[BLDG-SIM] DOE2.1E Chiller performance
Steve Gates
stvgates at pacbell.net
Fri May 16 09:27:05 PDT 2003
As a rough rule-of-thumb, you can expect about a 1%-1.5% change in
efficiency for every degree change in chilled-water supply temperature.
----- Original Message -----
From: "Varkie Thomas" <Varkie.Thomas at som.com>
To: <BLDG-SIM at gard.com>
Sent: Thursday, May 15, 2003 3:05 PM
Subject: [BLDG-SIM] DOE2.1E Chiller performance
Jon
This is for a "pre-conceptual?" phase of a project and the only interest
here at the moment is whether there is difference in chiller energy
consumption. As the project progresses we will be looking at other issues.
I cannot give numbers from this rough "pre-analysis?" of the project because
this is a confidential internal matter. You could check out chiller and
building component energy use with the various energy programs available.
Each chiller size has to be at least 1000 tons and the building could be
anything. I only brought up this issue on BLDG-SIM because I think there
might be a bug in the DOE2.1E program.
Varkie
-----Original Message-----
From: Jon McHugh [mailto:mchugh at h-m-g.com]
Sent: Thursday, May 15, 2003 3:53 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] DOE2.1E Chiller performance
Varkie,
The percentage higher energy consumption at different leaving water
temperatures is more useful than, " was higher, but not significantly higher
(relative to potential savings in the pump operating, heat transfer
equipment and piping costs)". How much higher was the energy consumption in
percentage?
When you are talking about "heat transfer equipment" above are you talking
about coils or something else? If you are talking about coils - the next
sentence says you haven't investigated this.
How much did the coil loads change (%) from reducing the leaving water
temperature?
How much did chiller efficiency change (%) from reducing the leaving water
temperature?
How much did pumping energy change (%) from reducing leaving water
temperature?
Was piping diameter resized?
Thanks,
Jon McHugh
-----Original Message-----
From: Varkie Thomas [mailto:Varkie.Thomas at som.com]
Sent: Thursday, May 15, 2003 12:58 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] DOE2.1E Chiller performance
This is in response to comments and questions that I received.
This was a preliminary attempt using DOE2.1E to find out large tonnage
chiller energy usage at decreasing LWTs and a fixed EWT to reduce the
CHW-flow. I may not have used the DOE2.1E correctly because results showed
the chiller LWT was always the default value of 44F. The test building was
a single zone per floor, 70% single glass, with multiple floors to produce
over 6000 tons. The DOE2 program was run with SOM office building template
defaults. The TRACE program was run twice, with all TRACE defaults for an
office building, VAV system and water-cooled centrifugal chillers, first
with CHW temp range of 38 to 56 and next with 42 to 56. In the first case
the program gave warning messages for LWT < 40 and CHW-DT > 15.
The energy usage of a chiller operating from 38 to 56 was higher, but not
significantly higher (relative to potential savings in the pump operating,
heat transfer equipment and piping costs) than 42 to 56. This might be
because of limitations in the energy program algorithms, and actual physical
tests with chillers might produce different results. Cooling coil sizes in
terms of fins, rows, etc are going to be affected. I did not check this out
using cooling coil selection programs. I did not check or compare the
results of the air-side system equipment performance.
What would be the results from other energy programs such EnergyPlus, HAP
and eQUEST? I would be particularly interested in the results from HAP. We
do not have this program in this office. I would also be interested in
comments from Trane regarding the results from TRACE. Was the program used
incorrectly?
Varkie
-------------------------------------------
-----Original Message-----
From: Varkie Thomas
Sent: Thursday, May 15, 2003 8:48 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] DOE2.1E Chiller performance
To those who responded to this inquiry:
We tested the two conditions with TRACE-700. There is little difference in
the energy consumed by the chillers for CHW temp range of 38F to 56F and 44F
to 56F particularly in the large tonnage range. This is also indicated in
chiller performance data catalogs. There is a big difference in pumping and
piping costs.
Varkie Thomas
---------------------------------------
We are trying to compare the performance of a 2000 ton chiller operating at
(1) 42 F LWT and (2) 38 F LWT. The chiller EWT is 56 in both cases. The
tower temp range is 85 F to 100 F. We want to know how the chiller COP
varies under these conditions.
