Flow and heat transfer in microchannels with dimples and protrusions

Flow characteristics and heat transfer performances in a rectangular microchannel with dimples/protrusions are studied numerically in this research. The height and the width of the microchannel is 200 m and 50 m, respectively. The dimple/protrusion diameter is 100 m, and the depth is 20 m. The effects of Reynolds number, streamwise pitch, and arrangement pattern are examined. The numerical simulations are conducted using water as the coolant with the Reynolds number ranging from 100 to 900. The results show that dimple/protrusion technique in mcirochannel has the potential to provide heat transfer enhancement with low pressure penalty. The normalized Nusselt number is within the range from 1.12 to 4.77, and the corresponding normalized friction factor is within the range from 0.94 to 2.03. The thermal performance values show that the dimple protrusion cases perform better than the dimple smooth cases. The flow characteristics of the dimples/protrusions in microchannel are similar to those in conventional channel. Furthermore, from the viewpoint of energy saving, dimples/protrusions in microchannel behave better than those in conventional channel. Also from the viewpoint of field synergy principle, the synergy of the dimple protrusion cases are much better than the dimple smooth cases. Moreover, the synergy becomes worse with the increase in the Reynolds number and decrease in the streamwise pitch.