refrigerants and their application -...
Post on 08-Feb-2018
233 Views
Preview:
TRANSCRIPT
1
1
Refrigerants Refrigerants and theirand their
ApplicationApplication
Presented by
Thomas E. Watson, P.E.Fellow ASHRAE
McQuay InternationalStaunton, Virginia USA
11
What is a Refrigerant?What is a Refrigerant?
• In a refrigerating system, the medium of heat transfer
which picks up heat by evaporating at a low
temperature and pressure, and gives up heat on
condensing at a higher temperature & pressure.
• (Refrigerating fluid) fluid used for heat transfer in a
refrigerating system which absorbs heat at a low
temperature and low pressure of the fluid and
transfers heat at a higher temperature and higher
pressure of the fluid, usually involving changes of state
of the fluid.
Ref: ASHRAE Terminology of Heating, Ventilation, Air Conditioning, & Refrigeration
22
2
2
Agenda / TopicsAgenda / Topics
• Introduction
• History of Refrigerants
• Basic Refrigerant
Chemistry
• Refrigerant Properties
• Refrigerant Applications
• Refrigerants In The
Future?
• Alternative Refrigerants
• Ozone Depletion &
Montreal Protocol
• Global Warming
• Summary
33
History of RefrigerantsHistory of Refrigerants
• 1830s - Jacob Perkins - Vapor Compression (ether)
• 1851 - John Gorrie - Patent for Air Cycle
• 1859 - R-717 / R-718 (Ammonia / Water)
• 1866 - CO2 - Marine Applications
• 1873 - R-717 (Ammonia) Commercial Refrigeration -
Carl Linde
• 1875 - R-764 (Sulfur dioxide)
• 1920s -R-600a (Isobutane) & R-290 (Propane)
• 1922 - Willis Carrier - R-1130 (Dielene)
• 1926 - R-30 (Methylene Chloride)
44
3
3
Solving Problem of Toxicity was a Large Problem to Development of Refrigeration
1927 Leo Szilard &Albert Einstein
Improved on von Platen / Munters Absorption DesignElectromagnetic Pumping Patent
Toxicity Toxicity -- Best Minds Tried to SolveBest Minds Tried to Solve
55
Challenged to Find Refrigerant:Challenged to Find Refrigerant:
• Non-flammable
• Good Stability
• Low Toxicity
• Atmospheric Boiling Point between -40oC & 0oC
66
4
4
Common Refrigerants in 1920sCommon Refrigerants in 1920s
Ammonia (R-717) NH3
Carbon Dioxide CO2
Sulfur Dioxide SO2
Hydrocarbons CnHm
Methyl Choride CH3Cl
Water H2O
77
History of RefrigerantsHistory of Refrigerants
88
5
5
History of RefrigerantsHistory of Refrigerants
HC N O F
S ClBr
Midgley SelectionsMidgley Selections
99
Hydrocarbon Formula NBP
Methane CH4 -260 F -162 ̊C
Ethane C2H6 -127 F -88 ̊C
Propane C3H8 -44 F -42 C̊
Refrigerant ChemistryRefrigerant Chemistry
1010
6
6
Refrigerant ChemistryRefrigerant Chemistry
1111
Refrigerant ChemistryRefrigerant Chemistry
1212
7
7
Refrigerant ChemistryRefrigerant Chemistry
1313
Refrigerant ChemistryRefrigerant Chemistry
1414
8
8
FluorocarbonsFluorocarbons
• CFCs, HCFCs, HFCs & HFOs
• Limited Combinations
