Plate heat exchanger 2

[mech225]

Please could someone comment on the max. tempareture difference allowed for a plate heat exchanger to cool water successfully? Please could you give me a tempareture range that one could go and utilize such and exchanger? Advantages/disadvantages of plate vs shell and tube and plate vs spiral.

Thanking you

Mech225

 

[kenvlach]

The maximum practical temperature differential is that which will almost form ice on the exterior (ice is a poor conductor). This of course depends upon the &[ignore]Delta[/ignore];T, thickness and thermal conductivity of the HXer wall, surface transfer coefficients, and agitation. To make it easier, Tranter has a table of AVERAGE OVERALL HEAT TRANSFER COEFFICIENTS, U=Btu/hr sq ft °F, for various Platecoil® HXers. Values are given for both natural and forced convection cooling of watery solutions using water, Freon and brine as the cooling fluid.

http://www.tranterphe.com/phe/PDFs/PCC-3.pdf

My experience is with Platecoil® HXers used in open top, rectangular process tanks, as in the metal finishing business. The Platecoil® is hung about 2” from the back wall of the tank, leaving room for natural convection. The process solution isn’t pumped (except for filtration), but air agitation may be used. Platecoil® HXers are fairly easy to clean.

Other HXer types are more effective where both solutions are pumped, especially for countercurrent heat transfer. For more information on various types of HXers, see the Product Literature page at

http://www.tranterphe.com/phe/literature.htm

See also “Selecting a Heat Exchanger” at

http://www.lytron.com/support/ex_select.htm

The Heat Exhanger Institute has impartial publications:

http://www.heatexchange.org

Spiral or serpentine HXers are less expensive due to ease of manufacture. I get very competitive pricing in 316 SS, Ti and Zr serpentine HXers from

http://www.astrocosmos.com/

http://www.titanmf.com

 

[rmw]

Plate hx's have what I call the 300-300 limitation. That is, 300 PSI, 300F, but not both conditions at the same time. The gaskets are usually the limiting factor on temperature, and the large flat areas are the limitations on pressure. Plates offer much closer approach temperatures than S&T's, much closer, and they occupy less floor space comparing surface areas. They are completely cleanable. The flow passages are small relative to S&T's, so if fluids are not clean, they make excellent strainers, and hence, will plug up rapidly. Gaskets are a problem, but only if not properly installed. Unfortunately, gasket replacement is not the job that the best qualified mechanic in the shop usually draws. Normally "Bubba" gets to do it, and guess what. P&F's get the blame.

Post this question on the Heat Transfer thread, and I'll bet you get a lot of answers.