Skip to main content
rosa26791-Visitor
1-Visitor
April 22, 2018
Solved

MathCAD 15 solve block error

Hello,

I am working on creating a model to design an wastewater treatment process. I have set up the mass balances and but keep getting function errors dealing with the flow, which I am hoping to be able to change in further iterations to see how the system will handle it. I have checked and the guesses are within a reasonable range. I have reworked this many times and have been unable to get any answers. I am very new to mathCAD so I could be missing something relatively simple, I appreciate any help you all can give me!

terryhendicottAnswer
21-Topaz II
April 22, 2018

Hi,

 

Some of the equations in the solve block are not consistent units.  These need to be fixed first.  I try some of the equations prior to the solve block to test they are unit consistent.  You need to check them all.

View in thread

5 replies

terryhendicott21-Topaz IIAnswer
21-Topaz II
April 22, 2018

Hi,

 

Some of the equations in the solve block are not consistent units.  These need to be fixed first.  I try some of the equations prior to the solve block to test they are unit consistent.  You need to check them all.

Translate
rosa26791-VisitorAuthor
1-Visitor
April 25, 2018

Thank you all for you help! It was a problem with the units as suggested. I was able to fix the units issue by using L/mg wherever the unit less number was used and it started putting out the numbers I needed.

 

 

Translate
LucMeekes23-Emerald V
23-Emerald V
April 22, 2018

I see you're using Mathcad 15.

Apart from the fact that your equations must be unit-balanced, as Terry has pointed out:

I remember having read that Mathcad 15 cannot work with units in solve blocks. I hope I'm wrong.

 

Success!

Luc

Translate
terryhendicott21-Topaz II
21-Topaz II
April 22, 2018

Hi,

 

step one is to get the unit consistency in the equations.

step 2 is to get round the inability of the solve block to use units.

There is a workaround so don't be discouraged from solving the unit inconsistency in the equations first.

 

For instance i think the factor "Xrh" should be mg/L too?

 

Cheers

 

 

Translate
Terms & ConditionsAccessibility statement