Void fractions for condensing refrigerant flow in small channels: Part I literature review

The increasing demand for miniaturization, for instance in the cooling of compact electronic components, has led to research on two-phase flow in minichannels. The present study addresses void fractions for two-phase flow of refrigerant R-134a in minichannels during condensation, which is especially important for heat rejection to the ambient. In Part I of this investigation, a review of the state-of-the-art in void fraction measurement and modeling techniques is presented. Several measurement techniques are discussed and compared including their advantages and disadvantages for use in mini and micro-channels. Particular attention is given to image analysis techniques related to those used in Part II of this study. Numerous techniques, physical and empirical bases for modeling void fraction are categorized and comparisons of the strengths, applicability, and validity are given. The need for research that motivates Part II of this study concludes this review.