APS Chiller Seminar Don Brandt, CEM-AEE, BEAP-ASHRAE ASHRAE and IEEE Life Member 3/16/2017
Agenda for today • Refrigeration Cycle • Chiller Types and Refrigerants • Compressor Styles • Chilled Water Pumping Systems • Control of Chiller Plants • Improving Chiller/System Efficiency • Maintenance • Absorption Cycle • Questions & Answers – Anytime
Basic Refrigeration System
compressor
condenser
evaporator
expansion device
discharge line
suction line
liquid line
A
B
C
D
Compressor
low-pressure refrigerant vapor from evaporator
C B
high-pressure refrigerant vapor to condenser
Basic Refrigeration System
compressor
condenser
evaporator
expansion device
high-pressure side
low-pressure side
discharge line
suction line
liquid line
A
B
C
D
Chiller Styles
• Air Cooled – Packaged and Split System
• Water Cooled – Small, Medium and Large Tonnage
• Chillers with Evaporative Condensers • Modular Chillers • Packaged Chilled Water Plants
Packaged Air-cooled Chiller
air-cooled condenser compressor
evaporator propeller-type condenser fans
liquid/vapor separator
motor
oil separator
condenser
oil supply system
compressor
control panel
evaporator starter
Components of a Helical-rotary Water Chiller
Evaporator
eliminator liquid distributor orifice system
liquid refrigerant
tube bundle
chilled water return
cooling water
subcooled, liquid refrigerant
subcooler
hot, refrigerant vapor
85ºF [29ºC]
95ºF [35ºC]
Water-cooled Condenser
Shell-and-Tube Evaporator
refrigerant vapor
chilled water return
chilled water supply
tube bundle
baffles
liquid/vapor refrigerant
Cooling Tower sprays
from condenser
to condenser
sump
propeller fan
outdoor air
85ºF [29ºC]
95ºF [35ºC]
fill
water-cooled
• Greater energy efficiency
• Longer equipment life
air-cooled • Lower maintenance • Packaged system • Better low-ambient operation
Air-cooled or Water-cooled Comparison
Modular Chillers
• Typically Water-Cooled, some Air- Cooled
• Modules piped in Parallel from a water flow standpoint
• Compressors: Scroll, Screw and Centrifugal – older may have Reciprocating
Modular Chiller Applications High-efficiency Cooling Only
Refrigerants for Chillers
• Scroll and Recip: HCFC-22 , HFC-407C , HFC-410A , HFC-134A
• Helirotor or Screw: HCFC-22 , HFC-134A
• Centrifugal: HFC-134A , HCFC-123 • Future Refrigerants: Ammonia, HFOs • Classified by ASHRAE Std 15 – 2016
Refrigerants of the Future • HydroFluoroolefins – no ozone
depletion and low GWP • R-514A, low pressure, replace R-123
in Centrifugal Chillers, GWP = 2 • HFO-1234yf, medium pressure,
replace R-134a in automotive/transportation, GWP =4
• R-32, high pressure, replace R-410A in VRF, GWP = 675
Refrigerants of the Future
• R-452A, med pressure, replace R-404 in various application, GWP = 1945
• R-449A, high pressure, replace R-22 and R-407 in chillers and unitary, GWP=1282
• R-513A, medium pressure, replace R-134a in air cooled screw chillers, GWP =573
Refrigerants of the Future
• R-452B, high pressure, replace R-410A in unitary, residential and smaller HVAC equipment, GWP = 676
• Suggested reading-Honeywell website under Soltice refrigerants
Refrigerants of the Future
• Also check out websites for Chemours – Dupont and Arkema
• ASHRAE Std 15 -2016 has new classification of 2L for low flammability HFO’s as it relates to safety
• ASHRAE just approved $1.5 Million in research for safety guidelines.
Refrigerants of the Future
• California just announced it will no longer allow any new equipment with R-134a in the state, starting in Jan of 2020.
