Re: [EnergyPlus_Support] Pressure drop

["Jean Marais jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

I'm not supprised you broke it, Ned. I've yet to find a solver for air systems that solves loops using the gradient method (sort of like the hardy-cross method) as is the normal case for sprinkler, for example. Usually only tree type systems are supported. There are special loss-coeff. correlations for different things like t-pieces, ways, elbows, for round, rectangular, etc. It's quite a detailed subject...possibly the one thing I know more about than energy simulation. Biggest losses tend to be volume flow regulators and silencers (and coils). Duct leakage is usually neglected, unless you have very large systems under very high pressures like 1000 Pa (smoke exhaust). Perhaps, Dr Gu has some tips.

2017-04-27 21:22 GMT+02:00 'Edward G. Lyon' eglyon@xxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

 

Iâ??m not certain if this applies to nodes, but it may.  The airflow network does calculate zone pressures, and it is possible to define ducts and friction losses (though I broke the analysis code with my last try to model a mechanical system in the airflow network model), so it may be that the node pressures can be reported with variation when using a full airflow network simulation.

 

Ned Lyon, P.E. (MA, WV)
Staff Consultant

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From: EnergyPlus_Support@yahoogroups.com [mailto:EnergyPlus_Support@yahoogroups.com]
Sent: Thursday, April 27, 2017 2:21 PM
To: EnergyPlus_Support@yahoogroups.com
Subject: Re: [EnergyPlus_Support] Pressure drop

 

 

No. E+ does not calc hydraulics. You need to use ems or some other objects to change fan energy.

 

Am 23.04.2017 3:04 nachm. schrieb "alyelhefni@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@yahoogroups.com>:

 

Why does system node pressure in the output file give same pressure for each node on the same branch?

I expect it shows different values where after each component of the system a decrease in the value of pressure should happen. Why are the system node pressure values constant ?

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Posted by: Jean Marais <jeannieboef@xxxxxxxxx>

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