The liquid line is a pipe that carries the cold, liquid refrigerant from the condenser to the expansion device.

When compressor starts, it remove the refrigerant from the evaporator, which lowers the pressure in the evaporator. Thus evaporator / suction line pressure drops more rapidly during compressor starting. This phenomenon is known as the pressure drop or pressure pull-down during compressor startup

The secondary refrigerant is simply a medium that is used to transfer heat from the primary refrigerant to the heat sink. The secondary refrigerant does not undergo a change of state because it is not the refrigerant that is actually absorbing or releasing heat.

Ammonia has a high discharge pressure, which can put stress on the compressor and other components in the refrigeration system

Even if a large amount of Class A refrigerant is released into the air, it is unlikely to cause any harm to people or animals. Examples of Class A refrigerant are: ammonia, SF6, CO2, HFCs and Hydrocarbons

Dielectric strength indicate the insulation property of compressor oil.  It is important for compressor oil to have good dielectric strength, as it is used to insulate the electrical components of the compressor. If the oil has poor dielectric strength, it can allow electricity to flow between the components, which can damage the compressor.

When a refrigerant has a higher specific volume, it means that it occupies more space per unit mass at a given suction pressure and temperature. To handle a larger volume of refrigerant, a compressor with a higher displacement (capacity) is typically required.

Hot gas line mufflers are often located in the discharge line of the compressor near the outlet of the compressor. This directly absorb and dampen the pulsations generated by the compressor before the refrigerant reaches other components of the system.

Suction pressure is high, the compressor has to work harder to compress the refrigerant, which can reduce its capacity.

If the ambient temperature is high, the suction pressure will be high. This is because the refrigerant will have to work harder to absorb heat from the air

Reciprocating compressors require high maintenance because they have many moving parts that can wear out over time compared to centrifugal compressors. These parts include the pistons, cylinders, valves, and bearings.

Pilot solenoid valves are used to control the flow of refrigerant in the system. The third valve of a pilot solenoid valve is connected to the Thermostatic Expansion Valve (TXV). The TXV is a device that controls the flow of refrigerant to the evaporator.

Suction line carries a gas from the evaporator which has a much higher volume than the liquid entering the expansion control device upstream of the evaporator. Suction line should have large diameter to reduce pressure drop and prevent refrigerant vaporization.