Resources — Thermal Transport and Energy Harvesting

THERMAL TRANSPORT

Louis Guido, associate professor, and Guo-Quan Lu, professor, both jointly appointed in electrical and computer engineering and materials science and engineering, are developing nanoscale materials and devices to achieve the highest possible values of energy conversion efficiency in applications such as white-light generation (solid-state lighting) and solar energy conversion (alternative energy sources). The materials and devices under study include semiconductor quantum dots for light generation and detection, and metal nano-particle-based composite materials that enable advanced device packaging topologies.

Scott Huxtable, assistant professor of mechanical engineering, is doing research to understanding the mechanisms of thermal transport, or heat flow, between dissimilar materials at the molecular level. Huxtable will use laser techniques — timed by the picosecond, or one-trillionth of a second — to determine at the nanoscale how heat is transferred across the boundary between two materials. A primary goal of his project will be discovering what types of chemical modifications can be made to the surfaces of materials to control the flow of heat. Understanding heat flow at this level could help engender the design of nanostructured composite materials capable of controlling thermal conductivity. Better control of thermal conductivity could lead to the development of high-efficiency thermoelectric coolers, which offer distinct advantages over conventional refrigerators and other cooling devices becasue they have no moving parts to break down and do not use harmful chemicals. Another result of thermal transport research could be a way to manage the tremendous amount of heat generated by miniaturization of power electronics devices, including computers and cell phones. Heat is becoming the limiting factor in device performance. Controlling thermal transport at the nanoscale could help minimize the problem. His research is supported by his National Science Foundation CAREER award.

Danesh Tafti, associate professor of mechanical engineering, is studying designs of novel heat surfaces for heat exchangers in next generation CO2 refrigerant systems. CO2 is a natural refrigerant with no adverse environmental impact, and operates at extremely high pressures in the vapor compression cycle. This research is sponsored by Modine Manufacturing Co. and the U.S. Army.

ENERGY HARVESTING

Barbar Akle, a research scientist with the Researchers from the Center for Intelligent Material Systems, and Andrew Duncan, a student in the Macromolecular Science and Engineering program, along with others from chemical engineering, chemistry, and mechanical engineering are researching electromechanical transduction -- the phenomenon that couples an electrical potential applied across a conducting material with a resulting mechanical response. Ionic polymer transducers (IPT), flexible devices based on this coupling of physical domains, are composed of ion-conducting polymer membranes saturated with an ion-conducting diluent, an interpenetrating electrode layer, and an electrically conductive surface layer. IPTs attract attention in the area of alternative energy sources due to their ability to produce electrical current under repeated mechanical deformation. The magnitude of the current that IPTs generate lends itself to employment in long-term power harvesting and for powering low-energy devices.

Levon Asryan, associate professor of materials science and engineering, is developing theoretical approaches for enhancing energy output from light-emitting devices, which exploit tiny insertions of semiconductor material of one type in a host material of a different type. These insertions, in view of their small size (typically one hundredth of a micron), are called quantum dots and are stimulated to controllably produce light by applying an electrical current. Among perspective applications of quantum dot lasers are information and communication systems (such as Internet, high-speed fiber networks and mobile phone networks) and chemical sensing. This research is funded by a grant from the U.S. Army Research Office.

Romesh C. Batra, the Clifton C Garvin Professor of Engineering Science and Mechanics, is harvesting energy using piezoelectic materials in which a current is induced when they are deformed or mechanically stressed. The goal is to use these piezoelectic material patches to kill vibrations of a structure by converting the mechanical energy of vibrations into electrical energy, and storing the electrical energy for subsequent use. The energy can be stored in batteries, and/or capacitors.

Dwight Viehland, professor, and colleagues in materials science and engineering work with sensors and actuators. One application for sensors is the harvesting of energy in stray fields. Present emphasis area is in the harvesting of stray electro-magnetic inductances, which could be used to power unmanned underwater autonomous devices for harbor security.