OZONE OZONE SCIENCESCIENCE

Philippine Society of Mechanical Philippine Society of Mechanical EngineersEngineers

Outline of PresentationOutline of Presentation WHAT IS OZONE?WHAT IS OZONE? WHAT IS THE OZONE LAYER?WHAT IS THE OZONE LAYER? HOW IS OZONE CREATED AND DESTROYED?HOW IS OZONE CREATED AND DESTROYED? WHAT IS THE OZONE HOLE?WHAT IS THE OZONE HOLE? WHAT ARE THE EFFECTS OF OZONE WHAT ARE THE EFFECTS OF OZONE

DEPLETION?DEPLETION? WHAT ARE THE CAUSES OF OZONE WHAT ARE THE CAUSES OF OZONE

DEPLETION?DEPLETION? HOW CAN THE OZONE LAYER BE SAVED?HOW CAN THE OZONE LAYER BE SAVED?

WHAT IS OZONE? Is a gas that is naturally present in Is a gas that is naturally present in

the atmospherethe atmosphere Chemical symbol – OChemical symbol – O33

Derived from Greek word Derived from Greek word OZEINOZEIN Ozone molecules have relatively low Ozone molecules have relatively low

abundanceabundance

air molecules

THE GOOD AND BAD OZONE

WHAT IS OZONE LAYER?

The sun gives this earth light and life, but is also the main source of ultraviolet radiation.

THE SUN

The Ozone Layer is a thin, The Ozone Layer is a thin, fragile shield that envelops fragile shield that envelops the entire earth which the entire earth which efficiently and effectively efficiently and effectively filters and screens almost filters and screens almost all of the harmful ultraviolet all of the harmful ultraviolet raysrays

There are three categories of UV:

•UV-A: Most UV-A is able to reach the UV-A: Most UV-A is able to reach the earth’s surface. Generally not dangerousearth’s surface. Generally not dangerous•UV-B: 90% of UV-B is blocked off by the UV-B: 90% of UV-B is blocked off by the ozone layer. Harmfulozone layer. Harmful•UV-C: 100% of UV-C is blocked off by the UV-C: 100% of UV-C is blocked off by the ozone layer. Lethalozone layer. Lethal

What filters the dangerous radiation

from the sun that could practically burn all life on earth is the

OZONE LAYER.

Ozone molecules are created and destroyed high above the surface of the earth, about 20-40 km

above ground.

How is ozone created and destroyed?How is ozone created and destroyed?

WHAT IS THE OZONE HOLE?

The depletion or the loss of the blocking effect of the ozone layer against ultraviolet rays is what we call the OZONE HOLE

The Ozone Hole History

The Ozone Hole History

The Ozone Hole History

The largest ozone hole is the size of North AmericaAlthough the ozone hole is found in the Antarctica, the global ozone level throughout the stratosphere has also decreased by 3% every decade.

The largest ozone hole is found in Antarctica because:

- ODS are present throughout the atmosphere regardless of where they are released- The symmetry of the land of Antarctica affects the very cold climate - The temperature leads to chemical changes that promote the production of chemically active chlorine and bromine from ODS

WHAT ARE THE EFFECTS OF OZONE DEPLETION?

Ozone Depletion harms and endangers all living forms.

Effects of increased UV-B radiation

• More skin cancers• More eye cataracts• Weakened immune systems• Reduced plant yields• Damage to ocean eco-systems

and reduce fishing yields• Adverse effects on animals• More damage to plastics and

other building materials

Ozone depletion allows the entry of UV-B radiation

ManMan will find his will find his immune system immune system deteriorating making deteriorating making him prone to skin him prone to skin cancer, eye cataracts cancer, eye cataracts blindness rapid aging blindness rapid aging and other serious and other serious diseases. UV-B diseases. UV-B arrests the growth of arrests the growth of plants and trees and plants and trees and phytoplanktonsphytoplanktons. . UV-B also results in UV-B also results in degradation of degradation of building materials.building materials.

