A dynamic model of a centrifugal compressor capable of system simulation in the virtual test bed (VTB) computational environment is presented. The model is based on first principles, i.e. the dynamic performance including the losses is determined from the compressor geometry and not from the experimentally determined characteristic performance curves. In this study, the compressor losses, such ...

Mechanically refrigerated test chambers are classified as either single stage low (-40 °C) or cascade ultralow (-70 °C) temperature systems. While cascade systems are reliable and versatile, the potential for leakage between stages within a cascade heat exchanger remains. Further, the need for two compressors and increased control mechanisms can make the system more and more complex. The only m...

Linear time optimal parsing algorithms are very rare in the dictionary based branch of the data compression theory. The most recent is the Flexible Parsing algorithm of Mathias and Shainalp that works when the dictionary is prefix closed and the encoding of dictionary pointers has a constant cost. We present the Dictionary-Symbolwise Flexible Parsing algorithm that is optimal for prefix-closed ...

This work deals with numerical solution of first order hyperbolic equation or system in 2D or 3D. In the first part, the solution of a 2D linear scalar equation is investigated. Using this model problem, the results of different numerical schemes are compared from the point of view of accuracy and parallel efficiency. The next part describes 2D and 3D steady numerical solutions of the transonic...

Supervision of the performance of an industrial gas turbine is important since it gives valuable information of the process health and makes efficient determination of compressor wash intervals possible. Slowly varying sensor faults can easily be misinterpreted as performance degradations and result in an unnecessary compressor wash. Here, a diagnostic algorithm is carefully combined with non-l...