[Equest-users] Constructing chiller part load curves

[David Eldridge]

You may want to run through this document before you get too much further.
Skip ahead to “Part 2” of the document.



http://www.energydesignresources.com/media/2654/EDR_DesignGuidelines_%20HVAC_Simulation.pdf



In a nutshell – you should acquire a few more data points to develop a more
comprehensive matrix.  Right now your matrix would be equivalent to a line
through the middle of possible conditions, you need to extend your data set
over a wider range of water temperatures and load conditions.



David



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

Project Manager



Direct: (847) 316-9224 | Fax: (847) 328-4550

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*Grumman/Butkus Associates* | 820 Davis Street, Suite 300 | Evanston, IL
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*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Afaan Naqvi
*Sent:* Tuesday, January 18, 2011 8:33 PM
*To:* equest-users at lists.onebuilding.org
*Subject:* [Equest-users] Constructing chiller part load curves



After browsing the forums, it seems there are many users that have
constructed custom chiller curves based on selection data. I believe I have
all the data I need to do this, but am coming up with polynomial
coefficients and hourly results that do not make sense at all. Can someone
please walk me through how to go about building the 3 curves for a
centrifugal, water cooled chiller with a VSD based on the following data:



% Load

Capacity

kW in

Perf

Evap T in

Evap T out

Conden T in

Coned T out

100

85

53.6

0.63

54

44

85

94.8

75

63.8

29.8

0.47

51.5

44

75

82

50

42.5

13.3

0.31

49

44

65

69.5

25

21.3

6.9

0.32

46.5

44

65

67.2





I believe the additional data I need is calculated below, except for the dT
term which I am unclear on:



Load

PLR

kW

f PLR

85

1

53.6

1

63.8

0.751

29.8

0.556

42.5

0.500

13.3

0.248

21.3

0.251

6.9

0.129





Not sure if the dT term required by the curves is the difference in
condenser supply and return, or condenser and evaporator supply, condenser
supply and evaporator return, etc. Can someone please clarify?



Thanks





*Afaan Naqvi ** *PE  LEED AP**

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