– Adding Chlorine Or Bromine
Increases ODP
– Adding Fluorine Increases
GWP
– Adding Hydrogen Increases
Flammability And Lowers
Atmospheric Lifetime
HYDROGEN
CHLORINE FLUORINE
Flammable
Toxic
Long Atmospheric Lifetime(fully halogenated)
Refrigerant ChemistryRefrigerant Chemistry
1515
Refrigerant ChemistryRefrigerant Chemistry
1616
9
9
Refrigerant ChemistryRefrigerant Chemistry
1717
Refrigerant ChemistryRefrigerant Chemistry
1818
10
10
• Refrigerant Blends
– Two or More Refrigerants to Achieve Required Properties
• Flammability
• Volumetric Capacity
• Limit Discharge Superheating for Lower Disch Temp
• etc
• Two Basic Types
– Zeotropes
– Azeotropes
Refrigerant ChemistryRefrigerant Chemistry
1919
ZeotropesZeotropes
100806040200
-5
5
15
25
35
45
55T vap
T liq
ZEOTROPIC BEHAVIOR (32/134a)
% R-32
Tem
per
atu
re, °F
P= 64 PSIA
100806040200
-5
5
15
25
35
45
55T vap
T liq
ZEOTROPIC BEHAVIOR (32/134a)
% R-32
Tem
per
atu
re, °F
P= 64 PSIA
Refrigerant ChemistryRefrigerant Chemistry
2020
11
11
Zeotropic BehaviorZeotropic Behavior
• Fractionalization - Can be Separated by Distillation
• Service Procedures
Refrigerant ChemistryRefrigerant Chemistry
2121
AzeotropesAzeotropes
100908070605040302010033
34
35
36
37
38
39
T vap
T liq
AZEOTROPIC BEHAVIOR (R-125/R-143a)
% R-125
Tem
per
atu
re,
°F
P=100 PSIA
R-507 = AZEOTROPIC MIXTURE R-125/R-143a (50/50)
Refrigerant ChemistryRefrigerant Chemistry
2222
12
12
ASHRAE Standard 34ASHRAE Standard 34
2323
• Nomenclature
• Toxicity Classification
• Flammability Classification
ASHRAE Standard 34ASHRAE Standard 34
2424
13
13
ASHRAE Standard 34ASHRAE Standard 34
000 Series Methane Based
100 Series Ethane Based
200 Series Propane Based
300 Series Cyclic Organic Compounds
400 Series Zeotropes
500 Series Azeotropes
600 Series Organic Compounds
700 Series Inorganic Compounds
1000 Series Unsaturated Organic Compounds
Nomenclature
Code KeyCode Key
R - 1 2
+ 9 0
C H F
= 1 0 2
Rule of 90 - Example R-12
14
14
ASHRAE Standard 34ASHRAE Standard 34
2727
Entgegen Zusammen
HFOHFO--1234ye 1234ye StereoisomersStereoisomers
2828
15
15
• Toxicity Classification based on
Chronic (long term) Measure
- Class A has PEL > 400 PPM
- Class B has PEL < 400 PPM
PEL = Permissible Exposure Limit
ASHRAE Standard 34ASHRAE Standard 34
2929
• Flammability Classification based on:
ASTM E 681 with an Electrically
Activated match
ASHRAE Standard 34ASHRAE Standard 34
3030
16
16
Flammability Classification
• Class 1 - No Flame Propagation
• Class 2 - LFL > 0.10 kg/m^3
and hc < 19 MJ/kg
• Class 2L – Cl 2 w/ flame speed < 10 cm / sec
• Class 3 - LFL < 0.10 kg/m^3
or hc > 19 MJ/kg
ASHRAE Standard 34ASHRAE Standard 34
3131
ASHRAE Standard 34ASHRAE Standard 34
3232
17
17
A2L RefrigerantsA2L Refrigerants
3333
ASHRAE Standard 15ASHRAE Standard 15
3434
18
18
What is ASHRAE 15?
