day 2 session viii - 02 rs agarwal. consultant

8/18/2019 Day 2 Session VIII - 02 RS Agarwal. Consultant

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Overview of Alternatives to HCFCs

for RAC Applications in High-

Ambient Conditions

Radhey S. AgarwalSenior Advisor and Coordinator

Sector Phase-out Plan Unit INDIA


2/18

Cooling System Options

Vapour Compression Cooling Systems (VCS)

Quite effective & Reliable, energy intensive, requiresskilled maintenance, Environmental issues - ODP/GWP;

Vapour Absorption Cooling systems (VAS)

Utilizes waste heat if available/ low grade energy,skilled maintenance, bulky, mostly used for largecapacity units, use eco-friendly refrigerants;

Evaporative Cooling Systems

Simple, low initial and operating costs, lowmaintenance, ineffective during humid conditions;

Used in hot and dry climates and for pre-cooling ofventilation air; efforts are being made to improve itseffectiveness using regenerative cooling and usingdesiccants. 2


3/18

Vapour Compression Systems

Vapour Compression Systems are widely usedglobally. Approximately more than 90% of theglobal cooling requirements are met throughcompression systems

Fluorocarbon refrigerants are commonly used incompression systems;

Ambient temperatures play a vital role on theperformance of the system and selection ofrefrigerant.

3


4/18

Natural

Refrigerants, eg.HC-290,

Ammonia, CO2

Alternatives to HCFCs

HFOs, eg.,

HFO-1234yf

HCFCs

HFCs, eg.

HFC-134a, R-410AR-407C, R-404A

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5/18

CHFCl2 R-21

CCl4 R-10

CFCl3 R-11

CHCl3 R-20

CF2Cl2 R-12

CH2Cl2 R-30

CF3ClR-13

CH3ClR-40

CH2FClR-31

CHF2ClR-22

CH4 R-50

CH3F R-41

CF4 R-14

CHF3 R-23

CH2F2 R-32

Toxic

Higher PressureMore Flammable

Methane Derivatives With

Chlorine and Fluorine

5


6/18

Ethane Derivatives With

Chlorine and Fluorine

Toxic

Region

Higher PressureMore Flammable

C2Cl6 R-110

C2H3Cl3 R-140

C2H4Cl2 R-150

C2H5ClR-160

C2F2Cl4

R-112

C2F3Cl3 R-113

C2F4Cl2 R-114

C2F5ClR-115

C2F6 R-116

C2 HF5 R-125

C2 H2F4 R-134

C2 H3F3 R-143

C2 H4F2 R-152

C2 H5FR-161

C2H6 R-170

C2FCl5 R-111

C2H2Cl4

R-130

C2HCl5 R-120

C2HF3Cl2 R-123

C2H3FCl2 R-141

C2HF2Cl3 R-122

C2H2FCl3 R-131

C2HFCl4 R-121

C2H2F2Cl2 R-132

C2HF4ClR-124

C2H2F3ClR-133

C2H3F2ClR-142

C2H4FClR-151

6


7/18

HFCs and Blends of HFCs Only 5 HFCs could be identified out of several derivatives

of methane and ethane, eg., HFC-32, HFC152a, HFC-134a,HFC-143a and HFC-125;

HFC- 32, HFC-152a and HFC-143a being flammable couldnot be preferred as individual refrigerants;

HFC-125 being high pressure refrigerant, it is also notused as individual refrigerant;

HFC134a being nonflammable became the preferredchoice for many applications while phasing-out CFCs;

7

HFC d Bl d f HFC


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HFCs and Blends of HFCs

(cont…)

Due to lack of individual refrigerants,considerable R&D work was under taken to lookfor non-flammable blends by mixing two or more

of these 5 HFCs;

R-410A, R-407C, R-404A and some other blendscould be identified and used especially as

substitute for HCFC-22 and R-502 (a blend ofHCFC-22 and CFC-115).

