The discharge line carries the hot, high-pressure refrigerant vapor from the compressor to the condenser.

A higher superheat indicates that the refrigerant vapor is less dense, therefore compressor capacity drops due to reduction in the density of the gas

Centrifugal compressors are not efficient at pumping refrigerants with high condensing pressures. The higher the condensing pressure, the more centrifugal force is required to increase the pressure of the refrigerant. Therefore they are best suited for pumping refrigerants with low condensing pressures.

This is because the refrigerant needs to be in a high-pressure state in order to absorb heat from the air or other substance being cooled.

Depends on the size of the orifice, pressure difference between the high-pressure side of the valve and the low-pressure side of the valve, temperature of the refrigerant and type of refrigerant

The sensing bulb is located in the suction line, and it is connected to the expansion valve by a capillary tube. The sensing bulb is used to regulate the flow of refrigerant to the evaporator.

Superheating of the suction gas before the compressor is not desirable because it reduces compressor efficiency ( as  superheated refrigerant gas is less dense than saturated vapor leading to more compressing requirement of compressor), increase compressor wear and reduce refrigeration capacity.

Higher condensing temperature increases the power required to drive the compressor thereby reducing the capacity of the compressor

The relationship is not linear, however, and the capacity increases at a faster rate as the speed increases. This is because the compressor is able to compress the refrigerant more efficiently at higher speeds.

When the refrigerant temperature in the evaporator is constant, the temperature difference between the fluid and the refrigerant will decrease as the refrigerant absorbs heat from the fluid. As the temperature difference decreases, the amount of heat that can be transferred from the fluid to the refrigerant will also decrease. This will reduce the cooling capacity of the refrigeration system.

Refrigerants with a lower boiling point will have a higher latent heat of vaporization. The latent heat of vaporization is the amount of heat required to vaporize a unit mass of a substance. As a result, refrigerants with a higher boiling point will have a lower heat transfer efficiency.

The TXV or Thermal Expansion Valve is a metering device that controls the flow of refrigerant into the evaporator. It does this by sensing the temperature of the refrigerant at the evaporator outlet and adjusting the flow of refrigerant accordingly.

Water/moisture in refrigeration system can react with refrigerants to form acids. These acids can attack the metal components of the refrigeration system and cause them to rust or corrode.

Positive displacement compressors work by trapping a fixed volume of air and then reducing the volume of the chamber, which increases the pressure of the air. Some of the examples of positive displacement compressors are Reciprocating compressors, Rotary screw compressors, Scroll compressors and Vane compressors.

Air has a lower specific heat capacity (hold less heat per unit volume) than water and therefore air is not as effective at transferring heat as water.