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Báo cáo hóa học: " Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe | Park and Chang Nanoscale Research Letters 2011 6 284 http www.nanoscalereslett.eom content 6 1 284 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe Yu sun Park and Soon Heung Chang Abstract A two-phase flow experiment using air and water-based g-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction interfacial velocity interfacial area concentration and mean bubble diameter were evaluated and all of those results using the nanofluid were compared with the corresponding results for pure water. The void fraction distribution was flattened in the nanofluid case more than it was in the pure water case. The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid. This was the first attempt to measure the local two-phase flow parameters of nanofluids using a conductivity double-sensor two-phase void meter. Throughout this experimental study the differences in the internal two-phase flow structure of the nanofluid were identified. In addition the heat transfer enhancement of the nanofluid can be resulted from the increase of the interfacial area concentration which means the available area of the heat and mass transfer. Introduction The conventional method of increasing the cooling rate is to use extended heat transfer surfaces for exchanging heat with a heat transfer fluid. However because this approach requires an undesirable increase in the size of the system there is a need to develop advanced cooling techniques and innovative heat transfer performances than those presently available. Over the last several decades engineers have attempted to develop fluids which offer better cooling performances for a variety of thermal systems .