Empirical model for evaluating jet impingement heat transfer in presence of a spatially varying heat source

  • Ein empirischer Ansatz zur Auslegung des Wärmeübergangs von Prallstrahlen bei örtlicher Variation der Wärmequelle

Sabelberg, Enno; Kneer, Reinhold (Thesis advisor); de Doncker, Rik W. (Thesis advisor)

Aachen : RWTH Aachen University (2021, 2022)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021

Abstract

Jet impingement is a cooling technique with high local heat transfer rates and suitable for applications with high local thermal loads. In the field of power electronics, the power density of electrical components and modules has risen immensely in recent years. Due to high local thermal losses of electronic modules, jet impingement cooling is a promising approach for these applications. Yet, the numerical evaluation of jet impingement cooling is computational expensive, especially for more dimensional setups. Jet impingement is examined as cooling application focusing on the reduction of the computational effort. Therefore, methods are developed to calculate multi-dimensional temperature profiles for supplied spatially varying heat flux. The methods are extended with further heat conducting interlayer between heat source and jet impingement. The jet impingement issue is therefore continuously reduced to simplified problems, which are solved separately and later combined to solve the general issue. First, the simplified problem of rotationally symmetric jet impingement with partial heating along the wall is solved. Second, correlations for the temperature distribution along the wall are identified. Third, the correlations are combined with the principle of superposition to generate the temperature profile for rotationally symmetric but radially varying heat fluxes. The superposition method is extended to solve a two-dimensional temperature field with spatially varying heat fluxes. In order to find a solution for the heat transfer in jet impingement, including an interlayer, the superposition method is coupled with a thermal conduction model. Compared to simulation data, the iterative approach achieves adequate results and requires significantly less calculation efforts. This study presents stringent and reliable methods to solve the temperature field for different setups of jet impingement, focusing on cooling of spatially varying heat fluxes, which is for example supplied by a power electronic modules with multiple electrical components. This allows for a computational efficient design process for jet impingement coolers, in which additional interlayers have to be considered.

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