Performance assessment in V-trough solar water heater fitted with square and V-cut twisted tape inserts

• Published in: Applied thermal engineering 2016-06, Vol.102, p.476-486
• Main Authors: Saravanan, A., Senthilkumaar, J.S., Jaisankar, S.
• Format: Article
• Language: English
• Subjects: Deviation; Fluid flow; Friction factor; Mathematical analysis; Nusselt number; Reflection; Reflector; Solar heating; Square cut; Swirl flow; V-cut; V-trough; Water heaters
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2016.03.088

•Helix twisted tapes with minimum twist ratio 3 provide the better thermal performance than plain and other twist ratios.•Compared to helix, helix with V-cut has higher Nusselt number and is 9.13%.•Compared to square cut, V-cut has higher Nusselt number and is 3.08%.•Nusselt number, friction factor and thermal performance correlation are developed.•Obtained results are used to reduce the size of solar collector. The experimental investigation has been carried out in V-trough solar water heater fitted with helix twisted tape (HT), helix twisted tape with square cut (HSC) and helix twisted tape with V-cut (HVC), under two different twist ratios (Y=3, 4 & 5) in same operating condition. Solar concentration has increased while using additional reflection surface on the absorber plate which in turn increased thermal performance in Plain V-Trough (PVT) solar water heater. The experimental result has been verified with fundamental equation and the discrepancy is less than ±14.54% and ±5.5% for Nusselt number and friction factor respectively. The twist tape with lower twist ratio (Y=3) gives higher thermal performance than higher twist ratio (Y=5). The obtained results have shown that the Nusselt number and frictional factor are higher in HVC than in HSC. Correlations have been developed for Nusselt number and friction factor to match the experimental results and deviation fall within ±10.17% and ±4.395% respectively.