Help Needed - Air Cooler - Designed by Aspen

[r_rajesh82]

Dear Friend,
My boss had designed a air cooler using Aspen software and we had fabricated the same one. But now we have a problem that our cooler does not work properly.

Design Data for the Air cooler is
Shell Side Tubeside
Fluid Air Water
Design Temperature (degree celsius) 95 - 38 34 - 37
Design Pressure (Bar) 0.75 5
No.of Pass 1 6
Heat Exchanged 92958 K.cal/Hr
Material of construction we used is stainless steel 304 for entire equipment except tubes.
The tubes is A312 Gr.316L and with SS304 fins.

We checked the performance of the cooler with third party, shell inlet temperature is 86 and outlet is 56 and the Tubeside inlet temperature is 34 and outlet is 34.

The flow rate of the air is the same as that we used in the calculation. they have increase the water flow rate double the one used in the design still the temperature was 56. we do not know what was the real reason behind this and i seek help from you people to solve it. Help me.

I have attached the datasheet and the design details in post. Please have a look and help me in solving the problem.


Also i have a question whether the heat transfer will be same for pipe and tube of same size, same thickness, same length etc. if different can someone explain to me in details

[sniperel]

Hy!
Sorry I didn't understood your message. Let me get it: You have an aircooler that cools water from from around 86 C to 56 C, and you don't achive this profile? I suggest you should use Xace from HTRI, for the version 6 is a ********.
Hope I was helpfull! Have a nice day!
By!

[superandy]

Dear friend,

in order to make rating calculations on the air cooler, I need to have the data sheet of the equipment.

Please post it here.

Regards

superandy

[sniperel]

Hello!
I will look at your datasheet and I will tell my conclusion
By!

[sniperel]

Hy!
I have some questions and comments for you:
1. Can you tell me more about the process? Why the air has 95 C inlet temperature? and is a process constrain or client request the air outlet temperature?
2. My guess is that the low delta T between cooling water inlet and air outlet (34 vs. 38 deg. C) is causing the problems. Try to lower the cooling water inlet temperature to have a 10 deg C difference or if it is possible let the outlet air temperature higher.
3. What's the air design temperature? Because if the air design temperature is higher then 38 you can't obtain what you want.
4. The OD for the tubes have a unusual value (21.34 mm)
5. At point 6 the exchanger have an lenght of 698.34 mm but the tubes have an lenght of 0.96 m. Maybe I understood wrong but check this out.
6. If you solve this problem I suggest you to use HTRI instead of Aspen.
Have a nice day!

[A.Venugopal]

Mr Rajesh,

Please mail me details of this problem , it will be handy for me when I am at work on design review for you . I will try do the design check for you .

Best regards

venugopal
avgpaul@gmail.com