DOI: 10.36347/sjet.2020.v08i07.001

Pages: 117-126

Fatty acid methyl ester (FAME) is the most attractive alternative fuel for diesel engines which could resolve ongoing concerns about environmental issues and sustainable energy due to its carbon-neutral characteristic. The main objective of this research was to generate fundamental data on ignition delay and combustion characteristics of FAME. Experiments were carried out in a constant-volume combustion vessel under diesel-engine conditions to study the effects of temperature and pressure on ignition delay and combustion characteristics. Several kinds of BDF fuels (biodiesel fuel or FAME) produced from waste edible oil and having different properties were tested and compared to a standard gas-oil. The experimental results show the strong influence of temperature and pressure on the ignition and combustion processes for the tested fuels. It is shown that (i) the fresh BDF exhibits a longer ignition delay than the gas-oil (conventional diesel fuel), (ii) a small amount of isopropyl alcohol as an additive in BDF promotes the ignition, (iii) the oxidized BDF with acid value changed from 0.1 for the fresh one to 0.22 (KOHmg/g) has a shortened ignition delay, to almost the same as standard gas-oil, and (iv) the blend of BDF with twenty percent by volume to gas-oil results in a reasonable ignition delay. Additionally, the results at pressure 2MPa, which simulates conditions of PCCI (premixed charge compression ignition) engine operations in future engine trends, present two-stage ignition and low-temperature combustion characteristics for both BDF and gas-oil. These findings help improve considerations for the optimal design and operation of diesel engines fuelled with FAME.