4 replies to this topic

[Ghasem.Bashiri]

Dear my friends
Is there any general rule about pressure drop in heat exchanger.
My special concern is condenser of reboiler that such pressure drop is minimum.
I know that pressure drop is an economical factor for heat exchanger design.
But It is very difficult to perform such calculation.
If your have some recommendation please let me know your reference if it is possible.
Pressure drop in both side is very important for me: Shell and Tube
Regards
A.Bashiri

[srfish]

Your best bet is to purchase software for the pressure drop calculations in shell-and-tube heat exchangers. This is especially true if there is a change of phase and/or the heat transfer is non-linear.

If you do hand calculations, I suggest the Heat Exchanger Design Handbook(HEDH). A recent source for the shell side is "More Accurate Exchanger Shell-Side Pressure Drop Calculations". published in the June 2004 issue of Hydrocarbon Processing.

Good Luck
Dale Gulley

[Art Montemayor]

Everyone reading this:

Allow me to enter this thread, although I don’t plan on contributing to its subject.

However, what I can contribute is the recognition of someone who carries a large and positive reputation for heat exchanger design: Mr. Dale Gulley.

Dale Gulley is a recognized, experienced leader in the actual design and fabrication of heat exchangers. If he is recommending something (as he has kindly done in this thread), everyone would be wise to pay heed and write it down as expert advice. Although he doesn’t mention it here, Dale has a website that I highly recommend to everyone who has the interest, the need, and the desire to learn a lot about hands-on design of heat exchangers – down to the last detail. I highly recommend that all who are reading this go there and immediately access his section on engineering tips. It will astound you as to the detailed knowledge expounded there. I have personally downloaded all his tips and filed them in an Excel workbook for ready reference. I would recommend all do the same. This kind of knowledge doesn’t come around every day. The website in question is:

http://www.gulleyassociates.com/

Dale runs an engineering and software company in Tulsa, Oklahoma that specializes in heat exchanger design and process calculations. If you are ever in the need of engineering expertise and help in exchanger design, you couldn’t go wrong by going to him for help.

Dale, welcome to our Forums and thank you for your expert advice and recommendations. I sincerely hope that we can enjoy and learn by your frequent visits in the future.

P.S.
I think there is a typo error in Dale's reference. The referenced article came out in the July 2004 issue of Hydrocarbon Processing and is titled "More accurate exchanger shell-side pressure drop calculations - Use this method to reduce equipment size and pumping power cost", By D. Gulley.
You can obtain a reprint of this article at: http://www.hydrocarbonprocessing.com/

[Ghasem.Bashiri]

DearArt Montemayor
[b]Thank you for answer and good reference.
But in the site that you propose only typical pressure drop in exchanger are availavle.
I want to have allowable pressure drop. and for distillation condenser such pressure drop is very critical. we should minimize it as much as possible but I dont know limitation for it.[/b]

[Art Montemayor]

Bashiri:

Dale Gulley gave you the best response in your quest for calculating the pressure drop in a heat exchanger. His site gives you some expert tips on how to reduce the pressure drops in typical exchangers. I recommend you read and download all his tips.

You state that you "want to have allowable pressure drop". By this, I have to guess that you are seeking a figure that represents the allowable pressure drop for your condenser/reboiler/exchanger.

You, the process engineer, determine - in accordance with your process requirements and characteristics - just what is the allowable pressure drop that you can tolerate in your exchangers. We, or an exchanger supplier, can't identify that figure simply because we don't know or have any information on your process and the exchanger's application.

I think we all emphatize with your need to reduce the pressure drop through your exchangers as much as possible - and for that we have texts such as Kern's "Process Heat Transfer", and Ludwig's great "Applied Process Design for Chemical & Petrochemical Plants". We also can resort to recognized expert opinion and tips such as Dale's. I suggest you obtain the articles that he has written on the subject in Hydrocarbon Processing. That's why I went to the lengths of giving you the URL for his website and mentioning his Tips and articles in Hydrocarbon Processing.

There are other sources for such expert information. But Dale's is one of the best.

Can you give us SPECIFIC information as to what you are trying to do? For example, are you designing, modifying, or specifying a heat exchanger? What are the fluids, the process, the application and the design data for the exchanger? Have you approached or communicated with local or other exchanger designers and fabricators? We can all contribute detailed, concrete responses - but we need detailed, concrete basic data and information. Otherwise, all we can do is generalize.