11

REFRIGERATION, REFRIGERATION, COMPRESSED AIR SYSTEMS COMPRESSED AIR SYSTEMS & EFFICIENT USE OF ENERGY& EFFICIENT USE OF ENERGY

22

Principles of RefrigerationPrinciples of Refrigeration

Refrigeration means to Refrigeration means to

COOL AN OBJECT BELOW ITS COOL AN OBJECT BELOW ITS SURROUNDING TEMPERATURESURROUNDING TEMPERATURE

33

VapourVapour Compression Cycle Compression Cycle

CONDENSER

EVAPORATOR

COMPRESSOREXPANSION VALVE

2

1

3

4

Basic Components of the vapour Basic Components of the vapour compression refrigeration systemcompression refrigeration system

• Compressor

• Condenser

• Throttling Device

• Evaporator

44

VapourVapour Compression Cycle Compression CyclePRESSUREPRESSURE

COMPRESSIONCOMPRESSION

CONDENSATIONCONDENSATION

EVAPORATIONEVAPORATION

THROTTLINGTHROTTLING

REFRIGERATION EFFECTREFRIGERATION EFFECT WORK DONEWORK DONE

CONDENSER HEAT REJECTIONCONDENSER HEAT REJECTION

ENTHALPYENTHALPY

KN/m2KN/m2

KJ/KgKJ/Kg

Pd

Pe 1

23

4

CONDENSER

EVAPORATOR

COMPRESSOREXPANSION VALVE

2

1

3

4

55

VAPOURVAPOUR COMPRESSION COMPRESSION CYCLECYCLE

COMPONENTSCOMPONENTS

66

REFRIGERANTSREFRIGERANTSCHLOROFLUOROCARBONS (CFC)CHLOROFLUOROCARBONS (CFC)

• R-11R-11

• R-12R-12

HYDROCHLOROFLUOROCARBONS (HCFC)HYDROCHLOROFLUOROCARBONS (HCFC) R- 22R- 22 R-123R-123

HYDROFLUOROCARBONS (HFC)HYDROFLUOROCARBONS (HFC) R-32R-32 R-125R-125 R-134aR-134a R-143aR-143a

INORGANIC COMPOUNDSINORGANIC COMPOUNDS R- 717R- 717 R- 718R- 718 R- 729R- 729

77

Unit of RefrigerationUnit of Refrigeration

The unit of refrigeration is The unit of refrigeration is

TON OF REFRIGERATION ( TR )TON OF REFRIGERATION ( TR )1 TR = 12’000 Btu/hr 1 TR = 12’000 Btu/hr BRITISH UNITS BRITISH UNITS

1 TR = 3.517 KW 1 TR = 3.517 KW SI UNITSSI UNITS

88

Refrigeration Cycle EfficiencyRefrigeration Cycle Efficiency

The refrigeration cycle efficiency is known asThe refrigeration cycle efficiency is known as

COEFFICIENT OF PERFORMANCE COEFFICIENT OF PERFORMANCE (COP(COPREFREF) )

(COP(COPREFREF)) = = Refrigeration EffectRefrigeration Effect KJ/KgKJ/Kg

Work Done Work Done KJ/KgKJ/Kg

(COP(COPHPHP)) = = Condenser Heat RejectionCondenser Heat Rejection KJ/Kg KJ/Kg

Work Done Work Done KJ/KgKJ/Kg

99

Refrigeration Equipment Refrigeration Equipment EfficiencyEfficiency

The equipment efficiency is given as EER or kW/TRThe equipment efficiency is given as EER or kW/TRENERGY EFFICIENCY RATIO ENERGY EFFICIENCY RATIO (EER) (EER) Use for smaller capacity equipment such as Window type & Split type Use for smaller capacity equipment such as Window type & Split type

equipmentequipment

(EER)(EER) = = CapacityCapacity Btu/hrBtu/hr

Power Input Power Input WattsWatts

kW/TR kW/TR Use for large capacity equipment such as ChillersUse for large capacity equipment such as Chillers

