[EnergyPlus_Support] Condenser Water Plant - 4 Two-Speed Cooling Towers Parallel+Headered Pumps

["berlinclownfish" <SPlamp@xxxxxxxxxxxxxxxx>]

Dear EnergyPlus-Support,

I'd like to model a typical Condenser Water Plant consisting of four Two-Speed Cooling towers in a parallel arrangement and fed by a headered constant speed pump.

First attempts to incorporate a headered pump object instead of a common single and constant speed condenser water pump (reflecting total volume flow rate) ended in a fatal error with the following message:"The following pump is not the first component on its loop/branch: TOWERWATERSYS1 PUMP". Did I overlook anything, possibly a mistake in node connections and declarations?

As an alternative, I have modeled a single variable speed pump in an attempt to reflect a variable volume flow condenser loop depending on the demand by a set of 4 parallel Two-Speed Cooling towers.
However, I was unable to divert any flow into 3 of the 4 cooling towers, irregardless of the amount of trial combinations in creating various operation schemes and branch control types. Did I possibly miss a "smart" combination.

It turned out, that the very first cooling tower in the arrangement requested/received the entire amount of flow available from the variable speed pump. Replacing the condenser pump in this arrangement with a headered pump or constant speed pump was unsuccessful. By the way, a headered pump works extremely well for the staged arrangement of 4 parallel centrifugal chillers, supplying appropriate amounts of chilled water in a staged fashion.

As another alternative, I attempted to model branch pumps for each cooling tower, which also did not end very well.

I am well aware of simplification methods when modeling, but would like to reflect upon the free convection regime on all of the four cooling towers as realistic as possible and furthermore evaluate the option of replacing a single or two out of the four cooling towers by upgrading it to a variable speed tower, hence the effort.

EnergyPlus-Users, did anyone come across this challenge and succeeded? Submitting a working reference example file would be outmost generous and I would be very thankful!

Thank you,

Sandro





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