25 oct
25/10/2018 14:00


Soutenance de thèse : Chi-Kien NGUYEN

Full-scale experimental characterization of a non-isothermal realistic air jet for building ventilation: local interaction effects, moisture transport and condensation

Doctorant :  Chi-Kien NGUYEN 

Laboratoire INSA : CETHIL

Ecole doctorale :  ED162 : MEGA

Understanding room air distribution with coupled heat-air-moisture transport is essential to the design of building ventilation systems. In the past decades, although numerous research have been undertaken on air jet studies, there are still some issues that deserve a consideration. In fact, the majority of these studies focused on a symmetric arrangement of supply and exhaust air outlets with respect the room geometry. Besides, studies dealing with room coupled heat-air-moisture transport, which includes the condensation phenomenon on the room inner surface, are generally lacking in the literature. Hence, this work focuses on the following problematic: What is the behavior of a realistic air jet under interaction effects and how to characterize such air jets? In realistic indoor conditions promoting condensation on cold surface, would we be able to quantify the condensate mass flow rate? The two studies are experimentally investigated in the full-scale MINIBAT controlled test cell. The first part consists in characterizing a ceiling turbulent air jet in a realistic indoor airflow configuration. The experimental results show visible interaction effects of the room architectural elements on the air jet behavior: they have deviated the jet trajectory as well as deformed the jet cross- sectional shape. The jet main characteristics such as the spread rate, the velocity and temperature decay are quantified. A graphical-based method is proposed to quantify the jet shape deformation using a so-called deformation indicator. The second part of this work treats the phenomenon of moisture condensation on a glazing surface by reproducing a winter condition within the test cell. The condensation appearance and its growth mechanism are achievable using a macro-photography technique. The image post-processing enabled to estimate the condensation rate. Comparisons between experimental and theoretical results show some agreement, which could validate the feasibility of imaging techniques in full-scale condensation studies.