Heat transfer rate to heating time

[gemt]

i have set up an equation to get the heat transfer rate Q for a combined system where heat is transferred from a cylindrical outer wall set at 500 C. the wall heats a gas, which in turn heats a solid block of cylindrical metal positioned in the centre of the heated walls with a starting temperature of 20 C.

the equation i have is

Q=[1]\frac{}{}[/(A0/(h*A_lm1))+((r*A0)/(k*A2))+(A0/(h*A_lm3))+((r*A0)/(k*A4))+(A0/(h*A_lm5))]*A0*\DeltaT

and it give a result of 11.3213 Watts or the situation above.

but too me this seems small?? am i right in thinking this?

also can anyone tell me how i can relate this heat transfer to time. ie. know how long it would take to heat the central metal part.

Thank you in advance.

 

[quark1005]

could you fix the latex?

 

[gemt]

i could not get the equation editor to work properly (probaly the user to be fair) but i am included a hand written version as an attachment. i have managed to modifie it a bit which is giving me more sensible answers. But to get a value for time (in seconds#) i am using the below equation to get a value for q in joulse and then dividing q by Q.

q=cm\DeltaT

c = specific heat of the gas
m = mass of gas
delta T = the change in temperature

Thanks

 

[riscy]

Hi, can you send me eveything about this equation including details the of model, description of the variable and sketch, I will look into this...
My email address is riscy00@googlemail.com