Investigating a Hermetic Reciprocating Compressor Performance under Variable Lift Limiter Height using FSI Method


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Bacak A., Pınarbaşı A., Dalkılıç A. S.

PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS, PART E: JOURNAL OF PROCESS MECHANICAL ENGINEERING, vol.1, pp.1-15, 2024 (SCI-Expanded) identifier

Abstract

This groundbreaking study delves into the intricate dynamics of hermetic reciprocating compressors, highlighting the pivotal role played by mechanical, electrical, and thermal factors in shaping compressor efficiency. By employing advanced fluid-structure interaction methods, the investigation focuses specifically on discharge line energy losses, elucidating the profound impact of valve design parameters—length, thickness, and valve height—on enhancing overall compressor performance. In the development of a comprehensive 3D Fluid-Structure Interaction model, the discharge valve of a self-acting hermetic reciprocating compressor is ingeniously represented as a beam element. The utilization of the RNG k-ε model further scrutinizes the nuanced effects of reed valve thickness, length, compressor speed, and lift limiter height on pressure pulsation and, consequently, the efficiency of the compressor. Under ASHRAE conditions, operating at a challenging temperature range of 54.4°C to -23.3°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 mm, 16.222 mm, 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 mm, 1.05 mm, and 1.25 mm, coupled with a valve length of 17.722 millimeters, 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.