[Equest-users] Chiller curve ball

David Eldridge dse at grummanbutkus.com
Wed Mar 9 16:19:58 PST 2011


You’ll need to get more data than this for the custom curve to work well – I
think you can find some fairly recent discussion on one of the lists, but
the sample data from York only shows one load point at each ECWT, therefore
the eQuest curve won’t be accurate anytime that the load and ECWT don’t
match your data.



You’d prefer to have load and ECWT data in a matrix around all of these
points – i.e. several load and kW data points at 85F ECWT, 75F ECWT, 65F
ECWT.



My first suggestions is to try using report variables to show kW and chiller
production while using the default curves.  See if when conditions specified
below occur there is a reasonable match to the York data kW/ton.



If yes, use the defaults.  If no, ask York for more data.



*
*



David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP

*Grumman/Butkus Associates*

*
*





*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Sami, Vikram
*Sent:* Wednesday, March 09, 2011 5:54 PM
*To:* equest-users at lists.onebuilding.org
*Subject:* [Equest-users] Chiller curve ball



Ok – so I’m probably doing this all wrong.



I am trying to model a York scroll chiller in EQUEST. The table below
illustrates the Part Load rating Data



*Load % ** *

* **Capacity (Tons)  *

* **Cond. EWT (°F)  *

* **Cond. LWT (°F)  *

* **Compressor kW  *

*EER*

*COP*

*EIR*

100

135.8

85

95

104.1

15.6

4.6

0.217391

83.3

116.8

79.4

87.9

81

17.3

5.1

0.196078

66.7

96.9

73.5

80.4

60.1

19.3

5.7

0.175439

50

73.5

66.7

71.8

41.7

21.2

6.2

0.16129

33.3

48.2

65

68.4

26.6

21.7

6.4

0.15625

16.7

23.6

65

66.6

13.1

21.7

6.4

0.15625



eQUEST doesn’t seem to have a scroll chiller option – I assume screw is the
closest thing to it.



As far as I can tell – you need to define 3 performance curves:

1.       A curve that defines the EIR based on the condenser water temp

2.       A curve that defines the part load based on the condenser water
temp

3.       A curve that  defines the EIR based on the part load.





When I apply these curves to my chiller, my cooling energy goes up by 30%.
Seems like a lot.      Is this reasonable or am I doing something wrong with
my curve selection?
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