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Thermal-Hydraulics Experimental Laboratory for Multiphase Applications (THELMA)

Accurate prediction of the convective single- and two-phase heat transfer is very important in process and power engineering for reliability, security, and efficiency of related systems and devices. In this aspect, boiling is particularly interesting and complex phenomena, which may significantly enhance the heat transfer from the heated surface to the coolant flow. The detailed understanding of these phenomena is of great importance and, as such, is put under investigation in the THELMA laboratory.

 Thermal-Hydraulics Experimental Laboratory for Multiphase Applications (THELMA). 
Foto: Arne Hodalič, Katja Bidovec
Photo Arne Hodalič, Katja Bidovec Delo.




Flow boiling experiment

Backward Facing Step experiment

Taylor Bubble experiment

Thermal fluctuations in turbulent flow experiment



Measurement instrumentation

The facility is equipped with the following state-of-the-art measurement instrumentation:

  • PIV (Particle Image Velocimetry) system with a high speed camera (Phantom v 1212 1280 × 800 pixels, 12 kHz) and pulsed laser (LaVision double cavity Nd:YLF laser 527 nm, 2×15mJ at 1 kHz)
  • Fast IR camera FLIR (Long wave IR 7.5 - 12.0 µm, 640 x 512 pixels, 1 kHz)
  • Coriolis flow meters (MicroMotion elite CMFS) for accurate measurements in a wide range of flow rates
  • Kaye K170 water triple point reference for accurate temperature measurement
  • Custom designed pressurizer for establishing a well-defined pressure in the system
  • LAUDA 845C thermal bath for constant temperature control of the pressure
  • National Instruments PXIe 500 acquisition system with LabVIEW software (2 x 32 thermocouples, 10 analog channels)



Page editor: Anil Kumar Basavaraj

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