I disagree. I bypass path is in most real water systems.
Air can be compressed and a fan will not fully blocking the flow. Therefore, a bypass is not generally provided.
A variable balanced flow system cannot be implemented without some dedicated controller or computer control. For safety and other reasons, bypass are still provided in a real system.
For your SVG diagram, the constant speed pupmp has a constrant flow rate. The zone demand is addusted by varying the flow rate. The excess flow must go somewhere. Therefore, a by-pass path is provided. If there is only one branch in the loop, the system can use the on/off mode to control the supply capacity, because there is no other demand in the loop.
For the supply side by-pass, I visualize it as the link to the heating or cooling source. When the pump is off, the water can still be maintained at the set point temperature by cycling the source.
For a coal furnace, it cannot be shut off quickly. The pump is usuallby fitted with a bypass so that the demand is not completely disconnected. The furnace air intake is reduced, and the file will then be slowly extinguished.
The tower has a by-pass, because it also have a setpoint temperature to meet, even when the condenser loop pump is turned off from the demand side.
"By-pass" is not a redudent element for EPlus simulation purose only. It is also a reminder that they are in a real system.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Date: Tue, 14 Aug 2012 09:36:54 -0500
Subject: RE: [EnergyPlus_Support] What ByPass component means?
Vaibhav,
A bypass is an EnergyPlus idiosyncrasy that helps E+ balance mass flows in a loop. They are not always needed, but also, they don?t get used or affect results in a balanced loop. I think of them as a way to avoid certain problems in the simulation while I am solving other problems. I review the flows in the bypass after a simulation, and if there is flow when I don?t expect it, I investigate to determine its cause.
James V Dirkes II, PE, BEMP, LEED AP
The Building Performance Team Inc
1631 Acacia Drive, Grand Rapids, MI 49504
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Vaibhav Jain
Sent: Tuesday, August 14, 2012 10:08 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] What ByPass component means?
As I am not a mechanical engineer that's why I am curious to know - what does ByPass component means, which I see in both demand and supply side, and what is its function in real world systems, if any? I am attaching a picture (in line with text) to explain what exactly I mean. I somehow couldn't understand it very intuitively from documentation. Thank you!
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