Droplet Impingement and Spray Cooling
Spray cooling is one of the most effective method of cooling high heat flux applications. Numerous studies have explored the spray cooling heat transfer; however, the fundamental physics of this phenomena is still unknown. The lack of fundamental knowledge results in two common issues in spray cooling method, the dry-out and the excessive liquid accumulation. Therefore, the applications of spray cooling are limited, especially in high heat flux electronic cooling. Single droplet impingement has gained recent attention to provide comprehensive understanding of spray cooling technique. The main goal of this research is to experimentally investigate the heat transfer of a single water droplet impacting onto a heated surface under different conditions and surface temperatures.
Thermal Control of 3D Steerable Brachytherapy Needle
The goal of this project is to design an effective cooling system for a brachytherapy needle which is actuated with three shape memory alloy wires (SMA). The SMA wires respond to temperature gradient and contract when their temperature increases. This contraction is sufficient enough to bend a needle that has proper flexible or soft joints inserted throughout its axial direction. The heating process can be easily done utilizing joule heating, also known as resistive heating. However, the temperature of the body of the needle cannot exceed a certain allowable value. Also, the wires must be cooled down to a certain temperature in order to straighten back the needle, which will take quite a while if no cooling process is provided especially when the needle is at body temperature. Therefore, a thermal control system must be designed for these needles to keep the body of the needle at a constant temperature, heat and cool the SMA wires to desired temperatures to steer and deflect the needle.