WHAT CAUSES OZONE DEPLETION?

Causes of Ozone Depletion• CERTAIN CHEMICALS UPSET THE OZONE BALANCE,

>>> CALLED OZONE-DEPLETING SUBSTANCES

• OZONE-DEPLETING SUBSTANCES (ODS) ARE CHEMICAL SUBSTANCES THAT HAVE THE POTENTIAL TO REACT WITH OZONE MOLECULES IN THE STRATOSPHERE.

• THE ABILITY TO DEPLETE THE OZONE LAYER IS REFERRED TO AS THE OZONE- DEPLETING POTENTIAL (ODP)

OZONE DEPLETING SUBSTANCES (ODS) OZONE DEPLETING SUBSTANCES (ODS) AND THEIR USESAND THEIR USES

•CFCs are used in CFCs are used in refrigerators, air-refrigerators, air-conditioners, spray conditioners, spray cans, solvents, cans, solvents, foams, other foams, other applicationapplication

HALO-CARBONSHALO-CARBONS(CHLOROFLUOROCARBONS or CFCs and (CHLOROFLUOROCARBONS or CFCs and

HALONS)HALONS)

•Halons are Halons are primarily used in primarily used in fire extinguishersfire extinguishers

CFC AND ITS MOST COMMON CFC AND ITS MOST COMMON USESUSES

OZONE DEPLETING SUBSTANCES (ODS) OZONE DEPLETING SUBSTANCES (ODS) AND THEIR USESAND THEIR USES

•HYDROBROMOFLUOROCARBONS HYDROBROMOFLUOROCARBONS (HBFCs) are used in fire (HBFCs) are used in fire extinguishersextinguishers

•CARBON TETRACHLORIDE and CARBON TETRACHLORIDE and METHYL CHLOROFORM are used METHYL CHLOROFORM are used as solventsas solvents

•HYDROCHLOROFLUOROCARBONS HYDROCHLOROFLUOROCARBONS (HCFCs) were developed as the (HCFCs) were developed as the first major CFC replacement first major CFC replacement

OZONE DEPLETING SUBSTANCES (ODS) OZONE DEPLETING SUBSTANCES (ODS) AND THEIR USESAND THEIR USES

•METHYL METHYL BROMIDE BROMIDE (CH(CH33Br) is used Br) is used as a fumigant as a fumigant and in and in quarantine quarantine treatment treatment

•BROMOCHLOROMETHANE BROMOCHLOROMETHANE (BCM) is used as fire (BCM) is used as fire extinguishing agent and extinguishing agent and solventsolvent

HOW CAN THE OZONE LAYER BE SAVED?

THE OZONE LAYER CAN BE SAVED ONLY

BY PHASING OUT THE USE OF CFCs,

HALONS AND OTHER OZONE DEPLETING

SUBSTANCES

HOW CAN WE HELP PROTECT AND PRESERVE THE OZONE LAYER?

Five ThingsFive Things ConsumersConsumers

must remember to help must remember to help save the Ozone Layersave the Ozone Layer

1. Check the 1. Check the labels of labels of consumer consumer goods and goods and patronize patronize ODS ODS alternatives.alternatives.

Most aerosols and brand new Most aerosols and brand new refrigerators and air-refrigerators and air-conditioners do not utilize conditioners do not utilize CFCs anymore. However, CFCs anymore. However, some second-hand refs and some second-hand refs and aircons available in the market aircons available in the market still use the ozone-depleting still use the ozone-depleting CFCs. Consumers are advised CFCs. Consumers are advised not to patronize these.not to patronize these.

2. Consumers are encouraged 2. Consumers are encouraged to patronize tear gas and to patronize tear gas and metered-dose inhalers (used metered-dose inhalers (used by asthma patients) that do not by asthma patients) that do not contain CFCs.contain CFCs.

