Improving the heat transfer characteristics of a Spiky Central Receiver Air Pre-heater (SCRAP) using helically swirled fins

[摘要] ENGLISH ABSTRACT: The purpose of this project is to investigate the effect of helically swirled finson the heat transfer coefficient and pressure drop in the spiky central receiverair pre-heater (SCRAP).First a theoretical analysis was done to investigate the effects of a swirl on theheat transfer coefficient and pressure drop. After this, the effects of swirledfins were simulated numerically and investigated. Experiments were then conductedto provide validation of the numerical model.Empirical correlations indicated that there is an increase of 20%- 30% in theheat transfer coefficient at low Reynolds numbers (Re=6600 andm˙ =0.03 kg/s),while maintaining pressure losses below 20 %. Higher (Re larger than 22 000and m˙ >0.1 kg/s) Reynolds numbers introduced large pressure drops, surpassinga 100% increase, accompanied by mediocre heat transfer coefficientincreases of 34 %.For the straight duct the average difference between analytical and numericalresults was 14.8% for the heat transfer coefficient and 7.5% for the pressuredrop. The curved duct simulation deviates from the analytical results by14.3% for the heat transfer coefficient. For the pressure drop a maximum of11.2% deviation is experienced, with a accuracy of 4% within the region of5000

[发布机构] Stellenbosch University