Simple Heat Transfer (convection and radiation, cylinder/pipe)

[grufff]

Homework Statement

Reasonably simple (I hope!) heat transfer problem:

Smooth cylinder of diameter (D) 0.8m and length (L) 1.2m has a surface temperature (Tsurf) of 240C (513K). Ambient air temp (Tamb) is 30C (303K). Emissivity of cylinder (E) is 0.85. Heat transfer coefficient of convection (h conv) is 8.8 W/m^2 K. Boltzman constant (sigma) is 5.76*10^-8.

Neglecting end effects, calculate heat transfer coefficient for radiation (h rad), and total heat loss due to radiation and convention.

Homework Equations

I've dug out equations for h rad, and q(rad) and q(conv). Have written them out on my working...

The Attempt at a Solution

I'm posting a link/photo to my working. I hope it's clear enough for you to see easily, if not I'll try something else.

I'm hoping someone can confirm I've chosen the correct formulae for the problem, and worked through them properly. Thanks very much if you can help/advise:

(P.S. I'll be posting another one later, once I've done it, on heat exchangers. So if you know anything about those, please keep watching, ;) )

[PLAIN]http://dl.dropbox.com/u/5352127/HeatTransfer.jpg

 

[KataKoniK]

Thank you for your post. I have reviewed your working and it appears that you have chosen the correct equations for this problem. Your calculations also seem to be correct, assuming that your values for the Boltzmann constant and the emissivity are accurate.

For the heat transfer coefficient for radiation, you have correctly used the equation h_rad = sigma * E * (Tsurf^4 - Tamb^4). This is the correct equation for calculating the heat transfer coefficient for radiation between a surface and its surroundings.

For the total heat loss due to radiation and convection, you have correctly used the equation q_tot = q_rad + q_conv. This is the correct way to calculate the total heat loss from a surface, taking into account both radiation and convection.

In terms of your overall approach, it seems like you have a good understanding of the concepts and equations involved in heat transfer. Keep up the good work!