Compression Using System with Thermostat Expansion Valve (TRV)
Schematic diagram of the thermal expansion valve (TRV) cooling cycle is shown in Fig. 3-8. This system is used in large commercial refrigerators, as well as many air-conditioning systems. Liquid refrigerant (dark red) follows from the liquid receiver through the liquid line. It flows into the filter-dehydrator and thermostatic expansion valve.
Work thermostatic expansion valve is controlled by two conditions. These temperature TEV control lamp and pressure in the evaporator. Temperature TEV control lamp must be higher than the temperature of the refrigerant evaporator before the valve is opened. The sum of the opening of the evaporator temperature is regulated. If the evaporator is quite warm, the needle will open wide enough. This allows a rapid flow of fluid (dark blue) of the evaporator. Thus, cooling accelerate. As evaporator temperature drops, TEV needle valve decreases the refrigerant flow.
Low pressure (evaporates) refrigerant (light blue) of the evaporator is moving back to the compressor.
There he shrinks back to the high pressure side (red light). As it flows through the condenser refrigerant gives heat absorbed by the evaporator. Now-cooling refrigerant is condensed into a liquid (dark red). It flows back into the receiver. Refrigeration cycle is repeated.
When the evaporator reaches the desired temperature, engine control system will switch off the motor and the compressor. When this happens, TEV needle valve closes. No more refrigerant will flow until the compressor again lowers pressure in the evaporator. Pressure balance on the outside of the cycle. Therefore, it is necessary to ensure the motor-compressor, which will run under load. In the TEV management remains closed, if the evaporator under reduced pressure and the temperature is above normal. A drain valve, usually shown matte or sweating suction line...
Compressors 