Thermal and flow characteristics of micro-encapsulated phase change material slurry in helical coil heat exchanger with reversed loops.
Proposed and fabricated a newly designed helical coil heat exchanger test section. Flow and thermal behaviors of fluids flowing through the test section are investigated both experimentally and numerically (ANSYS Fluent).
Latest Projects
Pool boiling on horizontal heaters with and without nano-structures.
In a nutshell, we were aiming to test the potentials of improving boiling heat transfer efficiency for different nanostructure coatings on the silicon wafer. Boiling heat transfer, with a high heat dissipation ability (W/m^2), can be the solution for high cooling demand, for example, cooling for supercomputer center and chip cooling. I did nano-coatings to the silicon wafer using chemical vapor deposition and photolithography techniques before applying the silicon wafer as the pool boiling heater.
PROJECTS
5+ years of engineering project experience. Selected graduate level projects are listed include both experimental and numerical work mostly focusing on heat transfer, fluids and energy.
Synthesis of silicon hard shells micro-capsules for micro-encapsulation.
Porous hollow inorganic microcapsules are a promising material for many different types of potential applications such as protection of biologically active agents, encapsulation and controlled release of various substances. A fabrication process via the double-emulsion method is proposed for hollow porous silica hard shell which is the base of silica hard shell micro-capsules (HSMCs) before its encapsulating process. It was found that silica HSMCs with diameter of 100 μm, which was usually around 20 μm from all previous fabricating process, would have the best performance for latent-heat transport application. Therefore, instead of a formerly used homogenizer, a new mixer is employed for mixing process during double emulsion method in order to push the particle size limit towards 100 μm.
Microchannel device design for constant wall temperature studies on non-porous and copper mesh channels.
Extensive analysis on the design of a copper microchannel device was made in order to allow the study of the thermal performance of microchannels sitting on a porous meshed copper substrate, once fabrication of these meshes has been completed. This study involved examining the microchannel device and optimizing it for experimentation in constant wall temperature studies. The essential criteria for the microchannel device involved: keeping the flow in the thermally developing region, ensuring constant wall temperature conditions are met, and ensuring dominant heat loss mechanisms. Our analytical and computational results from the optimization of the device showed that 8 microchannels are needed to ensure sufficient heat loss through forced convection and channels of length of 10 mm to be in the thermally developing region. Also, simulation results concluded that dynamic entrance effects play a significant role since impingement at the microchannel entrance greatly decreases wall temperature.
InSb Chip Cooling Analysis (COMSOL).
In aerospace, infrared (IR) detector is widely used for thermal imaging. However, a low operating temperature is necessary to get a good IR detector performance to eliminate the influence from noise and dust to the IR detector circuit chip. One of the main goals is to reduce the circuit chip temperature from ambient temperature to 80 K-100 K after launch as soon as possible. A cooling substrate can be attached to the chip and apply liquid nitride cooling on the other side of the substrate. We constructed a simplified chip geometry and conducted a numerical heat transfer analysis using COMSOL with consideration of impinging convection, heat conduction boundary condition and 2-D heat distribution. By comparing the analytical and numerical results, we aim to find new path to improve the traditional chip cooling methodology.
