Cool Down Experiment

1
Cool Down Experiment

• ME 340-1
• Kyle Dallon, Natalie Gibb
• March 29, 2010

2

• Objective
• Test the accuracy of convection equations in real
  life application.
• Experiment
• Predict time to cool down
• boiling water in 2 cases
• 1. With cross flow
• 2. With natural convection

3
Forced Convection Method

• Treat pot of boiling water like a tube and use
  equations for forced convection around a
  cylinder.
• Use Hilpert equation, NuD.027Re.805Pr1/3
• Use lumped capacitance to calculate time.
• Not accurate time estimate.

  Calculated Results Measured Results
Time, Case 1 81 min 13 min
Time, Case 2 488 min 30 min
Results
4
Flat Plate in Parallel Flow

• Treat pot of boiling water like a flat plate in
  parallel flow.
• Use NuD 0.664Re1/2Pr1/3
• Use lumped capacitance to
• calculate time.
• Much more accurate estimation.

 Results Calculated Results Measured Results
t (min) Case 1 9.7 min 13 min
t (min) Case 2 36.8 min 30 min
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Conclusions/Recommendations

• Case 1
• Forced Convection Method was not valid for our
  experiment.
• A pot of boiling water is better modeled as a
  flat plate in parallel flow.
• Case 2
• Free Convection modeled
• as a horizontal plate was
• reasonably accurate.