intelligent system design - madison ashrae · parallel 137.6 18.8 30.6 32.1 219.1 series free...
TRANSCRIPT
Intelligent System Design
Justin WiemanChiller Systems EngineerTrane, A Division of Ingersoll-Rand
Member AHRI Systems CommittesASHRAE Member since 2000
When you buy a HVAC System would you rather buy:
Individual HVAC Components An Entire HVAC System
air handlers
controls
chillers
piping
ductwork
Similar components, maybe, likely … Vastly different results!
Building System Solutions with and for customers
air handlers
controls
chillers
piping
ductwork
• First Cost
• Operating Cost
• Comfort
• Indoor Air Quality
• Acoustics
• Carbon Footprint
Design HVAC systems to optimize
the building’s performance“for life”.
Intelligent™ Systems
( )C
45%
B
42%
+D
12%
+A
1%
+1=IPLV
AHRI Conditions
Chilled Water: 54°/44°F (12°/7°C)
Condenser Water: 3 GPM/Ton
D= 25% Load @ 65°F (18°C)
C= 50% Load @ 65°F (18°C)
B= 75% Load @ 75°F (24°C)
A= 100% Load @ 85°F (30°C)
For example: Evaluate Real Chiller EfficiencyUsing IPLV or NPLV as a simple payback tool
1%@ 85°F
57%@ 65°F
57%@ 65°F
IPLV/NPLV – is it good or bad? … NEITHER; it is just a rating point
Simple Comparative Tool?
is simply WRONG!
How do the chillers in
your plant run?
Efficiency Calculations Index Rating vs. Real-World (because every project is unique)
1IPLV =
1%
A42%
B
12%
D+ ++
45%
C
Efficiency ComparisonIPLV/NPLV – Good or Bad?
IPLV (along with FULL load efficiency) is *good* for
determining minimum efficiency requirements such as in
ASHRAE Standard 90.1:
► Full load performance determines peak energy consumption, impacting
utility demand charges and ratchets
► Part load performance reduces energy consumption as the load and lift
decrease
IPLV is *bad* for:
► Energy analysis
► Accurately representing a chiller’s system energy use
► Indicating a financial payback
► Comparing VSD to non-VSD chillers
ASHRAE Journal December 2009
IPLV is Neither Good nor Bad. It is a Rating Point.
Efficiency Comparison
• Real Payback Require Real Analysis
TRACE 700
Chiller Plant
Analyzer
System
Analyzer
Building Energy
Analysis Tool
EnergyPlus
Integrated
Environmental
Solutions
Design tools available for accurate prediction.
Trane myPLV™Accurately Predicting Your Future
Chiller Part Load Performance
myPLV™
IPLV myPLV
Weather
Weighted average of 29 cities across the U.S.A,
represented 80% of chiller sales from 1967 to
1992.
Customized to your location (Global)
Building TypeWeighted average of all types based on a DOE
study 1992.
Closely matched building type capabilities(building use, chiller plant design)
Operation
Hours
Weighted average of various operations
with chiller plants only, taken from the DOE study
1992and BOMA study 1995.
Operational hours calculated
SystemsWeighted average of systems with and without
some form of economizer included.
Selectable number of chillers
condenser control strategy customizable
Assumptions Comparison
Performance is calculated based on national averages
myPLV™
• Because every project is unique
Accurate performance based on unique project needs!