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9/18

Higher Hydrocarbon CompoundDerivatives with Chlorine and Fluorine

The global chemical producers have developed newmolecules by fluorination of higher hydrocarboncompound;

These compounds are unsaturated HFCs also known asHFOs which have very low GWP. The potential HFOrefrigerant is HFO-1234yf;

HFO-1234yf HFO-1234ze 9


10/18

Natural Refrigerants

Natural Refrigerants like ammonia, propane and CO2 areknown much prior to the CFCs and HCFCs wereintroduced;

Ammonia is used widely in industrial refrigeration, foodprocessing and storages. A limited use in supermarketsand in central air-conditioning because of its flammable(A2L) and toxic characteristics;

HC-290 has similar vapour pressure as HCFC-22 but it ishighly flammable. It is one of the potential alternatives toHCFC-22 for small capacity units;

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11/18

Current Options for Air ConditioningAir conditioning Sub

SectorApplication Viable Option

Ductless Room AirConditioners

Home, small offices(Charge limitation)

R-410A (HFC); HFC-32* ;R-290*

Ducted System Commercial A/C R 410A, R 407C (HFCs)

Chiller - Air Cooled Central Systems R 410A, R134a (HFCs)

Chiller - Water Cooled Central Systems HFC 134a (HFC)

VRFs (Variable

Refrigerant Volume)Commercial A/C R 410A (HFC)

Rail Coach AirConditioner

Railways, Metros R 410A (HFC), R-407C

Others - Marine &

DefenceSpecial Application

R-410A, R-407C (HFCs)

* Subject to n at ional regu lat ion s

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12/18

Specific Requirements for HighAmbient Conditions

Higher condensing temperature for air-cooledsystems due to higher ambient;

Higher cooling capacity for similar spacevolume;

Longer operating cycle in comparison tomoderate climates because of highertemperature difference between outdoor andindoor.

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13/18

Impact of High Ambient Temperatureon the System Performance

An Increase in Condenser

Pressure results in the

following:

Decrease in Cooling:

From (h1 – h4) (h1 – h4’)

Decrease in volumetric efficiency

Increase in work of compression:

From (h2 – h1) (h2’ – h1)

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Impact of High Ambient Temperatureon the System Performance (Contd..)

100 150 200 250 300 350 400 450 500 550 600

101

102

103

104

105

h [kJ/kg]

P [

k P a ]

60°C

25°C

-4.21°C

-30°C

0.2 0.4 0.6 0.8

1 . 7

1 . 8

1 . 9

2

2. 1 k J

/ k g - K

R22

1

234

5

6

7 8 9

-100 0 100 200 300 400 500

101

102

103

104

104

h [kJ/kg]

P [

k P a ]

35°C

-25°C

-45°C

0.2 0.4 0.6 0.8

1 . 2

1 . 3

1 . 4

k J / k g

- K

R410A

1

2

3456

7 8 9

71.4

96.2

14


15/18

Additional Constraints on Availability

of Alternatives

Refrigerants with higher critical temperature forthe required performance;

Preferably non-flammable refrigerants as chargequantity will be higher due to increasedcooling capacity requirement for similar spacevolume;

Preferably Lower discharge temperatureespecially for hermetic systems to reducefrequency of maintenance.

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16/18

Potential Available Refrigerants for

High Ambient Conditions

HFC-134a being non-flammable and have relativelyhigher critical temperature;

R-410A and R-407C being non-flammable and widely

used refrigerants in various climatic conditions,possibly systems could be designed for high ambient;

HFC-32 is a mildly flammable refrigerant, technicallybetter than R-410A, could be used if national regulationallows;

R-290 is a flammable, can be used for small coolingcapacity units because of charge limitation, if national

regulation permits; 16


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Concluding Remarks

Globally including high ambient there are very limited

options like HFC-134a, R-410A, R-407C and HFC-32. Allthese are HFC refrigerants;

R-290 is a highly flammable refrigerant. It is technicallyone of the potential refrigerants for small cooling

capacity units provided safety issues are addressed andnational regulations allow;

The A/C systems to be designed and developed taking

into account the special requirements of high ambientconditions especially the performance and safety;

Regulatory framework is required if flammablerefrigerants are to be adopted especially for safety of theusers, installers and servicing technicians. 17


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Thank You

for you rK ind A t ten t ion

day 2 session viii - 02 rs agarwal. consultant

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