Studying Ignition Delay Time of Lubricant Oil Mixed with Alcohols, Water and Toluene in IQT and CVCC 2020-01-1422

The auto-ignition of liquid fuel and lubricant oil droplets is considered as one of the possible sources of pre-ignition. Researchers are continually finding new ways to form advanced lubricant oil by changing its composition and varying different oil additives to prevent the occurrence of this event. This study investigates additives for lubricants to suppress its auto-ignition tendency. Three sets of mixtures were prepared. The first set of mixtures were prepared by adding different alcohols namely ethanol, and methanol to the commercial lubricant oil (SAE 15W-40) in ratio of 1 - 5 % by vol The second set of mixtures were prepared by mixing SAE 15W-40 with aforementioned alcohols (1 % vol.) and H₂O (1 % vol.). Lastly, the third set of mixtures were prepared by adding toluene to SAE 15W-40 in (1 % - 5% by vol.). Two experimental setups were used in the current work. An Ignition Quality Tester (IQT) was used to investigate the mixtures’ ignition delay time (IDT) following standard ASTM D6890 procedure, and a larger constant volume combustion chamber (CVCC) was used to investigate the combustion characteristics of a suspended single oil droplet. In the CVCC chamber, the droplet was ignited in an atmosphere of air at 300 °C and pressure ranging from 4 bar - 22 bar at 6 bar interval pressures.

IDT of lubricant oil was considered as the base IDT, which was compared to those of other mixtures. Addition of alcohols and water in lubricant oil showed a significant increase in IDT compared to toluene addition. On the contrary, the addition of toluene resulted in a decrease in IDT. Among the alcohols, methanol addition showed higher IDT than ethanol addition. Alcohols increased the IDT effectively only beyond the addition of > 4 % by vol.