Transcript Thank You For Today’s Opportunity

Thank You For
Today’s Opportunity
Agenda
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Introductions
Chiller Plant Design Criteria
Chiller Plant Configurations
Different Chiller Technologies
Refrigerants
Chiller Plant Optimization Techniques
Introductions
• John Calcagno-Formosa Account Manager
– Sales Engineer/Account Manager-Carrier Corporation
– BSME Rutgers University
– Over 27 Years HVAC Industry Experience
Chiller Plant Design
• This presentation applies to typical
chiller plants. The type of building or
process the plant serves will affect the
design.
• Different criteria for different
applications.
• This presentation will focus on chillers.
Chiller Plant Design
• Type of application
• Process
• Data Center
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Reliability, durability, life cycle cost
Reliability, life cycle cost, cold
condenser water.
Health Care
Reliability, first cost, efficiency
Higher Education First cost, life cycle cost
Office
First cost
District Cooling Reliability, life cycle cost
Design Criteria
• Review capacity
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Design Criteria
7
Optimizing Chiller Plant Design
Components of Chiller Plant
• Chillers
• Chiller Heat Rejection
• Distribution System
• Load
Piping Configurations
• Variable Primary
(Variprime)
Chiller Plant Configurations
• “Keep things as simple as possible but
no simpler”
Single Chiller Constant Flow
Single Chiller Constant Flow
• Advantages
• Simple
• Low first cost
• Disadvantages:
• No redundancy
• Chiller cannot efficiently match the load
• Does not take advantage of varying load
• Part load-pumping water not needed
Multiple Chillers ParallelConstant Flow
Multiple Chillers ParallelConstant Flow
• Advantages
• Redundancy
• Can better match capacity at part load
• Disadvantages
• Part load- one chiller off – mixing of chilled water
supply
• Part load- pumping water around that is not needed
Multiple Chillers ParallelConstant Flow
Temp
Mixing
Multiple Chillers Parallel
Part Load Flow Reduction
Shut down one
chiller/pump at part
LOAD. But what
about the flow?
Multiple Chillers Parallel
Part Load Flow Reduction
• Advantages
• Redundancy
• Ability to match load by staging chillers
• Saves pump energy at part load
• Disadvantages
• Significant reduction of flow at part load
• Chiller production loop is hydraulically tied to chiller
consumption loop
Multiple Chillers in SeriesConstant Flow
Multiple Chillers In SeriesConstant Flow
• Advantages
• Eliminates temperature mixing and flow problems
• Full flow at all loads
• Series/counterflow arrangement-efficiency
• Disadvantages
• Flow rate through each chiller is entire system flowdouble the flow for parallel chillers
• Pressure drop is additive-bigger pumps and more
energy
• Part load-pumping water around building not needed
• Limited to two chillers
Multiple Chillers In Parallel
Primary/Secondary System
Decoupler pipe
Multiple Chillers in ParallelPrimary/Secondary System
• Advantages
• Decouples or separates the chilled water production
piping from the chiller water consumption piping
• Eliminates temperature mixing and flow reduction
• Part load-match chiller capacity to load
• Part load-reduced flow
• Disadvantages
• More pumps required
• Moderately complicated controls required
• Water balancing important
Multiple Chillers In ParallelVariable Primary System
Multiple Chillers In ParellelVariable Primary System
• Advantages
• Eliminates set of pumps
• Efficient
• Disadvantages
• Must coordinate minimum flow and rate of change with
chiller manufacturer
• Moderately complicated controls
Variable Primary Flow
Principles to follow:
• Confirm chiller vendors minimum acceptable
flow rate (may require higher initial design
cooler pressure drop)
• Specify flow meters or DP transmitters to
measure/ maintain chiller minimum flows
• Design bypass for flow rates below minimum
• Find out what rate of change in flow is
acceptable from chiller vendor(s) and put this
in sequence of operation
• Provide ton-hr metering to measure machine
capacity for sequencing logic (note, 23XRV
speed is directly proportional to capacity, so
speed can be used to sequence machines)
Variable Primary Flow – Rate of
Change
Carrier
Other
Model
23XRV
Single
Centrifugal
Multiple
Compressors
Rate of
Change
(%/min)
70%
30%
10%
Minimum Loop
Volume (gal)*
450
900
Industry Best!
* = 300 Tons Comfort
Cooling Application
1,800
Compressor response time in VPF
system
If the evaporator flow to the chiller is halved, the load is
halved.
If the chiller does not unload quickly enough (VFD, IGV
staging), the chilled water temperature will drop and either
result in:
1. Recycle (LCWT too far below set point) or
2. Worst Cases, Freeze Trip (LCWT below freeze
protection value) or Surge Trip (at least for a
centrifugal compressor).
In VPF applications, select a machine with high
acceptable rate of flow change and specify rate (in %
change/Minute).
