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The paper aims to provide an assessment of the Homogeneous Charge Compression Ignition (HCCI) combustion, compared to a well-established alternative such as Direct Injection Compression Ignition (DICI) combustion, under the criteria of CO2 emission reduction potential. The assessment is performed by reviewing the relevant literature and analyzing the commercial products available on the market that are featuring these two technologies. DICI engines have demonstrated in the real world the ability to deliver top fuel conversion efficiencies of about 50%, and fuel conversion efficiencies largely above 40% over most of the load and speed range. Research-only HCCI engines have delivered fuel efficiencies well below 40% in the very few carefully selected map points where they working during carefully performed laboratory experiments.

A combustion fuel tank, an internal combustion engine (ICE), and a generator provide the best opportunity to store extra energy onboard battery electric vehicles (BEV). This energy may be used for on-demand electricity production when needed, for example, rural or interstate driving. Specific to this work, the design of a high-efficiency ICE that works at a single speed and a single load, continuously, during the operation of this series hybrid vehicle is considered. The ICE and generator provide a fuel conversion efficiency chemical to electric η~50%. The series hybrid vehicle may deliver miles-per-gallon-of-gasoline (MPG) 13% better than current production plug-in hybrid electric vehicles (PHEV), and miles-per-gallon-of-gasoline-equivalent (MPGe) 12% better than the BEV of the same platform with a larger battery pack to permit capital cities commuting.

Direct injection (DI) and jet ignition (JI), plus assisted turbocharging, have been demonstrated to deliver high efficiency, high power density positive ignition (PI) internal combustion engines (ICEs) with gasoline. Peak efficiency above 50% and power density of 340 kW/liter at the 15,000 rpm revolution limiter working overall λ=1.45 have been report-ed. Here we explore the further improvement in power density that may be obtained by replacing gasoline with ethanol or methanol, thanks to the higher octane number and the larger latent heat of vaporization, which translates in an increased resistance to knock, and permits to have larger compression ratios. Results of simulations are proposed for a numerical engine that uses rotary valves rather than poppet valves, while also using mechanical, rather than electric, assisted turbocharging. While with gasoline, the power density is 410-420 kW/liter, the use of oxygenates permits to achieve up to 475 kW/liter working with methanol.

Data of battery electric vehicles (BEV) with and without a range extender internal combustion engines (ICE) are reviewed and integrated with weight and performance models. A BEV with an on-board, high efficiency, electricity generator based on positive ignition (PI) ICEs is proposed to improve the uptake of the BEV targeting city commuters while improving their economic and environmental impacts. The small ICE, that is working stationary, fixed load and speed, and the generator similarly optimized for a single point operation, permit an efficiency fuel chemical-to-electric of about 49%. This is much better than producing electricity centralized from combustion fuels (average efficiency with included distribution and recharging losses), and it does not require any electric recharging infrastructure. The range of cars can be extended to about the same values of today's car with traditional combustion 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.

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.

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.

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.

The Wankel engine for Unmanned Aerial Vehicle (UAV) applications delivers advantages vs. piston engines of simplicity, smoothness, compactness and high power-to-weight ratio. The use of computational fluid dynamic (CFD) and computer aided engineering (CAE) tools may permit to address the major downfalls of these engines, namely the slow and incomplete combustion due to the low temperatures and the rotating combustion chambers. The paper proposes the results of CAD/CFD/CAE modelling of a Wankel engine featuring tangential jet ignition to produce faster and more complete combustion.

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.

The paper discusses the benefits of a four stroke engine having one intake and one exhaust rotary valve. The rotary valve has a speed of rotation half the crankshaft and defines an open passage that may permit up to extremely sharp opening or closing and very large gas exchange areas. This design also permits central direct injection and ignition by spark or jets. The dual rotary valve design is applied to a naturally aspirated V-four engine of 1000cc displacement, gasoline, methane or hydrogen fuelled with central direct injection and spark ignition. The engine is modeled by using a 1D engine & gas dynamics simulation software package to assess the potentials of the solution. The novelty in the proposed dual rotary valve system is the combustion chamber of good shape and high compression ratio with central direct injector and spark plug or jet ignition, coupled to the large gas exchange areas of the rotary system.

