Thermal-hydraulic performance enhancement analysis of microtube with superhydrophobic surfaces

•The functions of friction factor and Nusselt number are obtained in slip flow.•The ratios of flow rate between slip flow and no-slip flow are deduced.•A method to analyze thermal-hydraulic performances of microchannels is developed.•The critical parameters between superhydrphobic and smooth microtube are derived. Microchannels have an excellent thermal performance but they acquire a large pressure drop. Recent studies show that microchannels with superhydrophobic surfaces may provide an innovative approach to achieve a balance between thermal and hydraulic performances. In this work, the fluid flow and heat transfer in microtube with superhydrophobic surfaces are analyzed at fully developed laminar flow, and the formulas of fRe and Nu are obtained. Comparisons of thermal resistances on superhydrophobic and smooth microtubes are performed at identical flow rate, pressure drop and pumping power, respectively. At indentical flow rate, superhydrophobic surface can’t enhance the thermal-hydraulic performance. At identical pressure drop or pumping power, the critical pressure drop and pumping power exist respertively, which is the boundary point of the thermal-hydraulic performance between superhydrophobic and smooth microtubes. The critical parameters are deduced to help determining whether superhydrophobic surfaces enhance thermal-hydraulic performance.