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Coil Wound Heat Exchanger


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#1 kachan

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Posted 11 September 2014 - 05:48 AM

Good day to all !  Somebody knows how to calculate the Coil wound Heat Exchanger(CWHE) in  hysys. Or is there any program to calculate the CWHE  design. In general, where to find information on the calculation of the CWHE

 

Thanks and Regards, 


Edited by kachan, 11 September 2014 - 05:51 AM.


#2 Art Montemayor

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Posted 11 September 2014 - 03:22 PM

Kachan:

 

What do you specifically mean by "coil wound heat exchanger" and in what service do you intend to design it for?  Is this an academic project or a real industrial application?

 

There are many forms and shapes of coil wound heat exchangers.  One is the type used in cryogenic cooling of natural gas to produce LNG.  Is this what you mean?  Other versions are spiral (Archimedes spirals) versions using tubes.  Yet another version is spiral plates as fabricated by such manufacturers as Alfa Laval.

 

I seriously doubt that you will find any simulation program that can accurately calculate correct size and shape of a coil wound exchanger.   This type of heat exchanger is fabricated under proprietary know-how and although there are articles published on the subject, most (or all) are either theoretical or very general in nature - not enough to enable anyone to process design a coil wound exchanger.

 

I have designed and fabricated about 25 such units which I used as compressor intercoolers and small gas coolers.  I used empirical, overall U's to calculate the size and copied the techniques of such manufacturers as Graham.  The units worked very well and were extraordinarily efficient.  I never used a computer program for this; I used a slide rule.



#3 kachan

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Posted 12 September 2014 - 01:03 AM

 

Dear Art Montemayor!

 

Thanks for your answer!  Respect you as a person with extensive experience in the art of designing!

 

1.This is an academic project.

2. This is cryogenic cooling of natural gas to produce LNG.

 

Сan you help me with the value of the overall  U's for this type heat exchanger?



#4 Art Montemayor

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Posted 12 September 2014 - 09:02 AM

Kachan:

 

Sure, I will be glad to look into my files and try to find what Overall U I used in my units.  But you have to help me also by answering my basic questions.  Tell me all your basic data regarding the fluids used, their conditions, and the mechanical design or type of exchanger.



#5 kachan

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Posted 15 September 2014 - 12:31 AM

Kachan:

 

Sure, I will be glad to look into my files and try to find what Overall U I used in my units.  But you have to help me also by answering my basic questions.  Tell me all your basic data regarding the fluids used, their conditions, and the mechanical design or type of exchanger.

 

 

Art Montemayor:

Thanks for your quick reply! I would like to take as a basis  the CWHE Linde (as an example) and  to find for him approximate U. I need the approximate size for this heat exchanger with a specific performance. Could you help me to find approximate U for this type Heat exchanger? I think if i take approximate U i will find the required surface area and   the basic dimensions. That's what I meant. I drew a diagram of the heat exchanger with  the main thermodynamic parameters(components Flow /mass flow/temperature/pressure). And I can give you this picture. Are you can help me with this problem?

 
Sincerely , Kachan!

Edited by kachan, 15 September 2014 - 12:33 AM.


#6 Art Montemayor

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Posted 15 September 2014 - 12:57 PM

Kachan:

 

You are obviously a student, so you have difficulty understanding the complexity of a coil-wound heat exchanger (CWHE) as opposed to what we normally see and use – a TEMA-based shell and tube heat exchanger.  There is a world of difference in the technology and methods employed and one has to be very mindful of the objectives and challenges that confront a CWHE design.  If you are dealing with a Linde CWHE, then you have probably one of the most arcane and proprietary limited designs in heat exchangers.  This type of design is primarily applied in cryogenic projects – but very big and expensive, world-scale projects.  This is a heat exchanger application that consumes the time and efforts of perhaps several teams in a typical world-scale LNG plant design.  You will never find any HTRI program to design this type of heat transfer unit – and much less in HySys.  There are only a few companies that can be trusted, in my opinion, with a credible and dependable design – such as Air Products, Linde, and a few others.  And they are not going to share their hard-earned and expensive expertise with anyone.

 

I believe you are dealing with an LNG or similar application and I don’t see what you can prove by developing an academic calculation (or “estimate”) when no one in academia is going to be able to determine or guess if your estimate (or guess) is correct or not.  All you can do is guess at what you think is an appropriate overall “U” and leave it at that.  Who is going to challenge it?  Besides, there is little that you can do with an overall “U” when it comes to a CWHE because you can’t accurately determine the physical shape and size of the ultimate exchanger.  You can’t do this because of the very complex constraints and demands that you have to confront with respect to thermal expansions and stresses that are built up due to cryogenic temperatures as well as the very tight and narrow temperature approaches that you must meet in order to make the finished product capable of meeting very efficient heat transfer demands.  You are not going to find the tools to solve these problems in a text book - or in a classroom lecture.

 

If I were you, I would simply make an educated guess at a conservative overall “U”, guess at the overall dimensions and weights, and leave it to others to prove otherwise.  No one will contradict or challenge you – unless they have done the real thing before, which I highly doubt will be the case.

 

 



#7 Rudrad Raz

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Posted 03 September 2015 - 04:08 PM

 Design of CWHE is really complex.I would like to do the Energy Balance of Precooling,liquifying and subcooling of three stages coil wound heat exchanger.Could anyone provide the diagram of CWHE with stream specification?






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