STUDY OF A HEAT TRANSFER MECHANISM AND CRITICAL HEAT FLUX AT NANOFLUIDS BOILING

摘要

In view of the extreme importance of an effective cooling of power equipment, as confirmed by accidents that have taken place in nuclear reactors, development of nanofluids and study of their properties, intensity of heat transfer, including boiling crisis, are very important today. For this purpose, test units for pool boiling of nanofluids investigation were constructed. A nichrome wire at alternating current has been used as a heating source. Nichrome resistivity depends on a temperature. This fact is taken as a basis of the heater's temperature determination. All measurements, data collection, and calculations of the parameters (current, voltage, critical heat flux, heat transfer coefficient, etc.) were performed by a computer and developed software data acquisition and processing system in real time. Simultaneously graphical relationships were built that specified the above variables and parameters. The obtained results allowed some conclusions to be made about essential increase of a specific heat flux that defines the boiling crisis for a number of nanofluids, influence of initial concentrations of nanoparticles in liquids, presence of dispersants, nature of nanoparticles and regimes of a fluid flow on a boiling crisis, and a heat transfer coefficient. There were preliminary conclusions also made concerning possible mechanism of nanopar-ticle influence on a heat transfer at nanofluids boiling.