Hydrogen Internal Combustion Engine (ICE) vehicles using a traditional ICE that has been modified to use hydrogen fuel are an important mid-term technology on the path to the hydrogen economy. Hydrogen-powered ICEs that can run on pure hydrogen or a blend of hydrogen and compressed natural gas (CNG) are a way of addressing the widespread lack of hydrogen fuelling infrastructure in the near term. Hydrogen-powered ICEs have operating advantages as all weather conditions performances, no warm-up, no cold-start issues and being more fuel efficient than conventional spark-ignition engines. The Wankel engine is one of the best ICE to be converted to run hydrogen. The paper presents some details of an initial investigation of the CAD and CAE modeling of a novel design where two jet ignition devices per rotor are replacing the traditional two spark plugs for a faster and more complete combustion.

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.

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.

Real driving cycles are characterized by a sequence of accelerations, cruises, decelerations and engine idling. Recovering the braking energy is the most effective way to reduce the propulsive energy supply by the thermal engine. The fuel energy saving may be much larger than the propulsive energy saving because the ICE energy supply may be cut where the engine operates less efficiently and because the ICE can be made smaller. The present paper discusses the state of the art of hydro-pneumatic drivelines now becoming popular also for passenger cars and light duty vehicle applications permitting series and parallel hybrid operation. The papers presents the thermal engine operation when a passenger car fitted with the hydro-pneumatic hybrid driveline covers the hot new European driving cycle. From a reference fuel consumption of 4.71 liters/100 km with a traditional driveline, the fuel consumption reduces to 2.91 liters/100 km.

The paper presents a novel concept of a very efficient transportation engines for operation with CNG, LNG or LPG. The paper considers the options of single fuel design with jet ignition and dual fuel design with Diesel and gas. In the first option gas fuel is injected into the main chamber by a direct injector and ignited by jet ignition. In the second option gas fuel is injected into the main chamber by a direct injector and ignited by the direct injection of a small quantity of Diesel fuel. Injection and ignition may be tuned to control the amount of premixed and diffusion combustion to produce the best fuel conversion efficiency vs. load and speed requirements within the prescribed pressure and temperature constraints.

The paper presents a novel design for a two stroke thermal engine that delivers excellent fuel economy and low emissions within the constraints of today's cost, weight and size. The engine features asymmetrical port timing through a novel translating and rotating piston mechanism. The engine is externally scavenged and supercharged, has wet sump and oil pressure lubrication, direct injection, it is lightweight, easy to build, with minimal number of parts, low production cost, ability to be balanced and compact design. The two stroke mechanism produces a linear motion of the pistons as well as an elliptical path on the surface of the cylinder. This allows the piston to sweep as well as travel past the ports. Suitable slots around the raised lip of the piston generate the asymmetry that makes the exhaust port to open first and to close first. The inlet port remains open to complete the cylinder charging and allow supercharging. Direct fuel injection is adopted for best results.

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.

The paper presents a survey of the opportunities to convert compression ignition heavy duty truck engines to work on single or dual fuel modes with CNG. In one popular option, the compression ignition engine is converted to spark ignition with throttle load control and port injection of the CNG. In another option of increasing popularity, the LNG is directly injected and ignited by direct injection of pilot Diesel. This latter option with direct injection of natural gas and diesel through separate injectors that are fully independent in their operation is determined to be the most promising, as it is expected to deliver better power density and similar part load fuel economy to Diesel.

Kinetic energy recovery systems (KERS) placed on one axle coupled to a traditional thermal engine on the other axle is possibly the best solution presently available to dramatically improve the fuel economy while providing better performances within strict budget constraints. Different KERS may be built purely electric, purely mechanic, or hybrid mechanic/electric differing for round trip efficiency, packaging, weights, costs and requirement of further research and development. The paper presents an experimental analysis of the energy flow to and from the battery of a latest Nissan Leaf covering the Urban Dynamometer Driving Schedule (UDDS). This analysis provides a state-of-the-art benchmark of the propulsion and regenerative braking efficiencies of electric vehicles with off-the-shelve technologies.