ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
NUMERICAL ANALYSIS OF THE EFFECTS OF HYPERGRAVITY ON FLOW BOILING CHARACTERISTICS IN MICROCHANNELS
Résumé
Three-dimensional numerical simulations of flow boiling of R134a in a circular microchannel under diverse hypergravity levels (1−15 g) and directions (0°−180°) were conducted. Flow patterns, temperature and pressure fields are obtained based on the VOF model, and then the effects of hypergravity on flow boiling characteristics are analyzed. The results demonstrate that the effects of hypergravity are significant. When the hypergravity is perpendicular to the flow (θ = 90°), the flow evolves into a quasi-stratified flow with the increasing hypergravity, the heat transfer coefficient decreases and the frictional pressure drop decreases slightly. When the hypergravity has the same direction as the flow (θ = 0°), the vapor phase changes into a quasi-ellipsoidal/spherical shape, the heat transfer coefficient remains basically invariable, while the frictional pressure drop decreases. When the hypergravity has the opposite direction with the flow (θ = 180°), the vapor phase converts into elongated slugs, the heat transfer coefficient keeps almost unchanged, while the frictional pressure drop increases.