2 replies to this topic

[kumaqal.engr]

my question is that why we find corrected temperature differene Ft, and how can we decide what should be taken in shell side and which stream should be taken in tube side, why we find Jh factors in designing of heatexchanger what is the importance of clean over all coefficient, and Ud in heat transfer calculation. i want brief answer. so once again looking for your precious response:) THANK YOU

[aliadnan]

Hi kumaqal.engr
Answer regarding to your questions are

1) About Ft. In a shell and tube Heat exchanger we have 1 shell pass and 2 tube passes (I am talking about the simplest 1-2 shell and tube heat exchanger) the flow in the tubes is co-current at one pass and on the other pass it is counter-current with respect to the shell side fluid. Since we know that there is higher temperature difference during the counter-current flow between shell and tube fluids than in co-current. In 1-2 pass exchanger we have both these flows so we cannot calculate the actual LMTD, so we use Ft correction factor to account for both counter and co-current flow and calcuate the corrected LMTD.

2) Well the alloction of streams in the shell and tube sides depends upon many factors like

a ) Whether fluid is corrisive or not, fouling fluids are usually taken in the tube side because the cleaning is much easier.

b ) If you have high pressure steam, then it flows through the tube side, while if you have to generate low pressure steam then this is done in the shell side, because of the mechanical advantages.

Some of the other factors are discussed on this forum earlier

http://www.cheresour...?showtopic=1651 <----- Click Here

Well I hope these answers will help you.
Regarding answers of other questions, I hope some other people on this forum will help you in those

Please correct me if I am wrong in any of my statements.
Regards
Ali

[Art Montemayor]

Ali:

Good work! You have given some very good responses to some general and non-specific questions. This is about as good a response as one can give when “a brief answer” is requested.

kumaqal.engr:

Your query is very non-specific, is multi-subject, and so basic that it requires a book to address all your concerns and lack of understanding. Such a book is:

“Process Heat Transfer”
Don Q. Kern
McGraw-Hill Book Co.
1950

This book contains the answers to all your queries and then some. If you are going to be doing heat transfer work now or in the future, I strongly recommend you obtain a copy of this book and study it with relish.

Good Luck.