Abstract:
Cryogenic fluids are frequently encountered in many applications, such as cryogenic
cooling, material processing, biological tissue preservation, food engineering, aerospace
field, cooling of superconducting devices and chemical process etc. It has been
understood in pool quenching experiments, that the thin low thermal conductive coating
layer on the wall can greatly improve the cooling performance, while less is known about
flow quenching. In the present study, the experiments are to investigate cryogenic flow
quenching of the horizontal stainless steel tubes with different coating layers on the inner
walls. Two types of coating layers with various thicknesses were prepared with the help of
paint epoxy on the inner surface of the tube. To investigate the thermo-electric property
and thickness of the coating layer on the quenching performance, as compared with the
uncoated and epoxy coated tube. Here we are using magnetic stirring and sonication
method for coating. It is shown that a thin coating layer on the inner tube wall can
significantly shorten the quenching time and enhance the heat transfer performance. To
analyse the heat transfer characteristics, an inverse heat conduction equation with
consideration of variable thermo-physical properties and thermal contact resistance was
numerically solved to obtain the inner wall temperature and heat flux. The reason for the
quenching enhancement can be attributed to the shortening of the film boiling regime of
cryogenic quenching in the inner surface by the coating layer which allows the improvement
of Leidenfrost point (LPF) temperature.
