Abstract: Tortuous passageways are provided in a substrate component that is retained within a holding chamber. Fuels and fuel mixtures to be comparatively tested are introduced into the holding chamber and into the tortuous passageways of the substrate component. The substrate component is controllably maintained at an elevated temperature during a specified number of defined test cycles. The substrate component is then removed and its after-test weight compared with an initial weight before the test. The tortuous passageways of the substrate component provide increased surface area subject to deposit formation and extended residence time for fuel to remain in contact with the substrate surface, thereby greatly enhancing the measured difference between tested fuels and fuel mixtures.

Abstract: Tortuous passageways are provided in a substrate component that is retained within a holding chamber. Fuels and fuel mixtures to be comparatively tested are introduced into the holding chamber and into the tortuous passageways of the substrate component. The substrate component is controllably maintained at an elevated temperature during a specified number of defined test cycles. The substrate component is then removed and its after-test weight compared with an initial weight before the test. The tortuous passageways of the substrate component provide increased surface area subject to deposit formation and extended residence time for fuel to remain in contact with the substrate surface, thereby greatly enhancing the measured difference between tested fuels and fuel mixtures.

Abstract: A method and apparatus for determining the propensity of fuel materials to leave deposits in compression ignition engines is disclosed. The apparatus consists of a closed chamber fitted with conduits to supply fuel composition, air, and other test fluids to its interior, and arranged to contain or substantially contain a substrate. Substrate is placed in the chamber to provide interaction between a fluid passing through and the substrate. Substrate may be a monolithic machined element or a collection of discrete bodies. The chamber conduits are connected to at least two metering devices, one controlling fuel and one air flow, whereby the substrate is exposed to measured quantities of fuel compositions and air. Heating devices are in thermal communication with the substrate and the source of air provided to the chamber, thus providing a method of controlling the temperature of the substrate and air flowing through the chamber.