A Comparative Numerical Analysis of the Energy Efficiency of a Pneumatic Pressure Booster with Energy Recovery

Pneumatic systems are widely used in industry; however, compressed air remains an expensive energy source. To save energy, supply pressure is often reduced, but this leads to insufficient pressure in specific sections of the pneumatic circuit that require higher pressure. Pneumatic pressure boosters (PPBs) are used to address this issue, yet traditional designs lose a significant amount of energy during the exhaust phase. This paper proposes a pressure booster with energy recovery (PPB-R), in which the energy of the exhaust air is directed into an additional expansion chamber to perform useful work by moving the piston. A comparative numerical analysis of the energy efficiency of the PPB and PPB-R was conducted using the “air power” method. A mathematical model of the system was developed, incorporating force and mass flow balance equations under an isothermal assumption, with friction forces estimated from experimental data. The results indicate that the energy efficiency of the PPB-R may exceed that of the standard PPB by 3–6%, and its boost ratio improvement increases from about 3% at 200 kPa to 13% at 800 kPa. Furthermore, optimal expansion chamber diameters were determined for different supply pressures (85, 95, and 110 mm at 300, 500, and 800 kPa, respectively). The established pressure–flow characteristics confirm that the PPB-R maintains a nearly constant relative pressure advantage of about 15% under all load conditions. A quantitative energy balance shows that approximately 66% of the recovered energy is converted into additional useful output. The practical significance of this work lies in the potential to reduce compressor outlet pressure (thereby saving electricity) or to increase pressure at the point of use without increasing air consumption. The findings can be applied to the design and modernization of industrial pneumatic systems.