Most of the refrigeration and air conditioning equipments in the
world today uses
fluorocarbon refrigerants to facilitate the heat transfer process. Fluorocarbon
refrigerants are synthetic chemicals which causes a high global warming potential,
and are a greater threat to the ozone layer as well if released to the atmosphere.
There are alternatives to these HFC's that can help to mitigate some of the
environmental risks.These are called ‘natural’ refrigerants because
the substances also occur in nature, these alternatives are:
1) Ammonia,
2) Carbon Di Oxide
3) Hydrocarbons
Ammonia (R717)
Ammonia is a naturally-occurring substance that can
be used as a substitute to fluorocarbon refrigerants in
refrigeration systems.
Properties
A) Ammonia (NH3)- R717 is a colorless gas with high pungent smell at atmospheric
pressure, and possesses the ideal environmental properties for a refrigerant – it has
both a zero ozone depletion potential (ODP) and a zero global warming potential (GWP).
B) These properties make ammonia an attractive prospect as a refrigerant, given that
fluorocarbon (HFC) refrigerants can have global warming potentials as high as 3900.
C) Many people are familiar with ammonia as an ingredient in fertilizers and other products.
Ammonia carries a B2 safety classification, meaning that it has a high toxicity, and also
carries a medium flammability risk.
D) Ammonia is not compatible with commonly used refrigeration system lubricants.
It is not suited for use with polyol ester (POE) and poly vinyl ether (PVE) lubricants,
and it has only limited applications with poly alkylene glycol (PAG) lubricants.
Safety Issues
A) A glass of drinking water can contain as much as 1mg of ammonia, a 200gms steak
as much as 13mg, and some food additives can contain as much as 18mg.Cigarette
smoke and even the air we breathe also contains ammonia in small amounts.
B) This demonstrates that the human body can deal with ammonia in small quantities.
Generally, any amount in the atmosphere below 20 parts per million (ppm) is regarded
as not dangerous. At amounts of up to 53 ppm, ammonia’s characteristic odor will be
noticeable.
C) In amounts of 300-400ppm, prolonged exposure will become unpleasant, and in amounts
over 700ppm it can cause burns and serious damage to eyes. In amounts of 5000ppm or
above,exposure can be lethal to humans within five minutes.
Thermodynamic Properties
A) Vapor mass is lighter than air ( 0.6 compared to air 1.0).
B) Ignition will occur at 651 C when vapor concentration is between 15% and 28%.
C) Ammonia corrodes galvanized metals, cast iron, copper, brass & copper alloys.
D) It weighs 5.15 pounds(2.34Kgs) per gallon(3.78 Liter) in liquid conditions
(water weight 8.33 pounds per gallon).
E) Boiling point of liquid ammonia at atmospheric pressure is -2.22 C.
F) Liquid ammonia expands 850 times its liquid volume at atmospheric pressure.
fluorocarbon refrigerants to facilitate the heat transfer process. Fluorocarbon
refrigerants are synthetic chemicals which causes a high global warming potential,
and are a greater threat to the ozone layer as well if released to the atmosphere.
There are alternatives to these HFC's that can help to mitigate some of the
environmental risks.These are called ‘natural’ refrigerants because
the substances also occur in nature, these alternatives are:
1) Ammonia,
2) Carbon Di Oxide
3) Hydrocarbons
Ammonia (R717)
Ammonia is a naturally-occurring substance that can
be used as a substitute to fluorocarbon refrigerants in
refrigeration systems.
Properties
A) Ammonia (NH3)- R717 is a colorless gas with high pungent smell at atmospheric
pressure, and possesses the ideal environmental properties for a refrigerant – it has
both a zero ozone depletion potential (ODP) and a zero global warming potential (GWP).
B) These properties make ammonia an attractive prospect as a refrigerant, given that
fluorocarbon (HFC) refrigerants can have global warming potentials as high as 3900.
C) Many people are familiar with ammonia as an ingredient in fertilizers and other products.
Ammonia carries a B2 safety classification, meaning that it has a high toxicity, and also
carries a medium flammability risk.
D) Ammonia is not compatible with commonly used refrigeration system lubricants.
It is not suited for use with polyol ester (POE) and poly vinyl ether (PVE) lubricants,
and it has only limited applications with poly alkylene glycol (PAG) lubricants.
Safety Issues
A) A glass of drinking water can contain as much as 1mg of ammonia, a 200gms steak
as much as 13mg, and some food additives can contain as much as 18mg.Cigarette
smoke and even the air we breathe also contains ammonia in small amounts.
B) This demonstrates that the human body can deal with ammonia in small quantities.
Generally, any amount in the atmosphere below 20 parts per million (ppm) is regarded
as not dangerous. At amounts of up to 53 ppm, ammonia’s characteristic odor will be
noticeable.
C) In amounts of 300-400ppm, prolonged exposure will become unpleasant, and in amounts
over 700ppm it can cause burns and serious damage to eyes. In amounts of 5000ppm or
above,exposure can be lethal to humans within five minutes.
Thermodynamic Properties
A) Vapor mass is lighter than air ( 0.6 compared to air 1.0).
B) Ignition will occur at 651 C when vapor concentration is between 15% and 28%.
C) Ammonia corrodes galvanized metals, cast iron, copper, brass & copper alloys.
D) It weighs 5.15 pounds(2.34Kgs) per gallon(3.78 Liter) in liquid conditions
(water weight 8.33 pounds per gallon).
E) Boiling point of liquid ammonia at atmospheric pressure is -2.22 C.
F) Liquid ammonia expands 850 times its liquid volume at atmospheric pressure.
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