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aardvarcus,
Firstly, please understand my mentioning your experience was academic and not for fun.
I value what the folks here can teach me, but in general we seldom mention our failures- and these are priceless. Personally, when I find someone with the humility and honesty to willing write up an (again, please forgive) "Epic Fail", I am forced to acknowledge they are probably a better person than I.
I tip my hat to you sir.
That said, I assume the gas tank doesn't warm itself and most tanks are not attached to parts that generate large amounts of heat. And you mention yours was only partially covered. We can infer (since you didn't mention it) that there was no "forced convection" to cool the tank.
From this I would suggest the mechanism of heat transfer to your tank was via radiation, and that this radiation would have normally been transferred to another site (by conduction) where convective loss could occur, or (with respects to Thenorm) the primary mechanism of heat loss from the heat producing agent is via radiation.
I also have noticed some modders using screen coverings, I'm assuming steel or Aluminum. As I write this I'm looking at a 12'X12" Al screen with 1/8" holes and can easily imagine it absorbing radiant energy from a 1,000º catalytic converter or a 700º muffler. This screen would begin radiating the same energy downhill. First to a cool vehicle itself (that warms up quickly because it dissipates heat poorly), and then into the planet itself- which wouldn't even notice it.
As my screen is mostly just "holes", there is nothing there to prevent radiation going into the ground to start with. But I also imagine there IS enough there to promote laminar flow of air over it as well as significant pressure drops though it.
In other words, again with respects to Thenorm, I'm not buying that radiation is "not effective" and that "Convection (forced air) is really the only real way to shed heat in vehicles.". Indeed, it seems the opposite may be true.
Convection IS important, but it is also linear and I do not see how it can account for even half of the heat flux, especially (as Thenorm mentioned) radiant loss increases to the 4th power of the dT.
I may be wrong though, and will continue reading on this.
Once more, my respects to you and your work. Thank You.
drrbc
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