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Wade,
You
can make your own HW-Blr-HIR-fPLR cubic curve for PowerDoe using Excel.
You can plot boiler efficiency and the boiler input ratio (as defined by
powerdoe) and create a third order polynomial trend line of the resulting
graph. Have Excel display the trendline equation and then input the
coefficients into a new curve fit in Powerdoe. The Powerdoe Help files and
documentation do a good job of discussing how curve fits work and how to create
your own. There is also a detailed help screen that discusses the
Boiler Heat Input Ratio.
If you
add your curve fits to a custom library they will always be there for you to
use.
Good
luck,
Mike
Tillou, PE
etc
Group, Inc.
SLC,
Utah
-----Origi nal
Message-----
From: postman@xxxxxxxx [mailto:postman@xxxxxxxx] On
Behalf Of Wade McLaughlin
Sent: Wednesday, February 12, 2003 12:05
PM
To: BLDG-SIM@xxxxxxxx
Subject: [BLDG-SIM] Boiler
Performance Curves
Hello All,
As part of a comprehensive energy study for a new
elementary school, we are analyzing fuel savings opportunities for a
proposed boiler with fully modulating burners as compared to a
base-case sectional lo-hi-lo boiler. So far, we have found that, all
things being equal, there are no significant savings associated with such a
measure (at least not for the boiler size and models we've been
considering).
We use PowerDOE for most of our energy
simulations. In the course of this study, we have come to question the
default boiler part-load heat-input-ratio curve (HW-Blr-HIR-fPLR) found in Bdllib.dat. Until now, we have applied
this curve to most base-case boiler calculations (perhaps mistakenly?).
Does anyone know of the origins of this curve or what it would have been based
upon? Most manufacturers we have spoken with state that peak boiler
efficiency occurs between 25% and 50% load. Using the default
curve, peak performance occurs at full load and efficiency
decreases by nearly 10% at half load.
Also, if this curve is in error, can anyone
suggest a method for developing a more reasonable curve estimate?
Thanks,
Wade
Wade McLaughlin
DMI
450 Lexington
St.
Newton, MA 02466
p 617-527-1525 x103
f
617-527-6606
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