3. Consumers are 3. Consumers are advised to support advised to support service shops that are service shops that are accredited by the DTI to accredited by the DTI to ensure that their ensure that their technicians are capable technicians are capable of handling refrigerants of handling refrigerants and are not recharging and are not recharging their aircons or refs with their aircons or refs with incompatible incompatible refrigerants.refrigerants.

4. Owners of cars with R-134a as 4. Owners of cars with R-134a as refrigerant in their aircon should refrigerant in their aircon should not back-convert or change their not back-convert or change their system into CFC-12 or R-12 system into CFC-12 or R-12 because car models 1999 up to because car models 1999 up to present that use R-12 will no present that use R-12 will no longer be registered at the Land longer be registered at the Land Transportation Office starting Transportation Office starting January 2006.January 2006.

5. Owners of cars with R-12 5. Owners of cars with R-12 manufactured 1998 and below manufactured 1998 and below are advised to retrofit or are advised to retrofit or change their aircon system to change their aircon system to an alternative system (R-134a an alternative system (R-134a or HC).or HC).

OZONE and the OZONE LAYEROZONE and the OZONE LAYER Creation and destruction of OZONECreation and destruction of OZONE The OZONE HOLEThe OZONE HOLE The effects of ozone depletionThe effects of ozone depletion The causes of ozone depletionThe causes of ozone depletion Ways to help save the ozone layerWays to help save the ozone layer

Wrap-UpWrap-Up

Save OSave O33ur Sky: ur Sky:

Ozone-Friendly Ozone-Friendly Planet, Planet,

Our TargetOur Target

The most common refrigerants are the fluorinated hydrocarbons, but numerous other substances also function well as refrigerants, including many inorganic compounds and hydrocarbons.

TYPES OF REFRIGERANTS USED IN AIR-CONDITIONING

TYPES OF REFRIGERANTS USED IN AIR-CONDITIONING

Haolocarbon compounds

The halocarbon group includes refrigerants which contain one or more of the three halogens chlorine, fluorine, and bromine. The numerical designation, the chemical name, and the chemical formula of some of the commercially available members of this group are shown in the Table.

The numbering system in the halocarbon group follows this pattern: the first digit on the right is the number of fluorine atoms in the compound; the second digit from the right is one more than the number of hydrogen atoms inthe compund; and the third digit from the right is one less than the numver ofcarbon atoms. When the thrid digit is zero, it is omitted.

TYPES OF REFRIGERANTS USED IN AIR-CONDITIONING

Numericaldesignation Chemical name Chemical

formula11 Trichloromonofluoromethane CCl3F12 Dichlorodifluoromethane CCl2F213 Monochlorotrifluoromethane CClF322 Monochlorodifluoromethane CHCLF240 Methyl chloride CH3Cl

113 Trichlorotrifluoroethane CCl2FCClF2114 Dichlorotetrafluoroethane CClF2CClF2

Some halocarbon refrigerants

TYPES OF REFRIGERANTS USED IN AIR-CONDITIONING

Azeotropes

An azeotropic mixture of two substances is one which cannot be separated into its components by distillation. An azeotrope evaporates and condenses as a single substance with properties that are different from those of either constituent. The most popular azeotrope is refrigerant 502, which is a mixture of 48.8 percent refrigerant 22 and 51.2 percent refrigerant 115.

TYPES OF REFRIGERANTS USED IN AIR-CONDITIONING

Numericaldesignation † Chemical name Chemical

formula717 Ammonia NH3718 Water H2O729 Air744 Carbon dioxide CO2764 Sulfur dioxide SO2

Some Inorganic refrigerants

† The last two digits are the molecular weight.

TYPES OF REFRIGERANTS USED IN AIR-CONDITIONING

Hydrocarbon refrigerants

† Follows same principle as the halocarbon scheme.