(kW/TR)(kW/TR) = = Power InputPower Input kW kW

Capacity Capacity TRTR

1010

P-h DIAGRAM FOR REFRIGERANT 134aP-h DIAGRAM FOR REFRIGERANT 134a

1111

1.1. Face-out of Face-out of CFCCFC in year in year 20052005

2.2. Introduction of Quota for Introduction of Quota for HCFCHCFC in in year year 20152015

3.3. Face-out of Face-out of HCFCHCFC in year in year 20402040

MONTRÉAL PROTOCOL OBLIGATIONSMONTRÉAL PROTOCOL OBLIGATIONS

1212

ASHRAE Standard 34-1992 ASHRAE Standard 34-1992

Refrigerant Safety ClassificationsRefrigerant Safety Classifications

Group A3Group A3 Group B3Group B3

Group A2Group A2 Group B2Group B2

Group A1Group A1 Group B1Group B1

INC

RE

AS

ING

F

LA

MM

AB

ILIT

Y

INCREASING TOXICITY

HigherFlammability

LowerFlammability

No FlamePropagation

LowerToxicity

HigherToxicity

1313

Refrigerant Data & Refrigerant Data &

Safety ClassificationsSafety Classifications

REFRIGERANTREFRIGERANT CHEMICALCHEMICAL

FORMULAFORMULA

CHEMICALCHEMICAL

NAMENAME

REFRIGERANTREFRIGERANT

SAFETYSAFETY

CLASSIFICATIONCLASSIFICATION

AMOUNT OF AMOUNT OF REFRIGERANTREFRIGERANT

PER OCCUPIEDPER OCCUPIED

SPACE (ppm)SPACE (ppm)

TLV-TWATLV-TWA

(ppm)(ppm)

R-11R-11 CClCCl33 TrichlorofluoromethaneTrichlorofluoromethane A1A1 4’0004’000 C1’000C1’000

R-12R-12 CClCCl22FF22 DichlorodifluoromethaneDichlorodifluoromethane A1A1 40’00040’000 1’0001’000

R-22R-22 CHClFCHClF22 ChlorodifluoromethaneChlorodifluoromethane A1A1 42’00042’000 1’0001’000

R-134aR-134a CHCH22FCFFCF33 1,1,1,2-tetrafluoroethane1,1,1,2-tetrafluoroethane A1A1 60’00060’000 1’0001’000

R-717R-717 NHNH33 AmmoniaAmmonia B2B2 500500 2525

1414

• In-expensive Refrigerant best suited for industrial In-expensive Refrigerant best suited for industrial useuse

• Higher refrigeration effect Higher refrigeration effect 474 Btu/lb,474 Btu/lb, comparison; R-12 = 50 Btu/lb , R-22 = 70 Btu/lb, comparison; R-12 = 50 Btu/lb , R-22 = 70 Btu/lb, R-134a = 64 Btu/lb, R-404A = 48 Btu/lb R-134a = 64 Btu/lb, R-404A = 48 Btu/lb

7- times higher refrigeration effect!!!7- times higher refrigeration effect!!!

• Specific volume of suction gas is high 8 ftSpecific volume of suction gas is high 8 ft33/lb /lb compare to 1.2 ftcompare to 1.2 ft33/lb of R-22, needs larger pipes, /lb of R-22, needs larger pipes, compressorscompressors

• Higher delivery temperatures 210 Higher delivery temperatures 210 ººF, needs water F, needs water cooled heads for compressorcooled heads for compressor

AMMONIA (NH3) R-717AMMONIA (NH3) R-717

1515

COOLING TOWER (CT)COOLING TOWER (CT)INDUCED DRAUGHTINDUCED DRAUGHT

1616

COOLING TOWER (CT)COOLING TOWER (CT)CROSS FLOWCROSS FLOW

1717

COOLING TOWER (CT)COOLING TOWER (CT)FORCED DRAUGHTFORCED DRAUGHT

1818

WATER PUMPSWATER PUMPSVERTICAL IN-LINEVERTICAL IN-LINE

1919

FAILURESFAILURESDETECTION OF SIMPLEDETECTION OF SIMPLE FAILURESFAILURES

Refrigeration Plant should function properly, if the Refrigeration Plant should function properly, if the following checks are OK.following checks are OK.

