Closed loop Chilled water system - pressurisation units

dulenz · Nov 4, 2008, 03:11 PM

You can locate pressurisation unit anywhere you want. If your chiller and pumps are located on level 0 than locating the pressurisation unit at highest level will make it smaller and cheaper than if you locate it on level 0. However bare in mind that it might not be feasible to locate pressurisation unit at highest level (no plantrooms).

Cut in and out points will depend on pressure in piping that you want to keep. When pumps are not operating the pressure in piping should be above atmospheric (positive gauge) at all points of the system to prevent air infiltration. Typically you need around 30 kPa positive pressure.

ASHRAE formulas are ok. For sizing

Chilled water is closed system so pumps should be sized for pressure loss through piping, coils and fittings only! Not for static head.

Location of the pressurisation unit has nothing to do with pump selection. Pumps will be the same wherever you put your pressurisation unit.

Let me know if you need more help

Gouravnim · Jun 9, 2009, 02:46 AM

How to calculate the head and flow for chilled pumps primary & secondary?

ronald123 · Jan 9, 2012, 03:42 AM

Dear kdagencies,

Appreciate your answer.
What about the flow rate capacity of the pressurization pump?

To anvarpb,
What is the Q in your equation above?
Is it the sensible heat you mean?

Hope to hear you soon.
This is a good thread to share ideas.

baneshpai · Apr 30, 2012, 11:43 AM

I was following above questions. can anybody tell me what will be the pressure at the highest / top level of the building?

Chill Man · Sep 26, 2012, 07:00 AM

I like to add a smole correction for this. If consider the pump head as same as the hight of the building you will never reach to the top. First calculate the head loss of the piping arrangement and add that to this. That is your pump head. But do not forget to keep the safety factor.

Alireza Avizheh · Nov 25, 2012, 03:13 PM

Hi
And also for calculating open exp. tank volume you can use below eq.

V = 1.5 x ( Q / 1000)
Q = boiler heat Capacity, Kcal/hr
V = open exp. tank volume, Lit.

jumayjuma · Dec 2, 2012, 05:33 AM

Salam
This is a common problem in New Dubai
Was sudden District Cooling become the favorite choice for newly developed towers because of more investment advantages?
However
Observations:
* Secondary chilled water pumps are at full speed (VFD) and sometimes even stand-by pump is on.
* Lower floors tenant are paying high energy (BTU Meter) Bills.
* Higher floors are not getting enough cooling.
* When humidity level rise, condensation & fungus will hit the tower.
* DC-Provider is not satisfied of less cooling consumption
Reasons:
* Form of air pockets.
* Wrong location of Chilled Water Pump
* Wrong location of make-up pressurization pumps
* Using bad quality of Air Vent Valves
* Unbalanced chilled water system (Can't be balanced as it is)
* DC-Provider control the flow depending on Temp. Diff, while tower control's flow depending on Pressure, no integration or communication between both systems
For Corrective Action & Solution
Please send me your e-mail so I will send you a presentation
Thanx
Eng. Juma Yousef
Getco-Green Earth Technology Co.
+971-50-4948385
jumayjuma@gmail.com

Patrik-bc · Apr 25, 2013, 05:38 AM

Dear Caibuadday,

In a chilled water system (primary secondary and tertiary pumps with chillers), how to determine the maximum allowable pressure at the pressurozation unit to use in the calculation it is too much confusing and not clear for chilled water system.

And if the pressurization unit is installed at the suction of the pump how it keeps the pressure constant at this point? In other way if we install the pressure unit at the discharge side of the pump why negative pressure will come at the suction?

I wish your supportive answer since no one is able to answer me and even in the BS and ashrae these 2 points not clear.

Thank You so much!

Patrik-bc · Apr 25, 2013, 05:41 AM

Quote:

Originally Posted by dulenz

You can locate pressurisation unit anywhere you want. If your chiller and pumps are located on level 0 than locating the pressurisation unit at highest level will make it smaller and cheaper than if you locate it on level 0. However bare in mind that it might not be feasible to locate pressurisation unit at highest level (no plantrooms).

Cut in and out points will depend on pressure in piping that you want to keep. When pumps are not operating the pressure in piping should be above atmospheric (positive gauge) at all points of the system to prevent air infiltration. Typically you need around 30 kPa positive pressure.

ASHRAE formulas are ok. For sizing

Chilled water is closed system so pumps should be sized for pressure loss through piping, coils and fittings only! Not for static head.

Location of the pressurisation unit has nothing to do with pump selection. Pumps will be the same wherever you put your pressurisation unit.

Let me know if you need more help

Dear Dulenz,

In a chilled water system (primary secondary and tertiary pumps with chillers), how to determine the maximum allowable pressure at the pressurozation unit to use in the calculation it is too much confusing and not clear for chilled water system.

And if the pressurization unit is installed at the suction of the pump how it keeps the pressure constant at this point? In other way if we install the pressure unit at the discharge side of the pump why negative pressure will come at the suction?

I wish your supportive answer since no one is able to answer me and even in the BS and ashrae these 2 points not clear.

Thank You so much!

Closed loop Chilled water system - pressurisation units

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