Numericaldesignation † Chemical name Chemical formula

50 Methane CH4170 Ethane C2H6190 Propane C3H8

TYPES OF REFRIGERANTS USED IN AIR-CONDITIONING

Refrigerant

Evaporating

pressure,kPa

Condensing

pressure,Kpa

Pressureratio

Refrigerating

effectKJ/kg

Suctionvapor flowper kW of

refrigeration

COP

11 20.4 125.5 6.15 155.4 4.90 5.0312 182.7 744.6 4.08 116.3 0.782 4.7022 295.8 1192.1 4.03 162.8 0.476 4.66

502 349.6 1308.6 3.74 106.2 0.484 4.37717 236.5 1166.6 4.93 1103.4 0.462 4.76

Thermodynamic characteristics of several refrigerants

Operation on a standard vapor-compression cycle with an evaporating temperature of -15C and a condensing temperature of 30C

Air Conditioning System Heat Load Determination

General MethodShow how to compute the total heat load for an air condition building fitted with windows, internal heat from people and machines and heat transmission grains from wall, roof and floor.

Step 1. Determine the design outdoor and indoor conditions.Inside condition 75 °F RH °60% enthalpy – 30BTU/lbOutside condition Tdry = 98°F Twet = 80 °F enthalpy 45BTU/lb

Step 2. Calculate required BTU/hr to control space temperature to be cooled.assumed air changed per hour in a room = 2.5Inside condition outside condition

temp 75°F temp 98°F dry bulbRH 60% temp 80°F wet bulbenthalpy 30 BTU/lb enthalpy 45BTU/lb

Space to be cooled = sensible heat + latent heatSensible heat = floor area (ft²) x (8’ ht) x 2.5 air change/hr x 0.076x

0.24 x (98°-75°) = floor area (ft²) x 8.45

Latent heat = floor area (ft²) x (8’ ht) x 2.5 air change/hr x 0.076 x (h2 – h1)

= floor area (ft²) x 8 x 2.5 x 0.076 x (45-30)= floor area x 22.80

Space to be cooled BTU/hr = Area (ft²) x (8.45 + 22.8)

BTU/hr = Area (ft²) x (31.25)

Step 3. Compute heat loss thru glass, roof and wallsHeat loss thru a building surfaceHL = U area ▲tHL = Heat loss in BTU/HrU = coefficient of heat transmission for the material▲t = Temperature difference (Outside Temp. - Inside temp.)

Typical area and heat transfer coefficient

Building surface Type U BTU/sqft. Hr °F Walls 8” thick brick 0.5

Residential wall 0.25Commercial wall 0.33

Roof 2” concrete 0.82Residential roof & ceiling 0.31Commercial roof & ceiling 0.40

Windows Ordinary glass 1.13 Storm window 0.45

Double window 0.65

3.A Heat less than Roof

BTU / hr = .82 x Area of roof ( sq. ft ( ∆t )

3.B Heat less than Walls

BTU / hr = 0.5 x Area of wall ( sq. ft ) ( ∆t )

3.C Heat less than Windows

BTU = 1.13 x Area of windows ( sq. ft ) ( ∆t )

Step FourCalculate the heat generated by occupants, allow 600 BTU per person.

Occupant BTU/Hr = number of people x 600

Step FiveCalculate the heat generated by each item of machinery - copiers, computers, ovens etc. Find the power in watts for each item, add them together and multiply by 3.4

Equipment BTU/Hr = total equipment watts x 3.4

Step SixCalculate the heat generated by lighting. Find the total wattage for all

lighting and multiply by 4.25Lighting BTU/Hr = total lighting watts x 4.25

Step SevenAdd the above together to find the total heat load.

Total heat load BTU/hr = Area BTU/hr + Total Window,walls & roof BTU/hr + Occupant BTU/hr + Equipment BTU/hr + Lighting BTU/hr

Step EightAircon capacity in tons = total heat load BTU / hr

12 000 BTU / hr

BY: R.A. LOZADA

GIVEN:

AREA TO BE AIR-CONDITIONED

18 m

36 m1. Get the total area to be air-conditioned. (m2)

A = L x W

PROPOSED HANDYMAN (Hardware Store)

18 m

36 m1. Get the total area to be air-conditioned. (m2)

A = A = 648 m2

PROPOSED HANDYMAN (Hardware Store)

