[Boatanchors] Bird Termaline Question - Update (long)

[McDonald, J Douglas]

-----Original Message-----
From: Boatanchors [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Doug Hensley
I'm also curious if anyone knows if the volume of that Termaline load, which holds 1 pint of Transformer Oil, is the volume of oil whose maximum sustainable capacity for heat is 150 watts ?

Doug W5JV




The answer is no. Its easy to calculate the temperature rise of a device with a 1/2 inch element in
alarger cylinder, I will assume a 2 inch diameter one, based on the thermal conductivity of transformer oil
which I looked up as 0.126 watt/(meter- degree C). Its T = 14 P where T is in degrees C and P is watts. 
But that's meaningless as it assumes no convection. There will be convection and hence the temperature rise far less.

Its also easy to calculate the temperature rise assuming that the device as a whole is well thermally insulated. 
This does use the one pint. I also looked up the data for that and its either 1.47e-3 or 1.29e-3 degree C/Joule
which translates to 13.2 degree per minute for 150 watts (for 1.47e-3). 

At 13 degree per minute convection will do a respectable job and fins on the outside will matter a lot,
perhaps they will be the dominant thing. 

Doug McDonald