LN2 dewar in a airplane
LN2 dewar in a airplane
(OP)
Here's my system (at the design stage):
-Two Dewar to hold each one infrared sensors.
-The Dewar are filled with liquid nitrogen
-The Dewar are inside a vacuum chamber, so we'll have LN2 feed through for refill and exhaust. Four in total.
-The vacuum chamber is inside a small plane (bigger than a Cesna, but still small)
I presume there will be around 1L or less of liquid nitrogen, spend over the course of 12 hours.
I don't know a lot about cryogenic stuff, or airplane, as a matter of fact.
Here's my questions
-Does anyone know if there can be problem if we have the pressure relief valve inside the aircraft? They can stay in flight for at least 4 hours, at an altitude of 5000m?
-Do you think that if we provide a tube with an interface to the in-line relief pressure valve and one end is outside the airplane, it can clog up to the point it is dangerous to build-up a pressure?
-Two Dewar to hold each one infrared sensors.
-The Dewar are filled with liquid nitrogen
-The Dewar are inside a vacuum chamber, so we'll have LN2 feed through for refill and exhaust. Four in total.
-The vacuum chamber is inside a small plane (bigger than a Cesna, but still small)
I presume there will be around 1L or less of liquid nitrogen, spend over the course of 12 hours.
I don't know a lot about cryogenic stuff, or airplane, as a matter of fact.
Here's my questions
-Does anyone know if there can be problem if we have the pressure relief valve inside the aircraft? They can stay in flight for at least 4 hours, at an altitude of 5000m?
-Do you think that if we provide a tube with an interface to the in-line relief pressure valve and one end is outside the airplane, it can clog up to the point it is dangerous to build-up a pressure?





RE: LN2 dewar in a airplane
Have you thought of using TEC for the sensors? (thermo electric cooler)
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: LN2 dewar in a airplane
Another solution is a Stirling cooler, but it produce too much vibration as we have positioning requirement for the sensor of about 3µm.
---------
Jonathan Lavoie
Physics engineer
Optical designer, Space photonics
RE: LN2 dewar in a airplane
Then you could just vent the exhaust through a control valve.
And the TEC would only be cooling from the LN2 temp.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: LN2 dewar in a airplane
If I have a sensors that produce X watts, a thermal conduction and loss through the Dewar of Y watts and a light-electricity conversion loss of Z watts.
I need an amount of nitrogen that is converted to gas with an energy of boiling of X+Y+Z watts.
If I have a TEC to cool my sensor down, it needs to cool it down of X+Y+Z watts, but produce T watts in the process.
If I use the system for 4 hours, I need the system to be stable, so I need an amount of nitrogen that is converted to gas with an energy of boiling of X+Y+Z+T watts.
So I use more nitrogen, but can achieve lower temperature, but I don't need that.
---------
Jonathan Lavoie
Physics engineer
Optical designer, Space photonics
RE: LN2 dewar in a airplane
Have you considered frost build up?
How stable does you temperature need to be? Adding LN2 or venting the N2 will change the temperature.