Linear compressor

About: Linear compressor is a research topic. Over the lifetime, 1332 publications have been published within this topic receiving 8188 citations.

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).

Comparison between a crank-drive reciprocating compressor and a novel oil-free linear compressor

Abstract: Reciprocating compressors, driven by induction motors through a crank mechanism, have been commercially used over many years for refrigeration. An oil-free linear compressor driven by a moving magnet motor was designed, for a refrigeration system with a compact heat exchanger. Measurements using nitrogen are reported here to compare the motor performance and overall efficiencies of the two types of compressor with comparable design parameters. The experimental results show that the moving magnet linear motor has a much higher motor efficiency than the conventional induction motor, particularly at low power inputs. However, with a much smaller clearance volume (approaching zero), the crank-drive compressor demonstrates a higher volumetric efficiency based on the swept volume, that is approximately 20% higher than the linear compressor when operated at its maximum stroke (13 mm). It is anticipated that with a revised design, the overall performance of the linear compressor could be enhanced further.

A Resonant Frequency Tracking Technique for Linear Vapor Compressors

Abstract: A linear vapor compressor operates most efficiently at resonant frequency which varies with piston stroke and operation conditions. A novel resonant frequency tracking technique is proposed in order to achieve high efficiency operation of a linear compressor system. This is based on the fact that for given amplitude of the motor current, the linear compressor system reaches its maximum stroke and maximum input and output powers at its resonant frequency. By evaluation of the input power to the compressor and implementing a perturb and observe algorithm, the proposed technique can adjust the frequency of the motor current to match the resonant frequency of the compressor operation. The proposed technique does not require a position sensor, and can be easily implemented in a digital controller. Simulation and experimental results have demonstrated the validity of the proposed technique.

Analysis of Nonlinear Dynamics in a Linear Compressor.

Abstract: In linear electrodynamic oscillating compressors, gas force has nonlinear characteristics depending on the stroke of piston. Static and dynamic components of the force are coupled to each other. Furthermore, mechanical part is coupled with electromagnetic part. Hence, dynamics analysis of the whole system is very complicated. In this paper, the gas force is represented in terms of equivalent stiffness and equivalent damping by employing the describing function approach so that analysis of steady state response characteristics and jump phenomenon can be done in a way simpler than by the full nonlinear model. In order to illustrate accuracy of the equivalent model, the frequency response characteristics of the proposed model are compared with those of the full nonlinear model. Jump phenomena depending on the amplitude of supply voltage is also investigated by using the equivalent model and the necessary conditions for jump to occur are derived.