Numerical Investigation of Natural Convection in a Simplified Engine Bay

Minovski, Blago; Löfdahl, Lennart; Gullberg, Peter

doi:10.4271/2016-01-1683

Cited by 8 publications

(11 citation statements)

References 4 publications

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“…The soak condition results from the abrupt decrease of the cooling air flow in the engine bay after intensive driving. A sudden decrease of convective heat flux causes the surface temperatures of the components adjacent to the exhaust section to raise [3,4]. Predicting accurately buoyancy-driven heat flow in the engine bay is thus of high relevance during the thermal soak period, as well as for prolonged times when a vehicle is parked in a quiescent environment.…”

Section: Intoductionmentioning

confidence: 99%

“…The numerical procedure employs a transient 1D thermal analysis for the engine solids and a steady-state 3D CFD solution for the fluid flow. This choice was motivated by the authors' previous study [4], which showed that modeling of the radiation and convection heat transfer is dominant over high-resolution flow for accurate predictions of the air temperature [4]. The intention with this approach is to strike the balance between accuracy and computational speed while capturing the relevant physcis of the vehicle underhood.…”

Section: Intoductionmentioning

confidence: 99%

“…Previous studies indicate that radiative heat transfer takes an important part in the total heat transfer in cases of conjugate natural convection [4,15,16]. Due to very high temperatures in the vicinity of the exhaust manifolds, it is necessary to take into account the effect of the heat radiation on the buoyancy-driven flow.…”

Section: Thermal Radiationmentioning

confidence: 99%

“…The governing equations of the fluid flow are numerically solved in STAR-CCM+ and a polyhedral computational mesh with a total cell count of 25 million is generated from the CAD model of the enclosure and the containment area [4]. The average spatial discretization varies within the limits of 2 and 120 mm depending on the location.…”

Section: D Cfd Numerical Solver For the Fluid Flow And Heat Transfermentioning

confidence: 99%

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

et al. 2019

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Energy efficient vehicles are essential for a sustainable society and all car manufacturers are working on improved energy efficiency in their fleets. In this process, an optimization of aerodynamics and thermal management is most essential. The objective of this work is to improve the energy efficiency using encapsulated heat generating units by focusing on predicting temperature distribution inside an engine bay. The overall objective is to make an estimate of the generated heat inside an encapsulation and consecutively use this heat for climatization purposes. The study presents a detailed numerical procedure for predicting buoyancy-driven flow and resulting natural convection inside a simplified vehicle underhood during thermal soak and cool-down events. The procedure employs a direct coupling of one-dimensional and three-dimensional methods to carry out transient one-dimensional thermal analysis in the engine solids synchronized with sequences of steady-state three-dimensional simulations of the fluid flow. The boundary heat transfer coefficients and averaged fluid temperatures in the boundary cells, computed in the three-dimensional fluid flow model, are provided as input data to the one-dimensional analysis to compute the resulting surface temperatures which are then fed back as updated boundary conditions in the flow simulation. The computed temperatures of the simplified engine and the exhaust manifolds during the thermal soak and cool-down period are in favorable agreement with experimental measurements. The present study illustrates the capabilities of the coupled thermal-flow methodology to conduct accurate and fast computations of buoyancy-driven heat transfer. The methodology can be potentially applied to design and analysis of multiple demand vehicle thermal management systems in hybrid and electrical vehicles.

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Section: Intoductionmentioning

confidence: 99%

Section: Intoductionmentioning

confidence: 99%

Section: Thermal Radiationmentioning

confidence: 99%

Section: D Cfd Numerical Solver For the Fluid Flow And Heat Transfermentioning

confidence: 99%

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

et al. 2019

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“…Buoyancy-driven flow in the automotive underhood has been the subject of a number of previous studies, which dealt with experimental and numerical strategies to predict this phenomenon. 10,11 Most of them share a common finite-element approach to model flow and heat transfer based on the solution of Navier–Stokes equations in their three-dimensional form. Non-laminar flow regimes require the use of turbulence models to correctly describe the Reynolds stresses in the momentum equation.…”

Section: Numerical Modelsmentioning

confidence: 99%

A numerical investigation of thermal engine encapsulation concept for a passenger vehicle and its effect on fuel consumption

Minovski

Andrić

Löfdahl

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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Increasingly tough regulations for emission levels and a growing demand for an environmentally clean motor industry impose high requirements in modern automotive development. During recent decades, carmakers have been utilizing various strategies to minimize energy losses in the powertrain to meet legislative and market demands. A great part of research efforts has been focused on improving engine performance during cold starts characterized by increased friction losses. Thermal engine encapsulation is an effective design choice to reduce engine friction in applications with frequent cold starts. In the present work, a coupled 1-D–3-D system-level approach is used to investigate the effects of a novel engine-mounted encapsulation concept featuring air shutters on fuel consumption in a Volvo S80 passenger vehicle. Simulations are performed for sequences of the Worldwide harmonized light vehicles test cycle (WLTC) drive cycle, which include different time intervals of engine inactivity when the car is parked in air of an quiescent ambient temperature. The results show that engine encapsulation with high area coverage (97%) can retain engine oil temperature above 19°C for up to 16 h after engine shutdown at an ambient temperature of 5°C, leading to 2.5% fuel saving during engine warm-up when cold starts occur between 2 and 8 h after key-off. Encapsulations with a lower area coverage (90%) have proven to be less effective, with fuel saving of 1.25% as the temperatures of the oil and engine structures decrease more quickly after key-off compared to the fully enclosed encapsulation.

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

Yuan

Sivasankaran

Dutta

et al. 2020

Applied Thermal Engineering

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Numerical Investigation of Natural Convection in a Simplified Engine Bay

Cited by 8 publications

References 4 publications

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

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

A numerical investigation of thermal engine encapsulation concept for a passenger vehicle and its effect on fuel consumption

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

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