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 NOx 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.