A comprehensive model of a miniature-scale linear compressor for electronics cooling

Abstract

A comprehensive model of a miniature-scale linear compressor for electronics cooling is presented. Linear compressors are appealing for refrigeration applications in electronics cooling. A small number of moving components translates to less theoretical frictional losses and the possibility that this technology could scale to smaller physical sizes better than conventional compressors. The model developed here incorporates all of the major components of the linear compressor including dynamics associated with the piston motion. The results of the compressor model were validated using experimental data from a prototype linear compressor. The prototype compressor has an overall displacement of approximately 3cm3 , an average stroke of 0.6 cm. The prototype compressor was custom built for this work and utilizes custom parts with the exception of the mechanical springs and the linear motor. The model results showed good agreement when validated against the experimental results. The piston stroke is predicted within 1.3% MAE. The volumetric and overall isentropic efficiencies are predicted within 24% and 31%, MAE respectively.

Sensitivity analysis of a comprehensive model for a miniature-scale linear compressor for electronics cooling

“…Figure 2 compares the resonant frequency predicted from this approach and the experimentally obtained resonant frequencies. The experimental data presented were obtained using the methodology outlined in previous work (Bradshaw et al, 2011). The experimental prototype linear compressor in this work was tested at evaporation pressures between 537 and 561 kPa,at pressure ratios of 1.11 to 1.26, and with a constant superheat of 4.5 K. The predictions match the experimental measurements well, with a Mean Absolute Error (MAE) of 0.5%.…”

“…Bottom Dead Center [-] Bradshaw et al (2011). The model was also validated against experiments conducted on a prototype linear compressor constructed for the purpose.…”

“…The model presented previously in Bradshaw et al (2011) utilizes a two degree of freedom system to describe the piston motion. These two degrees of freedom are the desired piston translation and the undesired rotation of the piston within the cylinder.…”

“…The desired piston stroke is one of the necessary specifications in the design of a linear compressor. Therefore, the utility of the linear compressor model developed in Bradshaw et al (2011) is enhanced here by allowing for the desired stroke to be specified. Since the piston driving force is an input to the two-degree-offreedom piston vibration model used to determine the piston behavior, a numerical algorithm is used to adjust the piston driving force until the desired piston stroke is achieved..…”

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AbstractA comprehensive model of a linear compressor for electronics cooling was previously presented by Bradshaw et al (2011). The current study expands upon this work by first developing methods for predicting the resonant frequency of a linear compressor and for controlling its piston stroke.

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