Investigation on the thermohydraulic performance and entropy-generation of novel butterfly-wing vortex generator in a rectangular microchannel

In the present study, a 3D numerical analysis is carried out to understand the effect of the butterfly-wing vortex generator on the thermohydraulic performance and entropy-generation in a rectangular microchannel. To validate the numerical model, experiments are carried out in the plain microchannel of width (W) = 1 mm, height (H) = 0.63 mm, and length (L) = 50 mm. Further, the simulation is extended to study the effect of several geometric parameters of the butterfly-wing vortex generator, i.e., height (h) = 0.05, 0.1 & 0.2 mm, bigger width (w) = 0.24, 0.36 & 0.48 mm, smaller width (b) = 0.12, 0.18 & 0.24 mm, length (l) = 1, 2 & 3 mm, and number of wings (n) = 5, 8 & 11 with varying Reynolds number (Re) in the range of 142-945. Thus, a total of tweleve different combination of microchannel are formed by varying the geometric parameters of the butterfly-wing to carry out the parametric study. The simulation results reveal that the presence of the butterfly-wing vortex generator enhances the convective heat transfer rate (10–26) % with an increase in pressure drop (3–14) %, and reduces the total entropy-generation (3–16) % when compared to a plain microchannel. It is also found that with an increase in h, n, and w, the friction factor (f) increases (7–13) %, (3–8) % and (1–9) %, respectively,while the average Nusselt number (Nuavg) increases (4–11) %, (4–9) %, and (5–12) %, respectively, by increasing Re value from 142-945. However, the l has no significant effect on f and Nuavg. A decreasing trend of Nuavg is seen for increasing b, whereas f does not vary significantly with b. The total entropy generation (SG) decreases with the increase in h, n, and w and remain invariant for b and l. For the studied geometric parameters and Re values, the maximum increase in performance of 23 % and a maximum reduction in total entropy-generation of 16 % are obtained for the microchannel with butterfly-wing of w = 0.48 mm, b = 0.24 mm, l = 3 mm, h = 0.1 mm, n = 5 at Re = 945.