The comparison of combustion, engine performance and emission characteristics of ethanol, methanol, fusel oil, butanol, isopropanol and naphtha with n-heptane blends on HCCI engine

Abstract

Recently, there has been increased emphasis on the homogenous charge compression ignition (HCCI) engine which offers higher thermal efficiency and ultra-low NOx and soot emissions. The central thesis of this paper is that the effects of different alternative fuels with different physical and chemical properties on combustion, performance and emissions in a HCCI engine. Ethanol (E25), methanol (M25), fusel oil (F25), butanol (B25), isopropanol (IP25) and naphtha (N25) were used alternative fuels blended with n-heptane 25% by volume. The experiments were performed at 333 K intake air temperature (IAT) and with various excess air coefficient in a single cylinder SI-HCCI test engine. The parameters such as in-cylinder pressure, heat release rate (HRR), start of combustion (SOC), combustion duration, CA50, indicated thermal efficiency (ITE), COVIMEP, maximum pressure rise rate (MPRR), HC and CO emissions were investigated. In addition, operating range of the fuels were also defined. The results showed that N25 has the largest operating range among all the test fuels. The maximum indicated mean effective pressure (IMEP) value was obtained for E25 as 5.71 bar at 800 rpm engine speed and λ = 1.3. Knocking tendency were determined for all test fuels but it decreased with increasing lambda value. The highest HC and CO emissions were obtained for F25 due to the water content of the fuel. On the contrary, the lowest HC and CO emissions were obtained for N25.