Experimental and numerical investigation of boiling flow in a vertical pipe with phase change using a multi-fluid modelling approach

摘要

Multi-phase boiling flow inside a vertical pipe is simulated as part of a preliminary study of the heat transfer characteristics of coolant flow inside water cooling jackets in IC engines. Based on increasing demands for higher efficiency inside the engine cooling block, heat transfer plays an important role in a conceptual and thermal analysis used to provide efficient cooling. The simulations of thermal and flow phase change characteristics inside a vertical pipe boiling system were made to prevent component failure and to create a uniform temperature distribution inside the water cooling jacket. The developed boiling mass transfer model, such as the BDL (Boiling Departure Lift-off) model, has empirically correlated heat transfer coefficients and is implemented within the commercial computational fluid dynamics code AVL FIRE(r). Governing equations are based on the Eulerian multi-fluid approach which treats each phase as interpenetrating continua coexisting in the flow domain, with inter-phase transfer terms accounting for phase interactions. Turbulence is modelled by using an advanced k- ζ-f/ model. In this paper, we focus on comparison and suitability of the mentioned boiling model with two different boundary condition approaches to determine the HTC (heat transfer coefficient) for multi-phase boiling flow inside the vertical pipe. Temperature measurements along the height of the pipe were performed at three different positions. Comparison with the available experimental data for different boundary conditions is presented. Simulation results exhibit good agreement with the experimental data.