Browsing by Author "Grobbelaar, Dewald"

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    Improving the heat transfer characteristics of a Spiky Central Receiver Air Pre-heater (SCRAP) using helically swirled fins
    (Stellenbosch : Stellenbosch University, 2019-04) Grobbelaar, Dewald; Von Backstrom, T. W.; Lubkoll, M.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering (CRSES)
    ENGLISH ABSTRACT: The purpose of this project is to investigate the effect of helically swirled fins on the heat transfer coefficient and pressure drop in the spiky central receiver air pre-heater (SCRAP). First a theoretical analysis was done to investigate the effects of a swirl on the heat transfer coefficient and pressure drop. After this, the effects of swirled fins were simulated numerically and investigated. Experiments were then conducted to provide validation of the numerical model. Empirical correlations indicated that there is an increase of 20%- 30% in the heat transfer coefficient at low Reynolds numbers (Re=6600 andm˙ =0.03 kg/s), while maintaining pressure losses below 20 %. Higher (Re larger than 22 000 and m˙ >0.1 kg/s) Reynolds numbers introduced large pressure drops, surpassing a 100% increase, accompanied by mediocre heat transfer coefficient increases of 34 %. For the straight duct the average difference between analytical and numerical results was 14.8% for the heat transfer coefficient and 7.5% for the pressure drop. The curved duct simulation deviates from the analytical results by 14.3% for the heat transfer coefficient. For the pressure drop a maximum of 11.2% deviation is experienced, with a accuracy of 4% within the region of 5000