Blackbody globe thermometer

[MintJulep]

Needing some quick mean radiant temperature readings, I've made a quick-and-dirty blackbody globe thermometer from a cheap aluminum tea kettle.

Not being an actual globe, I suppose it is actually an aspherical globe thermometer. My aspherical globe thermometer is in fact a cylinder.

The formula provided in the ASHRAE handbook to obtain MRT from the globe thermometer reading contains a term for the globe diameter.

What should I use as the value for this term with my cylindrical thermometer?

My thought would be use a value of D for a sphere of equal surface area as my cylinder.

 

[Maui]

My thought is that the geometry you have selected is not consistent with the model that you're attempting to use. You need to calculate the heat transfer solution to your problem by using the cylindrical geometry that you've selected. In order for anyone here to assist you in that respect, much more deatil about your specific problem and the boundary conditions needs to be specified.

Maui

 

[IRstuff]

I think that there are two issues:

1> The radiant component won't match a sphere. You may have to take each surface and independently determine the view factors.

2> The convective component would seem to be best kept as a cylinder

TTFN

FAQ731-376