Pressure Drop Analysis Using the Homogeneous Model for Open Microchannel With Manifold (OMM)

Abstract

Flow boiling in microchannels has the ability to dissipate high heat fluxes due to the associated small hydraulic diameter and latent heat effects. However, flow instabilities and early critical heat flux have often limited the heat transfer performance of such systems. In a previous study, the open microchannel with manifold (OMM) design was introduced to address these issues. Low pressure drop at high heat flux were obtained with this configuration. In this work, theoretical modeling of pressure drop for the OMM geometry with a uniform and a tapered manifold is undertaken. Applicability of the homogeneous model is evaluated using seven different viscosity averaging schemes. Experiments were performed with two test sections (one plain and one with open microchannels) and with four different manifolds (one uniform and three tapered). All experimental data with various configurations were compared with the different viscosity models. The viscosity model of Owen et al. predicted the highest value of pressure drop, while the lowest value was obtained with that of Dukler et al. All models underpredicted for uniform manifold with plain and microchannel chips with an average MAE of 50%. For tapered manifolds, plain chip underpredicted, while good agreement was obtained with microchannel chip for McAdams et al. and Akers et al.