Rho V^2 in heat exchanger 2

[kyong]

I would like to learn something.
In heat exchanger, what importance does Rho V^2 has?
Is it very important parameter? If so, why?
Can anyone help me out?

 

[Shmulik]

Hi kyong,

Rho V^2 parameter value is important when you come to determine the necessity of impingement protection and entrance / exit areas. Definitions are in TEMA standard:
RCB-4.61 Shell Side Impingement Protection Requirements: An impingement plate or other means to protect the tube bundle against impinging fluids, shall be provided when entrance line values of Roh V^2 exceed the following: non-corrosive, non-abrasive, single phase fluids, 1500: all other liquids, including a liquid at its boiling point, 500: For all gases and vapors, including all nominally saturated vapors, and for liquid vapor mixtures, impingement protection is required. V is the lineal velocity of the fluid in feet per second and Rho is its density in pound per cubic foot. A properly design diffuser may be used to reduce line velocities in shell entrance.
RCB-4.62 Shell or Bundle Entrance and Exit Areas: In no case shall the shell or bundle entrance or exit area produce a value of Rho V^2 in excess of 4000 where V is the lineal velocity of the fluid in feet per second and Rho is its density in pound per cubic foot.

I hope it helps,
Best regards.

 

[kyong]

Shmulik,

Thank you very much for your help.

 

[ChasBean1]

kyong, more simply put this appears to be velocity pressure. Rho*v^2 works to be a pressure unit in psi, pounds per square foot (as per the 1,500, 500, and 4,000 maximum values per the standard posted by Shmulik above) or Pascals; denser fluid allows less impingement fluid velocity; lighter fluid allows higher speed.