Diesel Deposits as Influenced by Fuels and Operating Conditions 380149
FUEL deposition and ring-sticking tests are described which were performed in several single-cylinder and multicylinder service Diesel engines in the laboratory.
The development of an accelerated test method is outlined with special reference to the effects of engine variables on deposition. Decrease in load, speed, or jacket temperature or increase in altitude were found to increase fuel deposition. Increase in running time increased the exhaust deposits linearly but, within the combustion-chamber, equilibrium deposition was reached in a few hours of operation.
Marked differences were found among fuels in the single-cylinder test engine after 24 hr. of operation under the accelerated conditions. Fuels doped with different types of cetane-number improvers indicated that ignition quality is a factor in fuel deposition under certain operating conditions in some engines.
The results of the tests in one of the single-cylinder engines were compared with the results obtained in the other engines. Although they correlate closely with the relative fuel deposition in certain of these engines, they were not indicative of the results obtained in other engines which are relatively insensitive to fuel differences.
The tests demonstrated that the engine designer has much greater control over the quantity of fuel deposits formed than has either the fuel refiner or the engine operator.