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CenterHighPerformanceBuildingsPurdue / ACHP

A python-based air conditioning and heat pump system model
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Fin Correlations #42

Open OmarZaki96 opened 4 years ago

OmarZaki96 commented 4 years ago

In FinCorrelations file, there are 2 issues:

  1. The height and width of the fin is calculated with (N+1) where N is number of tubes or rows; this is based on assuming the fin extends 0.5 spacing on both sides at the end.

This is not accurate as there is (N-1) spacings between the tubes, and assuming (2*0.5) additional spacing on the ends would make the total number is (N) not (N+1)

  1. WavyLouvered Fin correlations where Re is below 1000 has something wrong with it, there is discontinuity in the correlation before and after Re = 1000;
abahman commented 4 years ago

Hello Omar, Thank you for your inquiry. Can you please refer to the lines in the code. Thank you

OmarZaki96 commented 4 years ago

For:

  1. Line 482, Taking N+1 spacing would depend on the staggered configuration, not necessarily (N+1) Height = P_t * (Ntubes_bank+1) #Height of heat exchanger [m] # assuming that fin extends 1/2 pt above/below last tube in bundle

  2. Lines 227, 228, 229 Here is a plot of the correlation against Re f_plot

abahman commented 4 years ago

Omar,

1- Your justification makes sense. Can you PR after making all the changes? 2-Correlations always have limitations and that why sometimes you need to tune the model. This correlation was based on Wang et al. (1998) (https://doi.org/10.2514/2.6354). If you have any recent correlation that is more accurate, we will be happy to update the model.

Thank you

OmarZaki96 commented 4 years ago

Dr. Ammar,

Thanks for your fast response.

  1. I will do the necessary modifications, and PR with the changes.
  2. I don't think there is any recent correlation that can be used; however, I will try to work on this matter.