18 x 36

DESIGNATION A/C SYSTEM FLR AREA/ TR REQ’D

(m2/TR)A. Common Mall AreasB. Rentable areas

1. Fine Dining/ Fast Food

8. Amusement Center

6. Department Stores 7. Supermarket

2. Food Court

3. Retail Stores (dry) 4. Hardware (Handyman) 5. Stores/ Anchor Stores

CENT

RAL

WAT

ER-

COOL

ED C

HILL

EDW

ATER

SYS

TEM

20

12

18

1818

12 181818

2. Get the floor area/ton of refrigeration required from chart. (m2/TR)

DESIGNATION A/C SYSTEM FLR AREA/ TR REQ’D

(m2/TR)A. Common Mall AreasB. Rentable areas

1. Fine Dining/ Fast Food

8. Amusement Center

6. Department Stores 7. Supermarket

2. Food Court

3. Retail Stores (dry) 4. Hardware (Handyman) 5. Stores/ Anchor Stores

CENT

RAL

WAT

ER-

COOL

ED C

HILL

EDW

ATER

SYS

TEM

20

12

18

1818

12 181818

2. Get the floor area/ton of refrigeration required from chart. (m2/TR)

Use 18 m2/TR for Hardware

3. Calculate Tons of Refrigeration (TR)

TR = Total Area

Floor Area/ TR

=648 m2

18 m2/TR

TR = 36 TR

Use 40 TR

4. Divide the area to be air-conditioned equally spaced 6m x 6m.

6m

6m

5. Calculate TR per 6m x 6m.

6m

6m

Aper square = 36 m2

TRper square = 36 m2

18 m2/TR

= 2 TRper square

6. Calculate CFM/nozzle:

2 TR

= 2 TRper square

x 400 cfm/TR

7. Make proposed Air Distribution Layout:

branch 1

branch 2

branch 3

diffuserTotal number of diffusers = 18

40 TRAHU

8. Calculate Air Distribution and Duct sizing:

Total CFM = 40 TR x 400 cfm per TR

16,000 cfm=

Total number of diffusers = 18

CFM/diffuser = 16,000

18= 880 cfm per diffuser

To get CFM for each branch:

Note: branch 1 = branch 2 = branch 3CFMper branch = 6 x 880 = 5,280 cfmper branch

For one branch:

880 cfm 880 cfm 880 cfm 880 cfm 880 cfm 880 cfm

5280 cfm 4400 cfm 3520 cfm 2640 cfm 1760 cfm 880 cfm

To compute sizing of branch:

800 cfm 800 cfm 800 cfm 800 cfm 800 cfm 800 cfm

5280 cfm 4400 cfm 3520 cfm 2640 cfm 1760 cfm 880 cfm

To compute sizing of branch:

5280 cfm

To compute sizing of branch:

Note: for 3 consecutive diffusers useonly one size of duct for economical use

Q = AV Use 2000 fpm for Velocity

A = 52802000

= 2.64 ft2

Acircle = D2/4

D = 4 x 2.64

5280 cfm

To compute sizing of branch:

Note: for 3 consecutive diffusers useonly one size of duct for economical use

Q = AV Use 2000 fpm for Velocity

A = 52802000

= 2.64 ft2

Acircle = D2/4

D = 1.83 ft x 12 in/ft

= 22 inches ø

2640 cfm

To compute sizing of branch:

Do the same procedure for the nextthree diffusers

Q = AV Use 2000 fpm for Velocity

A = 26402000

= 1.32 ft2

Acircle = D2/4

D = 4 x 1.32

2640 cfm

To compute sizing of branch:

Do the same procedure for the nextthree diffusers

Q = AV Use 2000 fpm for Velocity

A = 26402000

= 1.32 ft2

Acircle = D2/4

D = 1.2 ft x 12 in/ft

= 15 inches ø

9. Draw the final layout including duct size

40 TRAHU

22” ø 15” ø

- END OF LECTURE -

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