Study Of Pool Nucleate Boiling Heat Transfer With Concept Of "Interfacial Vaporization Heat Sink

Boiling is a heat transfer process with phase change in which a series process of the formation,growth and departure of a number of boiling vapor bubbles exists so that it includes various underlying phenomena. The interfacial vaporization heat sink coming with the evaporation of micro-liquid film at interface has the enhancement effect on boiling heat transfer. The mechanism of pool nucleate heat transfer and phenomena in its process are analyzed with the concept of interfacial vaporization heat sink in this present thesis. The method of LDCT and simultaneously measuring heat transfer is used to separate the effect of interfacial vaporization heat sink. The experimental results are given to show this effect in pool nucleate boiling.As fast development in new technology such as microelectronic device,pool boiling heat transfer is an attractive to the removing amount of heat from a heat transfer system with small volume because it has extremely high heat transfer coefficient. In recent years,pool boiling has come to the forefront of high-heat-flux thermal management research for many applications. The influence of hysteresis of boiling process on the operation of microelectronic components attracts many researcher's attention. In this thesis,the mechanism of boiling hysteresis are analyzed in several aspects based on the formation of a boiling bubble nucleus and the concept of interfacial vaporization heat sinkDissolved gas may have the effect on the heat transfer in a nucleate boiling process. The experimental results of the effects of dissolved gas on boiling hysteresis and on the heat transfer are explained based on the concept of effect of interfacial vaporization heat sinkThe experiment is also conducted to investigate the effects on the boiling hysteresis and on the effect of inter facial vaporization heat sink of two water soluble surfactants (AEDT and HBS). The results show that we are still far from a systematic theory or explanation for the effect of surfactant additives on the boiling heat transfer. It seems that some more fundamental work should be done for this problem.The nucleate boiling heat transfer of formation < growth and departure of a single bubble is primarily analyzed,and the mathematical results with the numerical method are given to character the change in surface temperature during the evaporation of micro-liquid film.In a gas-lift loop apparatus,the experiment is conducted to study the heat transfer characteristic of alcohol drobble evaporating while rising in a column of the hot sucrose solution with high viscosity. The experimental results show that the evaporating heat transfer can be augmented by the effect of interfacial vaporization heat sink. At the bottom of the drobble,there is the vague interface on which sucrose nucleation takes place because of the opposite diffusions of alcohol and water.