Sambhav,
EnergyPlus uses several curves to define performance mathematically. I think that is a common practice for almost all energy modeling software ? read up on the use of performance curves!
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
COP of chiller is 1/EIR (Energy Input ratio) in eQuest/DOE-2. There is a curve in the program that relates theses parameters.
John R. Aulbach, PE
Sambhav,
EnergyPlus uses several curves to define performance mathematically.? I think that is a common practice for almost all energy modeling software ? read up on the use of performance curves!
?
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504USA
616 450 8653
?
From:Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sambhav Tiwari
Sent: Friday, August 22, 2014 6:55 AM
To: bldg-sim
Subject: [Bldg-sim] Chiller COP
?
Hi Friends,
? ? ? ? ? ? ? ? ?Is there any mathematical formula which co relates cop of chiller with chilled water temperature and condenser water entering temperature.
?
?
Warm Regards
Sambhav?
?
_______________________________________________
Bldg-sim mailing list
http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
To unsubscribe from this mailing list send? a blank message to BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
I don't know to which program you're referring, but all of them should have performance
curves that adjust the nominal performance of the chiller based on the air or water
temperatures, and part-load-ratio.
In DOE-2, for example, a hermetic centrifugal chiller has a bi-quadratic curve
(HERM-CENT-EIR-FT) with 6 coefficients that modifies the EIR as a function of the entering
condenser water temperature (TIN) and the leaving chilled water temperature (TOUT). There
are default coefficients, or if you have more specific data from the manufacturer, you can
also derive your custom coefficients.
In EnergyPlus, the chillers are modeled the same way, and in fact I recall that at least
one of them was copied from DOE-2.
Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
Pure theory the chiller is a Rankine cycle and there is a formula to derive the cycle from the evaporating and condensing temperature of the chiller then you multiply the Rankine cycle by the efficiency of the motor driving the compressor and get COP.
Jim and Joe are correct that the simulation program does this for you ( in most cases), however if you want to design your own chiller I would suggest the cool tool program that Mark Hydeman derived many years ago which I believe can de downloaded from the Taylor Engineering website.
Peter Simmonds, Ph.D., ASHRAE Fellow and DL
Mobile US: +1-310-383-9911
Mobile HKG: +852-9845-4902
Mobile UK: +44 7711 926317
The bi-quadradic equations in DOE-2, EQUEST, and Energyplus are good if you have real data to "tune" them. These are what Hydeman's toolkit are based on. Otherwise, the work by Jeff Gordon and K. Ng on semi-empirical chiller models is helpful, and has lumped thermodynamic properties. ASHRAE RP 827 is also helpful for in-situ situations.
Jeff
8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) 8=() 8=) 8=| 8=) :=') 8=) 8=?
Jeff S. Haberl, Ph.D.,P.E.inactive,FASHRAE,FIBPSA,......jhaberl at tamu.edu
Professor........................................................................Office Ph: 979-845-6507
Department of Architecture............................................Lab Ph:979-845-6065
Energy Systems Laboratory...........................................FAX: 979-862-2457
Texas A&M University...................................................77843-3581
College Station, Texas, USA, 77843..............................URL:www.esl.tamu.edu
8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) :=) 8=) 8=! 8=) 8=? 8=) 8=0
Sambhav,
EnergyPlus uses several curves to define performance mathematically. I think that is a common practice for almost all energy modeling software ? read up on the use of performance curves!
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
COP of chiller is 1/EIR (Energy Input ratio) in eQuest/DOE-2. There is a curve in the program that relates theses parameters.
John R. Aulbach, PE
Sambhav,
EnergyPlus uses several curves to define performance mathematically.? I think that is a common practice for almost all energy modeling software ? read up on the use of performance curves!
?
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504USA
616 450 8653
?
From:Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sambhav Tiwari
Sent: Friday, August 22, 2014 6:55 AM
To: bldg-sim
Subject: [Bldg-sim] Chiller COP
?
Hi Friends,
? ? ? ? ? ? ? ? ?Is there any mathematical formula which co relates cop of chiller with chilled water temperature and condenser water entering temperature.
?
?
Warm Regards
Sambhav?
?
_______________________________________________
Bldg-sim mailing list
http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
To unsubscribe from this mailing list send? a blank message to BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
I don't know to which program you're referring, but all of them should have performance
curves that adjust the nominal performance of the chiller based on the air or water
temperatures, and part-load-ratio.
In DOE-2, for example, a hermetic centrifugal chiller has a bi-quadratic curve
(HERM-CENT-EIR-FT) with 6 coefficients that modifies the EIR as a function of the entering
condenser water temperature (TIN) and the leaving chilled water temperature (TOUT). There
are default coefficients, or if you have more specific data from the manufacturer, you can
also derive your custom coefficients.
In EnergyPlus, the chillers are modeled the same way, and in fact I recall that at least
one of them was copied from DOE-2.
Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
Pure theory the chiller is a Rankine cycle and there is a formula to derive the cycle from the evaporating and condensing temperature of the chiller then you multiply the Rankine cycle by the efficiency of the motor driving the compressor and get COP.
Jim and Joe are correct that the simulation program does this for you ( in most cases), however if you want to design your own chiller I would suggest the cool tool program that Mark Hydeman derived many years ago which I believe can de downloaded from the Taylor Engineering website.
Peter Simmonds, Ph.D., ASHRAE Fellow and DL
Mobile US: +1-310-383-9911
Mobile HKG: +852-9845-4902
Mobile UK: +44 7711 926317
FYI:
The bi-quadradic equations in DOE-2, EQUEST, and Energyplus are good if you have real data to "tune" them. These are what Hydeman's toolkit are based on. Otherwise, the work by Jeff Gordon and K. Ng on semi-empirical chiller models is helpful, and has lumped thermodynamic properties. ASHRAE RP 827 is also helpful for in-situ situations.
Jeff
8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) 8=() 8=) 8=| 8=) :=') 8=) 8=?
Jeff S. Haberl, Ph.D.,P.E.inactive,FASHRAE,FIBPSA,......jhaberl at tamu.edu
Professor........................................................................Office Ph: 979-845-6507
Department of Architecture............................................Lab Ph:979-845-6065
Energy Systems Laboratory...........................................FAX: 979-862-2457
Texas A&M University...................................................77843-3581
College Station, Texas, USA, 77843..............................URL:www.esl.tamu.edu
8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) :=) 8=) 8=! 8=) 8=? 8=) 8=0