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Pipe Insulation using Functions

ELSID
4-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
ELSID
4-Participant
(To:ELSID)

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

ELSID
4-Participant
(To:ELSID)

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

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

ELSID
4-Participant
(To:HarveyHensley)

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.

Try this.

ELSID
4-Participant
(To:ELSID)

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

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

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

ThermCondUnit.png

Attached might be of some help.

Alan

ELSID
4-Participant
(To:AlanStevens)

Alan,

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

ELSID
4-Participant
(To:ELSID)

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.

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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