Investigating a hermetic reciprocating compressor performance under variable lift limiter height using FSI method

Abstract

This study examines discharge line energy losses using advanced fluid-structure interaction methods to show how valve design parameters-length, thickness, and height-improve compressor performance. An innovative 3D fluid-structure Interaction model represents a self-acting hermetic reciprocating compressor's discharge valve as a beam element. The RNG k-epsilon model examines how reed valve thickness, length, compressor speed, and lift limiter height impact pressure pulsation and compressor efficiency. Under ASHRAE conditions, operating at a challenging temperature range of 54.4 to -23.3 degrees C, the study meticulously explores the intricate interplay of discharge valve characteristics. Specifically, varying valve thicknesses (0.127, 0.152, 0.178, and 0.2 mm) and lengths (14.722, 16.222, and 17.722 mm) are examined in conjunction with different compressor speeds (1300, 2100, and 3000 rpm) according to the design specifications. Upon meticulous examination of discharge line losses at a compressor speed of 1300 rpm, intriguing insights emerged. For lift limiter heights of 0.8, 1.05, and 1.25 mm, coupled with a valve length of 17.722 mm, the study unveiled remarkable average energy losses of -6.91%, 2.83%, and -8.52%, respectively. The exploration continued at 2100 rpm, revealing a dynamic pattern with average losses for the same lift limiter heights at 0.94%, -1.26%, and -4.43%, respectively. In a succinct summary, the valve in focus demonstrated a noteworthy disparity in discharge line losses, reaching a maximum variation of 9.15%, -3.83%, and -8.30% when operated at the challenging speed of 3000 rpm.