- #1

thestudent101

- 21

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Here's some pictures of what I've calculated and assumed

https://ibb.co/mxz0T5

https://ibb.co/f1GQvk

When looking up the heat transfer coefficients, on the engineering toolbox it listed the coefficients for water-copper-water as 340-455W/m^2K http://www.engineeringtoolbox.com/overall-heat-transfer-coefficients-d_284.html

From my calculations though I've found the coefficients to be 1189 and 823W/m^2K, which changes the length required from 104m to 41m with the calculated coefficients. The engineering toolbox coefficients assume a "practically still fluid", but my velocities are only 0.33m/s and 0.11m/s. This just seems like a very big difference in length required for such low velocities, so just wondering if I went wrong somewhere in my calculations.

One other question, when calculating h1 & h2, I've used the thermal conductivity of water rather than the copper pipe. Is this correct?