Editing Heat exchanger (section)

==Helical-coil==
[[File:HCHE.jpg|thumb|Helical-Coil Heat Exchanger sketch, which consists of a shell, core, and tubes ([[Scott S. Haraburda]] design)]]
Although double-pipe heat exchangers are the simplest to design, the better choice in the following cases would be the helical-coil heat exchanger (HCHE):
* The main advantage of the HCHE, like that for the Spiral heat exchanger (SHE), is its highly efficient use of space, especially when it's limited and not enough straight pipe can be laid.<ref name=patil>{{cite journal  | author1 = Patil, Ramachandra K. | author2=  Shende, B.W. | author3=  Ghosh, Prasanfa K. | title = Designing a helical-coil heat exchanger | url= https://www.researchgate.net/publictopics.PublicPostFileLoader.html?id=54daea37d5a3f295028b45be&key=cd7c7059-0d79-41f2-9d51-56d00af44bad  | journal = Chemical Engineering | pages = 85–88 |volume= 92 |issue= 24 | date = 13 December 1982 | access-date= 14 July 2015 }}</ref>
* Under conditions of low flowrates (or [[laminar flow]]), such that the typical shell-and-tube exchangers have low heat-transfer coefficients and becoming uneconomical.<ref name=patil />
* When there is low pressure in one of the fluids, usually from accumulated pressure drops in other process equipment.<ref name=patil />
* When one of the fluids has components in multiple phases (solids, liquids, and gases), which tends to create mechanical problems during operations, such as plugging of small-diameter tubes.<ref name= haraburda>{{cite journal  | author = Haraburda, Scott S. | title = Three-Phase Flow? Consider Helical-Coil Heat Exchanger | url= http://www.chemengonline.com/articles.php?file=1985-1999/Vol102/chevol102_num7_68.html | journal = Chemical Engineering | pages = 149–151 |volume= 102 |issue= 7 | date = July 1995 | access-date= 14 July 2015 }}</ref>  Cleaning of helical coils for these multiple-phase fluids can prove to be more difficult than its shell and tube counterpart; however the helical coil unit would require cleaning less often.

These have been used in the nuclear industry as a method for exchanging heat in a [[Sodium-cooled fast reactor|sodium system]] for large [[liquid metal fast breeder reactor]]s since the early 1970s, using an HCHE device invented by [[Charles E. Boardman]] and [[John H. Germer]].<ref>{{cite patent  | inventor-last = Boardman | inventor-first = Charles E. | inventor2-last = Germer  | inventor2-first = John H.| issue-date = 1974  | title = Helical Coil Heat Exchanger | country-code = US | patent-number = 3805890 }}</ref>  There are several simple methods for designing HCHE for all types of manufacturing industries, such as using the [[Ramachandra K. Patil]] (et al.) method from [[India]] and the [[Scott S. Haraburda]] method from the [[United States]].<ref name=patil /><ref name=haraburda />

However, these are based upon assumptions of estimating inside heat transfer coefficient, predicting flow around the outside of the coil, and upon constant heat flux.<ref>{{cite thesis | type= Ph.D.  | author= Rennie, Timothy J.  | title= Numerical And Experimental Studies Of A Doublepipe Helical Heat Exchanger | publisher= McGill University | location=  Montreal  | year = 2004 | pages= 3–4 | url = http://webpages.mcgill.ca/staff/deptshare/FAES/066-Bioresource/Theses/theses/308TimothyJohnRennie2004/308TimothyJohnRennie2004.pdf  | access-date =14 July 2015 }}</ref>