Pressure Pulsation in the Reciprocating Compressor with Stepless Capacity Regulation
The stepless capacity regulation by means of delayed closure of the suction valves plays an important role in energy conservation for the reciprocating compressor. Serious gas pulsation usually occurs during the capacity regulation, and its analysis and suppression is a challenge due to the varied components of the pulsation excitation under different conditions. This paper presents a numerical and experimental study of the gas pulsation in the compressor piping with stepless capacity regulation. An approach was proposed to calculate the pulsation excitation in the case of stepless capacity regulation, which was further incorporated into the frequency-domain modeling of the gas pulsation based on the plane wave theory. A test rig was built up and an experimental investigation was conducted. The amplitudes as well as waves of the pressure pulsation in positions of suction and discharge valve chambers were measured as the compressor capacity was regulated by changing the closing time of the suction valves. The test data were compared with the simulated results, which indicated a good agreement. The validated model was applied to conduct the parametric study. The results showed that the effect of delayed closure of the suction valves led to the non-linear increase of the pressure fluctuation in the suction pipeline system. Meanwhile, the gas pulsation of main excitation frequency linear increased in the suction pipeline system, and linear decreased in the discharge pipeline as the opening time of the suction valve increased. Furthermore, In order to estimate the preliminary sizing of the pipeline system, we proposed a set of equations to describe the relationship between the gas pulsation of main excitation frequency and the delayed closure time of the suction valve.