Table of Contents
Why do you need to maintain the refrigerant pressure in the evaporator coil?
The lower the pressure of the coil the lower the temperature and the higher the pressure the higher the temperature. For the evaporator we want low pressure so that its at a low temperature that will absorb heat. The refrigerant super heating at 100\% vapor will still continue to absorb heat as it enters the compressor.
What does an evaporator do in a refrigeration cycle?
The evaporator works the opposite of the condenser, here refrigerant liquid is converted to gas, absorbing heat from the air in the compartment. When the liquid refrigerant reaches the evaporator its pressure has been reduced, dissipating its heat content and making it much cooler than the fan air flowing around it.
Why must the refrigerant leaving the evaporator be superheated?
Superheat is critical in HVAC because it ensures the liquid refrigerant is boiled off before it leaves the evaporator and heads to the compressor. Even small amounts of liquid can cause detrimental damage to a compressor in an HVAC system.
Where does the refrigerant go when it leaves the evaporator?
compressor
The refrigerant boils in the evaporator at a constant low pressure and temperature. Heat is removed from the fluid being cooled. After leaving the evaporator, the vaporized refrigerant flows through the compressor.
What is the effect of evaporator pressure on the refrigeration effect work and cop?
Both cooling capacity and COP increase almost linearly with evaporator temperature [26,29,30]. The mass flow rate remains fixedwhile the primary stream is choked in the primary nozzle. On the contrary, the entrained flow rate rises with evaporator pressure, thereby increasing the cooling capacity and COP of the system.
How is the refrigerant used in the air refrigeration cycle?
As refrigerant absorbs heat from indoor air, it transitions from a low-pressure gas to a high-pressure liquid. The refrigerant then cools down and turns back into a low-pressure gas. Another fan located inside the home blows air over the cool coils to distribute the resulting cold air throughout the building.
Why does refrigerant need to be compressed?
we need a compressor to compress the vapor to convert it to liquid. At high presser the temperature of the refrigerant increases and reject heat through the condenser. the compressed liquid is expanded to absorve the latent heat of vaporization in the evaporator.
Why is there a need for the refrigerant to be superheated before it enters the compressor?
The refrigerant vapor is superheated mainly to ensure that dry gas enters the compressor. Many control systems, such as thermal expansion valves, also regulate by means of the outlet temperature, and so superheating is necessary to achieve stable control of the evaporation process.
Why is refrigerant recovery necessary?
Refrigerants are recovered to prevent them from leaking or being dispersed into the atmosphere. If refrigerant is vented into the atmosphere there will be one of two effects: The Chlorine contained in CFC/HCFC refrigerants will work it’s way up into the atmosphere and will end up causing damage to the O-Zone layer.
Why refrigerant evaporates when it enters in the evaporator?
As its name implies, refrigerant in the evaporator “evaporates”. The heat comes from the warm, moist room air blown across the evaporator coil. As it passes over the cool coil, it gives up some of its heat and moisture may condense from it.
Why refrigerant is compressed?
To cool a room down, you need to collect the heat and dump it somewhere else. The air in this “somewhere else” must be a lower temperature than the refrigerant for you to be able to dump the heat. To make sure this is possible, the refrigerant is compressed so that the temperature increases.