Numerical investigation of buoyancy-driven heat transfer within engine bay environment during thermal soak

Abstract

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Heat retention analysis with thermal encapsulation of powertrain under natural soak environment

“…The buoyancy-driven flow behaviour and heat transfer modelling under vehicle soak conditions was developed and detailed previously in Yuan et al [8]. In the following, a brief description of the methodology is discussed The Lattice-Boltzmann Method (LBM) was used provided by PowerFLOW, SIMULIA [11] to solve the transient flow dynamics [12][13] with detailed vehicle and engine bay geometries.…”

“…However, from simplified geometries to full designed geometries of the engine bay compartment, to capture the natural convection flow and the convective heat transfer coefficients at around the engine, the computing resources are usually found demanding [4][5][6][7][8][9]. A 384 ~ 2,720 CPU-hours was used for simulating 1 minute transient flow structure in a simplified engine model [4], and 24,000 CPU-hours was used for a 16 hours simulated drive cycle with intermittent steady-state flow analysis of the full-geometry engine CFD model coupled with transient 1D thermal engine model [5].…”

“…A coupled transient flow dynamics 3D CFD and 3D vehicle thermal model for the full-size designed geometries of a passenger vehicle and its under-hood region took 258,000 CPU-hours for 30 minutes soak simulation [7]. The transient numerical approach were found to be essential to accurate predict natural convection flow solutions, the heat transfer in between the surrounding air flow and the engine solids, and the overall heat transfer behaviours of the engine compartments [4,[7][8]. On the other hand, a sensitivity analysis on the internal heat transfer coefficients in between the internal fluids (coolant and oil) and solid components (engine and transmission units) was conducted in a passenger vehicle under-hood region with detailed CFDheat transfer modelling [8].…”

“…The transient numerical approach were found to be essential to accurate predict natural convection flow solutions, the heat transfer in between the surrounding air flow and the engine solids, and the overall heat transfer behaviours of the engine compartments [4,[7][8]. On the other hand, a sensitivity analysis on the internal heat transfer coefficients in between the internal fluids (coolant and oil) and solid components (engine and transmission units) was conducted in a passenger vehicle under-hood region with detailed CFDheat transfer modelling [8]. It was found that the values of the internal heat transfer coefficients were not critical to the prediction of the end temperatures of the fluids 9 hours cool-down.…”

A Coupled 1D–3D Numerical Method for Buoyancy-Driven Heat Transfer in a Generic Engine Bay

“…Their computational results for the air flow, based on fully transient coupled simulations with detached eddy simulation turbulence model were in good agreement with the experimental measurements. Recently, Yuan et al [11] proposed optimum (simulation time/accuracy) modeling procedure based on coupled transient 3D CFD-1D heat transfer simulations for investigating the benefits of engine encapsulation to fuel efficincy in a passenger vehicle. Their study predicted successfully the temperature of the working fluids under a nine-hour cool-down event.…”