Hello Everyone,

I have a question about Digital Scroll Compressors. As we know that a Digital Scroll operates in two stages - the "loaded state", when the solenoid valve is normally closed and "unloaded state", when the solenoid valve is open. During the loaded state the compressor operates like a standard Scroll and delivers full capacity and mass flow. However, during the unloaded state, there is no capacity and no mass flow through the compressor. The capacity reduction is achieved by modulating the solenoid with a PWM controller. The PWM cycle is 20 seconds. In other words, if we want to have 50% capacity, in each cycle, the compressor will be in loaded state for 10 seconds and in unloaded state for the next 10 seconds. As the compressor is on/off in every 10 seconds, I wonder that both the discharge pressure and the suction pressure will fluctuate greatly. The system always does not work in a stable condition and it is almost impossible for the EXV to maintain a stable superheat. Is this the way a Digital Compressor works? Are there any ways to make the system pressures stable?

Any comments and suggestions are welcome. Thanks.