Hello,
-I am looking to simulate a water-side economizer in EE4 (DOE-2.1E) by
altering the .doe file.
-I have added the highlighted text below into the "Plant-Parameters" section
of the .doe file.
PLANT-PARAMETERS
BOILER-CONTROL = STANDBY
HW-BOILER-HIR = 1.0870
CHILLER-CONTROL = STANDBY
$ Cooling Tower $
TWR-SETPT-CTRL = FIXED
TWR-SETPT-T = 85.0
TWR-DESIGN-WETBULB = 73.0
TWR-DESIGN-APPROACH= 12.0
TWR-DESIGN-RANGE = 10.0
TWR-THROTTLE = 5
TWR-CAP-CTRL = ONE-SPEED-FAN
TWR-CELL-CTRL = MIN-CELLS
DIRECT-COOL-MODE = STRAINER-CYCLE
DC-MAX-OAT = 39.0
DC-MAX-CHILL-WTR-T = 44.0
DC-TWR-WTR-SETPT = 44.0
DIRECT-COOL-KW = 0.055
$ Condenser Water Pumps $
TWR-MOTOR-EFF = 0.917
TWR-IMPELLER-EFF = 0.790
TWR-PUMP-HEAD = 60.00
..
-After running the simulation and comparing it to previous results, there
are savings on "Space Cooling" but there is also a greater energy usage in
"Heat Reject" as show in the table below. The DOE-2 guide suggests entering
the condenser water pumping power as kW/ton but maybe I should be entering 0
for DIRECT-COOL-KW if I'm accounting for the condenser water pumps twice?
This is for a project in Nova Scotia so I think there should be savings from
turning off the chillers throughout the winter but it doesn't make sense
based on these results.
Energy Use Category
Before Change
After Change
Savings
(MBtu)
(MBtu)
(MBtu)
% Sav
Area Lights
2,252.2
2,252.2
0
0.0%
Misc. Equipment
1,629.1
1,629.1
0
0.0%
Space Heat
2,062.0
2,062.0
0
0.0%
Space Cool
615.6
475.7
140
22.7%
Heat Reject
121.5
295.6
-174
-143.3%
Pumps & Misc.
1,136.2
1,136.2
0
0.0%
Vent Fans
2,168.4
2,168.4
0
0.0%
DomHot Water
587.6
587.6
0
0.0%
TOTAL
10,572.6
10,606.8
-34
-0.3%
Best regards,
Jake R. Martell, EIT
From the DOE2.1E Supplement:
DIRECT-COOL-KW
specifies the electrical input to direct cooling auxiliary equipment.
The default varies according to the direct cooling mode.
IT DIRECT-COOL-MODE = THERMO-CYCLE, you should
specify DIRECT-COOL-KW as kW /ton of operating capacity
for the period during which the compression chillers are operating
in this mode. The chiller electrical input is assumed to be
DIRECT-COOL-KW multiplied by the operating capacity
and the fraction of the hour the chiller ran. If
DIRECT-COOL-MODE = STRAINER-CYCLE, you should
specify DIRECT-COOL-KW as the electrical input to the
condenser water pumps (and other added equipment), calculated
as kW /ton of SYSTEMS peak cooling load. Usually, this
value is zero as the chilled water pumps are assumed to provide
all motive energy. If a heat exchanger is used to isolate the
tower from the chilled water loop, then this value should be
non-~ero to model the condenser pumping energy. In this case,
the condenser water pumping energy is calculated using the
value of DIRECT-COOL-KW as the kW per ton of the design
SYSTEMS load. (Fluid flow to the tower is assumed to be the
design chilled water flowrate). For both modes of direct cooling,
THERMO-CYCLE and STRAINER-CYCLE, the chilled
water pumps are assumed to run as usual.
>> Christopher Jones, P.Eng.