Research

Thermal Energy Storage:

Thermal energy storage (TES) materials rapidly absorb and release heat to improve efficiency and to prevent devices or components from overheating and failing. Key challenges are demonstrating high energy storage density and high cooling power densities in stable, reversible systems. We have demonstrated:

Eutectic PCMs for bespoke thermal storage media.
Strategies and tools for optimal design of high cooling-power thermal composites.
Material-specific nucleation catalysts, resulting in significant decrease in subcooling in multiple classes of PCMs.
Thermophysical properties of advanced phase change materials and composites.
Figure of merit based approaches to directly compare the performance of different materials and optimized composites.

Applications: Buildings, Electronics, Aviation/Automotive, Batteries, Oil & Gas, Appliances

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Dynamical Neuromorphic Materials:

Neuromorphic devices may enable higher performance for traditional metrics (e.g., energy consumption per operation), or allow entirely new functionalities (e.g., neuroplasticity) by emulating the function of the brain. We focus on developing materials that exhibit resistance switching (either reversible, or non-volatile) to enable new computational architectures. We have:

Developed reversible metal-insulator transitions that exhibit desired IV response.
Discovered new time-dependent responses to make neuromorphic devices more tunable.
Identified switching mechanisms and intrinsic sources of device variability.

Applications: Neuromorphic Computing, Reconfigurable Electronics, Memory

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Thermal Management

Thermal management describes the application of a variety of strategies to maintain a device within an allowable temperature range. Thermal management is a critical component of all electronics, electrical machines, buildings, and a variety of other high power systems.

Thermal management relies on mechanisms to effectively transport heat, to dissipate heat to the surroundings (generally by means of convection or radiation). If environmental conditions limit the ability to reject heat, we rely on endothermic transformations or rejections to assist the rejection of heat. To this end, we have investigated the use of phase change materials, desorption and dissociation materials, and porous conductive wicks to enhance transient heat rejection. We have demonstrated:

Composite zeolite-desorption materials that exceed 1 MJ/kg energy densities.
Strategies to enhance wicking of water in microporous aluminum foam evaporators.
Dynamical anti-resonant behavior in PCM slabs.

Applications: Buildings, Electronics, Aviation/Automotive, Batteries

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Caloric Effect Materials and Cycles

Magnetic domains in NiCoMnSn Ferrocaloric materials (magnetocaloric, barocaloric, elastocaloric, electrocaloric) serve as transducers, transforming changes in an external field to a change in the temperature or entropy of a system. This can be used to design high-efficiency refrigeration cycles or heat pumps. Despite this promise, transformation kinetics, thermodynamic irreversibilities, and other real aspects of the first order phase transformation detract from the ability of thermodynamic cycles to perform useful work. We have:

Identified methods to modify the hysteresis in caloric effect materials
Explained size-dependencies in thin films and small particles
Developed an approach to analyze arbitrary thermodynamic cycles for different classes of materials on an equivalent basis

Applications: Buildings, Aerospace/Automotive, Gas Liquifaction, Appliance, Cryogenic Cooling

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