|
Fracture Formation Around a 1.3 mm Cryogenic Tube
Biothermal Technology Laboratory Department of Mechanical Engineering Carnegie Mellon University
|
|
|
To demonstrate fracture formation around a cryogenic tube, in order to identify whether fracture formation around the cryosurgical probes in parallel studies is related to the specific cryoprobe design, or if it is an inherent effect of the freeze\thaw cycle.
Methods A cryogenic tube is immersed in water. The tube is cooled with liquid nitrogen, supplied from a hand-held container, and pressurized with compressed air.
Observations and Comments 1. At low cooling rates, fracture formation can be completely prevented. 2. Fractures always form within seconds from the beginning of rewarming. 3. While it is possible to prevent fracture formation during cooling by reducing the cooling rate, we could not prevent fracture formation at the beginning of the rewarming stage, regardless of the experimented thermal protocol.
Cryogenic tube diameter = 1.3 mm Beaker diameter = 65 mm Two freezing periods separated with a 10 seconds interval of no liquid nitrogen flow. Elapsed time in is shown on each photo (min:sec).
|
|
|
Period I: Liquid nitrogen flow started
|
Period I: Liquid nitrogen flow stopped at 5:40
|
|
Period I: Liquid nitrogen flow stopped at 5:40
|
Period II: Liquid nitrogen flow restarted at 5:50
|
|
Period II: Liquid nitrogen flow stopped at 14:45
|
Period II: Liquid nitrogen flow stopped at 14:45
|
Biothermal Technology Laboratory Copyright©