Search Results

This paper describes the demands and potentials of current and future gasoline combustion systems regarding the fuels gasoline, natural gas, and Hydrogen. At first, fuel specifications that are crucial for the spark ignition process are compared. These are compared with the requirements of the combustion system. Potentials for the compensation of power loss, efficiency improvement and emission reduction using alternative fuels are discussed taking into account fuel-specific properties. While full load drawbacks with natural gas compared with gasoline can be reduced to less than 5% by combustion system tuning, Hydrogen operation with port injection leads to reductions of about 25 to 30%. These drawbacks can be compensated with boosting where both methane and Hydrogen are qualified due to their burning characteristics. Compared with λ=1 operation especially Hydrogen offers efficiency benefits of up to 30% in a wide mapping range due to quality control.

Based on the TurboDISI engine presented earlier [1], [2], a new Spray Guided Turbo (SGT) concept with enhanced engine performance was developed. The turbocharged engine was modified towards utilizing a spray-guided combustion system with a central piezo injector location. Higher specific power and torque levels were achieved by applying specific design and cooling solutions. The engine was developed utilizing a state-of-the-art newly developed charge motion design (CMD) process in combination with single cylinder investigations. The engine control unit has a modular basis and is realized using rapid prototyping hardware. Additional fuel consumption potentials can be achieved with high load EGR, use of alternative fuels and a hybrid powertrain. The CO2 targets of the EU (120 g/km by 2012 in the NEDC) can be obtained with a mid-size vehicle applying the technologies presented within this paper.

Reduced resources of mineral oil and growing world energy consumption will increase the demand for alternative energies. Natural gas is gaining interest due to the worldwide ratio of assured reserves of natural gas and crude oil shifting towards natural gas. The main motivation for the use of gas are oil substitution, source diversification and independency of fuel supply as well as the reduction of greenhouse gases especially CO2. Natural gas operation usually reduces the torque of a naturally aspirated engine due to fuel properties. The paper shows that an optimization of a naturally aspirated engine layout can reduce the loss significantly. Besides compression ratio optimization also intake manifold and camshaft redesign for natural gas specific application can reduce the torque loss to a minimum. Super charging or turbo charging of spark ignition engines can effectively overcome the torque loss.

Increasingly stringent pollutant and CO2 emission standards require the car manufacturers to investigate innovative solutions to further improve the fuel economy of their fleets. Among these techniques, an extremely lean combustion has a large potential to simultaneously reduce the NOx raw emissions and the fuel consumption of spark-ignition engines. Application of pre-chamber ignition systems is a promising solution to realize a favorable air/fuel mixture ignitability and an adequate combustion speed, even with very lean mixtures. In this work, the combustion characteristics of an active pre-chamber system are experimentally investigated using a single-cylinder research engine. Conventional gasoline fuel is injected into the main chamber, while the pre-chamber is fed with compressed natural gas. In a first stage, an experimental campaign was carried out at various speeds, spark timings and air-fuel ratios.