Summary
• No right configuration for all plants
• Must evaluate the design criteria
• Take advantage of chiller’s modern
controls
Questions
Water Cooled Chiller Technologies
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Centrifugal
Helical Rotary (Screw)
Scroll
Absorption
Direct Fired Absorption
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Water Cooled Chiller Technologies
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Centrifugal
Helical Rotary (Screw)
Scroll
Absorption
Direct Fired Absorption
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Water Cooled Chiller Technologies
WATER-COOLED CHILLERS
Product Portfolio
0
100
250
Q2 - 2013
500
1,0
00
1,5
00
Q2 - 2014
1,8
75
2,2
50
3,0
00
30MP 15-45 Tons
30HX 75-265 Tons
30XW
150-300 Tons Single Circuit
325-400 Tons Dual Circuit
23XRV 275-550 Tons
23XRV 200-550 Tons
19XR(V) Single Stage 200-1,600
19XR(V)E Two Stage 800-1,600 T
19XR6 Two Stage 1,600-2,250 Tons
SCROLL
CENTRIFUGA SCREW
Scroll Compressor
Helical Rotary/Screw
Compressor
2 or 3
• Use variable frequency drive to slow down the compressor
Carrier 23XRV – Simple
Simple: 3 moving parts
No surge
No purge
No shaft seals
No guide vanes
No slide valves
No EXV’s
No chlorine
No phase-out
No refrigerant pumps
No pressurization systems
No bearing capacitors to change
No pumps, hoses or clamps for VFD
No glycol cooling required for VFD
No motor heat rejection to the room
Given the choice, aren’t fewer worries better?
Centrifugal Compressor
• Use inlet guide vanes and variable frequency drive for
unloading
Impeller
IMPELLER
WHEEL
39
Shroud
Funnel-type device
that ensures that the
refrigerant flows
through the
compressor.
40
Diffuser
PIPE
DIFFUSER
41
Medium Pressure vs Low Pressure
• Evaporator – water, contaminants are sucked into the chiller
Positive Pressure Design
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Keeps Air and Contaminants Out
Keeps Refrigerant In
Store Refrigerant Inside Chiller
Equipment Life Extended
Efficiency Losses Avoided
Purge Maintenance Eliminated
Refrigerants
• HCFC-123 Low pressure refrigerant
• Subject to phase out-MAJOR reduction in production
NOW (2015)!
• HFC-134a Medium Pressure Refrigerant
• No phase out!
Semi Hermetic Versus Open
Drive Design
Semi Hermetic Versus Open
Drive Design
• Semi-hermetic: Motor and Compressor are
one sealed assembly. Motor is cooled by
refrigerant.
• Open Drive: Motor and Compressor are
separate assemblies. Compressor has shaft
seal to contain refrigerant in compressor.
Shaft Seals-Leakage Source
“Open drive seals lose 2% of total refrigerant charge
annually.” ARI Report 11/98
Replacement of open drive
shaft seals costs $3000 to
$5000 every 3 to 5 Years.
Motor Cooling From
Ambient Air
Ventilation vents let
contaminants in!
(dirt, salt, production
debris etc)
Open Drive Design
Airborne dirt and
contaminants in
Open Drive design
• Only ONE Major Manufacturer makes an open drive
chiller.
• If a design is used so that it is easy to repair, shouldn’t
this cause some concern?
Motor Health
Open Motor
Hermetic Motor
Heat – most common
cause of premature
failure. “Each 10C rise
above the rating may
reduce the motor
lifetime by one half” NEMA
“Class B Rise” results
in 120C (248 F)
operating temperature.
Motors can
operate cool
enough that
insulation is
applied to prevent
sweating.
Dirt – abrasion can
cause insulation
failure, buildup
increases operating
temperature
Motor completely
exposed to dirt, dust
and debris in
mechanical room as it
actively pulls air
through the motor
internal vents to cool
itself.
Motor completely
isolated inside
clean, cool
refrigerant
boundary,
unexposed to
mechanical room
dirt, dust or debris.
Motor Health
Open Motor
Hermetic Motor
Moisture – reduces
motor insulation
resistance, can cause
catastrophic failure.
Open motors must be
equipped with internal
heaters to prevent
condensation.
Condensation on
motor windings is
not possible – it is
sealed in
refrigerant circuit.
Vibration – can cause
bearing fatigue and
failure, or cracks in
insulation system and
failure.
Compressor and motor
balanced separately.
Coupling can increase
balance issues.
Compressor and
motor dynamically
balanced together
– no coupling.
Mechanical Room Renovation
When you need to install equipment, move a pipe , paint
or do some sort of renovation in mechanical room …
should you turn your chillers off?
Yes …
Turn chillers off and
cover motor intakes.
Provide temporary
cooling or no cooling at
all.
