All,
I'm modeling a university campus building with heat provided by central
plant steam boilers, providing 15# steam. I've done this by eliminating
boilers in the model and attaching a steam meter to the hot water loop.
My problem is with pumping energy. Equest requires that a pump be attached
to the hot water loop, but the actual installation has gravity return
condensate. How do I zero out the pumping energy? I have set pump head =
0, but this gives me pages of error reports. Any other methods?
Thanks,
Steven Savich
David,
Tried that. The program ignores the 0 pump power input and calculates the
required power, even with actual flow and head input. PS-C report still
shows pump energy consumption by the heating water loop pump.
FYI I'm using eQuest ver 3-61e. Do later or earlier versions allow this 0
kW workaround?
Steven Savich
Try setting the pump kW itself to 0, or at least 0.0001 if 0 doesn't
work.
John R. Aulbach, PE, CEM
Steven,
The program will calculate one of the pump input parameters acording to
the relationship between power, efficiency, head and flow. Try assigning
an almost 0 kW power, and leave another parameter free (for example
head) for the programe to use the formula to calculate this parameter
instead of overriding the almost 0 kW power.
*Xavier Garc?a Casals*
All,
John's solution below works. Setting the pump kW to zero causes the program
to ignore the input, but if you input a vanishingly small pump kW input it
will be used by the program. Of note, if you also input actual head and
flow along with the 0.00001 pump kW, eQuest gives you an error message -
"PUMP design input is unreasonable Check Values". So it's necessary to
specify ONLY the PUMP-KW if you're doing this workaround.
Two things -
check the PS-C report to be sure that it's working. Pump Elec use should be
zero.
Heating energy use will increase since there is no pump energy loss into the
heating loop working fluid.
Thanks for all the responses and suggestions!
Steven Savich
Steven
I would not try and eliminate pumping power all together.
To minimise reduce pressure to a low level, apply good mech efficiency so not much heat is added to the loop by the pump.
Then at the end of the process simply do not include pumping energy in your results (i.e. working with totals, subtract the heating water pump energy from the total energy use).
These values can be taken from the sim file. Or the approach I would take is to get an hourly or monthly output file for the all parameters you wish to monitor.
Cheers
Jack Manning
Here is another way to deal with this issue:
? Create a linear curve fit with coefficients of
o a = 0
o b = 0
? Assign this curve to Pump keyword "Pump Power f(flow)". You don't
need to change any other pump parameters. Check Report PS-C to see that the
KWH is 0.
Jay Keazer, EI