At a glanceAt a glance

• Suction sweatSuction sweat

• Warm liquid line & clear sight glass from bubblesWarm liquid line & clear sight glass from bubbles

• Condenser outlet air warmCondenser outlet air warm

• Condenser water in & out has significant feel of temp Condenser water in & out has significant feel of temp deferencedeference

Using measuring equipmentUsing measuring equipment• Manifold Gauge Set - measure the pressure of refrigerantManifold Gauge Set - measure the pressure of refrigerant• Clip-on Ammeter - measure the current flow and voltageClip-on Ammeter - measure the current flow and voltage

• Sling Psychrometer - measure the dry bulb & wet bulb temp.Sling Psychrometer - measure the dry bulb & wet bulb temp.

• Anemometer - measure the air flowAnemometer - measure the air flow

2020

FAILURESFAILURESDETECTION OF SIMPLEDETECTION OF SIMPLE FAILURES …cont.FAILURES …cont.

Detection by observation - A/C unit malfunction if the following Detection by observation - A/C unit malfunction if the following observations are foundobservations are found

• Sweating down stream of the Filter/dryer – Sweating down stream of the Filter/dryer – Filter BlockFilter Block• Ice build up at compressor – Ice build up at compressor – Over Charge, damaged comp. Over Charge, damaged comp.

valvesvalves• Ice build up at evaporator – Ice build up at evaporator – Under charge, gas leak, air filter Under charge, gas leak, air filter

clogged, cooling coil blocked, fan belts are looseclogged, cooling coil blocked, fan belts are loose • Bubbles in the sight glass- Bubbles in the sight glass- lack of refrigerant or blocked lack of refrigerant or blocked

filter/drierfilter/drier• Oil drops near refrigerant pipe fittings, components etc. – Oil drops near refrigerant pipe fittings, components etc. –

Refrigerant leaks in the system.Refrigerant leaks in the system.• Condenser shell cooler & evaporator shell warmer Condenser shell cooler & evaporator shell warmer

(Centrifugal Chiller) – at low condensing temperatures, (Centrifugal Chiller) – at low condensing temperatures, refrigerant migrates to evaporatorrefrigerant migrates to evaporator

2121

COMPRESSED AIR SYSTEMSCOMPRESSED AIR SYSTEMS

2222

Provides air under Provides air under compression to pneumatic compression to pneumatic drivesdrives

Use reciprocating or screw Use reciprocating or screw compressors with storage compressors with storage receiverreceiver

Use pressure regulators at Use pressure regulators at the air user point to reduce the air user point to reduce the air pressurethe air pressure

Use water separators to Use water separators to prevent water vapour prevent water vapour entering the air user entering the air user equipmentequipment

Compressed air system provides……..

2323

ROTARY SCREW ROTARY SCREW COMPRESSORSCOMPRESSORS

Pulsation free airPulsation free air 100% continuous duty100% continuous duty Quiet operationQuiet operation Energy efficient at full loadEnergy efficient at full load Extended service intervalsExtended service intervals Reliable long lifeReliable long life Improved air qualityImproved air quality

2424

TIPS FOR COMPRESSED AIR SYSTEMSTIPS FOR COMPRESSED AIR SYSTEMS

Locate the compressor closest to the largest air Locate the compressor closest to the largest air user to reduce pressure drop through the air line user to reduce pressure drop through the air line

Ventilate the compressor wellVentilate the compressor well Keep 3 feet around the compressor unitKeep 3 feet around the compressor unit Surrounding temperature should be below 115 Surrounding temperature should be below 115 ººFF Avoid extreme humidityAvoid extreme humidity Keep air filters clean all the timeKeep air filters clean all the time Use refrigerated and desiccant dryers to reduce Use refrigerated and desiccant dryers to reduce

water vapour concentrationwater vapour concentration

2525

EFFICIENT USE OF ENERGYEFFICIENT USE OF ENERGY

Resources are limited and conserve energy Resources are limited and conserve energy

RefrigerationRefrigeration Reduce heat transferReduce heat transfer Select energy efficient equipmentsSelect energy efficient equipments

Compressed air systems Compressed air systems Fix all leaks in the pipingFix all leaks in the piping Regulate lowest pressure at air userRegulate lowest pressure at air user Reduce blow-offsReduce blow-offs Shut-off air supply to off-line air usersShut-off air supply to off-line air users Consider multi staged compressorsConsider multi staged compressors

2626

THANKTHANK