Heat Transfer Through Concrete Pile Cap

Sure - how about posting them as pictures here?

Dejan,

the best bet for you is to go to Wikipedia and seek; Heat Transfer Co-efficient. Or just Google it and pick up the Wiki link, to give you a concise understanding of the process. Then go to: www.engineeringtoolbox.com/thermalconductivity-d429.html which will give you some common values from which you will be easily able to do your calculations.

Cheers,

Stu.

Look up the equation for Conductive Heat Transfer, and get the coefficient for the type of concrete, and you will need to know the thickness, and of course the temperature of the hotter side. Best of Luck!

You will have to find the h, k (and then R or you can work with U) for the materials and surrounding surfaces of all materials - as stated above you can get good usable values, otherwise go the engineering journals that will provide excellent data but it costs $$$$.

This is plain simple conductive calculations - just remember that if there is a wind factor it must be taken in account.

You can do a simple Excel speadsheet similar to this one attached for pipes.

This one gives the water temp change according pipe length with the kw lost to atmosphere.

Regards

if concrete slab is sun irradiated, see the ASRHAE cooling load calculation manual. Energy stored in slab will make an transient process

From College Physics - 4th Addition - Franklin Miller Jr.

Q=KAT (t2-t1/d)

Where Q is the thermal energy transferred, K is the thermal conductivity, A is the area of the plate, T is the time, t2 is the hot side temperature, t1 is the cold side temperature, and d is the thickness of the plate.

The thermal conductivity is the reciprocal of the R value of the material and can probably be found in the CRC Physics and Chemistry Manual or on the internet. It is critical that the value for the conductivity is from the same system as the units for the other values. I would suggest working in the Standard International MKS system and then converting to what ever system you need.

If the cold side sinks to an enclosed area then the rate of transfer will decrease as the temperature of the cold side surrounding medium increases.

This is a freshman physics problem; depending on the "risk" associated with inaccurate data it may be useful for you. If it involves the potential for critical events then spend the money to hire a pro.

What's under the cap?

Gavilan

Use Fourier's Law: q = -k(dT/dx)

k is the thermal conductivity of the slab, which should be around 2 (W/m-K), and also, by knowing the temperature difference and width of the slab, you now have the heat transfer per unit area.