Numerical Thermohydraulic Analysis of Flow Boiling in Geometrical-Modified Microchannels

One of the major issues of flow boiling in microchannels is ensuring adequatemanagement of thermohydraulic instabilities which severely impact the system’s efficiency in terms of pressure drop and heat transfer coefficient(HTC). The current study focuses on microchannels with geometric modifications, varying inlet conditions and geometry dimensions with view on mitigating thermohydraulic instabilities and improving overall performance.The study used Computational fluid dynamics (CFD) software -ANSYS Fluent -with the Volume of Fluid (VOF) model to simulate the flow boiling in microchannels.The flow is transientand laminar in a 3-D domain with water (H2O-liquid) as working fluid. Theflow and heat transfer characteristics in baseline rectangulararecompared withconstricted inlet-, and expandinginlet microchannels. Pressure drop, heat transfer coefficient, Nusselt number, and frictional factor are studied and visualized across varying mass fluxes3000 –7000 kg/m2s(for all microchannels) and angle of divergence0.2o–1o(for the expanding inlet). The expanding inlet microchannel showed a better thermohydraulic performance, having a 63.25% increase in HTC and a 64.16% reduction in pressure drop compared to the baseline design, highlighting its potential for enhancing thermohydraulic stability. Also, the angle of divergence gave more insights to the expanding inlet microchannel with 0.2ohaving a better performance. These findings solidify the critical role of geometric modifications in optimizing microchannel performance, with the expandinginlet design resulting as theconfiguration for a better heat transfer performance and pressure stability, thus giving valuable insights for advancements in microchannel designand flow boilingapplications.