System Design for CO2 Secondary Coolant Based System
of 38
Transcript of System Design for CO2 Secondary Coolant Based System
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
1/38
www.danfoss.com
Hernan Hidalgo, Danfoss Inc.System Design for CO2 Secondary Coolant Based System
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
2/38
System Design for CO2 | Hernan Hidalgo April 2012 | 2Danfoss Automatic Controls
Content
Most Common Refrigeration Systems
Considerations for CO2 use Brine Principle. Volatile vs. Glycol
Pressure Rating Considerations
Energy Consumption Analysis
Control in CO2 High Temp Rooms
Defrost Strategies
Moisture in CO2 systems
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
3/38
System Design for CO2 | Hernan Hidalgo April 2012 | 3Danfoss Automatic Controls
NH3 systems. Low,Medium,High Temp
NH3/Glycol Systems. Medium Temp
NH3/CO2 Cascade systems. Medium/Low Temp NH3/CO2 Brine systems. Medium / Low Temp
Systems overview
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
4/38
System Design for CO2 | Hernan Hidalgo April 2012 | 4Danfoss Automatic Controls
Indirect Cooling - Considerations
NH3chargereduction
Largenumberofstaffinprocessareas
InsurancePremiums Riskassessment
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
5/38
System Design for CO2 | Hernan Hidalgo April 2012 | 5Danfoss Automatic Controls
NH3/Glycol Layout
NH3 NH3
Cold Glycol
Warm Glycol
Supply Pump
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
6/38System Design for CO2 | Hernan Hidalgo April 2012 | 6Danfoss Automatic Controls
Large Footprint
Typically two large expansion tanks required for
pump units Larger Pipe Sizes / More Insulation
Higher Pumping kW
Glycol Mixture Monitoring
Glycol Systems
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
7/38System Design for CO2 | Hernan Hidalgo April 2012 | 7Danfoss Automatic Controls
CO2 Overview
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
8/38System Design for CO2 | Hernan Hidalgo April 2012 | 8Danfoss Automatic Controls
NH3 Compresor(s)
Cascade
Heat
Exchanger
Evaporator
ICM Motorized valve
CO2 pump
NH3 CO2pumped
CO2 separator
Low temperature CO2 High Side - NH3
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
9/38System Design for CO2 | Hernan Hidalgo April 2012 | 9Danfoss Automatic Controls
NH3CO2on PH
-15 oC (23 bar)
Enthalpy
CO2+5 oF (333 psi)
Enthalpy
R717
+30 oC (12 bar)
+86o
F (171 psi)
-20 oC (1,9 bar)-4 oF (28 psi)
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
10/38System Design for CO2 | Hernan Hidalgo April 2012 | 10Danfoss Automatic Controls
CO2highdensityprovides
considerableadvantages
inwetordrysuctionlines
Pressuredrop
equivalentto
loweringevaporating
temperature1.8F
CO2 Wet Suction Pressure drop
Evap Temp. NH3 CO2
32F 2.3 psig 14.5 psig
-4F 1.2 psig 9 psig
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
11/38System Design for CO2 | Hernan Hidalgo April 2012 | 11Danfoss Automatic Controls
HighPressureCascadeHeatExchanger
RefrigerationloadinCO2asbrinesystembalances
automatically
Oilfreeoperation
LowerPumpingkW
Lowerenergyconsumptioncomparedtoglycol
counterparts
CO2 Pump Systems
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
12/38System Design for CO2 | Hernan Hidalgo April 2012 | 12Danfoss Automatic Controls
CO2 Pump System PH Overview
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
13/38System Design for CO2 | Hernan Hidalgo April 2012 | 13Danfoss Automatic Controls
High Heat Transfer Coefficient
Higher efficiency is noticeable at the cascade
heat exchanger TD between NH3/CO2 is considerably lower than
NH3/glycol
Higher suction temp of cascade fluid
Line sizes are significantly reduced
Lower Pump Power
EnergyEfficiencyCO2asBrineSystems
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
14/38System Design for CO2 | Hernan Hidalgo April 2012 | 14Danfoss Automatic Controls
PipeLineSizeComparison
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
15/38
System Design for CO2 | Hernan Hidalgo April 2012 | 15Danfoss Automatic Controls
Low Recirculation rates than ammonia systems
Recirculation varies between 1.1 to 1.5
