Influence of W-cut twisted tape inserts on heat transfer characteristics of a counter flow heat exchanger using CeO2 nanofluid – an experimental and numerical investigations

Abstract

The motive of the study is to determine the influence of W-cut twisted tape (TT) inserts on heat transfer rate (HTR) and the pressure drop of a TTCFHEx. The TT inserts involved a constant twist ratio (TR = 3) with variations in width ratio (WR) and the depth ratio (DR), respectively. Cold fluid (CeO2 nanofluid) Reynolds number (Re) varied from 2,436 to 11,626 while the hot fluid Re (Re = 8,322) is kept constant. From the study, insertion of TT insets in a TTCFHEx creates a swirl flow along with secondary vertex flow in the flow direction, leads to disruption of boundary layer thickness and which helps in improve the heat dissipation rate. Further, important findings from the study is noted that the Nusselt number (Nu) increases significantly at higher WR and DR with considerable increase in the pressure drop. However, at ϕ = 0.3% with insertion of TT inserts in a TTCFHEx, Nu number advanced by 71.52%, 80.40%, 127.65% than the base fluid without inserts. Further, at higher WR and DR the augmentation of HTR is found to be 1.5-times higher than the plain tube (PT) with considerable increase in the pressure drop. In the presence of nanofluid with W-cut TT inserts, the overall heat transfer coefficient (HTC) is enhanced by 34.68%, 41.82%, 52.65% and 36.26%, 44.25%, 50.14% for WR (4/15, 8/15, 12/15) and DR (2/15, 4/15, 6/15) compared to base fluid water with PT for both numerical and experimental investigations are considered in range of Re studied. Also, the computed experimental and numerical performance evaluation criteria (PEC) is found to be 2.16 and 2.09 for WR = 12/15 and DR = 6/15, respectively, at higher values of Re number.