View Full Version : water flow design
10-28-2006, 06:13 AM
i am a dubai based hvac design engineer, i always used to design the water flow[Cooling application] as 2.4 USgpm per TR ,But presently i have come across a project and the design consultants have considered only 1.5 USgpm per TR will this make sense?
10-28-2006, 07:49 AM
in some cases, yes.
10-28-2006, 12:56 PM
In many locales such as yours, the "Extremely" high mineral content of the surface water and the low velocity conditions when the 2.4-2.5 GPM/TR "Will" result in premature scaling of the the condenser tubes in the leaving pass.. I have seen several chillers that in 2 years of operation a 1/4" all thread rod had to be driven thru the tubes so some sort of mechanical cleaning could be performed.
Increasing the velocity in the tubes to 7-8 FPS by inreasing the GPM/TR to 4-4.2 virtually eliminated the tube scaling.
"However".....Tube "Erosion" started to occur after 5-6 years....
Tubes were replaced w/316SS and the erosion problem was also cured....
As far as "Reducing" the GPM/TR to stated value....I cannot imagine such reasoning in your locale..
I can name many places where artesian spring water is used at a rate of 1 GPM/TR @ a year round temperature of 65-67 deg./f with Nooooo' problem...
I do question the possibility of you achieving this supply temperature constantly in your region....
I have "NO" doubt that the Engineering group involved is aligned with the big "T" and actually swallows the line of B.S. in their claims of the amount of energy conserved when going to this ridiculos and assinine low flow rate...
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