Electrical motor stator current signals have been widely used to monitor the condition of induction machines and their downstream mechanical equipment. The key technique used for current signal analysis is based on Fourier transform (FT) to extract weak fault sideband components from signals predominated with supply frequency component and its higher order harmonics. However, the FT based metho...

This paper presents a method for the numerical simulation of reciprocating compressors for household refrigeration. The compressor is regarded as a set of volumes and one-dimensional, variable-area ducts connected together. The model describes all relevant features of the compressor, including suction and discharge mufflers and automatic valves. The equations governing the unsteady flow of a re...

In this work a previous steady-state model [1] of a hermetic reciprocating compressor has been improved using an unsteady-state analysis of the compression cycle which allows a direct computation of the heat, work and mass flow rates. The new model requires the geometry of the machine, refrigerant inlet temperature and pressure, vapour discharge pressure, electric and mechanical efficiencies as...

Computer simulation of the thermodynamics and dynamics of an intercooled two-stage two-cylinder reciprocating air compressor system is reported and the obtained results discussed. The main emphasis is placed upon modeling the pressure-wave motion in the interconnecting pipework for which the governing equations were solved by means of two different methods: the characteristic mesh method and th...

This paper proposes a method of evaluating the performance of reciprocating compressors. An analytical formula of the volumetric efficiency is presented. This formula, based on both theoretical and empirical approach, takes account of the most important factors, which occur during the working process of the compressor and affect the refrigeration performance. An accurate determination of the cl...

The instantaneous mass flow was measured during the intake and discharge processes of a reciprocating gas compressor (1)*. The purpose of these measurements was to identify the mechanism which caused a loss of adiabatic and volumetric efficiency that could not be accounted for by valve flow losses. The measurements were made wi ·th square-edged orifices and fast response differential pressure t...

From the COP （Coefficient of Performance） equation, there are two ways to improve cooling efficiency cryocoolers: （1） increasing capacity, and （2） decreasing electrical input power. In recent years, we have focused on possibility method for a 4 K-GM （Gifford-McMahon） cryocooler. this paper, 7 kW class compressor, which is commonly connected cold head, was replaced with low power consumption （2 cl...