[BLDG-SIM] DOE2.1e HP HEAT-EIR-FPLR Problems
Glenn Haynes
glenn.haynes at rlw.com
Wed Apr 4 10:08:42 PDT 2007
Chris,
I think the curve in DOE2 is actually the EIR as a function of PLR times
the PLR. Hence, the term MPLR (modified part load ratio) is sometimes
used to differentiate.
The default RESYS linear curve (0.125, 0.875) is not theoretically valid
at low PLR because the actual EIR is increased too much and the EER
tends toward zero. The actual product of EIR and PLR must tend toward
zero as PLR tends to zero, and the EER multiplier should not go below
about 0.75 due to realistic minimum run times per cycle (4 to 6 minutes
for most residential systems, maybe longer for commercial). You may be
better off at low PLR values if you simply assume modified EIR-PLR is
equal to the PLR, as depicted by the linear curve (0,1), suggesting to
DOE2 that EER is not a function of PLR at all.
If you are interested, I have developed an empirical cubic function (0,
0.83, 0.358, -0.188) that represents this relationship for a typical
RESYS application, but am not satisfied with it yet.
Glenn Haynes, PE
RLW Analytics, Inc.
860-346-5001x202
________________________________
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Chris
Jones
Sent: Wednesday, April 04, 2007 11:19 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] DOE2.1e HP HEAT-EIR-FPLR Problems
It looks like my table is all messed when I arrives. Hopefully you can
make sense of it.
At 10:41 2007-04-04, Chris Jones wrote:
I am comparing the default
DOE2.1e HP heating curves to the
performance data from various manufacturers. In particular the
EIR-FPLR curve does not fit what the manufacturers show in their
data. The default curve shows the EIR dropping as the part load
ratio drops. My assumption is that PLR = Operating Capacity/Design
Capacity. With the Trane, McQuay, and Waterfurnace data, the EIR
increases as the PLR goes down. I am assuming that part load is a
result of lower flow through the unit or from higher entering dry bulb
temperature. So when I do create my set of heating curves
HEAT-EIR-FT, HEAT-CAP-FT and HEAT-EIR-FPLR, the performance is
significantly worse than with the default DOE2.1e curves.
Am I misinterpreting how to plot the data points for the HEAT-EIR-FPLR
curve? Example from Trane:
COP CAP
EIR
Ent
DB Ent
WT PLR
EIR/EIR
Design GPM
FPLR
4.2 112000
0.238 68
68
1.000
1.000
24.5
(1.000, 1.000)
3.1 62675
0.323
70
20
0.560
1.355
12.1
(0.560, 1.355)
3.1 64639
0.323
70
20
0.577
1.355
18.4
(0.577, 1.355)
3.2 65641
0.313
70
20
0.586
1.313
24.4
(0.586, 1.313)
3.3 71123
0.303
70
30
0.635
1.273
12.1
(0.635, 1.273)
3.4 73541
0.294
70
30
0.657
1.235
18.4
(0.657, 1.235)
3.4 74631
0.294
70
30
0.666
1.235
24.4
(0.666, 1.235)
3.5 79943
0.286
70
40
0.714
1.200
12.1
(0.714, 1.200)
3.6 82643
0.278
70
40
0.738
1.167
18.4
(0.738, 1.167)
3.6 83991
0.278
70
40
0.750
1.167
24.4
(0.750, 1.167)
3.7 88881
0.270
70
50
0.794
1.135
12.1
(0.794, 1.135)
3.8 91903
0.263
70
50
0.821
1.105
18.4
(0.821, 1.105)
3.9 93457
0.256
70
50
0.834
1.077
24.4
(0.834, 1.077)
4 98031
0.250
70
60
0.875
1.050
12.1
(0.875, 1.050)
4 101429
0.250 70
60
0.906
1.050
18.4
(0.906, 1.050)
4.1 103173
0.244 70
60
0.921
1.024
24.4
(0.921, 1.024)
4.2 107353
0.238 70
70
0.959
1.000
12.1
(0.959, 1.000)
4.2 111199
0.238 70
70
0.993
1.000
18.4
(0.993, 1.000)
4.3 113135
0.233 70
70
1.010
0.977
24.4
(1.010, 0.977)
4.4 116795
0.227 70
80
1.043
0.955
12.1
(1.043, 0.955)
4.4 121041
0.227 70
80
1.081
0.955
18.4
(1.081, 0.955)
4.5 123169
0.222 70
80
1.100
0.933
24.4
(1.100, 0.933)
4.5 126363
0.222 70
90
1.128
0.933
12.1
(1.128, 0.933)
4.6 130957
0.217 70
90
1.169
0.913
18.4
(1.169, 0.913)
4.7 133313
0.213 70
90
1.190
0.894
24.4
(1.190, 0.894)
Thanks for any help!
Chris Jones, P.Eng.
14 Oneida Avenue
Toronto, ON M5J2E3
Tel. 416 203-7465
Fax. 416 946-1005
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Chris Jones, P.Eng.
14 Oneida Avenue
Toronto, ON M5J2E3
Tel. 416 203-7465
Fax. 416 946-1005
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