• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Effectiveness to calculate the outlet temperatures of a heat exchanger

  • Thread starter PCal
  • Start date
14
2
Hi, I am working this same question at the moment and I have got the same answers you did for the outlet temperatures and the heat transfer rate of TC2 = 66.25°C and TH2 = 37.5°C, and the transfer rate of 129.15kW.
I am now struggling with the correction factor part of the question. Following the equations given in the lessons which are as you mention above I am not getting to 0.59.

I get :
∆Tc = Φ / UA
129.15 / (0.36 x 14)
∆Tc = 25.625°C
Then

F=∆Tc/LMTD

LMTD = (TC2 - TC1) / In [(TH - TC1) / (TH - TC2)]
= (66.25 - 15) / In [(140 - 15) / (140 - 66.25)]
LMTD = 97.13°C

F=∆Tc/LMTD
25.625 / 97.13
F = 0.264
Please can someone point me in the right direction please as I am going round in circles.
Thanks in advance.
 

BvU

Science Advisor
Homework Helper
12,184
2,713
I suspect your LMTD expression -- It looks wrong and it should have four temperatures as argument, not three

By the way, if you start a new thread, you appear on the 'unanswered' list (Threads with no replies) which is seen by many helpers. Now only the participants in this thread get a signal.
 
19,276
3,818
The effectiveness factor is the ratio of the heat transfer rate to the maximum possible heat transfer rate. The maximum heat transfer rate is what you get if you have countercurrent flow. With countercurrent flow, you have different inlet and outlet temperatures than the ones given.
 

Want to reply to this thread?

"Effectiveness to calculate the outlet temperatures of a heat exchanger" You must log in or register to reply here.

Related Threads for: Effectiveness to calculate the outlet temperatures of a heat exchanger

Replies
10
Views
6K
  • Posted
Replies
2
Views
21K
  • Posted
Replies
5
Views
882
  • Posted
Replies
9
Views
793
  • Posted
Replies
17
Views
3K
  • Posted
Replies
0
Views
1K
Replies
9
Views
5K
Replies
1
Views
595

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top