The department of measurement technologies includes two areas of responsibility. In the first one projects which primarily deal
with the application of special measure-ments are accomplished. Secondly the department provides the administration and technical
service of measuring devices which are used in other projects.
The measurement technology available at OWI comprises a variety of devices. Many of them are standard instruments which are used
in a lot of test rigs. Exhaust gas analysers, mass flow meters and controllers, thermocouples and pressure transducers are widely
used in different variants adapted to the various measurement tasks, so that the technical staff of OWI is trained in the
handling of these instruments.
Apart from these standard devices several measuring instruments for specialised tasks are available at OWI, such as hot wire
anemometers for one- or multidimen-sional measurements of flow velocities in gases, different microphones and frequency
analysers for recording and analysis of sound levels und spectra as well as a high speed thermo camera, which captures short-wave
infrared radiation with a frame rate up to f = 870 Hz and an accuracy of ΔT = 20 mK (s. figure 1). When applying
these highly specialised technologies the project team is supported by specialists in measurement and data analysis.
Figure 1: IR-snapshot of a turbulent bunsen flame
To ensure utilisability and reliability the systems underlie determined service- and calibration cycles. Appropriate calibration devices for multiple devices such as mass flow meters and -controllers as well as hot wire anemometers are available at OWI (s. figure 2).
Figure 2: Test rig for the calibration of hot wire anemometers with a Betz-manometer
Another current key activity is the preparation of gas chromatographic measurement methods for the analysis of gas compounds.
Here the determination of residual hydrocarbons in synthesis gas from the reforming of liquid combustibles is emphasised.
Projects which focus on the application of such special measurement tasks are accomplished within the department of measurement
technologies itself. Thus in several projects concerning the acoustical characterisation of burners, boilers and machine
components the sound power radiated into the surroundings of the boiler has been determined or the appearance of pressure
oscillations inside the combustion chamber was analysed.
As a continuation of numerous studies accomplished at the end of the 1980s respectively at the beginning of the 1990s at
the department of heat and mass transfer of the technical university Aachen, OWI maintains a test rig for the quantitative
determination of particles in the exhaust gas, which has bees used in several projects.
Measurement of the total suspended particles (TSP) is performed according to the relevant standards (VDI 2066, DIN EN 13284-1)
by isokinetic extraction of a partial flow from the exhaust gas, which is then conducted through a planar filter. The
quantitative determination of the particle emissions is achieved by differential weighing of the filter on a precision
scale, achieving a good repeatability.
Additionally to the TSP the size distribution of the particles in the range between 30 nm and 16 µm can be determined
with a 10-stage low pressure impactor in collaboration with the technical university Aachen (s. figure 3).
Figure 3: Particle emissions of oil-burning domestic heating devices