Flat Plate Cooling Using Liquid Nitrogen

[elfman]

Hello! I have a process I am trying to control and need to cool a round, flat plate - localized temperatures can get as high as 500°C. We currently use a fixture that has cooling water flowing through it, but we believe that as the plate that needs to be cooled gets hot, deformation occurs and there is some surface separation and we aren't getting a proper contact between the cooling fixture and the flat plate and thus not cooling like we need to. We have tried using heat transfer grease, but we still think there is a separation issue. We have been toying with the idea of using Liquid Nitrogen, but I don't have a clue as to even where to start the investigation/research. I am looking for design resources(nozzle design, estimated transfer rates, etc.), ideas, suggestions as to where I might go with this... Please?

Thanks in advance!

"To be or not to be, that is the question" - William Shakespeare via Hamlet

 

[racookpe1978]

You need to establish the movement (separation) exists at all, and that it is in the assumed direction, at the current "low" temperatures you now have, before you attempt to "solve" it by introduing the much greater temperature change from an extremely "low" temperature of liquid nitrogen introduces even more distortion.

Where are the constraints on the current heat source and current round plate heating from ambient (assumed assembly temperature) to local hot spots of 500 degrees? Is it now fastened in the center, around the edges, both, neither, only by a press fit or just resting on the hotter surface with no fastener or clamp or spring pressure? In a fixed assembly or jig somehow? In a "bath" of hot liquid with the current coolant flowing inside? (Doesn't seem likely).

If the LN2 is used, will it be started before the heatup begins? If so, then you have significant shrink forces, followed by an immediate expansion of the heated assembly, then more relative movement as the very, very cool plate begins heating up and shrinking the much hotter assembly. If the cooler plate is left to heat up as the assembly is heats, then the LN2 flow is started, you get possible cracking in the cooler.

try a flexible pressure device - maybe like a vice-grip or spring clamp that is not a screwed fit. Either will allow for movement and expansion while keeping the two pressed together.