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Re:[EnergyPlus_Support] Primary pump and secondary pump



I didn't model a system 8 before. I'd like to join the discussion.
Do you mean pump power instead of fan power?
In my opinion, the primary pump is used to cycle chilled water in the primary pipe and chiller, the secondary pump is used to supply water to the end users. Thus, the primary pump pressure drop should be lower and constant running. Why not find a two stage pump HVAC system description for reference?
Where do you find the system8 example?
Han Xing


At 2011-09-01 09:15:25,Xing <xing.shi.2006@xxxxxxxxx> wrote:
 

We have a system 8 and a primary-secondary pump system for chilled water. We are not sure about how to use E+ to model them. The approach we are taking now is:

1. Use the default pressure drop value in E+ and let fan power and volume flow rate be autosized, for both pumps.
2. Check the output results and get the flow rate for both pumps and they are the same.
3. Use the flow rate and apply the ASHRAE code requirement (349 kW for 1000 L/s) to get the required fan power.

At this step, we are a little confused. This calculated fan power should be the power required for the pump SYSTEM. How to distribute it between the two pumps?

We generated a system 8 IDF from E+ website and noted that it uses two different pressure drops for the primary pump and secondary pump and their ratio is approximately 2:1, meaning that the primary pump needs to overcome a pressure drop larger than the secondary pump.

Please help. Thanks!





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