Fundamental to the law of thermodynamics, heat is an inevitable by-product for all processes. Some heat must be wasted in and rejected from heat engines. Heat must be generated in energy conversions such as electrical machines, power generators, electrical transformers and inductors, and piezoelectric actuators. Heat must be generated when energy is transferred such as electrical current in electrical wires, fluids flowing in pipes, and work transfer in a mechanical system. For the processes to continue sustainably, heat must be continuously removed effectively so that the temperature in the system is below the safety limits that are dictated by the material and reliability constraints. Techniques and designs associated with the heat removal for meeting the temperature requirements are called thermal management, which is essential to many technologies, industrial processes, engineering applications, and products.
From the late 20th century to the 21st century, scientific and technological advances have been driving continuous size reduction and power increase in systems and devices. The increased power densities usually result in high heat fluxes due to the increase of heat flow and decrease of heat transfer area. This is happening to microelectronic components, high performance computers, data centers, and also in military, automotive, power, energy, and aircraft systems.
Thermal engineers are facing challenges for developing high-heat-flux thermal designs and cooling schemes.
Most high-heat-flux cooling schemes rely on direct liquid cooling using flows such as free surface flows (droplets, jets, sprays) and internal flows (mini/micro channel flows). Research has been focusing on the enhancement of liquid cooling performance by improving flow characteristics and fluid thermos-physical properties, modifying surface conditions, using two-phase heat transfer, and so on.
Dr. Sunny Li and his team are dedicated to developing thermal management solutions, addressing thermal
issues, and investigating fundamental fluid and thermal physics.
