HAJI Operation in a Hydrogen-Only Mode for Emission Control at Cold Start

Experimental and computational analysis of the combustion evolution in direct-injection spark-controlled jet ignition engines fuelled with gaseous fuels

“…While the diesel truck and gasoline passenger car models are validated versus engine dynamometer data, the LPG truck model is not validated because the DI-JI engine concept is still in a preliminary stage with funding for prototyping and experimental testing still unavailable. However, considering that the predicted fast rates of combustion of the DI-JI engine concept are in line with previous experiments with inhomogeneous charge [19] and homogeneous charge [15][16][17][18][19][20][21] configurations, they are therefore quite reliable; the brake efficiency predictions just follow these fast rates of combustion and share their reliability. The predicted top brake efficiencies, but even more so the predicted part-load efficiencies of the DI-JI LPG engine, are very significant, because they show the opportunity to achieve not only the diesel top brake Computed brake efficiency map of a 4-l, naturally aspirated, stoichiometric gasoline engine for a passenger car (BMEP versus engine speed for various brake efficiencies (per cent)) efficiencies but also the diesel part-load brake efficiencies on igniting with reacting jets controlled by a spark discharge to produce a slightly lean mixture within part of the in-cylinder volume.…”

“…The latest modelling activity provides a novel detailed description of the phenomena governing the pre-chamber and mainchamber mixture formation and combustion evolution, providing both a better understanding of the potentials of DI coupled to JI to achieve very fast combustion rates in the case of mixtures that are also very lean (only conjectured in previous experiments [19]) and something that is worth sharing with the wider community. The computed fast rate of combustion of the DI-JI engine concept is also in line with the other experiments performed on different pre-chamber and main-chamber geometries in the case of PFI and homogeneous charge [15][16][17][18][19][20][21]. The computed fast rate of combustion of the DI-JI engine concept has therefore to be considered reliable.…”

Direct Injection and Spark Controlled Jet Ignition to Convert A Diesel Truck Engine to LPG

“…The jets of reacting gases enhance combustion of lean stratified mixtures within the main chamber through a combination of large thermal energy, multiple ignition points and presence of active radical species. Prior simulations and experiments jet igniting homogeneous charges of hydrocarbon fuels have shown the opportunity to achieve very fast combustion rates with reduced formation of HC and CO even running very lean [24][25][26][27][28][29][30]. Lean stratified mixtures are expected to further enhance the always lean burn option enabled by jet ignition.…”

“…This is a major limitation of traditional pre-chamber engines even at very lean operating conditions. The jet ignition device was originally intended to replace a standard 14 mm thread spark plug in port fuel injected engines with lean premixed combustion [24][25][26][27][28][29][30]. Minimum development investments could allow production of miniaturized jet ignition devices the same size as a traditional spark plug with better opportunity for the technology to be applied to existing engine layouts.…”

“…The JI pre-chamber is designed to be fitted within the traditional spark plug thread =14 mm to only marginally increases the level of complexity of designing a cylinder head with a JI pre-chamber replacing the standard main chamber SP and allow testing on existing hardware. The 1-1.5 cm 3 volume and the operation with a slightly fuel rich mixture are the ones that have provided so far the best results [24][25][26][27][28][29][30]. A standard LP GDI injector (for example the low pressure ones proposed in [11,14]), can be used as the pre-chamber injector for prototype applications where again durability and dry run capability are not an issue with all the fuels.…”