Estudo dos Mecanismos de Ebulição em Permutadores de Calor Líquido/Gás - Water Charge Air Cooler (WCAC)

Gonçalo Gil Dos Santos Cunha

Key information

Authors:

Gonçalo Gil Dos Santos Cunha (Gonçalo Gil Dos Santos Cunha)

Supervisors:

António Luís Nobre Moreira (António Luís Nobre Moreira); Ana Sofia Oliveira Henriques Moita (Ana Sofia Oliveira Henriques Moita)

Published in

October 23, 2020

Abstract

The continuous search for more efficient heat exchangers - in particular, those with liquid coolant - promotes, depending on the working conditions, the occurrence of boiling. Consequently, the performance, integrity of the equipment components and coolant can be compromised. The present work was held in collaboration with the JDEUS company with the aim of understanding the physics behind boiling phenomenon in an intercooler under development for the automotive industry. In order to better understand the aforementioned problem, a theoretical background overview is presented, with special focus on its onset mechanisms. In addition, a number of studies to predict the onset of nucleate boiling were analysed, including information on key assumptions, model development and incipient heat flux empirical correlations. The experimental work was mainly performed on the company's test bench, equipped with different sensors, which allowed the validation of numerical simulations (developed by the company) and detection and quantification of the coolant boiling intensity under several operating conditions. Furthermore, an experimental setup was developed with optical access to detect the occurrence of boiling in its early stages. Theoretical and mathematical analysis of the previous studies' correlations allowed a better comprehension of boiling physical principles. Experimental test bench results exhibited good agreement with the previously obtained numerical results. Additionally, a set of outlet parameters was identified as reliable quantifiers of the boiling degree. The laboratory experiments corroborated the occurrence of boiling in less severe working conditions, for which the test bench was not able to identify.