Volatile brine vs. Glycol sensible heat gain
CO2 pumps consume on average 90% less
energy required compared to water basedbrines
Energy Consumption
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
16/38
System Design for CO2 | Hernan Hidalgo April 2012 | 16Danfoss Automatic Controls
A system operating at 14F (-10 C)
Mglycol = Q / (C T )
MCO2 = Q / H Latent heat CO2 at 14F (-10C): 112BTU/lb
(260kJ/kg)
Cglycol = 0.72 BTU/lb-F (3.42) ; T = 7.2F (4K)typical
Mass flow required to reject 247BTU/s (260kW)
cooling load
MCO2: ~ 2.2 lbs/s (1 kg/s) vs. ME. Glycol: 45.4 lbs/s(20 kg / s)
CO2 vs. Glycol Mass Flow Comparison
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
17/38
System Design for CO2 | Hernan Hidalgo April 2012 | 17Danfoss Automatic Controls
Calculation Example
Capacity: 142TR (500kW)
CO2 recirc. rate : 1.5 to 1
Differential Head: 82 ft (25m)
T glycol inlet/outlet: 7.2F (4K)
CO2 = 75%
CO2 vs. Glycol Pump Power Comparison
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
18/38
System Design for CO2 | Hernan Hidalgo April 2012 | 18Danfoss Automatic Controls
CO2 vs. Glycol Relative PumpingPower
FluidPower kW
14 F (-10C) .-4 F(-20C)
CO2 0.97 0.85
CaCl2 13.34 14.22Hycool 16.02 16.15
Ethylene Glycol 15.87 18.8
Propylene Glycol 14.03 16.68
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
19/38
System Design for CO2 | Hernan Hidalgo April 2012 | 19Danfoss Automatic Controls
SimplifiedAssessment.(Nodefrostandothervariablesconsidered)
Prequired=Pcompr+Ppumps
Pcompr= Qoadjusted/COP
COP:Calculationpurposes1.9for4F airand3.8
for32
F
UsingPackCalculationIIandCO2brinecalculator
v.3.91:fora215TR(750kW)plantandroomair
temperatureof39F(5 C)
Total Energy Consumption
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
20/38
System Design for CO2 | Hernan Hidalgo April 2012 | 20Danfoss Automatic Controls
Total Energy Consumption
CO2
Ethylene
Glycol Units
Air temperature, tair 39 39 F
Cooling power, Qo 215 215 TR
Circulation rate, n 1.5 -Temp. dif. in evap., dtevap 9 13 F
Temp. dif. in PHE, dtPHE 7.2 9 F
Brine temp. dif., tout - tin 0 7.2 F
Evaporating temp., to 25 19.5 F
Additional heat gains, kq 5% 7% %
Additional heat gains, Qadd 37.5 50.6 kW
Pump head pressure, Hpump 37 37 psig
Pump power cons., Ppump 1.6 16.6 kW
Adjusted cooling power,
Qo,ad 789.1 815.6 kW
Compr. power cons., Pcomp 170.8 196.2 kW
Total install energy cons. 172.4 212.8 kW
Total daily energy cons. 3,112.9 3,930.3 kW*h
Energy savings 21% %
Table 2. Energy Consumption Comparison
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
21/38
System Design for CO2 | Hernan Hidalgo April 2012 | 21Danfoss Automatic Controls
CO2offersfasterreactiontime.However:
Savingsalsodependon
LoadPatterns
DefrostType
ControlStrategy
Useof
VFD
Results
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
22/38
System Design for CO2 | Hernan Hidalgo April 2012 | 22Danfoss Automatic Controls
Inanattempttovalidatetheoreticalcalculations,datafromtwodistributioncentersforfruitslocated
intwo
different
climates
has
been
analyzed
Anadjustmenthasbeenmadetooffsetclimate
influence
Two Sites Comparison
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
23/38
System Design for CO2 | Hernan Hidalgo April 2012 | 23Danfoss Automatic Controls
Two Sites ComparisonConditions / Location North Italy The Netherlands
Storage type Fruit Fruit
Air temperature Avera 34F Aver 32F
Suction temperature 8.6 F 13 F
Brine Type Glycol CO2
Media temperature (for glycol in/out) F .=17.6 / 25 18.5
Temperature difference in cascade heat exchanger difference,
F 9 to 12 5.5 to 7.2
Cooler temperature difference, F 8 to 12 8
Lighting, estimated from the total load 10% 5%
Total fans installed, kW 74.145.3 (fans are running only
20% of the time)
Total consumed, kW h (measured figure) 1.300.000 2.700.000
Total compressors and pumps, kW h (calculated, excluding
lights and excluding fans) 576607 1245025
Region corrected consumption, kW h, by PackCalculation II
software, according to the assumptions above, everythingadjusted to the Netherlands climate 518000 1245025
Average consumption, kW (calculated by PackCalculation II
