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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 concept of very efficient transportation engines for operation with CNG, LNG or LPG. The combustion system permits mixed diesel/gasoline-like operation changing the load by quantity of fuel injected and modulating the premixed and diffusion combustion phases for high fuel energy transfer to piston work. A waste heat recovery system (WHRS) is then recovering the intercooler and engine coolant energy plus the exhaust energy. The WHRS uses a power turbine on the exhaust and a steam turbine feed by a single loop turbo-steamer. The WHRS is the enabler of much faster warm up of the engine and further improvements of the top fuel conversion efficiency to above 50% for the specific case with reduced fuel efficiency penalties changing the load or the speed.

The consumption of fossil fuels is one of the largest problems facing humankind. One of the heaviest users of non-renewable energy sources is the transport industry. Tightening worldwide legislation aims to place restrictions on the transport industry to reduce its use of fossil fuels and reduce the levels of pollution being released to the atmosphere. Although several different alternatives to the vehicles only powered by internal combustion engine (ICEs) have been investigated, none have as yet become equally widespread. Alternative research into development of hybrid vehicles was specifically concerned with electric hybrids especially for passenger vehicles. Currently there is a resurgence of interest in the Hybrid Hydraulic Vehicle (HHV) in application to commercial and to a lesser degree to passenger vehicles. This paper gives an overview of hydraulic hybrid technology.

The introduction of advanced internal combustion engine mechanisms and powertrains may improve the fuel conversion efficiency of an engine and thus reduce the amount of 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 induction stroke therefore 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 power output of the engine. Results of vehicle driving cycle simulations of a light-duty gasoline vehicle with the advanced engine show dramatic improvements of fuel economy.

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.