• Performance value calculated
based on specific project
• Installation location
• Building type
• Operation conditions
• Chiller plant design
• Excel based
• Industry validated data
• Vendor agnostic
Real Life Example myPLV™ Approach
Real world
conditions for real
world buildings
Real Life Example myPLV™ Approach
Real world
conditions for real
world buildings
Approximate
Savings
Centrifugal
Chiller
= $3,155
Real Life
Example
myPLV™
Accurate
Estimate
Financial Payback
Calculation Made Easy
Why the Customer’s Like Low Condenser Flow
• System efficiency increases• Chiller works harder but is most efficient piece of equipment
• Lower flow equals less pumping energy and reduced pressure drops
• Pumps get smaller, so less horsepower
• Cooling towers get more efficient with smaller fans
• Cost of the job is reduced• Equipment costs go down
• Trane CTV stays about the same price or even cheaper
• Cooling towers are sized on flow, smaller with less gpm
• Pumps are smaller
• Pipe size is reduced
• Contractor costs go down
• A smaller cooling tower may require smaller concrete pad and footprint
• Labor to install smaller piping will be cheaper
• Outside sound levels are reduced• Smaller cooling towers generate lower dBA’s
• Additional capacity out of existing equipment
Quick Reference for Efficient Chiller Design
Tools available to help you
Cooling Tower Selection
Cooling tower cost can be reduced with lower condenser flow!
Low Condenser Flow - SummaryEfficiency
• 3 gpm/ton
• Chiller = 0.600 kw/ton
• Tower = 40 hp/500 tons = 0.060 kw/ton
• Cond pump = (1500 gpm * 20’ / 4000) / 500 tons = 0.015 kw/ton
• Evap Pump = (1000 gpm * 18’ / 4000) / 500 tons = 0.009 kw/ton
Total kw/ton = 0.684 kw/ton
• 2 gpm/ton
• Chiller = 0.620 kw/ton
• Tower = 20 hp/500 tons = 0.030 kw/ton
• Cond pump = (1000 gpm * 20’ / 4000) / 500 tons = 0.010 kw/ton
• Evap Pump = (1000 gpm * 18’ / 4000) / 500 tons = 0.009 kw/ton
Total kw/ton = 0.669 kw/ton
That’s a saving of 0.015 kw/ton (2.2%) and the installed cost is less!
myPLV version 3 - Condenser Flow Optimizer
Series-Counter Flow
Series-Counter Flow Questions
Efficient Chilled Water System - Maximized
What Delta Ts are needed?
What Temperatures are needed
How does it benefit energy performance?
Chilled Water Design Parameters
ASHRAE GreenGuide guidance
on parallel plants
Chilled water
12°F to 20°F ΔT
2.0 to 1.2 gpm/tonCondenser water
12°F to 18°F ΔT
2.5 to 1.6 gpm/ton
Series-Counter Flow
chiller plants
Chilled water
16°F to 22°F ΔT
1.5 to 1.1 gpm/tonCondenser water
15°F to 18°F ΔT
2.0 to 1.6 gpm/ton
What Temperatures Required
Remember the Rule of 2 to 1
For a given coil, a 1 degree increase in return water temperature requires a
supply temperature 2 degrees cooler
• Coil originally sized for 44/54 with a 10 degree delta T requires:
– 42 degree water for 13 degree delta T
– 40 degree water for 16 degree delta T
– 38 degree water for 19 degree delta T
• Low Flow Benefits
– Reduced pumping energy
– More tons out of the distribution pipes
Parallel-Parallel Chillers
55°F 37°F
98.9 o F
37 oF
62.9 o F Equal lift
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
55°F 37°F
37 oF
62.9 o F
85°F98.9°F85°F98.9°F
Series-Parallel Chillers
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
98.9 o F
37 oF
45.1 oF
53.8 o F
62.9 o F
85°F
Reduced lift = increased savings
55°F 37°F45.1°F
98.9°F 98.9°F
6% Reduction
Series-Series Chillers or Series-Counterflow Chillers
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
55°F 37°F
98.9 o F
37 oF
45.1°F
45.1 oF
54.8 o F
54.3 o F
85°F98.9°F 91.3°F
91.3 o F
Further Reduced lift = MORE savings!!
13% Reduction
Series-Series-Series Chillersor Series-Series-Counterflow Chillers
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
55°F37°F45.1°F
85°F98.9°F 91.3°F
EVEN Further Reduced lift = EVEN MORE savings!!
