Thermal energy transport is a critical aspect in a myriad of industrial processes involving power generation and energy transmission. Nucleate boiling has been employed for decades as an effective means of transferring large amount of thermal energy. Thus, if nucleate boiling heat transfer can be better controlled and enhanced, energy efficiency of these processes will be improved significantly. There are two primary goals of nucleate boiling heat transfer enhancement technologies: 1) to maximize heat transfer per unit temperature rise in the heated surface, and 2) to increase the upper limit of nucleate boiling heat transfer, also known as the critical heat flux, at which the surface is blanketed with dry vapor and catastrophic burnout may occur. The prevailing enhancement methods are based on chemically or topographically structuring the boiling surface. However, the main disadvantage of such surface structures is their static nature, which prevents active control of the spatiotemporally dynamic boiling process. Consequently, the available thermal performance of nucleate boiling is far below its enormous potentials. This project will explore a new venue to enhance nucleate boiling heat transfer by creating tunable adaptive boiling surfaces with the aid of electrowetting. It capitalizes on the complimentary roles of hydrophobicity and hydrophilicity played in nucleate boiling, and takes advantage of the ability of electrowetting to alter the surface wettability reversibly and robustly. This research will elucidate the effects of electrowetting-modulated reversible surface wetting on nucleate boiling as well as demonstrate the efficient and low-cost manufacturing of such tunable adaptive boiling heat transfer surfaces. By exploiting electrowetting, this work will provide a previously unexplored and powerful tool to actively control and optimize the key nucleate boiling processes.
Enhancing nucleate boiling heat transfer will improve the efficiency and reduce the size and cost of various energy systems. This project will provide a transformative approach to conquer the performance-limiting obstacles in nucleate boiling heat transfer technologies. Thus, it will have far-reaching impacts on industries that rely on nucleate boiling as the primary means of heat transfer. The design and fabrication techniques developed in this work will lay the foundation toward economical large-scale production of functional surfaces for boiling heat transfer applications. An integrated research and education program will be established at University of Houston, which is one of the most ethnically diverse research universities in the nation. The program will create new career opportunities for underrepresented groups by actively recruiting qualified minority and female students as undergraduate/graduate research assistants. The educational outreach activities will provide scientific training and laboratory experiences to K-12 teachers and students.