My Research - An Overview
Advanced Energy Research and Technology Center (AERTC), located in Stony Brook University's Research and Development (R&D) Park
Visual for an application of a thermoelectric generator using vehicle-produced heat.
Welcome to my ePortfolio! Immerse yourself in my experiences in the URECA Explorations in STEM program.
This summer (2013), I am expanding my understanding of sustainability by learning how a potentially far-reaching new alternative energy is developed. I will be learning mechanical engineering, solid-state physics, and materials science concepts through my research on thermoelectric generators (TEGs). These are devices that harvest waste heat to produce electrical energy. Imagine what you could do with a device like this! Fortunately, I am able to continue participating in this exciting research this summer because of support from Stony Brook University's Explorations in STEM program, a division of Undergraduate Research and Creative Activities (URECA).
The goal of this research, headed by Dr. Lei Zuo and Gaosheng Fu of the Stony Brook University Department of Mechanical Engineering, is to develop a TEG device that is directly applied onto a vehicle exhaust pipe. Through the Seebeck (thermoelectric) effect, the device can use a temperature gradient produced by the the exhaust pipe to generate electrical power. I will expand on this in the "Research" section of my ePortfolio.
For more information about this and other works in Dr. Lei Zuo's energy harvesting and mechatronics research lab, please visit http://me.eng.sunysb.edu/~lzuo/index.htm.
This summer, I am working in the lab of Dr. Lei Zuo (Assistant Professor), Mr. Gaosheng Fu (Ph.D. candidate), and Chao Nie (M.S. in Mechanical Engineering) of the Department of Mechanical Engineering. This lab is based in the West Campus of Stony Brook University in the Heavy Engineering buliding as well as in the Advanced Energy Research and Technology Center (AERTC) in the university's Research and Development Park.
Dr. Zuo's work is focused on energy harvesting and mechatronics design. To learn more about his work, please visit http://me.eng.sunysb.edu/~lzuo/index.htm. As the principal investigator of his lab, he supervises the research of post-doctorates, Ph.D. students, masters students, and some undergraduate and high school students in their related research projects and theses. These projects include the theories and applications of thermoelectricity, energy harvesting from shock absorbers, piezoelectricity, and electromagnetism.
As methods of energy harvesting, these technologies show promise in the search for "green" and carbon-free alternative energy sources. Energy harvesting is the process of deriving electrical energy from the environment. Electricity can be generated by collecting or "harvesting" thermal energy (heat), vibrational energy, electromagnetic energy, light, radio waves, and possibly more to come. See the following graphic illustrating energy harvesting.
Electrical energy can be harvested from various energy sources in the environment. Thermoelectric generators (TEGs) converts heat energy into electricity, while microgenerators and piezoelectric generators convert vibrational energy, rectennas convert radio waves, and photovoltaic (PV) cells convert light energy.
My focus is on thermoelectrics. That is, the production of electricity from heat. When speaking of thermoelectricity, one may be referring to either the Peltier or the Seebeck effect. The Peltier effect converts electricity to a temperature gradient, which allows for surface cooling or heating. The Seebeck effect, conversely, converts a temperature gradient to electricity. We are interested in the Seebeck effect, as it harvests energy from an environmental source, heat.
Thermoelectric generators employ temperature differences to generate electricity. Above is a thermocouple, which consists of two dissimilar conducting materials. In this case, the materials are both semiconductors, one an n- (negative) type and one a p- (positive) type. N- and p- signify the type of dopant, or impurity, in the semiconductor. N-type semiconductors are doped with electrons (blue circles with "-" signs), making them negative, whereas p-type semiconductors are doped with holes (yellow "+" signs), making them positive. Electrons and holes are charge carriers, responsible for electrical conductivity. Electrical conductivity is favorable, which is why we dope these materials. Also notice the temperature gradient produced on the ends of the thermocouple, a heated surface and a cold surface. The movement of charge carriers to the cold surface produces a voltage. This voltage is the electricity generated from a temperature difference applied to two dissimilar conductors, also known as the Seebeck effect.
Think about that. Anything with a temperature gradient could theoretically be converted to electricity! The world is teeming with temperature differences just waiting to be harvested. The only problem is efficiency is still low at the current state of thermoelectric research. Another problem is that materials that achieve high ZT, the figure of merit for thermoelectric materials, are often expensive and cannot be realistically scaled for industrial use. Some researchers work on increasing ZT, while others work on applications of already-existing thermoelectric materials.
We work on the applications side. A somewhat promising application of thermoelectrics is harvesting heat from vehicle exhaust systems to electrically power the vehicle itself. We are experimenting with various thermoelectric materials, such as magnesium silicide (Mg2Si) and filled skutterudites, to find the best material for such an application. We are also hoping to directly apply these materials onto the exhaust system using thermal spray.
Source: Stony Brook University Department of Mechanical Engineering Annual Student Research Poster Symposium, May 10, 2013 (Gaosheng Fu, Chao Nie, Lei Zuo, Jon P. Longtin, Sanjay Sampath)
This is Gaosheng Fu's design for the direct fabrication of thermoelectric material onto an exhaust pipe. The inner cylinder (light blue) with heat sink fins (spikes on inner surface) is the exhaust pipe. This will comprise the hot side for the thermocouples. Surrounding the outer surface of the exhaust pipe will be thermal sprayed an inner electrical insulation, inner electrical conducting strips, n- and p-type thermoelectric (TE) material, outer electrical conducting strips, and an outer electrical insulation layer. Surrounding these layers will be a coolant liquid and cooling jacket, which will comprise the cold side for the thermocouples.