Originally Posted by hammacks
OK, I've got to do it now.
Sometime this weekend I'll do the calculations for convection on the inside and outside of a chiller and set up the resistance network to show how minimal the higher conductivity of copper matters. It's all about the convection guys.
BTW, this is ALL I thought about through my entire heat transfer course I just finished up.
So I was feeling guilty that I was a dead beat on this. The main PIA is getting a decent calculation for the convective heat transfer.
I have a heat transfer LAB course now and wouldn't you know it, this week I will experimenting with counterflow heat exchangers. I should be able to get a decent h value from that. I'm pretty sure I'll be doing a resistance model of the system that will illustrate the whole idea well. And now I have to do it (or I get bad grades :-) ). My prof used to live in Portland and would take her students to microbreweries to see their industrial plate heat exchangers.
In the mean time, lookie what I found. Coefficient of entire heat exchange system (convection -> conduction -> convection)
Fluid-----Material-----Fluid------Transfer Coefficient ((Btu/ft2 hr °F) and (W/m2 K)
Water---Mild Steel---Water----60 - 70----340 - 400
Water---Copper------Water----60 - 80----340 - 455
Very rough, but based on the same velocity and flow characteristics for both so comparison between the two is valid. SS is similar to the mild. Point is, massive difference in conductive coefficients between steel and copper = very little impact on system.
Found it at a great reference site here:
Overall Heat Transfer Coefficients for some common Fluids and Heat Exchanger Surfaces
Look at how much better steam to water through copper than water to water (and that's not even considering the larger temp difference).