Hydrothermal Performance Augmentation of a Rectangular Channel Via Novel Designs of Transverse Turbulators: An Insight into Performance Improvement of Solar Air Heaters

• Published in: Experimental techniques (Westport, Conn.) Vol. 46; no. 5; pp. 889 - 903
• Main Authors: Khosravi, M., Khoshvaght-Aliabadi, M., Mortazavi, S.
• Format: Journal Article Magazine Article
• Language: English
• Published: Cham Springer International Publishing 01.10.2022; Springer Nature B.V
• Subjects: Air heaters; Applications Paper; Characterization and Evaluation of Materials; Chemistry and Materials Science; Design; Fluid flow; Friction factor; Heat transfer coefficients; Hydraulics; Materials Science; Performance enhancement; Performance indices; Pressure drop; Reynolds number; Novel designs; Passive technique; Solar air heater; Experimental study; Transverse turbulators
• ISSN: 0732-8818; 1747-1567
• DOI: 10.1007/s40799-021-00523-8

The current experimental study focuses on designing novel shapes of transverse turbulators to improve the performance of solar air heaters. Fourteen designs are derived from the original case having length × width × thickness of 30 mm × 15 mm × 0.8 mm. These turbulators are tested in a rectangular channel, and the thermal and hydraulic transport performances of the fitted channel are compared with those obtained for the vacant channel. Although the novel geometries may provide a weaker thermal characteristic through the channel, the penalty in the hydraulic characteristic is decreased significantly compared to the original shape, leading to better overall hydrothermal performances. It is found that the novel designs of transverse turbulators own lower values of heat transfer coefficient, that is ranging from 12.1% to 45.2%, whereas the pressure drop decreases within the range of 48%–91% at the studied Reynolds numbers ( Re  = 1643, 3286, and 4929). The results show that the Nusselt number ratio ( Nu fitted / Nu clear ) gets reducing trend with increasing Re , while the friction factor ratio ( f fitted / f clear ) gets increasing trend. An appropriate tradeoff between thermal and hydraulic characteristics is established by using a specific design which presents minimum values of pressure drop and maximum values of the performance index. The highest index of 1.69 is recorded for this turbulator design at Re  = 1643.