Due to the reduction of exhaust emissions in the last years, the percentage of particulate matter emitted
by non-exhaust sources has increased. Brakes play an important role emitting more than half of
this type of emissions.1 The FZD department is carrying a research in order to reach a better understanding
of the behavior of brake particle emissions and reduce them. For this purpose, real-drive
tests have been conducted in previous works and development of new setups to collect particles must
be achieved.
The aim of this Bachelor thesis is to develop concepts for measurements in test drives. It is necessary
to minimize losses of particles and take representative samples of particulate matter. With the intention
of accomplishing these necessities, a study of aerosol losses has been done. The objective of this
study is to optimize aerosol transport through sampling tubes.
Two concepts, a full brake enclosure device and a rim shell device, have been developed and their
basic operation system is explained. In the first concept, a full sealed shell around the brake is used
to minimize particles losses. This could be think to act in a similar way as the sealed chamber used
in dynamometer tests and the results should be similar. For that reason, this concept has been rejected.
The second concept tries to reach a realistic behavior of particles taking realistic flow conditions due
to the airstream entering to the collecting shell through an air scoop and the interaction of particles
with the inner surfaces of the rim. Due to the turbulent regime generated and the limited time to
manufacture and assembly the setup, its construction has been discarded.
In the study of transport losses different mechanisms have been studied. These mechanisms are diffusional
deposition, gravitational settling deposition in horizontal tubes and inclined tubes and inertial
deposition in bends. For each one its efficiency has been calculated for a size range of particles and
tube lengths. Furthermore, efficiency has been calculated for a particle transport system similar to
one that could be used in a test car. With this study, a general approach to the magnitude of transport
efficiency has been reached. It has been possible to conclude that losses are much higher for large
particles than for small particles. Finally, some considerations to optimize the transport of particles
have been presented.
