Analysis on heat transfer and friction factor characteristics of turbulent flow through heat exchanger fitted with peripheral square-cut twisted tapes arrangement

The present work presents the numerical investigation on heat transfer, friction factor and thermal enhancement behavior of a tube containing peripheral square-cut twisted tapes and plain twisted tape. Realizable k-ɛ (RKE) turbulence model was selected in present work for accurate prediction of adverse pressure gradient boundary layer flow. The effect of twist ratio, depth ratio and width ratio were investigated in turbulent flow regime. Reynolds number is in the range of 2000-20,000.Twist ratios (TR) considered were 2,3,5,7. Width ratios (WR) were0.2, 0.3, 0.4, 0.5. Depth ratios (DR) were 0.15, 0.25, 0.35, 0.45. The results obtained by numerical study were validated using established correlations available in literature. The results indicated that peripheral square-cut twisted tape presents a better thermal performance than plain twisted tape, due to enhanced swirl intensity and additional flow recirculation induced by square-cut. Heat transfer increases with decreasing twist ratio. Highest Nusselt number was observed at the lowest twist ratio (TR)=2, as compared to twist ratio (TR) =3, 5, 7 for all values of Reynolds number. Enhancement in the heat transfer (Nu) of 152.97%, 119.63%, 107.98%, 102.63%, enhancement in the friction factor (f. f.) of 118.19%, 114.63%, 111.085%, 107.53% and enhancement in the thermal performance factor (TPF) of 117.74%, 125.8% was obtained due to insertion of square-cut twisted tape as compared to that of plain twisted tape. 8%, 135.15%, 142.49.