A novel linear electromagnetic-drive oil-free refrigeration compressor using R134a

Abstract

A new type of oil-free moving magnet linear compressor with clearance seals and flexure springs has been designed for incorporation into a vapour compression refrigeration system with compact heat exchangers for applications such as electronics cooling. A linear compressor prototype was built with a maximum stroke of 14 mm and a piston diameter of 19 mm. An experimental apparatus was built to measure the compressor efficiencies and coefficient of performance (COP) of a refrigeration system with the linear compressor, using R134a. The resonant frequency for each operating condition was predicted using the discharge pressure, suction pressure and stroke. Refrigeration measurements were conducted for different strokes under each pressure ratio with a fixed condenser outlet temperature of 50 °C and evaporator temperature ranging from 6 °C to 27 °C. The results show that the COPs are around 3.0 for tests with a pressure ratio of 2.5 (evaporator temperature of 20 °C).

A review of linear compressors for refrigeration

“…For use in miniature VCR system for electronics cooling, linear compressor needs to be oilfree and miniaturized at higher operating frequency. Designs of Sunpower [32], Oxford [79,81], and Bradshaw [2,8] didn't reach miniature level. It can be seen that Sunpower and Oxford designs did offer high motor efficiency (over 80%).…”

“…Linear compressors, with clearance seals and flexure bearings, have been used for many years to power Stirling cycle cryocoolers, and the same technology, with the addition of valves, can be used for vapour compression refrigeration (VCR) systems, with the potential for using ammonia [3]. A number of linear compressors have been incorporated into vapour compression refrigeration units with heat exchangers (evaporator and condenser).…”

Performance investigation of multi-stage saturation cycle with natural working fluids and low GWP working fluids

“…Degree of superheating: 5 K; Whitman et al (2004). Isentropic efficiency is calculated as a function of the pressure ratio; Hwang (2004) (h isen ¼ 0:85 À 0:0467 Â PR) Compressor motor efficiency: 0.86; Liang et al (2014). Condensing temperature is 10 K higher than ambient air temperature; Hwang (2004).…”

Characteristics of a novel moving magnet linear motor for linear compressor

“…The non-linear characteristic of gas pressure makes it difficult to derive the exact gas spring stiffness. A simple linearization approach to obtain the approximation of gas stiffness was presented by Cadman and Cohen [14], which is widely adopted by Bradshaw [15] and Liang et al [16]. The experimental results by Liang [16] showed the feasibility of this approach.…”