponding to 82.4 g of CO₂ per km. Downsizing the engine to 1.2 liters as permitted by the torque assistance by KERS, further reduces the fuel consumption to 3.04 liters per 100 km, corresponding to 79.2 g of CO₂ per km. These CO₂ values are 11% better than those of today's most fuel efficient hybrid electric vehicle.
Journal Article

Novel Crankshaft Mechanism and Regenerative Braking System to Improve the Fuel Economy of Light Duty Vehicles and Passenger Cars

Improvements of vehicle fuel economy may be achieved by the introduction of advanced internal combustion engines (ICE) improving the fuel conversion efficiency of the engine and of advanced power trains (PWT) reducing the amount of fuel energy needed to power the vehicle. The paper presents a novel design of a variable compression ratio advanced spark ignition engine that also permits an expansion ratio that may differ from the compression ratio hence generating an Atkinson cycle effect. The stroke ratio and the ratio of maximum to minimum in-cylinder volumes may change with load and speed to provide the best fuel conversion efficiency. The variable ratio of maximum to minimum in-cylinder volumes also improves the full load torque output of the engine.
Technical Paper

Novel Engine Concepts for Multi Fuel Military Vehicles

The paper considers different options to design a multi fuel engine retaining the power densities and efficiencies of the latest Diesel heavy duty truck engines while operating with various other fuels. In a first option, an igniting Diesel fuel is coupled to a main fuel that may have any Cetane or octane number in a design where every engine cylinder accommodates a direct Diesel injector, a glow plug and the multi fuel direct injector in a bowl-in-piston combustion chamber configuration. Alternatively, an igniting gasoline fuel replaces the Diesel fuel in a design where every engine cylinder accommodates a gasoline direct injector, the multi fuel direct injector and a jet ignition pre chamber also with a bowl-in-piston combustion chamber configuration. Both these designs permit load control by changing the amount of fuel injected and Diesel-like, gasoline-like and mixed Diesel/gasoline-like modes of operation modulating the amount of the multi fuel that burn premixed or diffusion.
Technical Paper

Numerical Investigation of Dual Fuel Diesel-CNG Combustion on Engine Performance and Emission

With the purpose of reducing emission level while maintaining the high torque character of diesel engine, various solutions have been proposed by researchers over the world. One of the most attractive methods is to use dual fuel technique with premixed gaseous fuel ignited by a relatively small amount of diesel. In this study, Methane (CH4), which is the main component of natural gas, was premixed with intake air and used as the main fuel, and diesel fuel was used as ignition source to initiate the combustion. By varying the proportion of diesel and CH4, the combustion and emissions characteristics of the dual fuel (diesel/CH4) combustion system were investigated. Different cases of CFD studies with various concentration of CH4 were carried out. A validated 3D quarter chamber model of a single cylinder engine (diesel fuel only) generated by using AVL Fire ESE was modified into dual fuel mode in this study.
Technical Paper

Optimizing the Design of the Air Flow Orifice or Restrictor for Race Car Applications

Several race car competitions seek to limit engine power through a rule that requires all of the engine combustion air passes through a hole of prescribed diameter. As the approach and departure wall shapes to this hole, usually termed orifice or restrictor are not prescribed, there is opportunity for innovation in these shapes to obtain maximum flow and therefore power. This paper reports measurements made for a range of restrictor types including venturis with conical inlets and outlets of various angles and the application of slotted throats of the ‘Dall tube’ type. Although normal venturis have been optimized as subsonic flow measuring devices with minimum pressure losses, at the limit the flow in the throat is sonic and the down stream shocks associated with flow transition from sub-sonic to sonic are best handled with sudden angular changes and the boundary layer minimized by the corner slots between the convergent and divergent cones.
Technical Paper

Performances of a Turbocharged E100 Engine with Direct Injection and Variable Valve Actuation

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.
Journal Article

Progress of Direct Injection and Jet Ignition in Throttle-Controlled Engines

Direct injection and jet ignition is becoming popular in electrically assisted, turbocharged, F1 engines because of the pressure to reduce fuel consumption. Operation from homogeneous stoichiometric up to lean of stoichiometry stratified about λ = 1.5, occurs with fast combustion of reduced cyclic variability thanks to the enhanced ignition by multiple jets of hot, partially reacting products travelling through the combustion chamber. The fuel consumption has thus been drastically reduced in an engine that is, however, still mostly throttle controlled. The aim of the present paper is to show the advantages of direct injection and jet ignition based on model simulations of the operation of a high-performance throttle-controlled engine featuring rotary valves.

