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Pipe Insulation using Functions

ELSID
Participant

Pipe Insulation using Functions

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

12 REPLIES 12

Re: Pipe Insulation using Functions

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

Re: Pipe Insulation using Functions

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

Re: Pipe Insulation using Functions

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

Re: Pipe Insulation using Functions

Can you update the file to show me. I had a similar problem before, but cannot find the filewith my notes on how to do it. I am attaching a revised file.

Re: Pipe Insulation using Functions

Try this.

Re: Pipe Insulation using Functions

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

Re: Pipe Insulation using Functions

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

Re: Pipe Insulation using Functions

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

ThermCondUnit.png

Re: Pipe Insulation using Functions

Attached might be of some help.

Alan

Re: Pipe Insulation using Functions

Alan,

I think I can work with this. Need to "study" further, but in the correct direction.

Re: Pipe Insulation using Functions

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.

Re: Pipe Insulation using Functions

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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