[BLDG-SIM] Steam-Turbine Drive Centrigugal LiquidChillers

[Varkie Thomas]

Thanks for all the responses.  I think that the energy code is the only
building code that is dependent on computer software to show compliance
when submitting construction documents.  It is too early for measurement
& verification.  I am not if the software available today is ready for
this.  Are we allowed to use the program that produces the most energy
savings if these programs show different results?  How about energy
savings by inadvertently entering the wrong input assuming that nobody
is checking the input in detail?

 

I have used the DOE2.1E program to show energy savings for
occupancy-based ventilation, occupancy-based lighting, under-floor air
distribution, light shelves etc. by making assumptions and adjustments
within the DOE2 program input.  For example without light shelves the
light sensor is located 5' and 10' from the window for a perimeter space
depth of 15' and with light shelves the same light sensor locations
apply to a 20' perimeter depth.  Occupancy based lighting is modeled by
reducing the prototype building lighting profile values by 20% based on
10CFR435.  Occupancy based ventilation is modeled by applying an outdoor
air ventilation profile to the system that is the design OA fraction
times the occupancy profile from loads.  Displacement ventilation is
modeled by adjusting the design space temperature - the supply air has
to maintain the summer and winter space temperatures up to 7' above the
floor and the rest of the space volume up to the ceiling is not at
design conditions.  The space temperature is the weighted average of the
lower and upper volumes of the space which means that DV saves energy
with increasing ceiling heights.  Energy savings from PV panels is based
on the total annual energy on the net PV area times the percent energy
converted as claimed by the PV manufacturer (9% to 15%).  These are just
some examples

 

LEED and Code authorities should describe standard procedures for
different types of energy saving options so that we are all on the same
playing field.  Is there an acceptable procedure for showing energy cost
savings using steam-turbine centrifugal chillers for the ECB method?

 

Varkie Thomas

 

-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com] On Behalf Of
stvgates at pacbell.net
Sent: Friday, October 01, 2004 3:25 PM
To: BLDG-SIM at GARD.COM
Subject: [BLDG-SIM] Steam-Turbine Drive Centrigugal LiquidChillers

 

I want to correct some of the information I just put out there regarding
steam-turbine driven chillers.

 

At 150 psig, the steam temperature is about 350F, which corresponds to a
maximum thermodynamic turbine efficiency of about 30%; mechanical
efficiency would lower this.  And the steam turbines used in chillers
have better unloading characteristics than the turbines I looked at a
long time ago.  The net effect is that a steam-turbine chiller can have
about the same full load efficiency as a 2-stage absorption chiller.  

 

A useful article can be found at
http://www.york.com/products/esg/YorkEngDocs/964.pdf

 

	----- Original Message ----- 

	From: Konstantine Babets <mailto:babetsk at jbb.com>  

	To: BLDG-SIM at GARD.COM 

	Sent: Friday, October 01, 2004 8:51 AM

	Subject: [BLDG-SIM] Steam-Turbine Drive Centrigugal
LiquidChillers

	 

	Varkie,

	 

	From my experience in modeling similar plant combinations in NYC
and using Con-Ed steam and electric rates you mentioned, for a typical
office building you will see a benefit in using steam-turbine chillers
(either option 2 and 3, depending on your electrical load factor and
refrigeration full load hours). Of course, assuming that in all the
cases you use reasonably efficient refrigeration machines.

	 

	Here is how you do it in Doe2.1:

	 

	INPUT PLANT..

	 

	ELEC-DRIVE=PLANT-EQUIPMENT

	 TYPE=HERM-CENT-CHLR

	 SIZE=24

	 INSTALLED-NUMBER=1

	 MAX-NUMBER-AVAIL=1 ..

	 

	 

	STEAM-CHILLER = PLANT-EQUIPMENT

	TYPE = ABSOR2-CHLR

	SIZE = 24

	MAX-NUMBER-AVAIL=1 ..

	..