The hourly output for the design day from DOE2.1E shows chiller LWT of 44 F
(DOE2 default) no matter what the input. Here is the input and output for
the option with 38 F Chiller LWT. Can the Chiller LWT be changed from the
default value of 44 F ? How do I check that the CHW EWT & LWT temps are
being maintained? Is the input below correct to model the conditions
described?
----------------------------------------------------------------
PLANT-PARAMETERS
CHILL-WTR-T = 37 $ Def = 44. LWT at bottom of Thrott
Range $
CHILL-WTR-THROTT = 2.0 $ Def = 2.5. Thrott Range = 37 to 39. LWT =
38 $
TWR-SETPT-T = 85
TWR-DESIGN-RANGE = 15.0 $ Def = 10. Tower temp range :85 to 100 $
CCIRC-DESIGN-T-DROP = 18 $ Def = 10. Chiller EWT = 56 $
----------------------------------------------------------------
MMDDHH OPEN-CEN OPEN-CEN OPEN-CEN OPEN-CEN OPEN-CEN
OPEN-CEN
T-CHLR T-CHLR T-CHLR T-CHLR T-CHLR T-CHLR
LOAD ELECTRIC OPER PT FRAC HR ENTERING LEAVING
USE LD RATIO OPERATED COND TEM COLD TEM
BTU/HR KW FRAC.OR FRAC.OR F F
MULT. MULT.
----( 1) ----( 3) ----(10) ----(11) ----(12) ----(13)
7 1 1 0. 0.000 0.000 0.000 0.0 0.0
7 1 2 0. 0.000 0.000 0.000 0.0 0.0
7 1 3 0. 0.000 0.000 0.000 0.0 0.0
7 1 4 0. 0.000 0.000 0.000 0.0 0.0
7 1 5 0. 0.000 0.000 0.000 0.0 0.0
7 1 6 8887730. 528.301 0.328 1.000 84.6 44.0
7 1 7 20704076. 1019.228 0.760 1.000 83.7 44.0
7 1 8 25529894. 1301.530 0.940 1.000 84.3 44.0
7 1 9 25563408. 1312.150 0.944 1.000 84.7 44.0
7 110 22676038. 1142.870 0.838 1.000 84.9 44.0
7 111 23148816. 1167.610 0.855 1.000 84.7 44.0
7 112 22012680. 1103.797 0.813 1.000 84.7 44.0
7 113 22536236. 1132.213 0.832 1.000 84.7 44.0
7 114 22738694. 1144.069 0.840 1.000 84.7 44.0
7 115 22827700. 1149.287 0.843 1.000 84.7 44.0
7 116 22768860. 1146.011 0.841 1.000 84.7 44.0
7 117 21899154. 1097.228 0.809 1.000 84.7 44.0
7 118 20232738. 1007.025 0.747 1.000 84.7 44.0
7 119 0. 0.000 0.000 0.000 0.0 0.0
7 120 0. 0.000 0.000 0.000 0.0 0.0
7 121 0. 0.000 0.000 0.000 0.0 0.0
7 122 0. 0.000 0.000 0.000 0.0 0.0
7 123 0. 0.000 0.000 0.000 0.0 0.0
7 124 0. 0.000 0.000 0.000 0.0 0.0
==================
You received this e-mail because you are subscribed
to the BLDG-SIM at GARD.COM mailing list. To unsubscribe
from this mailing list send a blank message to
BLDG-SIM-UNSUBSCRIBE at GARD.COM
==================
You received this e-mail because you are subscribed
to the BLDG-SIM at GARD.COM mailing list. To unsubscribe
from this mailing list send a blank message to
BLDG-SIM-UNSUBSCRIBE at GARD.COM
==================
You received this e-mail because you are subscribed
to the BLDG-SIM at GARD.COM mailing list. To unsubscribe
from this mailing list send a blank message to
BLDG-SIM-UNSUBSCRIBE at GARD.COM
======================================================
You received this e-mail because you are subscribed
to the BLDG-SIM at GARD.COM mailing list. To unsubscribe
from this mailing list send a blank message to
BLDG-SIM-UNSUBSCRIBE at GARD.COM
More information about the Bldg-sim
mailing list