Browsing by Author "Fivaz, Michael Arthur"

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    Upgrading the compressor stage of a solar-hybrid twin-shaft micro gas turbine.
    (Stellenbosch : Stellenbosch University, 2024-02) Fivaz, Michael Arthur; Van der Spuy, SJ; Van Eck, H.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: Using a solar-hybrid gas turbine system for generating electricity combines the continuous high output power of a micro gas turbine (MGT) with the environmental benefits of a concentrating solar power (CSP) plant. An MGT's performance can be improved in a variety of options for solar-hybrid applications, with the compressor stage receiving particular focus. A centrifugal compressor, which is favoured over axial compressors due to higher per stage pressure ratios obtained, is used in the compression stage. An existing design methodology exists to assist in developing and testing a new centrifugal compressor for an MGT engine. The operational solar-hybrid MGT testbench operates with a very low engine efficiency and generates a low amount of output power. Therefore, the aim of this study is to upgrade the compressor stage of the solar-hybrid MGT through a proposed centrifugal compressor redesign to improve overall engine performance. After measuring the geometry to get an exact replica of the existing compressor impeller to establish its baseline performance, a new design is developed using a one-dimensional (1D) mean-line code. The redesigned compressor is subjected to a Computational Fluid Dynamics (CFD) simulation to produce performance charts that are imported into a thermodynamic software model of the engine for performance improvement evaluations. The new compressor design increases the MGT’s compressor stage’s compression ratio by 4.59% from the existing replica compressor of 1.48 to 1.55. Similar to the compression ratio, the efficiency of the compressor stage is improved from 78.3% of the existing replica compressor to 84.2% by the new compressor design. As a result, the MGT's output power increases by 22.7% from 18.1 kW to 22.2 kW, further improving overall engine efficiency. The improvement in performance enables the engine to be developed further, such as converting the output shaft power into electricity. The development of this MGT will ultimately assist in progressing the field of solar-hybrid gas turbine energy generation.