Experiments were conducted to study the drag-reduction and heat transfer performances of a newly synthesized zwitterionic surfactant solution (oleyl trimethylaminimide) in a two-dimensional channel. For testing the drag-reduction at subzero temperatures, a 20% ethylene glycol aqueous solution (EG/W) was used as solvent. The surfactant concentration ranged from 50 to 1000ppm and the temperature was 5 and 25℃, respectively. It was found that the novel zwitterionic surfactant solution showed both drag and heat transfer reduction characteristics, which were affected by concentration and temperature. The maximum drag-reduction was 83% at 25℃ for 200ppm surfactant solution. The effects of addition of NaNO2 to the surfactant solution were also investigated. For enhancing heat transfer of the surfactant drag-reducing flow, a destructive device, named Block, was designed and used in the experiments. The Block device has two contracting–expanding flow passages on both sides respectively with the central part blocked. It was found that the Block device can enhance the heat transfer performance of the novel zwitterionic surfactant solution to some extent while having a very small pressure drop penalty compared with other researcher's destructive devices due to the dominant action of elongational stress.

For the purpose of cooling electronic components with high heat flux efficiently, some experiments were conducted to study the flow boiling heat transfer performance of FC-72 on silicon chips. Micrpin-fins were fabricated on the chip surface using a dry etching technique to enhance boiling heat transfer. Three different fluid velocities (0.5, 1 and 2m/s) and three different liquid subcoolings (15, 25 and 35K) were performed, respectively. A smooth chip (chip S) and four micro-pin-finned chips with the same fin thickness of 30 lm and different fin heights of 60 lm (chip PF30-60) and 120lm (chip PF30-120), respectively, were tested. All the micro-pin-finned surfaces show a considerable heat transfer enhancement compared to the smooth one, and the critical heat flux increases in the order of chip S, PF30-60 and PF30-120. For a lower ratio of fin height to fin pitch and/or higher fluid velocity, the fluid velocity has a positive effect on the nucleate boiling curves for the micro-pin-finned surfaces. At the velocities lower than 1m/s, the micro-pin-finned surfaces show a sharp increase in heat flux with increasing wall superheat, and the wall temperature at the critical heat flux (CHF) is less than the upper limit, 85℃, for the reliable operation of LSI chips. The CHF values for all surfaces increase with fluid velocity and subcooling. The maximum CHF can reach nearly 150 W/cm2 for chip PF30-120 at the fluid velocity of 2m/s and the liquid subcooling of 35K.