• An industry standard that specifies safe design, construction, installation, and operation of refrigerating systems
• Establishes safeguards for life, limb, health, and property, and prescribes safety standards
ASHRAE Standard 15ASHRAE Standard 15
3535
Scope
• Design, Construction, Installation, Operation & Inspection of Mechanical and Absorption Machines
• Modifications if not Identical in Function and Capacity
• Refrigerant Substitutions with Different Designation
ASHRAE Standard 15ASHRAE Standard 15
3636
19
19
RequirementsBased on 3 Classifications
• Occupancy
• Refrigerating System
• Refrigerant
ASHRAE Standard 15ASHRAE Standard 15
3737
Occupancy Classifications Occupancy Classifications -- Ability to Respond to ExposureAbility to Respond to Exposure
• Institutional - Assistance Required
• Public Assembly - Large Numbers
• Residential - Sleeping
• Commercial - Business Transactions
• Large Mercantile - 100 Persons or More
• Industrial & Refrigerated Rooms - Access Controlled
• Mixed - Two or More in Same Building
ASHRAE Standard 15ASHRAE Standard 15
3838
20
20
Refrigerating System Classification
• High Probability - Leak Can Enter Occupied Space
• Low Probability - Leak Cannot Enter Occupied Space
ASHRAE Standard 15ASHRAE Standard 15
3939
Restrictions on Refrigerant Use - Section 7
• Standard 15 Gives Rules based on Occupancy, System, & Refrigerant Classification
• 3 kg or Less of Flammable Refrigerants may be used in Listed Equipment
• A2L Refrigerant Application Requirements NOT Included – Presently Under Consideration
ASHRAE Standard 15ASHRAE Standard 15
4040
21
21
Refrigerant Qty/vol Limits - See Std 34
• Acute Exposure / Ability to Escape
• Direct Systems
• Volume - Space to which Refrigerant Disperses in Event of Leak
ASHRAE Standard 15ASHRAE Standard 15
4141
ASHRAE 15 Users ManualASHRAE 15 Users Manual
4242
22
22
Location of inlet vents in relationto exhaust outlets ?
Location of roof drains ?
Rupture discoutlet locations ?
Purge vents to outside ?
Are safety rupturelines the right size ?
Is access to mechanicalroom restricted ?
Is there a tightseal on doors ?
Where do thefloor drains empty ?
Are drain valves connectedAre drain valves connectedto evacuation devices ?to evacuation devices ?
Are there anypit areas in theroom ?
Mechanical Room Safety CheckMechanical Room Safety Check
4343
Relief discharge shall be located not lessthan 20 ft (6 m) from ventilation opening andnot less than 15 ft (4.5 m) above ground level (9.7.8)
All indoor machineryrooms must be ventedto the outdoors utilizingmechanical ventilation98.13.3 & 4
Access to mechanicalroom shall be restricted.Tight fitting doors openingoutward (self closing if theopen into the building)adequate in number to ensure freedom of escape.No other openings that wouldpermit passage of escaping refrigerant (8.13)
Purge systems and relief devicesmust be vented to outside (8.16)
Refrigerant sensors are located in areas whererefrigerant vapor from a leak will be concentratedso as to provide warning at concentration notexceeding the refrigerant PEL
The total amount ofrefrigerant stored in amachinery room in all containers not provided with relief valves & piped in accordance with standard shall not exceed 330 lb (150 kg). (11.5)
Mechanical Room Safety CheckMechanical Room Safety Check
4444
23
23
Entrance / Exits
Drains
PitsPits
Just Above floorJust Above floorNext to ChillersNext to Chillers
Refrigerant Storage
*Examples not part of standard
Sample Sensor Locations* Sample Sensor Locations*
4545
No open flames that usecombustion air from the machineryroom (boilers) can be locatedwithin the mechanical as long as the combustion air is ducted fromthe outside to the boiler or shutdown sensors are installed (8.13.6)
A change in the type of refrigerant in a system shall not be made without the notificationof the authority having jurisdiction, the userand due observance of safety requirements. Therefrigerant being considered shall be evaluated for suitability (5.3)
Mechanical room should bedimensioned for easyaccess to all parts and adequatespace for service, maintenance,and operation. Clear head roomof not less than 7.25 ft (2.2 m) below equipment situated overpassageways. (8.12.1 &2,8.13.1)
Periodic tests of detectors, alarms & ventilation must be performed in accordance with manufacturers recommendationsand/or local jurisdiction. (11.7.3)
Mechanical Room per ASHRAE 15Mechanical Room per ASHRAE 15
4646
24
24
IIAR 2IIAR 2
4747
Back to the FutureBack to the Future
25
25
Refrigerants in the Future?Refrigerants in the Future?
