I assume you meant to say "Where is a king valve in refrigeration?" Anyhow, it is usually located downstream from a liquid line receiver.
king valve
Liquid refrigerant charging of a system is normally accomplished in the liquid line. For example, when a system is out of refrigerant, liquid refrigerant can be charged into the king valve on the liquid line or receiver.
A queen valve is the service valve (isolation valve) located at the inlet of the liquid receiver (between the condenser outlet and the liquid receiver). The king valve is the service valve at the outlet of the liquid receiver (between the liquid receiver and the liquid line). Queen valves seem to be in use much less than king valves.
The main two refrigeration giants are Thermo King and Carrier
The King valve is closed, starving the low pressure side, creating more vacuum while charging with a liquid
the reversing valve is what actually changes the refrigeration cycle from heat to cool. the reversing valve receives its signal from the thermostat.
When referring to the "king" valve, most air conditioning technicians are referring to the valve which is found downstream from a liquid line receiver. It is also commonly referred to as a liquid line service valve or an isolation valve. The name King valve is what Carrier calls its service valves. If you call a wholesaler or manufacturer for a king valve the answer you will receive is "Sir, we don't carry king valves." Every manufacturer calls service valves something different.
A piercing valve is a valve with a pointed sharp tip that is used to gain access to a sealed refrigeration system that does not have service valves or Schroeder ports. And is to be used as a temporary device .
Vapor compression in the refrigeration cycle is the process which turns heated vapor into a cold liquid. This allows the coolant to flow through the condenser and cool the air.
Tonne of refrigeration(TR) is the practical unit of refrigeration effect.Tonne of refrigeration(TR) is defined
Once the fluid travels through the radiator on the back of the refrigerator, the valve will open and use the force of the piston retracting to suck the fluid into the compressor, where the pressure will cool the refrigerant over again.
Back pressure regulating valve is used in ammonia refrigeration plant to maintain the minimum pressure in the evaporator coils. It helps in preventing ice formation / choke upin the PHE chiller.