Adjusting the operating characteristics to improve the performance of an emulsified palm oil methyl ester run diesel engine

The popularity of emulsified fuels as alternative to diesel is cumulative. The water in diesel emulsion is the most practiced one. The presence of water in emulsion and its micro-explosion reduces emissions. However, the emulsified biodiesel is not properly explored. The reason may be due to its lesser calorific value that does not augment efficiency. Alongside oxygenated biodiesel generally emits higher NOx than diesel. Therefore, the present investigation targets at finding the performance, combustion and emission characteristics of emulsified biodiesel in a diesel engine at an elevated compression ratio (CR) and retarded injection timing (IT). This is because; at this CR-IT combination emulsified fuel will be injected at the warmer environment, mechanically created inside the cylinder. The objective is to achieve a faster combustion, lower ignition delay (ID), improved performance and emission characteristics. The biodiesel used in this work is the palm oil methyl ester (POME). The prepared two-phase water in POME (WIP) emulsion is tested in a variable compression ratio (VCR) diesel engine at CR = 18 and IT = 20 degrees BTDC. The results obtained are then compared with the POME run engine data under the same CR and IT specifications. Additionally, experiments have also been conducted in the same engine at CR = 17.5 and IT = 23 degrees BTDC to compare its results with those of WIP and POME run engines. (C) 2013 Elsevier Ltd. All rights reserved.