Hot Dog! Allison Lee Victoria Lee. Experiment Set Up Compare the lumped capacitance method and...
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Transcript of Hot Dog! Allison Lee Victoria Lee. Experiment Set Up Compare the lumped capacitance method and...
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Hot Dog!
Allison Lee
Victoria Lee
Experiment Set Up
• Compare the lumped capacitance method and transient conduction
• Time it takes to cook a hot dog compared to time predicted
Assumptions• Hot dogs have the same properties as chicken
meat and water– hfg = 2257 kJ/kg
– vl = 1.044*10-3 m3/kg
– vg = 1.679 m3/kg
– cp = 4217 J/kg*K
= 0.0589 N*m
– km = 0.489 W/m*K
• Hot dogs are cylinders
Experiment• Initial Temperature = 15oC
• Final Temperature = 76oC
• Water Temperature at Boiling = 92oC
• Length of Hot Dog = 0.133 m
• Diameter of Hot Dog = 0.019 m
• Mass of Hot Dog = 0.049 kg
• Cooking Time = 249 sec
Lumped Capacitance Method
• q” = 1106857.1 W/m^2 Eq. 10.6
• h = 13021.8 W/m^2*K
• Bi = 126.8 Eq. 5.10
• Bi >> 0.1 invalid
• t = 2.55 sec << 249 sec
Transient Conduction
• Bi = 253.65 Table 5.1 = 2.4050
• C1 = 1.6018
• t = 676 sec
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Conclusions• Using the lumped capacitance method
when it is invalid will result in a extremely skewed answer
• The transient conduction yields a more accurate answer in this case
• Errors in predictions are due in part to differences in assumed and actual property values