4 replies to this topic

[harshad katre]

Dear All,
I need to calculate LMTD and draw the LMTD diagram often for the purpose of calculations of heat exchanger. Please let me know if there is any availability of software OR spreadsheet for LMTD calculations and LMTD diagram will be displayed directly when area and flow direction is specified.


Thanking You.

Regards,
Harshad

[breizh]

Consider this resource it might help :
http://www.chemsof.com/chemware.htm

Note : excel should be a good resource for this exercise!

Breizh

[harshad katre]

Thank You Sir.
But I need to have the temperature distribution diagram over the heat exchanger from the given temperatures showing the flow(direction) also. Is it available in any spreadsheet OR software?

Regards,
Harshad

[Steve Hall]

Harshad,
It sounds like you are looking for the temperature profile for the cold and hot fluids as they travel through an exchanger. To obtain this you essentially have to perform localized heat transfer calculations by dividing the exchanger into small zones, each zone sized such that the temperature change of the fluids within the zone is very small compared to the overall temperature change. Since the fluids usally run countercurrent, you don't know their temperatures. But the problem can be solved iteratively. This is one of the approaches used by commercially available heat exchanger sizing software such as HTRI and Aspen (formerly B-JAC).

I posted an explanation about temperature crosses last week, with a spreadsheet that performs an iterative calculation. It gives the temperature profiles. The spreadsheet could be modified to solve any configuration although the amount of work to make the modifications will be considerable if any of the basic assumptions must be changed (e.g., equal area per zone, constant overall heat transfer coefficient, etc.).

I'm reattaching the spreadsheet to this post for convenience.

Attached Files

•  exchanger zones.xls   105KB   57 downloads

[harshad katre]

Thank You Sir.
You are close to my point.
Actually I want to have the temperature distribution diagram with the help of which LMTD is calculated. For this we plot a graph of temperatures over area of heat exchanger for cold and hot fluid also defining their direction of flow (cocurrent OR counter current).
Will you please tell me where will I get spreadsheet for same? OR which software will serve the purpose?

Thanking You.

Regards,
Harshad