	 

	EQUIPMENT-QUAD

	ABSOR2-CAP-FT=CCAPT3

	ABSOR2-HIR-FT=EIRT3

	ABSOR2-HIR-FPLR=EIRPLR3

	..

	 

	.

	.

	.

	 

	Then in PLANT PARAMETRS you specify 

	 

	ABSOR2-HIR = ?

	 

	Hope this helps.

	 

	Please let me know if you have further questions

	 

	Konstantin Babets

	Jaros Baum and Bolles

	(212) 530 9455

		----- Original Message ----- 

		From: Varkie Thomas <mailto:Varkie.Thomas at som.com>  

		To: BLDG-SIM at GARD.COM 

		Sent: Friday, October 01, 2004 10:40 AM

		Subject: [BLDG-SIM] Steam-Turbine Drive Centrigugal
LiquidChillers

		 

		Steve:

		 

		I received other responses suggesting the same thing:

		 

		1. Use 2 stage absorption chiller with HIR of the
turbine

		2. Assign PLR curves of centrifugal chiller to
corresponding curves of absorption machine.

		 

		I assume this will produce reasonably accurate steam
consumption of the steam-turbine.  I need a sample DOE2 Plant "inp" or
"bdl" statements showing how to do this.  The chillers in question are
York model YST.  York will provide the performance data.  The location
is NYC and the utility rates are ConEd Steam Service Classification 2
(lower rates in summer) and ConEd Electric Service Classification 9 Rate
II - General Large Time of Use 

		 

	
http://q050-www5.coned.com/es/tariffs/ps.asp?URL=tariffs.htm&s=tariffs

		 

		Since there are several buildings in NYC that use a
hybrid plant of steam-turbine and electric-motor drive chillers, I
assume studies have already been done justifying this combination.  So
far I have found the ASHRAE Sept 2003 article: Advances in Steam Cooling
by Ian Spanswick

		 

		I would like to compare the following alternative
options: (1) two 2000-ton electric-drive chillers, (2) two 2000-ton
steam-drive chillers and (3) one 2000-ton electric-drive chiller and one
2000-ton steam-drive chiller sequenced to "start first" based on ConEd
year-round steam and electric rates.  This would be for (A) a building
that operates 24 hours per day such as a hospital, and (B) an office
building that operates 7 AM - 6 PM, Mon-Fri.  I would also like to see a
life cycle cost analysis of the alternative options.  Have such studies
been done for buildings located in cities with district steam (NYC,
Boston, Philadelphia, Minneapolis)?

		 

		The Trane TRACE700 program (which we also use in this
office along with Carrier's HAP program) models steam-turbine chillers.
However the building in question has already been modeled in detail with
DOE2.1E using electric chillers.  I prefer to use DOE2.1E directly (we
also have eQUEST and EnergyPro in the office) for LEED certification and
to show Code compliance.  The building description language (bdl)
provides flexibility and it can be read like a specification for others
to review.  Does this program have a future?  How many A-E design firms
are using EnergyPlus on large commercial building projects?

		 

		Varkie Thomas

		 

		 

		 

		-----Original Message-----
		From: postman at gard.com [mailto:postman at gard.com] On
Behalf Of stvgates at pacbell.net
		Sent: Thursday, September 30, 2004 5:13 PM
		To: BLDG-SIM at GARD.COM
		Subject: [BLDG-SIM] Steam-Turbine Drive Centrigugal
Liquid Chillers

		 

		You would need to model it as an absorption chiller.
The chiller's heat input ratio and performance curves would need to
reflect the combination of the steam turbine and the chiller compressor.

			----- Original Message ----- 

			From: Varkie Thomas
<mailto:Varkie.Thomas at som.com>  

			To: BLDG-SIM at GARD.COM 

			Sent: Thursday, September 30, 2004 12:58 PM

			Subject: [BLDG-SIM] Steam-Turbine Drive
Centrigugal Liquid Chillers

			 

			Has anyone modeled steam turbine drive
centrifugal chillers with DOE2.1E?  Is it possible to add this equipment
to DOE2, given the part load performance data?

			 

			Varkie Thomas

		 
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