Hi All,
Does anyone have a resource the shows the steps that eQUEST/DOE-2.2 uses to calculate the hourly power of a pump (CHW/HHW) with a variable-speed drive (assuming we already know full-load power)? The process for hourly-power for a "One Speed Pump" is straight forward and uses the Pump-Head-fFlow and Pump-Power-fFlow curves to simulate the pump riding its curve. For the "Variable Speed Pump," the eQUEST documentation says that the curves are "re-normalized" hourly to match the pump speed, but it seems the following is internal to the engine/software and not explained:
- function relating speed to hourly flow and head requirements
- how the PUMP-POWER-EXP keyword is used
- how the full-load VFD loss (kW) calculated
I usually use the DOE-2.1a Engineering Manual for my DOE-2 questions, but unfortunately the water-side of DOE-2.2 is quite a bit different than its predecessors. It also looks like most of the other software (IES, Trace, e+) uses specific VFD-Pump-Power curves to model power. Maybe an older version of e+ uses a similar method to DOE-2.2 that I can study?
Much thanks!
