Expanding the Experimental Capabilities of the Ignition Quality Tester for Autoigniting Fuels

This paper reports the development of new fuel ignition quality and combustion experiments performed using the Ignition Quality Tester (IQT). Prior SAE papers (961182, 971636, 1999-01-3591, and 2001-01-3527) documented the development of the IQT constant volume combustion chamber experimental apparatus to measure ignition qualities of diesel-type fuels. The ASTM International test method D6890 was developed around the IQT device to allow the rapid determination of derived cetane number (DCN).

Interest in chemical kinetic models for the ignition of diesel and biodiesel model compounds is increasing to support the development of advanced engines and fuels. However, rigorous experimental validation of these kinetic models has been limited for a variety of reasons. Shock tubes and rapid compression machines are typically limited to premixed gas-phase studies, for example. Since the IQT is a constant volume spray combustion system that allows ignition and combustion studies of low-volatility fuels, the IQT has potential to generate experimental data relevant to validating kinetic ignition models by virtue of its well-controlled temperature, pressure, and start of fuel injection. IQT-based DCN measurements have been shown to be reliable over a range of cetane numbers for middle distillate and some non-conventional diesel fuels. However, significantly improved understanding of the IQT's injection, ignition and combustion processes are necessary to facilitate expanded use of this device for fuels research. This paper reports on the development of the IQT as a heterogeneous combustion research device enabling the study of fuel ignition and combustion in terms of fuel chemistry and physical properties.

This development includes fuel injection process improvements based on detailed injection spray characterization and on-line measurement of NO_x as an indicator of combustion quality. The results illustrate the potential of the IQT as a research device, filling an experimental void for low-volatility fuels and enabling ignition studies of research fuels, which may only be available in small quantities.