Refconhvac

Essential properties required in a refrigerant are as follows:
1. High latent heat of v***rization
2. A High Suction gas density and a Low Compression ratio.
3. Non-corrosive, non-toxic and non-flammable
4. High critical temperature
5. Compatibility with the lubricating oil
6. High latent heat
7. Low boiling point
8. Low condensing pressure
9. High dielectric strength (for compressors with integral motors)
10. Should be cheap and readily available
11. Ease of leak detection
Refrigerant gas used in World War
– r12 refrigerant properties
– r22 refrigerant properties
How some refrigerants | HCFC’s and CFC’s got banned?
– r11 refrigerant (CCl3F) properties
What are Environmental friendly | Green Refrigerants?
a) r134a refrigerant properties
b) r134a and r407c refrigerant properties
c) r410a refrigerant properties
d) r404a refrigerant properties
e) r717 ammonia properties
f) r-401b Refrigerant properties
g) Carbon Dioxide refrigerant properties

1. High latent heat of v***rization

High latent heat of v***rization is desirable in a refrigerant because it results in high a refrigerating effect per unit weight of the refrigerant and low rate of circulation of the refrigerant.

More heat can be absorbed and ejected in each cycle of refrigeration.

2. A High Suction gas density and a Low Compression ratio.
High suction gas density at the compressor suction means low sized compressor and a lesser powered compressor motor because after the refrigerant passes through the ev***rator, the refrigerant gas expansion is not very high ie. Fluid to Gas expansion is low.

This property of refrigerant provided a low compression ratio for the compressor, the higher mass flow rate of the refrigerant leading to a low rate of circulation within the system.

3. Non-corrosive, non-toxic and non-flammable
Refrigerant must not be poisonous or lethal to air-conditioning, human health, and foodstuff. When coming in contact with metal parts like piping and compressor must not cause any sort of electrochemical corrosion.

Must be compatible with non-metallic parts such as nitrile rubber tubes, O-rings (used for sealing purpose).

As the refrigerant gets compressed under high pressure and temperature inside the compressor, it must not cause any explosion or catch fire within the system and continue its non-flammable properties.

Presence of moisture in the system may cause the formation of highly corrosive compounds (usual acids) which may react with compressor lubricating oil and with other materials in the system including metals.

Moisture may cause failure of compressor valves in case of hermetic compressor often causes breakdown of the motor winding insulation resulting in short-circuiting or grounding of the motor.

Presence of moisture in lubricating oil may deteriorate properties of lubricating oil and formation of metallic or other sludge which may lead to clogging or chocking of valves, filter, and other oil passages.

Moisture can enter into the system while charging of refrigerant, while repair ie. evacuation or vacuuming of the system where moisture can enter through leaky joints, moisture can exist as a free water although, a completely moisture free refrigerating system is not possible.

When moisture is present in the form of water it may lead to icing within the ev***rator coil and choking of the thermostatic expansion valve.

Avoid moisture formation by connecting a filter drier which absorbs moisture from the refrigerant.

4. High critical temperature
It is the temperature above which the vapour refrigerant remains in the vapour state and cannot be liquefied back into its liquid state even after passing through the condenser or any cooling medium at any given pressure.

This happens only when the refrigerant temperature reaches beyond its critical temperature, ie. when a refrigerant has a low critical temperature.

So, it’s better to select a refrigerant having a high critical temperature, to be able to condense these refrigerant gases into liquid form and subsequently heat transfer at the condenser can be carried out at a significantly higher temperature.

5. Compatibility with the lubricating oil
The refrigerant used must be compatible and miscible (means refrigerant can be easily separated) with the compressor oil as there are greater chances of intermixing inside the compressor, wherein such condition following problems can occur:

Acid or sludge formation.
Acidic corrosion decreases alkalinity in oil.
The decrease in viscosity leading to insufficient lubrication.
Oil carbonization with the rise in temperature.
Compressor damage due to the loss of the lubricating oil properties and load carrying property.

Refrigerants and Properties: r12|r22|r134a|r410a|r404A Detail description of refrigerant,r22,r12,r134a,r410a, R407C, R404A, R717 Ammonia,R-401B, Carbon Dioxide,properties and applications.

Basic refrigeration cycle:

How refrigeration compressors work
1.HERMETIC Refrigeration compressor or (fridge compressor)
2. Commercial Refrigeration Compressor
2a. Question: Why a coupling is needed in a commercial refrigeration compressor and motor?
2b. Question: What is the function of a Mechanical Seal in a refrigeration compressor?
3. Thermostatic expansion valve (TEV or TXV)| Metering valve?
4. Why an equalizing line required in thermostatic expansion valve (TEV) or metering valve?
5. FILTER-DRIER in a refrigeration system
6. Sight glass|Moisture indicator
7. Heat exchangers in a Refrigeration system
8. Solenoid Valve
9. Back Pressure Valve
10. Compressor Safety Devices:
10a. Refrigeration Compressor Unloader Safety device
10b. Compressor High Pressure cut out Safety Device
10c. Compressor Low Pressure cut out Safety Device
10d. Compressor Differential L**e oil pressure Safety Device
11. How to remove oil from Refrigeration System?
12. Why refrigeration compressor takes suction from its crankcase?
13. Thermostats
14. Pressure Relief Safety Device
There are three types of relief devices
15. Refrigeration system: Hot gas Bypass valve

Refrigeration basic schematic diagram separated into :

1. Compressor.
2. Condenser.
3. The thermostatic expansion valve (TXV or TEV) or Metering 4.Device.
5.Ev***rator.
6.Piping

The compressor in a Refrigeration system is to compress the low-pressure dry gas refrigerant from the ev***rator and raise its pressure and temperature to that of the condenser, to produce flow around the system.

The most easily recognizable compressor is a positive displacement type, which is the reciprocating or piston compressor.

Let’s take an example of a refrigerator when the refrigerant passes from the ev***rator, it changes its state from liquid to v***r by taking away the heat from the refrigerated space.

Now to convert back the refrigerant from v***r to liquid state, the compressor comes into action.

The compressor increases the refrigerant temperature and pressure so that the refrigerant gets converted into a liquid state by circulating hot surrounding air over the condenser coils.

In the absence of a compressor, the heat may start to flow from the condenser to the outside air.

Like in hotter regions the outside air temperatures can go up to 42°C – 48 °C with this hot outside air, the refrigerant gets cooled back from v***r to the liquid state.

This is possible due to the refrigerant property which is the “critical temperature of a refrigerant”.

Refrigeration Cycle: A Helpful Illustrated Guide - refconhvac.com Refrigeration cycle basics in an HVAC refrigeration system with explantion of heat and ton of refrigeration in btu. Metering valve(TEV), Ev***rator coil