Stable operation of both axial and radial compressors is constrained by the occurence of aerodynamic flow instabilities: rotating stall and surge. Developments in the understanding of the physics behind these instabilities and ideas of how t o stabilize the compressor system, have opened the door t o a new era in the field of compressor control. This study gives an overview of the current state...

To evaluate the effects of the thermal properties of components on the overall temperature distribution of a compressor, a heat transfer model employing the lumped thermal conductance approach has been formulated. The model has been verified with extensive measurements and the overall discrepancy of less than 7% is obtained. The discrepancies in the prediction are mainly the results of assumpti...

Motivated by the increase in storage space and Internet connection speed, as well as significant improvements in audio hardware, the interest for lossless audio compression has been greatly increasing, especially in the consumer market. In this article, we present a short performance comparison of the state of the art lossless audio compressors. The focus is on the OptimFROG symmetrical compres...

The profile gradient method has been recently introduced as a means of generating screw compressor rotor profiles. As a single parameter method, this procedure is convenient for the optimisation of screw compressor rotors and evaluating their quality. In this paper, the procedure is modified to adopt the pressure angle instead the profile gradient and applied to a screw compressor rotor rack. O...

There is a growing need for compressed air free of entrained oil to be used in industry. In many cases it can be supplied by oil flooded screw compressors with multi stage filtration systems, or by oil free screw compressors. However, if water injected screw compressors can be made to operate reliably, they could be more efficient and therefore cheaper to operate. Unfortunately, to date, such m...

As refrigeration compressor manufacturers introduce machineswith improved efficiencies there is a need for updatingperformance data.The compressor performance data which is published should bea true representation of the actual compressor performance,historically this has resulted in lengthy test programmes for thecompressor manufacturer. A system is required which c...

The adjustment and control mode of frequency conversion for an air-conditioner can make the refrigeration capacity adapt the variety of its load very well. Thus, it has many advantages such as low variety in in-door temperature, short time to reach the wished temperature, low energy consumption, low start electric current and low strike to electric source etc. This mode is widely used in room a...

If compressor manifolds are thin compared to the shortest wavel~ngth of i:r:tt~rest, the gene!al procedure developed by the authors [1, 2] for the analysis of curved, t~l? gas cav1hes can be apphed to the analysis of gas pulsations in multi-cylinder compres~?r head cav1t1es. The procedure for smgle input single output systems is extended to systems of multl-mputs. Four pole parameters and trans...

The destructive surge transient response is an expected phenomenon on a turbo charged automobile. Therefore a new intelligent controller to prevent the surge phenomenon to prolong the life cycle of modern turbo charged automobiles is proposed in this paper. In order to do so, the surge boundary for a particular turbo charger in a specific automobile must be determined first. A new systematic wa...

INTRODUCTION Investigators conducted a prospective experimental study to evaluate the effect of team size and recovery exercises on individual providers' compression quality and exertion. Investigators hypothesized that 1) larger teams would perform higher quality compressions with less exertion per provider when compared to smaller teams; and 2) brief stretching and breathing exercises during ...