A gas-liquid two-phase flow is a flow in which gas and liquid phases are mixed. The heat and mass transfer through the gas and liquid interfaces is used in various industrial equipment, such as heat exchangers, nuclear reactors, thermal management systems in space vehicles, chemical reactors, petroleum pipelines, computer chip cooling systems, air-lubrication systems in cargo ships, etc. The innovative design, optimization, safety evaluation, and performance assessment for two-phase flow equipment requires a comprehensive understanding of two-phase flow. This course introduces the fundamental concepts and methods of two-phase heat transfer. The main objectives of this course are: (a) to develop the fundamental principles of two-phase heat transfer and to explore the implications of these principles; (b) to study, analyze and design two-phase heat transfer systems through the application of these fundamental principles; (c) to develop the problem-solving skills essential to good engineering practice of two-phase heat transfer in real-world applications.