Gas pulsations excited by reciprocating compressors could introduce severe vibrations and noise in piping systems. When pulsating gas flows through the reducers, the changes in flow characteristics, such as velocity and damping coefficient, will affect the pressure pulsations. To circumvent these constraints, a two-tank element is introduced to control the gas pulsation that is still strong in the piping system with a surge tank. Installing another surge tank to form a two-tank element is more flexible and costs lower than replacing the original surge tank with a larger one. In this work, a theoretical model based on the wave theory was proposed to study the transferring mechanism of gas pulsations in the pipeline with the two-tank element. By considering the damping coefficient and the Mach number, the distributions of the pressure pulsations were predicted by the theoretical model and agreed with the three-dimensional fluid dynamics transient analysis. Three experiments were conducted to prove that the suppression capability of the two-tank element is as good as that of a single-tank element (surge tank) with the same surge volume. The volume optimization of the twotank element is implemented by selecting the best allocations of the two tanks' volumes to achieve larger reductions of pressure pulsations. Assuming that the total surge volume is constant, we found that the smaller the volume of the front tank (near the cylinder) is, the lower the pulsation levels are. The optimized result proves that in some conditions the two-tank element could control pulsations better than the single-tank element with the same surge volume.

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An elbow-shaped surge tank is proposed to suppress the pressure pulsations. The transfer matrix method was developed and the mathematical model was established to predict the distribution of pressure pulsations in the piping system (on which a surge tank was already installed) with an elbow-shaped surge tank. Simulation work of the whole piping system was performed. The results show that the elbow-shaped surge tank has good performance to attenuate the pressure pulsations. The frequency analysis shows that the amplitude for the first pulsation frequency is attenuated to a low level. The impulse response was analyzed to examine the efficiency of suppressing pulsations by using the suppressor. The theoretical analysis showed that there exists the optimal suppression performance when setting the distance between the elbow-shaped surge tank and the existing one. Meanwhile, modifying the ratio of length to diameter with a fixed surge volume could also impact the pressure pulsations. The analysis results can be used as a reference in designing and installing the elbow-shaped surge tank.

A volume-perforated pipe-volume suppressor is introduced to study its performance in attenuating pressure pulsations. On the basis of plane wave theory, the work developed a mathematical model to predict the distribution of pressure pulsations in a reciprocating compressor piping system with the proposed suppressor. The theoretical predictions were verified through experiments and three-dimensional fluid dynamics transient simulations, and good agreements were attained. Results proved that the pressure pulsations were attenuated significantly when the suppressor was used. In the frequency domain, the amplitude at the first pulsation frequency was decreased considerably. Both the perforation and cross-sectional areas of the perforated pipe could influence the attenuating capacity. Given a fixed ratio of perforation area to cross-sectional area, the best damping performance could be obtained by increasing the number of perforated holes and reducing the hole diameter. The geometric recommendations produced in this work are useful to control pulsations and vibrations under different functioning conditions.

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