色中色

Within his PhD research addresses three fundamental parts of the Metal-enabled Cycle of Renewable Energy (MECRE) that are unclear: at what temperature a single iron particle burns and if there is a correlation to the particle size, what the collective effect on the ignition and combustion of iron flames is and what mechanism enables the deposition of iron oxide particles on the reactor walls. To do this he developed a new method for measuring temperature to find out the time-resolved combustion temperature of iron particles. This method was used in an Induction Heating Single Particle Burner (IHSPB) and it showed that the maximum temperature reached during combustion of single iron particles increases with increasing particle size. Particle temperatures that are higher than those reported in the literature were measured. This was attributed to an internal convective force driven by Marangoni flow.

Jet-in-Hot-Coflow burner

Next to that a Jet-in-Hot-Coflow burner was used for this research. The Jet-in-Hot-Coflow (JHC) burner is designed to generate an electrically heated coflow of up to 1000 K with an internally cooled jet, which carries an aerosol of iron and air into the combustion zone. This combustor was used to show the effect of dust cloud concentration on combustion efficiency. When particles have a residence time sufficient to reach the temperature of the surrounding gas flow, the combustion efficiency, which is quantified by the elemental mole fraction of oxygen in the combustion products, increases with an increasing mass flow of iron. It is furthermore shown that particles completely react to magnetite after ignition. Particles that fail to ignite in a high-temperature environment form a thick oxide layer, which increases the ignition temperature of the particle, which may explain why some particles remain non-spherical and unignited.

The mechanism behind deposition

The JHC burner was used to study the fundamental mechanism behind deposition. When burning particles come into contact with a surface, there is a chance that the particles will stick to the surface. A basic model was developed, which assumes the dominant deposition mechanism to be the local melting of the wall material. Two different experimental studies were performed, one where the basic model was validated and one that showed the effect of active cooling of the surface on the deposition degree. It is shown that active cooling reduces the degree of deposition in materials that have a high specific heat capacity. In other materials, deposition mechanisms like mechanical locking are expected to play a larger role.

Title of PhD thesis: . Supervisors: Prof. Philip de Goey, Dr. Nico Dam and Dr. Tess Homan.