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Session: Experiments
Session starts: Tuesday 08 October, 15:40
Presentation starts: 16:20
Room: Willem Burger Zaal

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Piero Colonna (Process and Energy Dept., Delft University of Technology)
Mauro Gallo (Process and Energy Dept., Delft University of Technology)
Emiliano Casati (Process and Energy Dept., Delft University of Technology)
Tiemo Mathijssen (Process and Energy Dept., Delft University of Technology)

Abstract:
The Flexible Asymmetric Shock Tube setup has been designed and built at the Process and Energy Laboratory of the Delft University of Technology in order to study non-classical gasdynamic phenomena in flows of dense organic fluid vapors [1]. It operates according to the Ludwieg tube principle. One of the main objectives is the detection of rarefaction shock waves, which are theoretically predicted to occur at operating conditions close to the vapour-liquid critical point in the superheated vapor thermodynamic region of so called BZT fluids [2]. Fluids of the siloxanes family qualify as BZT fluids therefore they are employed in the FAST setup [3]. Siloxanes are also working fluids for organic Rankine cycle power plants [4]. Gasdynamic measurements performed with the FAST setup are therefore also relevant especially for the aerodynamic design of ORC expanders. The FAST can be operated at temperatures up to 400 °C and pressures up to 30 bar. Technical and experimental activities have been carried out to assess the performance of the main set-up components: the Fast Opening Valve (FOV), the vapor generator system and the thermal control system. Such activities have brought to light several problems which have hampered their correct functioning at the challenging test conditions. Therefore a partial redesign of the main components has been necessary and the current status with respect to the commissioning of the setup is illustrated. The FOV plays a key role for assuring the success of the experiment and, at the same time, its repeatability. Due to its mechanical complexity, time-consuming activities are necessary to make reliable its functioning. Therefore, a different fast opening system has been conceived and tested: the Induced Breaking Diaphragm (IBD). Even though the IBD shows limitations related to the experiment repeatability, it represents a temporary solution, which allows for performing gasdynamic measurements both with air and siloxanes. Through these tests it will be possible to perform the fine-tuning of the PID of the thermal control system at conditions very close to those necessary for the RSW generation. Moreover it will possible to optimize both the acquisition procedure and the post-processing of the digital signals provided by the dynamic pressure transducers used to detect the RSW travelling along the tube. The results of the mentioned tests will be illustrated at the conference.