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THE EFFECT OF DEWAR OPERATING PRESSURE ON THE THERMAL PERFORMANCE OF LIQUID NITROGEN COOLED CRYOPROBE
Journal
Proceedings of the Thermal and Fluids Engineering Summer Conference
Date Issued
2022-01-01
Author(s)
Gunjal, Anish A.
Kumar, Gulshan
Srivastava, Atul
Atrey, Milind D.
Abstract
In the present work, we report the effect of operating pressure on in-house developed liquid nitrogen (LN2)-cooled cryoprobe. The LN2 cryoprobes operate at much lower pressures compared to the Argon cryoprobes, thus making them more attractive in the clinical setup. Optics-based Lens-less Fourier transform digital holographic interferometric technique (DHI) is employed for real time tracking of freezing front as a function of varying pressure. Select numerical simulations have also been performed. The in-house developed cryoprobe having 3.2 mm diameter and 10 mm uninsulated tip was used. The cryoprobe is inserted 4 mm inside the biogel sample, which has the Agar concentration of 0.1% (gram/gram of water). The transient cooling characteristic is obtained for operating pressures of 3, 3.5, and 4 atm. It is observed that operating pressure of 4 atm is sufficient to remove the vapor lock formed in the LN2 transfer hose. The cooldown time and the fluctuations in temperature during the cooldown period were found to be less at 4 atm compared to that at lower pressure levels. The whole-field temperature was obtained using the numerical simulations, and the results were found to be within 10% accuracy levels as compared to the thermocouple readings recorded at the same locations during the experiment. The optics-based experimental approach combined with the numerical simulations could be a potential non-intrusive method for predicting the reliable whole-field temperature distribution and hence the cryoprobe's cooling performance.
Volume
2022-May
Subjects