software to fit the corrected consumption) 188 660
Per unit of cooling consumption kW h/kW cooling (corrected
consumption / average consumption) 2.75 1.88
Difference in Energy Consumption 32% HigherTable 3. Actual Energy Consumption site comparison
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
24/38
System Design for CO2 | Hernan Hidalgo April 2012 | 24Danfoss Automatic Controls
Measuredvalue:kW/kWh
Thougha32%differenceissubstantial,large
deviationsoccur
due
to
other
variables
Site Results
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
25/38
System Design for CO2 | Hernan Hidalgo April 2012 | 25Danfoss Automatic Controls
NH3 Systems Medium, High Temp
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
26/38
System Design for CO2 | Hernan Hidalgo April 2012 | 26Danfoss Automatic Controls
PWM in high temp CO2
PWM
Raising 15F by means of a pressureregulator requires a 106 psi increase in
CO2 pump pressure making it impractical
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
27/38
System Design for CO2 | Hernan Hidalgo April 2012 | 27Danfoss Automatic Controls
PWM Control Principle
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
28/38
System Design for CO2 | Hernan Hidalgo April 2012 | 28Danfoss Automatic Controls
CO2 Brine System Control
ICF valve stations feeding penthouse units
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
29/38
System Design for CO2 | Hernan Hidalgo April 2012 | 29Danfoss Automatic Controls
CO2 Brine Pump Package
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
30/38
System Design for CO2 | Hernan Hidalgo April 2012 | 30Danfoss Automatic Controls
CO2 receiver
AuxiliaryRefrigeration
system(Condensing)
Dedicatedgenerator
PS
Auxiliary cooling system - in case of power failure
Capacity dependent of system design and ambient temperature(~ 4kW / 1000 kW)
St a n d s t i l l t e m p e r a t u r e co n t r o l
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
31/38
System Design for CO2 | Hernan Hidalgo April 2012 | 31Danfoss Automatic Controls
Common defrost strategy for CO2 brine systems:
Electrical (similar to standard brines)
Brine defrost (additional system)
Water defrost (drain required)
Hot gas defrost. The availability of components rated at 754 psig (52 bar) hasmade possible to use one of the most efficient defrost strategies
(requires additional vessel and HE heated by HP stage) There is a system
available patented by Star Refrigeration - UK
D e f r o s t
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
32/38
System Design for CO2 | Hernan Hidalgo April 2012 | 32Danfoss Automatic Controls
H o t Ga s D e f r o s t Co n t r o l
PWM technology
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
33/38
System Design for CO2 | Hernan Hidalgo April 2012 | 33Danfoss Automatic Controls
El e c t r i c D e f r o s t
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
34/38
System Design for CO2 | Hernan Hidalgo April 2012 | 34Danfoss Automatic Controls
Moisture in CO2 Systems
W t S l bilit i h
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
35/38
System Design for CO2 | Hernan Hidalgo April 2012 | 35Danfoss Automatic Controls
Water Solubility in vapor phase
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
36/38
System Design for CO2 | Hernan Hidalgo April 2012 | 36Danfoss Automatic Controls
R134a
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
37/38
System Design for CO2 | Hernan Hidalgo April 2012 | 37Danfoss Automatic Controls
Moisture in CO2 vapor phase
RH = 0% RH = 100% RH >> 100%
Relative Humidity
Tem
perature[C
]
0
-40
Safe
Perform
ance
Other
Problems!
Chemical
Rection
Sensitive:
Solenoid
valves
Pistonequipment
Functionality ProblemsOtherequipment:
Strainers
Compressor
Free
Water
Ice
7ppm
50
ppm
90ppm
20
-
8/9/2019 System Design for CO2 Secondary Coolant Based System
38/38
Service
Infiltration
CO2 supplier
Start-upvacuum
Filter driers continuous process
Deep vacuum, extra careon commissioning and start-up
Where Moisture comes from ?
WatercontentinaCO2
system
Note: 1 gram of water in 1000 kg of CO2 1 ppm