No …
Run risk that dirt, dust or
debris in air will cause
motor failure or shorten
motor life.
Semi-Hermetic vs. Open
Motors
Condensation on motor windings is normal.
Moisture degrades insulation resistance.
Starting a motor with moisture on its winding can cause insulation failure
and require a rewind.
To prevent condensation, motor winding heaters are energized any time
motors are off.
If power to motor and motor winding heaters is lost, a megger test
should be performed to confirm insulation strength before starting.
All of this costs money. Is your customer willing to pay?
Motor Heat Rejection
•Open motors reject heat to the facility space,
which must be tempered (air conditioned) or
ventilated to a maximum of 104F indoor
ambient to assure design motor and starter
life
User
Chiller Load
Tons
500
Defined
Power Consumption
kW/Ton
0.60
Motor Efficiency
pts
kW
hp
pts
hp
Btu/Hr
0.95
Motor Cooling Load (Tons)
4.3
Calculated
Motor Loss
Motor Cooling Load
Competitor Open Motor Drive
Carrier Confidential
300
402
0.05
20.12
51,173
Motor Anti-Condensation Heaters
Open motors require no moisture intrusion at start up. Moisture in
windings at start up/after power loss can cause motor failure.
Megger motor test required
$ for insulation checks by
technician after idle periods
Strip Winding Heater required to
prevent moisture intrusion
$ in motor heater equipment costs
$$ yearly heater wattage costs
User
Full Load Tons
IPLV
Hours of Operation
Calculated Annual Mech Room Cooling
Annual kW Strip Heaters
Total Open Motor Parasitic
Actual IPLV
Tons
kW/ton
Hrs
kW
kW
kW
kW/ton
500
0.34
3000
5,046
3,456
8,502
0.350
Competitor Open Motor
Drive
Water Cooled Oil Cooler
• Requires regular
maintenance
(scaling/cleaning with
acid solution)
• Additional failure
modes created
– Oil in water (EH&S safety
issue)
– Water in oil (catastrophic
failure)
Additional Costs for Purchasing Open Drive Design
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Efficiency Comparison
– 3% for open motor
– 4% for harmonic filter
– 1-3% refrigerant loss
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Additional Unanticipated
Costs
– Air Conditioner for
Mechanical Room
– TEWAC Motor
– Harmonic Filter
– Storage Tank
– Sound Blanket
– Motor Heaters
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Maintenance and
Operating Costs
– Weekly – check the shaft seal
oil bottle
– 3-5 Year - Shaft Seal
maintenance cost
– Yearly – Motor Air Filter
maintenance cost
– As Necessary – Top off
refrigerant charge
– As Necessary – Winding
cleaning maintenance cost
– As Necessary – Possible
Megger Motor maintenance
check
– Yearly - Mechanical Room
Cooling operating cost
– Yearly – Strip Heater operating
cost
DID YOU FACTOR AN ADDITIONAL $ IN
COSTS FOR YOUR CHILLER
Open Drive vs. Hermetic
• Home refrigerator is a hermetic design
Automobile is an open design
Which design requires more
refrigerant to be added?
Advantages of Semi
Hermetic Design
Hermetic Motor vs. Open Drive Motor
Semi-Hermetic Motor
• Refrigerant cooled motor keeps
motor heat out of the mechanical
room
• Saves $ to cool mechanical
room
• Minimizes alignment, vibration
and shaft seal maintenance of
open motors
• Saves $ in maintenance and
shaft seal replacement costs
• Refrigerant cooled motors
operate in a clean, cool
environment.
• Saves $ in motor repair
costs
R134a Refrigerant Warranty
Carrier Corporation announces refrigerant warranty for
all new centrifugal chillers sold in USA at Engineering
Green Building Conference July 20, 2004.
Warranty applicable for all Evergreen centrifugal
chillers shipped after October 1, 2004.
Carrier will cover refrigerant leaks above 0.1% for the
first five years of operation and for the life of
the chiller if the owner has a service contract with
Carrier
Commercial Service.
The Right Technology
Questions
Chiller Part Load Performance
What is Part Load?
Part load performance can be…
• Part load capacity
• 90%, 80%, 70%…
OR
• Lower condensing temperature
• Condenser water off the tower (80, 75, 70
degrees…)
• Lower outdoor air temp (90, 85, 80
degrees…)
Full load is defined as 100% load on design day!
All other conditions are part load.
ARI 550-590
ARI Part Load Weighting Factors
1
IPLV
OR
NPLV
=
0.01 + 0.42 + 0.45 + 0.12
A
B
C
D
99
%
WEIGHT %
1%
42%
45%
12%
LOAD
100%
75%
50%
25%
ECWT
85
75
65
65
Chiller Energy
Like pumps, chiller energy consumption is a function of mass flow and differential
pressure. KW = Tons x Lift
Mass Flow X Lift
Load
Compressor Input kW ~
Chiller
Compressor/Cycle
Efficiency
Cooling
Tower
Lift Requires Energy
Imagine carrying a backpack of bricks up 55 flights of stairs.