Low Direct Global Warming Potential
• CO2
• Ammonia
• Hydrocarbons
• HFOs
4949
• Ammonia (NH3) R-717
– Efficient
– B2L Classification
– Industrial Applications
• Water R-718
– Absorption Chillers
– Centrifugal Compressors
– Axial Flow Compressors
• Carbon Dioxide (CO2) R-744
– Low Critical Point
Natural RefrigerantsNatural Refrigerants
5050
26
26
What about other stuff What about other stuff --HFOs?HFOs?
Refrigerant ApplicationsRefrigerant Applications
• pV = (m x Ru x T ) / MM
5252
27
27
Refrigerant ApplicationsRefrigerant Applications
• What is Pressure?
• Pressure = Average Impact of Molecules on a
given area.
• Pressure is dependent on the Kinetic Energy of
the molecules.
5353
Volumetric CapacityVolumetric Capacity
5454
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
0.1 1.0 10.0 100.0 1000.0
CFM/ton
Mo
lecu
lar
Mass
R-114
R-12
R-123
R-11R-245fa
R-1234zeR-1234yf
R-134aR-500
R-407CR-22
R-410AR-152a
R-32 R-40
R-290R-744
R-717 R-718
28
28
Compressor Types
Positive Displacement
Dynamic
Centrifugal
Axial
Reciprocating Rotary Orbiting
Scroll
Trochoidal
Singe Shaft
Single Screw
Moving Vane
Fixed Vane(Rolling Piston)
Twin Shaft Three Shaft
Twin Screw Tri-Screw
Compressor TypesCompressor Types
Compressor Volumetric Capacities
NOTE: Log Scale
0 1 10 100 1,000 10,000 100,000 1,000,000
Recip
Scroll
Rotary
Screw
Centrifugal
Axial
CFM
29
29
Refrigerant Flow RequirementsRefrigerant Flow Requirements
5757
0.1
1
10
100
1000
0.1 1.0 10.0 100.0 1000.0
CF
M/t
on
Suction Pressure, PSIA
R-114
R-12
R-123R-11
R-245fa
R-1234zeR-1234yf R-134a
R-500 R-407CR-22
R-410AR-32
R-40
R-290
R-744
R-717
R-718
• Compressors
– Vapor Pressure
– Temperature Lift
– Tons
• Evaporators
– Glide
• Condensers
– Glide
– Critical Temperature
Basic ConsiderationsBasic Considerations
5858
30
30
RR--11 Alternatives11 Alternatives
Refrigerant Molecular Mass
CFC-11 137.4
HCFC-123 153.0
HFC-245fa 134.0
5959
Refrigerant Molecular Mass
CFC-12 120.9
CFC-500 99.3
HFC-134a 102.0
HFO-1234yf 114.0
RR--12 Alternatives12 Alternatives
6060
31
31
RR--22 Alternative22 Alternative
Refrigerant Molecular Mass
HCFC-22 86.5
HFC-407C 86.2
6161
TEWI - Total Environmental Warming Impact
Consists of
• Direct GWP, from refrigerant discharge +
• Indirect, power plant CO2 discharge dominates
- Over 95% for Well Maintained Equipment
- CO2 from Power Generation depends on IPLV
Global WarmingGlobal Warming
6262
32
32
Global WarmingGlobal Warming
GWP
PowerGeneration
6363
�Ozone saving
�Global warming issue - Total Environmental Warming
Impact (TEWI)
�Safety
� Field availability
�Application
�Cost
�Compressor type
Summary Summary -- Refrigerant ChoiceRefrigerant Choice
6464
33
33
Questions?Questions?
6565
� www.ahri.org
� www.ashrae.org
� www.epa.gov/docs/ozone/index.html
� ASHRAE Handbook – Fundamentals - Refrigerants
� ASHRAE Standards 15 & 34
� IIR-2 Equipment, Design and Installation of Ammonia Mechanical Refrigerating
Systems
� Fluorocarbon Refrigerants Handbook - Ralph C. Downing, Prentice-Hall
� Trade-Offs in Refrigerant Selections: Past, Present, and Future - James M. Calm
and David A. Didion - Proceedings of ASHRAE/NIST Refrigerants Conference -
Oct 1997
� HFOS – New Low Global Warming Potential Refrigerants – S. F. Brown,
ASHRAE Journal August 2009
Information SourcesInformation Sources
6666
top related