Fundamental Issues of Critical Heat Flux Phenomena During Flow Boiling in Microscale-Channels and Nucleate Pool Boiling in Confined Spaces

This article presents a comprehensive literature review on the fundamental issues of critical heat flux (CHF) during flow boiling and nucleate pool boiling in microscale channels and confined spaces. First, distinction between macro- and micro-scale channels is discussed. Then the CHF mechanisms are discussed. Next, experimental and theoretical studies of subcooled flow boiling CHF in microscale channels together with the prediction methods are reviewed and analyzed. Following this, experimental and theoretical studies on saturated flow boiling CHF together with the prediction methods are summarized and discussed. Furthermore, experimental and theoretical studies on nucleate pool boiling CHF in confined spaces together with the relevant prediction methods are reviewed as well. So far, limited studies on CHF microscale channels and confined spaces are available in the literature. There are numerous discrepancies in the existing studies on CHF results, mechanisms, and prediction methods. Furthermore, there are no generalized prediction methods for CHF in microscale channels and confined spaces. According to this review, future research needs for the experiments, mechanisms, and prediction methods of CHF phenomena in microscale channels and confined spaces have been addressed.