Thermal management of heat-generating automotive powertrain hardware using spray evaporative cooling

Sarmadian, Alireza (2021) Thermal management of heat-generating automotive powertrain hardware using spray evaporative cooling. Doctoral thesis (PhD), University of Sussex.

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Thermal management of heat generating powertrain hardware in automotive vehicles is examined using spray evaporative cooling, particularly taking account of the effect of vehicle vibration and agitation. The heat transfer characteristics of spray evaporative cooling of vibrating surfaces are important for both automotive and aerospace applications but this thesis content focuses on automotive applications involving highly-boosted IC engines, power electronics, batteries, and electrical machines.
The fundamental physics of highly complex two-phase spray evaporative cooling is currently computationally intractable, therefore the thesis addresses (for the first time) construction and calibration of correlation models of spray evaporative cooling involving vibrating surfaces. Suitable correlation models are constructed using dimensional analysis involving the Generalized Buckingham Π-Theorem. Two nondimensional parameters are introduced in the form of Acceleration Number and Vibrational Reynold Number to account for dynamic effects resulting in models which accommodate the combined effects of vibration amplitude and frequency. The correlation models are fitted to experimentally-measured spray evaporative cooling data taken from an experimental test rig which includes instrumented test-pieces vibrated by a shaker to amplitudes and frequencies appropriate for real (on-road) vehicle conditions. The models provide dynamic predictions of heat flux in the nucleate boiling regime, and predictions of the Critical Heat Flux and its associated temperature. The experimental measurements alone show that dynamic effects do indeed influence heat transfer.
Thermal management in the nucleate boiling regime using a feedback control system for flat and curved surfaces with, and without vibration, has been subsequently studied in the thesis using simulation and experimental hardware. The performance of a PID controller within a thermal management system has been examined using the calibrated correlation models to provide an approximate description of the ‘plant’ physics. A detailed examination is made of the effect of the PID controller gains on the performance of a thermal management system in terms of stability and practical response requirements with, and without vibration.
The results of the study confirm that thermal management of heat-generating automotive powertrain hardware is a definite practical possibility using evaporative spray cooling.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: T Technology > TL Motor vehicles. Aeronautics. Astronautics
Depositing User: Library Cataloguing
Date Deposited: 24 Sep 2021 14:17
Last Modified: 24 Sep 2021 14:17

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