Energy Regulator for refrigeration system-hot gas bypass valve

The role and practice of hot gas bypass valve

The energy regulation of the refrigeration system generally consists of the following ways

Compressor parallel-multi-stage control; 

Variable speed compressor-frequency conversion, etc. ; 

With the unloading device of the compressor; 

Hot gas by-pass.

For a compressor refrigeration system that does not have its own energy regulating device, it is very economical to use hot gas bypass to regulate the energy of the system, hot gas by-pass valves provide a practical, economical and reliable energy regulation solution. [ source: refrigeration encyclopedia ] is especially suitable for compressors without self-regulating mechanism of energy. When the evaporator is under low load, it can better maintain the suction pressure, prevent the evaporator from freezing, and maintain better oil return performance. General Adjustment Range: 0-0.55 mpa; Safe Operation Pressure-2.75 MPA (400 psig) .

Two common practices for hot gas bypass valves:

1. Bypass directly to the return end; 

2. Bypass to the inlet of the evaporator;

Direct Bypass to the back end:

Bypass to the entrance of the evaporator and connect to the suction pipe, not through the evaporator but directly through the suction pipe back to the compressor, high-temperature and high-pressure hot gas from the evaporator and low-temperature and low-pressure refrigerant mixture, the suction pressure of the compressor is increased.

Bypass the entrance to the evaporator:

By-pass solenoid valve connected to the high-pressure side of the position can be entered into the condenser before any position on the pipeline. And connecting the low-pressure side of the pipeline, so the high-temperature and high-pressure hot gas coming from the high-pressure side enters the evaporator, increasing the load of the evaporator, can prevent the evaporator because of the evaporating pressure drop and cause the evaporator to freeze the possibility of damage,At the same time, it also increases the outlet temperature and pressure of the evaporator, and improves the operation condition of the compressor under low temperature operation.

Regulation of hot gas bypass valve:

The first step after the installation of hot gas bypass valve is to determine the minimum suction pressure under the operating conditions, as a hot gas bypass valve set point, adjustment steps:

1. Install a pressure gauge on the compressor suction line and measure the suction pressure after the system is stabilized. To make sure there is no hot gas by-pass, listen for the sound of air flowing through the valve or touch the outlet line of the valve. If the outlet line is hot, it means there is hot gas by-pass. 

2.Block hot air bypass. The utility model can cut off the power supply of the solenoid valve of the hot gas bypass pipeline or adjust the adjusting rod to make the hot gas bypass valve in a completely closed state. 

3. Reduce the load on the evaporator until the suction pressure drops to the point where hot gas bypass is required. The load of the evaporator can be reduced by closing the air outlet, covering the evaporator, reducing the air flow, closing the fan, and closing the bypass water of the water cooler. 

4. Make sure that the solenoid valve of the hot gas bypass pipeline is open at this time. Adjust the lever of the hot gas bypass valve so that the hot gas bypass valve begins to bypass the hot gas until the suction pressure no longer decreases and remains at the expected value.

Hot Gas by-pass valve regulation: the clockwise direction regulator will increase the pressure setting, the anticlockwise direction regulator will reduce the pressure setting, slow and small adjustments should be made, in order to make the system after each round of adjustment to run stable.