TY - JOUR
T1 - Moving heat source in a confined channel: Heat transfer and boiling in endovenous laser ablation of varicose veins
AU - de Boer, Amit
AU - Oliveira, Jorge L. G.
AU - van der Geld, Cees W. M.
AU - Malskat, Wendy S. J.
AU - van den Bos, Renate
AU - Nijsten, Tamar
AU - van Gemert, Martin J. C.
PY - 2017
Y1 - 2017
N2 - Motion of a moving laser light heat source in a confined volume has important applications such as in endovenous laser ablation (EVLA) of varicose veins. This light heats up the fluid and the wall volume by absorption and heat conduction. The present study compares the flow and temperature fields in a horizontal tube of 4 mm inner diameter in three idealizations of the EVLA procedure: water with a bare fiber tip, water with a carbonized layer on the fiber tip, and blood. Without boiling, the convection patterns in water and blood are similar and Grashof numbers are high enough to guarantee buoyancy induced flow and axial mixing, while preserving some stratification. A carbonized layer at the fiber tip promotes boiling in water at moderate laser powers. Boiling bubbles in water rapidly detach from the tip, with or without a carbonized layer, and promote mixing and a locally homogeneous temperature field. At 15 W laser power and 4 minis pullback speed in blood, a gas bubble may be formed that sticks at the fiber tip, causing strong local heating and possibly fiber damage. (C) 2017 Elsevier Ltd. All rights reserved
AB - Motion of a moving laser light heat source in a confined volume has important applications such as in endovenous laser ablation (EVLA) of varicose veins. This light heats up the fluid and the wall volume by absorption and heat conduction. The present study compares the flow and temperature fields in a horizontal tube of 4 mm inner diameter in three idealizations of the EVLA procedure: water with a bare fiber tip, water with a carbonized layer on the fiber tip, and blood. Without boiling, the convection patterns in water and blood are similar and Grashof numbers are high enough to guarantee buoyancy induced flow and axial mixing, while preserving some stratification. A carbonized layer at the fiber tip promotes boiling in water at moderate laser powers. Boiling bubbles in water rapidly detach from the tip, with or without a carbonized layer, and promote mixing and a locally homogeneous temperature field. At 15 W laser power and 4 minis pullback speed in blood, a gas bubble may be formed that sticks at the fiber tip, causing strong local heating and possibly fiber damage. (C) 2017 Elsevier Ltd. All rights reserved
U2 - https://doi.org/10.1016/j.ijheatmasstransfer.2017.05.068
DO - https://doi.org/10.1016/j.ijheatmasstransfer.2017.05.068
M3 - Article
SN - 0017-9310
VL - 113
SP - 153
EP - 165
JO - International Journal of Heat and Mass Transfer
JF - International Journal of Heat and Mass Transfer
ER -