Hey, I was doing some revison for a test and i came across this question which I cant get my head around(adsbygoogle = window.adsbygoogle || []).push({});

a clyndrical copper block, 0.3m in diameter and 0.4m long is initially at a uniform temp of 60°C and half its curved surface is exposed to a heat flux of 450w/m^2. If the complete surface is being cooled by convection heat transfer to the surrounding air at 20°C, determine the final temperature of the block, assuming it is uniform throughout.

Determine the time to cool the block from 60 degrees to the final temperature. assuming the convective heat transfer is constant throughout the cooling process and can be calculated using the average temperature of the block during the cooling process.

For each case, identify an appropriate system and energy balance and use the following date: p(copper) =8900 kg/m^3

C(copper) =400j/kg

convective heat transfer coefficient = 20w/m^2k

I'm haven't tried the second half of the question as I can not get the first part.

So far, i have said that:

Qdotin=Qdotout

flux*Half curved surface= h* Atotal * (Tsurface - Tair)

But my problem with this equation is to find an expression for T surface in terms of the final and initial temperature.

Am I on the right track?

Thanks

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# Convective and conductive heat transfer

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