Search Results

Twenty-three hydrocarbons were measured in the exhaust gases from a Volvo passenger car fitted with a 2.3 litre gasoline engine. Measurements were made in the absence of a catalyst, and in the presence of a fresh and an aged three-way catalyst, with particular attention being paid to the emission of benzene and other light aromatic compounds. Loss of catalytic activity through ageing led to an increase in hydrocarbons of ∼ 200% from 0.22 to 0.62 g/mile. Loss of activity was most evident for certain compounds notably alkanes (paraffins) although large increases in aromatic emissions were also apparent; catalytic control of ethyne (acetylene) was, however, completely maintained by the aged catalyst. Thus the work reported here demonstrates the selective manner in which a catalyst operates depending upon the chemical structure of hydrocarbons, and how this influences catalyst performance loss via ageing.

Optical studies of combusting diesel sprays were done on three different alternative liquid fuels and compared to Swedish environmental class 1 diesel fuel (MK1). The alternative fuels were Rapeseed Oil Methyl Ester (RME), Palm Oil Methyl Ester (PME) and Fischer-Tropsch (FT) fuel. The studies were carried out in the Chalmers High Pressure High Temperature spray rig under conditions similar to those prevailing in a direct-injected diesel engine prior to injection. High speed shadowgraphs were acquired to measure the penetration of the continuous liquid phase, droplets and ligaments, and vapor penetration. Flame temperatures and relative soot concentrations were measured by emission based, line-of-sight, optical methods. A comparison between previous engine tests and spray rig experiments was conducted in order to provide a deeper explanation of the combustion phenomena in the engine tests.

This paper presents an approach to simulating wear on both contact surfaces at the pad-to-rotor interface in disc brakes using general purpose finite element software. It represents a first step toward a method of simulating the brake pressure needed to effectively clean the rotor of unwanted oxide layers. Two simulation cases are presented. The first addresses running-in wear under constant load and corresponds to repeated brake applications at the same constant brake load. The second studies what will happen if a lower load is applied after the contact surfaces have been run-in at a higher load level. This lower load is applied to wear off an oxide layer after a sequence of repeated stop braking at higher load levels.