PRICE CHOPPER SARATOGA, NY - First cascade supermarket system in North America Installed and Started March of 2008
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
PRICE CHOPPER
SARATOGA, NY
First cascade supermarket system in North America
Installed and Started March of 2008
Why did we choose CO2? • Meets Corporate sustainability initiatives • Looking for ways to reduce our carbon footprint (reduced carbon footprint by???) • GWP of 1 versus 1,300 to 3,900 for HFC’s • Questionable future of HFC refrigerants • Reduced copper line sizing and component size • Refrigerant costs $1.00/pound versus $8.00/pound • Timing!
Pro‘s
Low Global Warming Potential (GWP =1)
Chemically inactive, non-flammable
Not toxic, it’s in your soda and BEER!
High volumetric refrigerating capacity
Subcritical: 6 to 8 times higher than for R22,
R404A or NH3
Low refrigerant mass flow
It’s NOT new! Used until 1940’s when man made
refrigerants of the 30’s replaced CO2Con‘s
Higher pressures
Operating pressures of 220psig for suction
pressure and 420psig for discharge pressure
Max pressures for low and high side for safety is
350psig and 575psig
safety aspects (regulations, UL) and component
design
Lower practical limit in air than with HFCs (3.5 to 6
times less)
– CO2 is odourless − for closed rooms this
requires special safety and detection systemsKey Properties of Refrigerants
CFC's / HCFC's HFC's HC's Natural
Refrigerant R290 R600a R717 R744
R12 R22 R134a R410A R407C R404A
Propane Isobutane Ammonia CO2
ODP 1 0.05 0 0 0 0 0 0 0 0
GWP (100 yr) 10,600 1,500 1,300 1,725 1,525 3,900 20 20 2 1
Flammable No No No No No No High High Low No
Toxic No No No No No No No No Yes No
S=0.20 s=0.25 s=0.30
-60 F 0F 60 F 100 F 140 F 200 F 300 F
1700
1600
1500
1400 Low Temp. s=0.35
1300
1200
Sub Critical CO2
1100
Pressure (psia)
1000
900
80F
800
700
60 F
600
500 40 F
400 20 F s=0.40
300 0F
200 -20 F
-40 F s=0.45
100
-60 F
0
-50 0 50 100 150 200
Enthalpy (Btu/lbm)1200
Critical temperature [88F] 31.06°C
1000
800
P r e s s u r e [p s i]
CO2
600
400 R404A
R22
200
0
-75 -50 -25 0 25 50 75 100 125 150 175
Temperature [°F]Our LT CO2 DX Cascade System • 250,000Btu/Hr of Low-Temperature CO2 Refrigeration • Uses POE Oil (supplied by compressor manufacturer) • R-404A on Upper-Cascade also chills 125,000Btu/Hr Medium-Temperature loads with PG secondary coolant system • Stepper EEV’s on are used on CO2 evaporators • Most components designed for R-410A can be applied to CO2 cascade systems • US component manufacturers slow to introduce equipment for CO2 • Equipment footprint reductions compared with CO2 secondary • Recommended Coleman grade CO2 – 99.99% pure. Readily available BUT long lead times.
AIR-COOLED
CONDENSER
MT Secondary Load: 145 kBtu/Hr
RECEIVER LT CO2 Cascade Load: 242 kBtu/Hr
UPPER-CASCADE (MT) WITH R-404A COMPRESSORS COAXIAL
SLHE
GLYCOL
PUMP
MEDIUM-TEMPERATURE LOADS
PARALLEL CONDENSER-EVAPORATOR
HEAT EXCHANGERS
RECEIVER
SOLENOID VALVES ON ALL
ELECTRONIC EXPANSION VALVES GLYCOL HEAT EXCHANGERS
ON ALL CONDENSER-EVAPORATORS
AND GLYCOL CHILLER
PLATE LOWER-CASCADE (LT) WITH CO2 COMPRESSORS
SLHE
LEGEND
R-404A Discharge
ELECTRONIC EXPANSION R-404A Liquid
R-404A Suction
VALVES ON ALL CO2
EVAPORATORS Glycol Return
Glycol Supply
CO2 Discharge
CO2 Liquid
CO2 Suction
LOW-TEMPERATURE LOADSNotes on System Design Concentration of CO2 in air In closed rooms appropriate safety and monitoring devices (CO2 detectors available) Inhalation of higher CO2 concentrations can lead to unconsciousness and suffocation! Threshold Limit Value-Time Weighted Average of 5,000ppm compared to 3,000ppm for R404A and 507. This is for 8hrs per day, 40hrs per week. CO2 is odourless and colourless and can therefore not be perceived directly in case of emission. (sensors required in closed areas)
General Comment on Refrigerants
• No single refrigerant (or group) ideal for all
applications
CO2 technology promising in various
applications
… but no general solution for the substitution of
HFC’s
HCs and NH3 - Convincing in thermodynamic
properties
… but strongly limited in application due to safety
aspectsOperational Experiences • Reduced copper lines as compared to R404A • Training required for installation crew and in house service technician’s (follow up training required as well) • Installation and startup was “no big deal” according to contractor. Just “follow the requirements” • Leak detectors are expensive. • Availability of Coleman grade CO2 is limited. Long lead times requires full charge on site.
Operational Experiences cont’d • Have had numerous leaks on Threaded fittings for Relief valve, gauges, etc. • Leaks found on ball valves. Discussing with manufacturer for solution. • Sporlan controller used for liquid stepper valves on heat exchangers. Requires pre-load spares be available. • Even with backup auxiliary condensing unit, we had pressure relief valves release. Need to review with manufacturer.
Other Improvements • ECM fan motors on all new cases. Noise issue • LED lighting in all Reach-in cases • Variable speed fans on condenser – early failure on 2 fans • Changed existing refrigeration systems from R22 to R404A. • Replaced all HVAC units with New AAON units
What’s Next? • New LEED project store that will have a total refrigerant charge 300 pounds for the whole store using CO2 secondary and glycol medium temp.
You can also read
