Physics Question: Does aluminum cool off faster than it heats up?

[TROLL]

Random, I know.

We're spraypainting an aluminum piece right now and it promped a bit of a debate over how its warming up to room temperature vs. cooling off to outside temperature.

So, anyone out there who understands the laws that apply here please shed some light to the debate.

Does aluminum (or any element for that matter) cool off faster than it heats up? Is it possible for something to change temperature in one direction at a different rate than it does in the other direction?

Lets hear it... this could be interesting, haha.
Bryan

[Scapegoat]

I'm just gonna sound like a dumbass answering this...

all I know is that when an object either heat up or cools off, its really just absorbing and retaining the energy (which is heat) that is around it. Aluminum is not a good material for heat transfer, as it does not retain that energy for long at all... which is why you can usually touch it after its been in the 400 degree oven for an hour

[Roadkilled75]

Edit: Nope, not correct

[james_ls]

So I assume the answer would be yes.

[TROLL]

I posed the question neutrally and won't take my side until its settled clearly, but do you have any fact / proof / laws to reference to back up what you're saying?

[HatchSurfer3]

Originally Posted by Roadkilled75

The rate of cooling or heating simply depends on, if all other conditions (air flow, orientation, etc) are constant, the temperature differential. So, if you warm it from 30 degrees outside to 70 inside, and then put it back outside, it will take the same amount of time to cool from 70 to 30 as it did to heat from 30 to 70.

I was gonna say brown...

[Renegade_]

The specific heat of aluminum is lower than most metals so it does cool off faster than most metals used in automotive stuff (hence why expensive rads are aluminum)

[Roadkilled75]

Yeah, my answer would have to assume constant heat flux, which very rarely happens. It'd take longer to warm up than to cool down. Looking for the right equation at the moment, and feeling stupid.

Troll, the backup to my first assertion would be the equation of heat flux during convection, q''=h(Ts-Ti) where Ts is the temperature at the surface of the aluminum and Ti is the temperature at infinity, i.e. the ambient temp of the room or outdoors. As you can see, if the temperature values were, say, 30 and 70, that equation would be either 40h or -40h, representing the same heat flux in the opposite direction for both cases. But like I said, that is only for heat flux, and it ought to be a differential equation with the appropriate characteristics of aluminum and air in order to answer the question correctly. Don't feel like figuring that out at the moment.

[lagos]

It depends on the situation. Put a torch to it, and it will heat up quickly. Stick it in the freezer and the opposite will happen. Since its such a thin metal, it can heat up and cool down a lot faster then other metals like steal.

It does have excellent thermal heat transfer properties and thats why its always used for Heatsinks, intercoolers, radiators etc... so i would say that it cools quickly, as long as ambient temps are cooler then its initial temperature.

So, no... it doesnt cool down faster then it heats up. its just faster/better all around at transferring heat or cold then other metals.

[xEJ20x]

The rate of heat transfer is directly related to the difference in ambiant temperature.

And object will cool off faster if the ambiant temp difference is much lower than the heated object.