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TN_96763581-Visitor
1-Visitor
October 17, 2020
Solved

Heat capacity unit error - ODE function

  • October 17, 2020
  • 2 replies
  • 2750 views

Hello everyone,

This is my first time ever using MathCAD. I have no ideas but watching some video help me to create this sheet. I got the error unit of Cp (heat capacity) = BTU/lb*F. MathCAD error is value should be scalar or matrix.

 

I also set up the ODE function. Would you please help me to take a look this and guide me where I was wrong?

 

Thank you so much for your help. I attached the file in this post

Best answer by Werner_E

As Valery pointed out you used F (Farad) instead of °F (Degree Fahrenheit).

Furthermore you have to be aware, the working with temperatures can be quite tricky! Prime converts all temperature values to K (Kelvin) and does the calculations in K. Because the conversion between K and °F is not homogenous (its not a simple factor) this quickly can create confusion and this is the reason why Prime offers °F AND Delta°F. Look at the picture below.

Werner_E_0-1602938062194.png

Another error in your sheet is that in the solve block you wrote the IC in two separate regions (one with "T(0 min)" and the other with "..=120°F".

 

Hope the attached sheet helps. Instead of "Delta°F" you may also use "R" (Rankine) as Valery had suggested.

2 replies

V
ValeryOchkov24-Ruby IV
24-Ruby IV
October 17, 2020

Farada.png

    T
    TN_96763581-VisitorAuthor
    1-Visitor
    October 17, 2020

    Thank you so much! I really appreciated your help. Thank you so much again

    W
    Werner_E25-Diamond IAnswer
    25-Diamond I
    October 17, 2020

    As Valery pointed out you used F (Farad) instead of °F (Degree Fahrenheit).

    Furthermore you have to be aware, the working with temperatures can be quite tricky! Prime converts all temperature values to K (Kelvin) and does the calculations in K. Because the conversion between K and °F is not homogenous (its not a simple factor) this quickly can create confusion and this is the reason why Prime offers °F AND Delta°F. Look at the picture below.

    Werner_E_0-1602938062194.png

    Another error in your sheet is that in the solve block you wrote the IC in two separate regions (one with "T(0 min)" and the other with "..=120°F".

     

    Hope the attached sheet helps. Instead of "Delta°F" you may also use "R" (Rankine) as Valery had suggested.

      T
      TN_96763581-VisitorAuthor
      1-Visitor
      October 17, 2020

      Thank you so much for the attached file. I have better ideas. Have a good day!

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