Critical Heat Flux in Multi-Microchannel Copper Elements with Low Pressure Refrigerants

Acknowledgements The completion of a doctoral thesis work is a long and complex task, and the author would like to thank all those who, over the years, have contributed to it. Special thanks go to Professor John Richard Thome for his support and encouragement. The discussion with him is always of interest and has yielded valuable progress continuously. I am also grateful for the lively discussion and suggestions of the thesis jury: fabrication of the heating elements. Many of the ideas in this work were developed in collaboration with my colleagues. I would like to thank the present and past LTCM members for their support and stimulating conversations. I would especially thank some who have contributed regularly over the years: I wish to acknowledge the ATSE technicians, especially Freddy, Laurent and Marc. I have always enjoyed working with them and have learned much from their experience. I must also record my gratitude to Cécile, Nathalie, Monique and Salomé for their careful aid for administrative work. On a more personal side, I wish to acknowledge my good friends who have made this school period more pleasant and enjoyable. I have appreciated the time of playing football, dining and tasting coffee and wine with them. I would especially thank Bogdan and Enio for their respect and friendship. I also wish to thank the friends in the Geneva Korean church and the Bible study group in Lausanne. Among them, I would especially thank Seorim's family with whom my family has made a lot of happy memories. I dedicate this thesis to my wife Seong Jin and our daughter Eunsu for their understanding and love. In his heart a man plans his course, but the LORD determines his steps. De nouvelles données de flux de chaleur critique (CHF) ont été obtenues expérimentalement dans deux évaporateurs différents, faits en cuivre et composés de micro-canaux, avec trois réfrigérants à basse pression (R134a, R236fa, R245fa). Une des sections d'essai avait 20 canaux rectangulaires une résistance électrique déposée sur une plaque de silicium. Des valeurs de CHF de surface de 37 à 342 W/cm 2 ont été mesurées pour des flux de masse de 100 à 4000 kg/m 2 s. En augmentant le flux de masse, on a observé que les valeurs de CHF augmentent et que le taux d'accroissement était plus petit à des flux plus élevés. La température de saturation en entrée (10 ≤ T sat …