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Experimental, Numerical, and Analytical Investigation of Transport through Porous Media

With an Application in Electronics Cooling and Highly Efficient Thermal Management Systems

Innovative porous filled heat exchangers are being developed in this lab with an application in electronics cooling and cooling of biomedical devices. The exponential growth in electronic power results in high heat production and temperature in these devices threatening the safety of the products. As such, cooling techniques have a key role to keep the temperature of electronics devices below a maximum operating temperature. The heat exchanger design employs jet impingement technique through high conductive porous material. The effects of single and multi inlet jet impingement and different nanofluid coolants are also investigated while studying different porous structure materials and characteristics. In addition, fundamental investigation of transport through porous media is performed for variety of working fluid; liquid, vapor and gaseous working fluid.

Experimental and Numerical Investigation of Multiphase flow and Phase Change

Thermal transport in heat pipes and thermosiphons are investigated experimentally and numerically while studying fundamentals of multi phase flow and phase change. Heat pipes are passive multi-phase heat transfer devices that are desirable for a wide range of thermal management and energy storage applications, such as electronics and biomedical cooling, geothermal cooling systems, food processing, cooling of solar panels, and fuel cells. The three main parts of a heat pipe include evaporator, adiabatic section and condenser. A thermosiphon is a wickless heat pipe that relies on the body force of gravity rather than capillary forces to return the working fluid from the condenser back to the evaporator. In this research, temporal temperature and volume fraction, pressure difference across the heat pipes and flow filed characteristics in heat pipes are studied for different heat pipe designs and pipe wall structures, different fluids and concentrations for a wide range of heat flux values. Boiling and phase change in micro channels, vapor bubble growth and flow boiling enhancement in plain and structured micro-channels are also investigated. A research collaboration has been established with the thermal engineers and researchers at NASA JPL. The outcome of the current project is accepted for poster presentation at 2025 NASA Thermal and Fluids Analysis Workshop (TFAWS), hosted by NASA Ames Research Center and San Jose State University: Ellerbe, M., Daimaru, T., Wong, Z., Roberts, S., Sunada, E., and Mahjoob, S., "Performance Enhancement of Oscillating Heat Pipes Through Use of Novel Channel Cross-Sections", 2025 NASA Thermal and Fluids Analysis Workshop (TFAWS), San Jose, August 2025.

Thermal Management of Electric Vehicle Batteries

Global warming and its destructive effects have indicated the importance of design and development of efficient vehicles and thermal systems. Fossil fuels in traditional vehicles generate pollutants during the combustion process and are responsible for smog and global warming, threatening human health, wildlife, and vegetation. As such, electric vehicles and employment of lithium-ion batteries have gained popularity in the past few years to protect the environment and address the climate change issues. However, one of the challenges in the development of these batteries and energy storage systems is the generated heat due to electro-mechanical process in the batteries during operation and recharging. That causes the temperature rise in such products while there are persistent limitations in the applied cooling technologies. As such, the demand for sustainable and more efficient cooling methods for lithium-ion batteries is increased in recent years. Active and passive cooling methods are being developed using single and multi-phase liquid and air cooling methods.

Turbomachinery and Gas Turbine Cooling Techniques

Transport through turbomachinery systems and cooling techniques in these devices are other research topics in the lab, such as simulation and development of fans, stators, wind turbine blades, and turbine blades. Gas turbine application ranges from jet engines to power plants. The blades of gas turbines are subject to high temperature exhaust gases leaving the combustion chamber and need to employ a cooling system. Improving the cooling effectiveness will result in more efficient gas turbines. Some of the cooling techniques include internal convection and external film cooling. Jet injection flow rate, jet cross section shape, size, spacing and orientation, employment of conductive porous insert, jet injection angle, channel design for internal cooling, material selection, and coolant properties are some of the key parameters for gas turbine cooling.

Numerical and Analytical Investigation of Transport through Biological Media

Investigation of thermal transport within living organisms, bioheat transfer, and study of temperature variations within biological tissues and body organs are of important biological and medical thermal therapeutic applications, such as hyperthermia cancer treatment and radiofrequency ablation. The biological media can be treated as a blood saturated tissue represented by a porous matrix. In this research, comprehensive computational and analytical investigations of bioheat transport through the tissue/organ are carried out including thermal conduction in tissue and vascular system, blood–tissue convective heat exchange, metabolic heat generation and imposed heat flux. Utilizing local thermal non-equilibrium and local thermal equilibrium models in porous media, thermal transport through biological media will be numerically and analytically modeled for a wide range of geometries and tissue characteristics. Temperature distributions in blood and tissue phases are analyzed incorporating the pertinent effective parameters, such as volume fraction of the vascular space, ratio of the blood and the tissue matrix thermal conductivities, interfacial blood–tissue heat exchange, tissue/organ depth, arterial flow rate and temperature, body core temperature, imposed hyperthermia heat flux, metabolic heat generation, and blood physical properties.