Prototype Powertrain in Motorsport Endurance Racing

Racing continues to be the singular, preeminent source of powertrain development for automakers worldwide. Engineering teams rely on motorsports for the latest prototype testing and research. Endurance racing provides the harshest and most illuminating stage for system design validation of any motorsport competition. While advancements throughout the 20th Century brought about dramatic increases in engine power output, the latest developments from endurance racing may be more impactful for fuel efficiency improvements. Hybrid powertrains are a critical area of research for automakers and are being tested on the toughest of scales. Prototype Powertrain in Motorsport Endurance Racing brings together ten vital SAE technical papers and SAE Automotive Engineering magazine articles surrounding the advancements of hybrid powertrains in motorsports.
Technical Paper

Reduced Warm-Up and Recovery of the Exhaust and Coolant Heat with a Single Loop Turbo Steamer Integrated with the Engine Architecture in a Hybrid Electric Vehicle

The paper considers a novel waste heat recovery (WHR) system integrated with the engine architecture in a hybrid electric vehicle (HEV) platform. The novel WHR system uses water as the working media and recovers both the internal combustion engine coolant and exhaust energy in a single loop. Results of preliminary simulations show a 6% better fuel economy over the cold start UDDS cycle only considering the better fuel usage with the WHR after the quicker warm-up but neglecting the reduced friction losses for the warmer temperatures over the full cycle.
Technical Paper

Regenerative Braking of a 2015 LMP1-H Racing Car

Regenerative braking coupled to small high power density engines are becoming more and more popular in motorsport applications delivering improved performances while increasing similarities and synergies in between road and track applications. Computer aided engineering (CAE) tools integrated with the telemetry data of the car are an important component of the product development. This paper presents the CAE model developed to describe the race track operation of a LMP1-H racing car covering one lap of the Le Mans circuit. The friction and regenerative braking is discussed.
Technical Paper

The Future of the Internal Combustion Engine After “Diesel-Gate”

The paper captures the recent events in relation with the Volkswagen (VW) Emissions Scandal and addresses the impact of this event on the future of power train development. The paper analyses the impact on the perspectives of the internal combustion engine, the battery based electric car and the hydrogen based technology. The operation of the United States Environmental Protection Agency (EPA), VW and the United States prosecutor, sparked by the action of the International Council on Clean Transportation (ICCT) is forcing the Original Equipment Manufacturers (OEM) towards everything but rationale immediate transition to the battery based electric mobility. This transition voids the value of any improvement of the internal combustion engine (ICE), especially in the lean burn, compression ignition (CI) technology, and of a better hybridization of powertrains, both options that have much better short term perspectives than the battery based electric car.
Technical Paper

Turbo/Supercharged Two/Four Stroke Engines with One Intake and One Exhaust Horizontal Rotary Valve per Cylinder and Central Direct Injection and Ignition

The present paper is an introduction to a novel rotary valve engine design addressing the major downfalls of past rotary valves applications while permitting the typical advantages of the rotary valves. Advantages of the solution are the nearly optimal gas exchange, mixture formation, ignition and combustion evolution thanks to the large gas exchange areas from the two horizontal valves per engine cylinder, the good shape of the combustion chamber, the opportunity to place a direct fuel injector and a spark or jet ignition device at the centre of the chamber. The novel engine design also permits higher speed of rotation not having reciprocating poppet valves and the reduced friction losses of the rotating only distribution. This translates in better volumetric efficiencies, combustion rates and brake mean effective pressures for improved power density and fuel efficiency. Additional advantages are the reduced weight and the better packaging.
Technical Paper

Two Stroke Direct Injection Jet Ignition Engines for Unmanned Aerial Vehicles

Unmanned Aerial Vehicles (UAV) require simple and reliable engines of high power to weight ratio. Wankel and two stroke engines offer many advantages over four stroke engines. A two stroke engines featuring crank case scavenging, precise oiling, direct injection and jet ignition is analyzed here by using CAD, CFD and CAE tools. Results of simulations of engine performances are shown in details. The CFD analysis is used to study fuel injection, mixing and combustion. The CAE model then returns the engine performances over the full range of loads and speeds with the combustion parameters given as an input. The use of asymmetric rather than symmetric port timing and supercharging scavenging is finally suggested as the best avenue to further improve power density and fuel conversion efficiency.
Technical Paper

Use of Bio-Ethanol and Bio-Diesel The Key Solution for a More Sustainable Road Transport

Life Cycle Analysis (LCA) of alternative transportation fuels clearly shows the advantages of reducing the use of non renewable fossil fuels vs. renewable biologic novel fuels to reduce the emissions of carbon dioxide. Being based on the natural recycle of carbon dioxide through the use of renewable energy sources, use of these renewable fuels do not imply depletion of natural resources and is therefore sustainable in the long term. Renewable fuels and advanced internal combustion engines and powertrains are the technologies that in addition to be the most likely to produce benefits in term of carbon balance and fossil fuel saving, are also those that unequivocally have the smallest ecological footprint considering all the environmental implication of transportation technologies, with all the other more exotic solutions having much higher environmental costs to produce, use and dispose of alternative transportation technologies.
Technical Paper

Use of Variable Valve Actuation to Control the Load in a Direct Injection, Turbocharged, Spark-Ignition Engine

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.