Refrigerants of the Future
• GWP of current refrigerants. • R-22, GWP = 1700,HCFC • R-123, GWP = 0.02, HCFC • R-134A, GWP = 1300, HFC • R-11, GWP = 4000, CFC • R-12, GWP = 2400, CFC
Refrigeration Compressors
• Reciprocating • Scroll • Helirotor or Screw-One, two and
Three Rotor • Centrifugal
scroll reciprocating
Air Conditioning Clinic TRG-TRC004-EN © American Standard Inc. 2000
helical-rotary centrifugal
Reciprocating Compressor
piston refrigerant vapor
cylinder
discharge valve
rod
suction valve
intake stroke
Reciprocating Compressor suction opening
motor
piston
cylinder
crankshaft
rod
discharge opening
headspace
Scroll Compressor stationary scroll
driven scroll
intake
discharge
intake
discharge port
motor shaft
Oil Supply System
master solenoid valve
oil tank sump
oil filter
oil separator
rotor bearings
rotor refrigerant vapor to condenser
compressor
1 2
Centrifugal Compressor refrigerant enters diffuser
path through compressor
veloc
ity
static
pres
sure
refrigerant enters impeller
refrigerant enters volute
Oil Less Centrifugal Compressor
• Magnetic Bearing Style – Danfoss, Diakin, and York direct drive with VFD
• Ceramic Bearing Style – Refrigerant cooled bearings with VFD
Methods of Compressor Unloading
• Reciprocating • Scroll
• Helical-Rotary • Centrifugal
Cylinder Unloaders Cycle On- Off, Digital,
VFD, Ported Slide Valve, VFD,
Ported Inlet Vanes, VFD
Cylinder Unloaders
unloader valve
refrigerant vapor
discharge
unloader solenoid valve
controller
cylinder piston
Digital Scrolls Provide Continuous Modulation
• Separation Of Scroll Elements Alternately Loads And Unloads Compressor
• By Controlling Separation Times, Compressor Is Precisely Operated Between 10-100%
• Power Linearly Related To Capacity
• Precise Temperature & Humidity Control
• Ideal For Light Commercial Split, Package And Chiller Applications
Loaded State
Unloaded State
Next Gen UltraTech Modulation Part Load Operation
Full Load Operation
Bypass Ports Sealed
Suction Pressure Communicated To Lift Chamber Via 3-Way Valve (Valve Energized)
Modulation Ring Moves Down, Sealing Bypass Ports
Bypass Ports Opened
Intermediate Cavity Pressure Communicated To Lift Chamber Via Three Way Valve (Valve De-energized)
Modulation Ring Moves Up, Opening Bypass Ports
Part Load Full Load
Benefits Of Multiples Tandems And Trios • Load Matching
Capability Via Multiple Steps Of Capacity
• Compressors Operate Together Or Individually
• Maintains High Part & Full Load Efficiency Levels
• Ideal For Commercial Splits, Rooftops And Chillers
Slide Valve
slide valve (closed)
slide valve
(open)
valve opening
to suction
full load part load
discharge port
Heli Rotor Compressor
• Unloader ports along the rotor that open back to the compressor suction to decrease the capacity
• VFDs change speed of rotors for capacity control
Inlet Vanes
25
75
10 14
63
pres
sure
diffe
renc
e
capacity
90
36 51
A
unloading line
vane position (degrees)
C B
Equipment Rating Standards
• Air-Conditioning, Heating & Refrigeration Institute (AHRI) – Standard 550/590–
2015: centrifugal and helical-rotary water chillers
– Standard 560–2000: absorption water chillers
Flow Rates and Temperatures
QBtu/hr = 500 × flow rate × ∆T
[ QW = 4,184 × flow rate × ∆T ]
equation for water only
ASHRAE Standard 15–2016
• Safety standard for refrigerating systems
• Mechanical equipment room – Refrigerant monitors – Alarms – Mechanical ventilation – Pressure-relief piping
ASHRAE/IESNA Standard 90.1–2016
• Energy standard – Building design and
materials – Minimum equipment
efficiencies – HVAC system design