Modeling of micro-channel critical flow with inlet sub-cooling: Metastable liquid and nucleation.

• A reliable two-fluid model of micro-channel critical flows is proposed. • The metastable liquid and bubble nucleation are included. • The reasonable constitutive relations of two-phase flow are selected. • The fluid flow, heat and mass transfer process in a micro-channel are studied. Critical flows are relevant multiphase phenomena in many applications or scenarios for chemical processes. The paper aims to propose a reliable two-fluid model to accurately simulate the micro-channel critical flow. The fluid density of the metastable liquid is determined using an isentropic transformation assumption. The onset of flashing is evaluated by solving conservation equations coupled with a nucleation model. The available constitutive relations (interfacial force and interfacial heat transfer) are compared and evaluated depending on the analysis of the transfer process in two-phase flow regions to seek reasonable constitutive relations. The paper compares the proposed model and separated flow models using available constitutive relations, especially for the pressure profile. The proposed model shows superior performance in critical flow simulations. To further advance the understanding of the critical flow, the fluid flow and transport phenomena in a micro-channel are studied intensively, especially for the cooling of micro-channels. [ABSTRACT FROM AUTHOR]