Simple vapour compression cycle is
a system where the suitable working substance is used
, called as a refrigerant. It evaporates and condenses at pressure and temperature closes to atmospheric conditions. The refrigerant used is carbon dioxide, ammonia etc.
How does a vapor compression cycle work?
The compressor takes in a
low temperature, low pressure refrigerant vapor, and compresses it into a high temperature, high pressure vapor
. … The heat from the source boils off the refrigerant through phase change heat transfer, and the low temperature, low pressure gas enters the compressor, completing the cycle.
What is the principle of VCR?
Initially, the VCRS is charged with
a liquid refrigerant until it reaches its correct operating pressure
. When the system turns on, the refrigerant passes through the compressor, turning it into a high pressure/high temperature vapor.
What vapour compression refrigeration cycle means?
Vapour-compression refrigeration or vapor-compression refrigeration system (VCRS),
in which the refrigerant undergoes phase changes
, is one of the many refrigeration cycles and is the most widely used method for air-conditioning of buildings and automobiles.
What is ideal Vapour compression cycle?
In an ideal vapor-compression refrigeration cycle, the
refrigerant enters the compressor as a saturated vapor
and is cooled to the saturated liquid state in the condenser. It is then throttled to the evaporator pressure and vaporizes as it absorbs heat from the refrigerated space.
Why is wet compression not preferred?
Wet compression is
undesirable as there may be accumulation of liquid inside the cylinder
, which in turn will wash away the lubricant resulting in severe mechanical difficulties. Thus, to avoid this, a 5 to 20 K superheat of the refrigerant is always desirable.
How many basic devices are there to run Vcrs?
Mainly there are
four components
in VCRS. (1) Evaporator (2) Compressor (3) Condenser (4) Expansion Device. First the refrigerant is compressed adiabatically in the compressor. The pressure and temperature of the refrigerant will increase.
What are the four stages of compression?
Compression occurs within the cylinder as a four-part cycle that occurs with each advance and retreat of the piston (two strokes per cycle). The four parts of the cycle are
compression, discharge, expansion and intake
.
Why does the compression refrigeration cycle have a high pressure side?
“high side”
removes the oil entrained in the discharge gas and returns it to the compressor crankcase
. “high side” allows the technician to visually see the dcondition of the refrigerant in the line.
What happens when refrigerant is compressed?
During compression,
the quantity of fluid remains the same but the volume decreases
, this increases the pressure and temperature. The refrigerant leaves the compressor as a superheated (hot) high pressure gas.
What is the principle of Vapour compression system?
The Vapor Compression Refrigeration Cycle
As the refrigerant circulates through the system,
it is alternately compressed and expanded, changing its state from a liquid to a vapor
. As the refrigerant changes state, heat is absorbed and expelled by the system, lowering the temperature of the conditioned space.
What are the major components of Vapour compression system?
The Vapor Compression Refrigeration Cycle involves four components:
compressor, condenser, expansion valve/throttle valve and evaporator
. It is a compression process, whose aim is to raise the refrigerant pressure, as it flows from an evaporator.
Which cycle is used in refrigeration?
The vapor-compression refrigeration
is the most widely used cycle for refrigerators, air- conditioners, and heat pumps.
What is COP formula?
COP =
|Q| W
. COP is defined as the relationship between the power (kW) that is drawn out of the heat pump as cooling or heat, and the power (kW) that is supplied to the compressor.
Why is the refrigeration cycle called a cycle?
It
has the maximum efficiency for a given temperature limit
. Since it is a reversible cycle, all four processes can be reversed. This will reverse the direction of heat and work interactions, therefore producing a refrigeration cycle.
Why is automatic expansion valve not used?
When the load on the evaporator is
high it won't allow more flow of the refrigerant as
per the requirement. … Thus the automatic expansion valve does not allow the control of the flow of the refrigerant through it which is very important for the efficient operation of the refrigeration plant.
