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ELSID1-Visitor
1-Visitor
March 23, 2012
Question

Pipe Insulation using Functions

  • March 23, 2012
  • 3 replies
  • 5799 views

Long time no write. I am attaching a Mathcad v14 file where I am attempting to solve the required insulation thickness using temperature and insulation splined functions. I know this is a multiline curve fit. At the bottom, you will notice two functions. If I disable the one on the left and turn on the one on the right, the graph works. As a by product, I will then need to figure out why the function generates a [2,1],1 vector

3 replies

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ELSID1-VisitorAuthor
1-Visitor
March 23, 2012

Updated file. Had "t" defined multiple times from another sheet I worked out. Still not getting a single answer when fixing the thickness and time

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ELSID1-VisitorAuthor
1-Visitor
March 24, 2012

Narrowed down the problem. The array dimensions in the denominator do not match! Seems so simple ... brain is fried

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HarveyHensley12-Amethyst
12-Amethyst
March 24, 2012

The "thick" variable is an array and there is no index for it in the argument in the last plot.

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ELSID1-VisitorAuthor
1-Visitor
March 25, 2012

See revised file

  • Fixed function definitions.
  • I still can not get the "multicurves" to plot (expect flybacks).
  • Help in finishing sheet. Questions embedded in worksheet and highlighted in yellow.

Message was edited by: ElSid to update and clean up the file

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ValeryOchkov24-Ruby IV
24-Ruby IV
March 25, 2012

My students keep in mind the constant 273.15.
I think that American students must keep in mind the constant 459.67.

Correct work with US temperature unit in an empiricl formula:

Funit.png

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ValeryOchkov24-Ruby IV
24-Ruby IV
March 25, 2012

I see than we use not correct Thermal Conductivity units in Europe and in USA:

ThermCondUnit.png

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ELSID1-VisitorAuthor
1-Visitor
March 25, 2012

Valery, my equations are correct. Use t=14.7 minutes (~200F) and it gives the same answer. Test at t=27.7 minutes to and k=.499 which follows the curve. (NOTE: max temp is 530F)

Thermal Insulation.png

I believe that I need a program instead of a solve block in the highlighted "yellow" sections below.

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ValeryOchkov24-Ruby IV
24-Ruby IV
March 25, 2012

You would like to find a minimum of the function of one argument?

Ath first You must to create the function of this function.

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