Investigations of Combustion Properties of Liquid Fuels in a Constant Volume Bomb

At the Marine Technology Centre in Trondheim, Norway, a “constant volume bomb” has been used since 1980 in the studies of ignition and combustion properties of liquid fuels.

These investigations have been performed in parallel with similar research activities on diesel engines. However, this test rig enables us to carry out far more detailed research on the behavior of liquid fuel sprays in a heated and pressurized combustion chamber.

A variety of sensors are installed, giving information on ignition delay, combustion intensity, and length of combustion. All data are collected and processed by a computerized data acquisition system. In addition, high-speed camera techniques are used to visualize the spray combustion process.

The main object of this research is to establish a correlation between fuel composition—especially for heavy residual fuels—and its ignition and combustion properties.

In establishing the fuel composition, different chromatographic methods together with conventional fuel analysis data are being used. A large number of fuel qualities ranging from light distillates via a variety of heavy residual fuels to Solvent Refined Coal II have been investigated, and typical test results showing the observed differences in ignition and combustion for various fuel types are presented.

Through contact with shipowners and engine builders, we have obtained access to heavy fuel samples that have caused operational problems and engine damages on board ships. Through tests on the just mentioned equipment with these “problem” fuels, we observe “normal” heavy fuels. These deviations as observed in the test rig may give an explanation of the problems encountered in service. Conventional fuel analysis data do not in these cases give an indication that operation on these fuels might lead to operational disturbances.