Master assignments

Among the many different ways of extracting useful products from biomass, one possibility is to convert the feedstock into oil through the pyrolysis process. The oil that results from this process is referred to as pyrolysis oil and can potentially be used as a liquid bio-fuel for industrial burners. However, the properties of pyrolysis oil are very different from fossil fuels like diesel. Application of this new fuel in industrial burners is therefore not as simple as just replacing the conventional fuel without any further modifications.

Spray combustion in a gas turbine

In order to increase the performance of burners fired on pyrolysis oil, it is crucial to study the quality of the fuel spray. This spray is created by the atomizer (fuel nozzle) inside the combustion chamber to convert the liquid into small droplets, which in turn evaporate to form a combustible gas. Most conventional atomizers are not suitable for pyrolysis oil and therefore produce droplets that are too large for fast evaporation, ignition and combustion.

The main goal of this assignment is to visualize the spray and determine its quality for different types of fuels and atomizers using optical techniques. The quality of a fuel spray will be expressed quantitatively in terms of spray cone angle, droplet size and droplet size distribution. A test setup has been designed and constructed in our laboratory located in Kleinhorst, which is fully dedicated to these spray measurements.

Analysis of the photos (see Figure 1 for an example) using MATLAB or other image analysis software provides the information needed to determine the spray quality. A Nd:YAG laser is available in the lab for illumination of the droplets.

The assignment will include the following activities:


Literature study on atomizers and optical measurement techniques.


Configuration of the lighting, the optics, the camera remote control and triggering system such that the pictures are of sufficient quality.


Performing measurements and optimizing the setup for different atomizers and liquids (water, diesel, pyrolysis oil).


Analysis of the photos to determine the number and size of the droplets using Matlab or other suitable software.


Discussion of the results leading to recommendations for improving the fuel spray.

Figure 1: Example of a shadow
image used for measuring droplet size

If you are interested, please contact Joost Sallevelt, Artur Pozarlik or Gerrit Brem for more information.

Joost Sallevelt

Room: HR N252

Tel: +31 53 489 4657