Investigation of effect of geometric structure on two phase flow heat transferin microchannels

In This research numerical investigation of two phase flow structure and heat transfer in microchannels with0.55 and 0.7 millimeter hydraulic diameter has been done. For this purpose, Ansys Fluent software has beenused and has wrote a UDF code for modeling of phase change process in this software. Inlet flow has beenassumed as super heat vapor of R134a and microchannel wall boundary condition is considered as constantheat flux. Effect of geometric cross section of microchannel in 3 cross section circular, square and trapezoidwith inlet mass flux range 100-600 𝑘𝑔/(𝑚2𝑠) on heat transfer coefficient and pressure drop has beenevaluated. Also two phase flow structure in two mentioned hydraulic diameter with same boundary conditionhas been studied. Under the same conditions of input mass flux and cross-section of the microchannel, it wasobserved that heat transfer coefficient in microchannel with 0.55 millimeter hydraulic diameter, is higherabout 15%. Also in a specific range of input mass flux, pressure drop in 0.55 millimeter hydraulic diameteris 3 times higher than 0.7 millimeter hydraulic diameter. Also in both two hydraulic diameter 0.55 and 0.7millimeter, square, circular and trapezoid microchannel have higher heat transfer coefficient in respect.