Linear Compressor, Aerostatic Bearing, Finite Volume Methodology, Piston Lubrication
Linear compressor uses a linear actuator to drive the piston directly in its reciprocating motion, eliminating several bearings that convert rotational into linear reciprocating motion, which is the common case in conventional reciprocating compressors. Â Additionally, the presence of side loads is minimized because the main forces in the mechanism are aligned to the axis of motion. Â Since the only sliding surface is the piston-cylinder interface, lubrication can be achieved using the refrigerant gas. Â In the present investigation, the equilibrium condition of capillary compensated gas lubricated piston for a linear compressor is fully explored. Â The main objective of the present work is to evaluate the performance of a pneumatic bearing and to understand the influence of some design characteristics as radial clearance, diameter of the capillary compensation channels and the position of the feeding ports on the bearing during operation. Â A mathematical model is developed and then the resulting equations are numerically solved by finite volume methodology. Â Results indicated that the linear piston is very stable, and that the gas leakage necessary to lubricate the piston-cylinder interface during the reciprocating motion, is very small. Furthermore, the geometry of the feeding channels to the clearance between piston and cylinder is an important design parameter in achieving a better performance of the aerostatic bearing.