Non-intrusive temperature measurements for transient freezing in laminar internal flow using laser induced fluorescence

Journal Article (2024)
Author(s)

B.J. Kaaks (TU Delft - RST/Reactor Physics and Nuclear Materials)

S.D. Couweleers (TU Delft - RST/Technici Pool)

Danny Lathouwers (TU Delft - RST/Reactor Physics and Nuclear Materials)

J. L. Kloosterman (TU Delft - RST/Radiation, Science and Technology)

Martin Rohde (TU Delft - RST/Reactor Physics and Nuclear Materials)

Research Group
RST/Reactor Physics and Nuclear Materials
DOI related publication
https://doi.org/10.1016/j.expthermflusci.2024.111184
More Info
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Publication Year
2024
Language
English
Research Group
RST/Reactor Physics and Nuclear Materials
Volume number
155
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Abstract

This work presents two color LIF temperature measurements for the transient freezing in a square channel under laminar flow conditions. This is the first time non-intrusive temperature measurements were performed within the thermal boundary layer during the transient growth of an ice layer in internal flow. A combination of a local outlier factor algorithm and a smoothing operation was used to remove the top to bottom striations and reduce the other measurement noise. The temperature uncertainty in our measurements was between σ=0.3∘C and σ=0.5∘C. For the largest temperature difference between the bulk and the melting point of 14.6 °C, good results were obtained. As such, the current campaign demonstrates the potential of LIF as a non-intrusive temperature measurement technique for solid–liquid phase change experiments. However, some artefacts were present within the vicinity of the ice-layer due to the scattering of the laser light, especially near the inlet of the channel where the ice-layer is curved instead of flat. LIF measurements taken within a short time span prior to the onset of ice freezing showed approximately 2 °C of subcooling, consistent with previous findings. In addition, an anomalous behavior within the thermal boundary layer was observed, with a much smaller temperature gradient within the first few mm above the cold plate and a point of inflection in the temperature profile. The anomalous temperature behavior is possibly attributed to enhanced natural convection as a result of the subcooling at the cold plate surface.