| Popis: |
Cooling techniques of superheated surfaces by jet impingement with taking advantage of phase change phenomena i.e. boiling heat transfer has proven to be an efficient method because of its high rates of heat transfer. Furthermore, at a specified heat transfer coefficient, flow required for cooling purposes can reduce two orders of magnitude comparing to free-wall parallel flow which is important regarding to energy and water sustainability issues in various industries. This research mainly concerns numerical simulation of hydrodynamics and heat transfer phenomena regarding phase-change jet impingement on nucleate boiling region. Rensselaer Polytechnic Institute wall boiling model based on Eulerian multiphase model and RNG K-ɛ turbulence model were employed. Each interfacial term was considered and selected based on proximity to real physical phenomena. The selected model in this research was validated by a previously done confined jet impingement subcooled boiling experiment (dielectric fluid-PF5060). Minimum error of 4% and maximum error of 15% were reached at stagnation point. As parametric study, the effect of jet Reynolds number based on nozzle hydraulic diameter at Re 2500 to 10000 and the effect of standoff distance of jet nozzle from target surface at H/D 2, 4 and 6 were investigated. |