95.1°F 88.1°F
50.0°F 41.0°F
95.1 o F
45.1 oF
50oF
98.9 o F
50 oF
91.3 o F
41 oF
88.1 o F
37 oF
50oF
51oF
48.9oF
19% Reduction
Arrangement Pumps
Cooling
Tower
(kW)
Evap Condenser CH
(kW)
Chilled
Water
(kW)
Condense
r Water
(kW)
Total
Plant
(kW)
Paralle
l
Parallel 6,489 14 18 480 7,001
Series Parallel 5,827 60 18 480 6,385
Serie
s
Series Counterflo
w
Duplexes
5224 60 126 480 5890
Comparison of Power Requirements
Series-Series-Series Chillers70% load ~constant speed pump
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
49.6°F37°F42.7°F
85°F94.7°F 89.4°F
EVEN Further Reduced lift = EVEN MORE savings!!
92.0°F 87.1°F
46.1°F 39.8°F
92.0 o F
42.7 oF
49.3oF
94.7 o F
46.1oF
89.4 o F
39.8 oF
87.1 o F
37 oF
49.6oF
50.1oF
48.6oF
Series-Series-Series Chillers70% load ~Variable Primary Flow
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
55°F37°F45.1°F
EVEN Further Reduced lift = EVEN MORE savings!!
50.0°F 41.0°F
91.9 o F
45.1 oF
46.8oF
94.5 o F
50 oF
89.4 o F
41 oF
87.1 o F
37 oF
48.4oF
50.1oF
44.5oF
4% Reduction
85°F94.5°F 89.4°F91.9°F 87.1°F
Free CoolingRefrigerant Migration or a Plate Frame
Base Design
Design Requirements
• 1400 ton building load
• 42/60 evap
• 85/2 gpm/ton cond
• VFDs
• N+1
Base DesignParallel-Parallel Chillers (identical)
60°F 42°F
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
60°F 42°F
85°F
98.9°F
85°F98.9°F
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
60°F 42°F
85°F
98.9°F
930 gpm
930 gpm
930 gpm
3 – 700 ton VFD chillers
Alternate Design
Configuration
• Qty 2 – 700 ton VFD chillers• 42/60 and 42/51 evap
• 85/1500 gpmT cond
• Qty 1 – 700 ton non VFD redundant chiller
• Free Cooling equipped
• 42/60 and 51/60 evap
• 85 / 1500 gpmT cond
• Series configuration
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
85°F
Free Cooling with No VFD (same price)
60°F 42°F51°F
111.7°F
98.2°F
60°F 42°F
98.9°F
85°F
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
Free Cooling DesignSeries-Counter-flow (free-cooling upstream)
930 gpm
1857 gpm
Off Design Condition
Building Loads
• 550 ton building load
• 38 WB
• 45°F Tower water available at max
airflow
Base DesignParallel-Parallel Chillers (identical)
60°F 42°F
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
60°F 42°F
52°F61.4°F
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
60°F 42°F0 gpm
0 gpm
730 gpm
3 – 700 ton VFD chillers
550
tons
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
Reverse Flow to Parallel in Free Cooling
Mode
60°F 42°F52°F
60°F 42°F
98.9°F
85°F
CHILLED
WATER
RETURN
CHILLED
WATER
SUPPLY
Free Cooling DesignSeries-Counter-flow (free cooling upstream)
0 gpm
730 gpm730 gpm
45°F 49.9°F
49.9°F
57°F
Bypass300gpm
300
tons250
tons
Arrangement Pumps
Cooling
Tower
(kW)
Evap Condenser CH
(kW)
Chilled
Water
(kW)
Condense
r Water
(kW)
Total
Plant
(kW)
Paralle
l
Parallel 137.6 18.8 30.6 32.1 219.1
SeriesFree
Cooling
Series* 65.3 19.3 36.15 37.4 158.2
Comparison of Power RequirementsOff Design
*Counter-flow during mechanical cooling mode, but flow is reverse and thus “in-line flow” during free-cooling mode.
28% Reduction in Energy Usage
