8 replies to this topic

[SadiqChemy]

Hello 

 

If I got overdesign% of heat exchanger very huge ( more than 1000 % ) what does it mean ?

 

What variables can I manipulate to get good overdesign % ? 

[spchauhan12]

Sadiqchemy:

 

Which type of heat exchanger is it?  Kindly share Process data sheet of this heat exchanger.

 

Please mention 1000 % of what?

 

Normally, in a heat exchanger the overdesign factor is applied to duty / Heat exchanged which is mostly 10% & varies a little bit from industry to industry.  This factor normally calculated during the exchanger design as shown below:

 

% Overdesign = {(A - A_Required) / A_Required } X 100
 

where,

A = design area of heat transfer in the exchanger;

A_Required = required heat transfer area.

 

Hope this may help you.

 

Regards,

 

SPC

[SadiqChemy]

SPC:

 

It is generic shell and tube heat exchange (TEMA TYPE - AEL)

 

Find the attached for process specification.

Attached Files

•  process specification.JPG   56.98KB   6 downloads

[spchauhan12]

SadiqChemy:

 

The Process Data Sheet shared by you is incomplete.  My intention is to check  the over design % in the Process Data Sheet which you have shared.

 

If this exchanger is existing in your plant, please check the original data sheet to find the over design %.

 

If it is new one, you may use HTRI or any software for thermal design to match allowable delta P & Over design %. Kindly refer to D Q Kern ( Process Heat Transfer book) to get more details.

 

If you are doing a new calculation, how are you getting a huge over design like 1000%?  This means there is a big error.

 

Revisit your calculation, referring to the D. Q. Kern book.

 

Hope this resolves your query

 

Regards,

 

SPC

[breizh]

https://checalc.com/..._exchanger.html

 

Consider the resource attached to support your work .

 

Good luck .

 

Breizh

[SadiqChemy]

Breizh:

 

We have change phase in LP steam, inlet is 100% vapor.  The output is 100% liquid.

 

So , What density shall I input? 

 

Is this spreadsheet only for a single phase heat exchanger ?

[breizh]

Hi,

 

I'm not sure I understand the question.  Your inlet stream is saturated steam.  The steam will condense due to heat transfer.  In other words, the heat exchanged is the mass of steam multiplied by the latent heat of steam.

 

Breizh

[SadiqChemy]

Breizh:

 

In the data sheet I have to put one density property for LP steam  besides other properties like specific heat, viscosity. Since Density of water in vapor phase much lower than density of water in liquid phase, so which density value shall I input?

[breizh]

Hi ,

You need to key in info related to steam ( Go for steam table where you will get the data needed)

 

http://www.thermexce...les/vap_eau.htm

 

Good luck

Breizh