Investigations on the effects of injection parameters and EGR in a glow plug assisted methanol fueled Hot Surface Ignition (HSI) Engine

Abstract

Methanol can be produced from renewable sources and is also clean burning. Hence it is an ideal alternative fuel for transportation applications. However, its low cetane number prevents its direct application in compression ignition (CI) engines. One of the promising but not widely explored methods is to use a hot surface for its ignition in CI engines at normal compression ratios. In this work a turbocharged automotive common rail diesel engine was modified to operate in the hot surface ignition (HSI) mode with methanol as the sole fuel with 3% by mass of lubricity and corrosion inhibiting additive. Initially, a single pulse injection (SPI) strategy was employed at different injection timings at a BMEP of 8 bar. Subsequently a double pulse injection (DPI) strategy was employed and the effects of gap between the injection pulses, injection timing and injection pulse width share among the two pulses were studied. The HSI mode of neat methanol performed with comparable brake thermal efficiency (BTE), reduced combustion rates and hence low NOx emission levels with respect to diesel operation when the DPI mode was employed with almost equal pulse width share. Engine performance was better at rail pressures of around 800 bar. Hot EGR of up to 8% was beneficial as it reduced the engine-out NOx without affecting the BTE. The engine was operated at different BMEPs in the range of 4–10 bar and compared with the baseline diesel operation. The BTE was similar to the baseline diesel engine at all loads. Engine-out NOx was lower than diesel operation by 23.6%–61.5% while near zero smoke levels and similar CO and THC emissions (after the DOC) were observed. Though slipped methanol and formaldehyde were the significant unregulated emissions, they were reduced to very low levels after the DOC.