- Refrigerant should be much more volatile than absorbent.
- Refrigerant properties must provide moderate +ve pressures same as VC.
- Both should be chemically stable at all operating conditions same as VC.
What are refrigerant pairs?
Case Studies: Natural Refrigerant Pair
The natural refrigerants which have been considered here are:
Ammonia, Carbon dioxide, Propane, Propylene, n-Butane, Isobutane, Ethane & Ethylene
.
What are the properties of refrigerant?
- Low Freezing Point. Refrigerants should have low freezing point than the normal operating conditions. …
- Low Condensing Pressure. …
- High Evaporator Pressure. …
- High Critical Pressure. …
- High Vapor Density. …
- High Dielectric strength. …
- High Latent Heat of Vaporization. …
- High Heat Transfer Coefficient.
What are the desirable properties of refrigerant absorbent mixture for Vars?
- The refrigerant should exhibit high solubility with solution in the absorber. …
- There should be large difference in the boiling points of refrigerant and absorbent (greater than 200°C), so that only refrigerant is boiled-off in the generator.
What are the different refrigerant absorbent working pairs?
The working pairs mainly used in absorption refrigeration system are
aqua-ammonia (H 2 0-NH 3 ) and water-lithium bromide (H 2 O-LiBr)
.
What is the most commonly used refrigerant?
- Chlorofluorocarbons (CFCs), including R12. This is known to contribute to the greenhouse gas effect. …
- Hydrochlorofluorocarbons (HCFCs), including R22. …
- Hydrofluorocarbons (HFCs), including R410A and R134.
Which was the first refrigerant used?
The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as “
aqua ammonia”
) was developed by Ferdinand Carré of France in 1859 and patented in 1860.
What are the major components of VAR system?
- 2 Absorber: The absorber is used to absorb the refrigerant. …
- 3 Pump: The pump will pump the strong solution of ammonia and water from the absorber to the generator.
- 3 Generator: …
- 4 Analyzer: …
- 5 Pressure Reducing Valve: …
- 5 Condenser: …
- 6 Expansion Valve:
Is refrigerant gas or liquid?
The refrigerant, a chemical compound that changes easily from liquid to
a gas
. When the refrigerant is pushed into the compressor, it is a low pressure gas.
What is VARS system?
Vapour Absorption Refrigeration Systems
(VARS) belong to the class of vapour cycles similar to vapour compression refrigeration systems. … Since these systems run on low-grade thermal energy, they are preferred when low-grade energy such as waste heat or solar energy is available.
What are the ideal properties of good refrigerant?
- Low boiling Point.
- High Critical Temperature.
- High latent heat of vaporisation.
- Low specific heat of liquid.
- Low specific volume of vapour.
- Non-corrosive to metal.
- Non-flammable.
- Non-explosive.
What is the ideal refrigerant?
It should be
non-explosive and non-inflammable
. It should be relatively cheap and easy to obtain. It should not be poisonous and should not give discomfort where gas leaks to the outer air. It should be of such nature that gas leaks are easily located by “smoke tests ” or similar methods.
What are the classifications of refrigerants?
There are four main groups of refrigerants and they are determined by their chemical constituents but are generally classified as
Chlorofluorocarbons (CFCs), Hydro chlorofluorocarbons (HCFCs), Hydro fluorocarbons (HFCs) and Natural Refrigerants
[7]. …
What are the main components of the absorption cycle?
… diffusion-absorption refrigeration cycle consists of
a generator bubble pump, an absorber, an evaporator, and a condenser
( Figure 1).
Which refrigerant is used in Vars?
Due to scarcity and increased cost of electricity VARS is gradually gaining importance. The most commonly used refrigerant–absorbent pairs are
ammonia–water and water–lithium bromide
.
What is the relative coefficient of performance?
Relative coefficient of performance defined as
the ratio of actual C.O.P. to the theoretical C.O.P. Relative C.O.P. = Actual C.O.P./Theoretical C.O.P.
