Conjugate forced convection and heat conduction in circular microchannels

The significance of scaling effects in a solar absorber plate with micro-channels

“…This may further explain the axial variation of ΔT pf observed in Figure 8 and Figure 9 above. [28,30,32,51]. A plot of Nusselt number against axial conduction number is shown in Figure 11; an inverse relationship can be observed.…”

“…Various explanations have been postulated for these low Nusselt numbers. For example, Celata, et al [47] attributed this to a heat loss term, Rahimi and Mehryar [32] and Nonino, et al [51] attributed it to conjugate heat transfer (axial heat conduction in the duct wall). This paper investigates the effects of some of these phenomena Figure 6 compares the measured and predicted friction factors; a similar trend can be observed in both predicted and measured values although measured friction factors are slightly lower than predicted values based on numerical Poiseuille numbers for rectangular channels (Po= 72.92 [52]).…”

An experimental and numerical investigation of the use of liquid flow in serpentine microchannels for microelectronics cooling

“…They observed that the Nusselt number ( ) and heat flux had much higher values in the region near the channel inlet due to the thin thermal boundary layer in the developing region, and its value varied around the channel periphery, approaching zero in the corners where the flow is weak. Heat sinks with rectangular [5,[7][8][9][10][11], trapezoidal [12][13][14], triangular [15] and circular microchannels [16][17][18] have been studied extensively, however a small number of experimental studies have demonstrated that other novel shapes, including U-shaped [19], wavy [20,21], tortuous [22,23] and serpentine [24] channels, can offer attractive performance advantages. A number of other channel shapes such as zigzag, curvy and step-shaped channels have been investigated numerically by Mohammed et al [25,26].…”

The effect of axial conduction on heat transfer in a liquid microchannel flow

“…Some of these studies [8,11,12] had an assumption of constant convective heat transfer coefficient at the channel wall, that is, the linkage between the channel wall and the fluid flow was treated approximately. In contrast, Nonino et al [13] analyzed the circular microtube using conjugate heat transfer, for which no approximation was introduced at the fluid-wall boundary. Recently, Kosar [14] analyzed the effect of the wall thickness and the wall material on heat transfer mechanism for a rectangular geometry with a fixed size, that is, only one geometry was studied.…”