Not normally
ordinary treated water (which most chilled water systems use) is at its
maximum density at about 4 deg C. The density decreases either side of this
temperature. Many chilled water systems have a flow temperature of around 4
deg C, making it difficult to predict which way natural convection will make
the water flow. This effect is occasionally overlooked and can cuase
problems with stratified storage vessels. In general the density change is
to0 small to produce a useful driving effect given the normally small
(around 12 deg C) supply/return temperature difference, and small effective
column heights.
cheers
Steve
-----Original Message-----
From: Paul Bowers [mailto:pbowers@pipingdesign.com]
Sent: Wednesday, January 28, 2004 5:32 PM
To: PipingDesign@yahoogroups.com
Subject: Re: [PipingDesign] Chilled Water Supply Header Connection
Should natural convection be a consideration?
> I am not aware of a normal practice for the entry points.
> The major factors driving the connection point are, from my
perspective:
> *minimum bends/section changes
> *serviceability of valves, expansion joints etc
> *arrangements to collect surface condensation
> *location of header
> *minimisation of system volume and surface area
>
> If you are using chillers with low pressure circulation Ch-W pumps
(i.e
> additional higher pressure zone distribution pumps to deliver cooling
to the
> users) it will pay to take some care in the suction and discharge
header
> arrangements so each chiller sees an equal pressure drop. Failure to
do this
> can cause difficulties in load balancing - the chiller with the lowest
> pressure drop will get the highest flow and will try to do most of the
work.
>
> Cheers
>
> Steve
>
>
> -----Original Message-----
> From: cs_ang [mailto:csang88@pd.jaring.my]
> Sent: Wednesday, January 28, 2004 3:23 PM
> To: PipingDesign@yahoogroups.com
> Subject: [PipingDesign] Chilled Water Supply Header Connection
>
>
> I am working on a project which involve installation of a central
> chilled water plant. There are 3 nos water chillers each of 750RT to
> be connected in parrallel to a supply pipe header. My question is
> what is the normal pratice to connect the chiller (chilled water)
> outlet pipes to the header:-
> 1) At the bottom of main header or
> 2) At the side of main header or
> 3) At the top of main header
> and why.
> Regards,
> CSAng
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