97 F Saturated Condensing
Temperature
55
42 F Saturated Suction
Temperature
Refrigerant Temperature
95F
85F
For refrigerant to
condense, it must be
warmer than leaving
condenser water.
95 F + 2F approach = 97F
44F
54F
Refrigerant temperatures are based on leaving water
temperatures! Lift = 97F-42F = 55F
To boil, refrigerant
must be colder than
leaving chilled
water. 44F – 2F
approach = 42F
Pressure Enthalpy Chart-LIFT
SCT
SAT.
LIQUID
Pressure
97
82
Reduced Lift
42
SST
95F /97 F / 120 PSI
80F /82F
42 F / 40 PSI
Heat Rejection
Refrigerant Effect
(Capacity)
Enthalpy
Lift = Sat Condensing Temp – Sat Suction Temp
Lift 1 = 97 – 42 = 55 deg F
Lift 2 = 82 – 42 = 40 deg F BETTER!!
Lower Lift = Less Work = Lower kW
SAT.
VAPOR
Pressure Enthalpy Chart-PRESSURE
SCT
SAT.
LIQUID
Pressure
97
82
Reduced Lift
42
SST
95F /97 F / 120 PSI
80F /82F / 90 PSI
59F /61F /60 PSI
42 F / 40 PSI
Heat Rejection
Refrigerant Effect
(Capacity)
SAT.
VAPOR
Enthalpy
60 PSI-40 PSI = 20 PSI. Sufficient differential to
provide proper refrigerant flow, oil return, and
efficient consistent operation.
Lower Lift = Less Work = Lower kW
How centrifugals change speed
Ideal Fan Laws Dictate the relationship between speed, flow
and lift
Flow ~ V, A
To increase flow, increase rotor
speed (with fixed flow area)
Lift ~ V
V
Flow
Area
2
To increase lift, increase speed
Diameter
Power ~ Flow x Lift ~
3
V
Without LIFT reduction, speed can
not reduce
A reduction in LIFT allows a speed reduction.
Lift is a function of the speed squared.
Power is related to the speed cubed!
All centrifugal chillers are subject to Ideal Fan
Law – Minimum speed approximately 65%, IGV
for remainder
SAVINGS FROM COLD
CONDENSER WATER
• Three 1400 ton Carrier 19XRV variable speed chillers
• Data Center
• Analyze savings operating chillers with 55 deg F
versus 65 deg F and 75 deg F
• 0.13 $/kwh simple rate
Net Present Worth Savings from 55 F vs…
ECWT
65F
75F
20 year life cycle
$217,550
$468,880
Additional Capacity
643
630
630
Carrier capacity
increases as
condenser water
temperature
decreases
Carrier
600
Tons
570
550
85oF
80oF
75oF
70oF
<65oF
Entering Condenser Water Temperature
Questions
Chiller Heat Recovery
• Instead of rejecting heat to the condenser
water loop, why not use this heat?
Heat Recovery Benefits
Chillers can transfer heat for as little as 25%
of the cost required to create heat with a
boiler.
80%
30XW Heat Recovery Chiller Savings vs.
Boilers
70%
60%
50%
71%
40%
30%
75%
50%
20%
10%
Natural Gas
Boiler ($12/1,000
ft3)
Electric Boiler
($0.10/kWh)
Fuel Oil Boiler
($ 3/gal)
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Hot Water Systems
How can we capture sufficient heat for useful purposes?
Building Heat
Service Hot Water
Process Heat
Why Heat Recovery?
ASHRAE 90.1-2004
Heat Recovery for Service Water Heating, Section § 6.5.6.2
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•
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Operates 24 hours a day
Total heat rejection exceeds about 400 tons of chiller
capacity
Service water-heating load exceeds 1,000,000 Btu/h
– 1,000 bed nursing home or 75 room full service hotel
Provide the smaller of:
• 60% of the peak heat rejection load at design conditions
or
• preheat of the peak service hot water draw to 85°F.
Exceptions:
• Minimum 30% recovery from condenser water heat for
space heating
or
• 60% or more of service water heating from site solar or
cogeneration, condensate subcooling, or solar panels.
Condenser Water Heat
Recovery
HEX Captures Condenser Water Heat
“Wasted” Heat for Service Hot Water Make-up
85°F Make-up Water
Caution: Higher LCWT Increases Chiller Lift, Reduces Efficiency
Heat
Out
Heat
Out
Heat In
Confirming Savings
Real World Example
i-Vu® Controls on 30XW Heat Machine at Charlotte
Factory
30XW
83
Questions
Thank You For
Today’s Opportunity