MIT Solar Thermophotovoltaic System Increase Solar Cell Efficiency Up To 80%

Researchers at MIT have developed a solar cell that is much more efficient than current solar photovoltaic cells. Using nanotechnology and material technology, the new cell captures a broader spectrum of light compared to a regular solar cell and transforms these into energy. This development can increase solar power output past current efficiency limits.

By adding an absorber-emitter device between photovoltaic cell and sunlight, the other undetected wavelengths of light is also converted into electricity through heat. Carbon nanotubes and photonic crystals are used as material for the absorber-emitter device.

Photovoltaic cells are solid state electrical devices that convert the energy of light directly into electricity by the photovoltaic effect (using light to convert to energy).

The present maximum theoretical efficiency of a solar cell is 33.70%. This is known as the Shockley-Queisser limit. With the new developed solar cell, the researchers believe once the technology is fully develop, it can break the limit and hit an efficiency rating of well over 80%.

Heat Dissipation at the Atomic Level Studied Through Nanotechnology

Researchers at the University of Michigan are studying the effects of heat at the nanoscale; between atoms. This study will help in understanding how heat behaves in nanoscale systems.

Moore's Law states that the number of transistors on integrated circuits doubles approximately every two years. This equates to computing processing power doubling every two years. For the last 50 years, the trend in computers and electronics adheres to Moore's law but technological evolution is fast approaching to the limit of transistors that can fit into a single silicon chip.

At last count, the current record for most number of transistors put on a chip is 2 billion.

With circuit boards getting smaller and smaller, one factor that scientists and engineers look at is heat. As devices get smaller and smaller, the laws of thermodynamics particularly in heat transfer and heat dissipation gets complicated.

The UM researchers are looking at measuring this process at the nanoscale which is the behavior of heat between individual atoms. This study can help develop devices that are smaller, energy efficient, and faster than those currently available. This is a major hurdle for Moore's Law since technology is now going towards atomic scale nano-electronics.

Because of this, the International Technology Roadmap for Semiconductors in 2010 adjusted the law and changed the period from every two years to every three years.

MIT News: Manipulating Heat Using Lenses and Mirrors

Thermal lattices, shown here, are one possible application of the newly developed thermocrystals. In these structures, where precisely spaced air gaps (dark circles) control the flow of heat, thermal energy can be "pinned" in place by defects introduced into the structure (colored areas).
Illustration courtesy of Martin MaldovanCredit: MIT

Nanostructured semiconductor alloy crystals were engineered to manipulate heat, either through reflecting or focusing it.

Nanotechnology is the science behind the manipulation of atomic and molecular objects. These materials measure from 1 to 100 nanometers (nm). One nanometer is equal to one billionth, or 10⁻⁹ meters.

Nanostructures are one of the products from this technology. Nanostructures are engineered as a component for a bigger device. Nanostructures give support, assist in the process, or brings out a particular property from the created device.

There are three dimensions to a nanostructure:

• Nanotextured surfaces have one dimension on the nanoscale - only the thickness of the surface of an object is between 0.1 and 100 nm (a dot).
• Nanotubes have two dimensions on the nanoscale - the diameter of the tube is between 0.1 and 100 nm; its length could be much greater.
• Spherical nanoparticles have three dimensions on the nanoscale - the particle is between 0.1 and 100 nm in each spatial dimension (Length, Width, Height).

MIT News: Increasing Heat Coefficients on Industrial Plant Condensers Through Nanotechnology

Students at the Device Research Lab (DRL) in MIT’s mechanical engineering department have designed and tested a coated surface of an industrial plant condenser with nanostructured patterns that greatly increase the heat-transfer coefficient.

The heat-transfer coefficient is important when it comes to condensers because it is a measure of how fast heat can be transferred away from it. Basically, it is the opposite of insulation where insulation is a measure of how long heat can be maintained.

The purpose of a condenser in an industrial plant, like a thermal power plant for example, is to condense water vapor back into steam for maximum efficiency and reuse the now transformed liquid water in the steam generator or boiler as boiler feed water. A condenser with a high heat-transfer coefficient would then be able to condense water vapor faster and more efficiently.

Nanostructures and its uses

Nanotechnology, specifically nanostructures, have been proven successful in creating materials or devices that perform in a particular way, usually increasing its efficiency in the process. Nanostructures are objects created at the nanoscale or atmolecular level. These are very tiny structures and creating a nanostructure involves manipulating an object's composition at a molecular level. It may involve moving molecules or atoms around, or creating patterns that will allow it to behave in a particular way.

These structures are made to either act as a container in a delivery system (like gas atom/molecule in a very tiny capsule), interact with other objects to achieve a predetermined outcome either structurally or chemically or to act as a base for a more complex structure.

In relation to the condenser created by MIT, the surface was coated with nanostructured patterns to influence the way water droplets behave on it (see embedded video below).

Studying the Behavior of Antifreeze Molecules For Commercial, Industrial, and Medical Applications

Scientists at New York University are studying the behavior of antifreeze molecules that one day can open up applications in the commercial, industrial, and medical fields.

Antifreeze proteins (AFP) are naturally occurring proteins that inhibit the formation of ice crystals when water temperature drops to freezing levels.

These proteins are usually found in organisms that live in subzero environments such as Antarctica. Certain vertebrates, plants, fungi and bacteria can inhibit the growth and recrystallization of ice in their bodies allowing them to survive in these temperatures.

Using Thermoacoustics To Develop Self-Powered Nuclear Reactor Backup Sensors

A thermoacoustic device uses sound waves to move heat from one place to another or use heat to create sound waves. Using this principle, a thermoacoustic engine uses either the heat transfer or the sound waves to produce electricity, cooling, or heat pumping.


Currently, researchers are looking into electricity created from pressure (piezoelectricity), refrigeration, and cryogenic applications.


Another category thermoacoustics can be of use, is in the development of sensors, particularly backup sensors for nuclear reactors. The Fukushima nuclear disaster is a prime example of this.


In the Fukushima incident, the power connections failed cutting off electricity to the backups, pumps, and sensor systems shutting them down. The reactors overheated due to the high radioactive decay heat and the nuclear plant's operators could not monitor the fuel rods in the reactor and spent fuel in the storage ponds.

Dung Beetles Use Dung As A Mobile Thermal Refuge For Thermoregulation

Dung beetles are also called scarab beetles. These are the same beetles worshiped by the ancient Egyptians. They believed that a giant dung beetle rolled the Sun across the sky and buried it at night.

They probably got the idea from observing that these beetles roll balls of manure across the plain and bury it under the ground. Dung beetles do this since they use these balls of dung for food or as a brooding ball where the female beetle will lay its eggs inside it. When the larvae hatches, they feed on the dung.

There are some dung beetles that feed on mushrooms, leaves, and fruits. Dung beetles that solely rely on dung as its food source, do not need to drink or eat anything else since all the nutrients are provided for by the dung.

Thermodynamics Used To Grow Nanorods Into Superparticles With Precision

Nanorods are a particular shape of nanoparticles. They are elongated and are similar to a hotdog and can range in size from 1 nanometer (nm) to 100nm, where 1nm= 1x10^-9 meters (one-billionth of a meter). Nanoparticles can also form into spheres and flattened sheets.

Nanorods are produced through chemical synthesis. A metal or semiconducting material are combined with several chemicals to produce nanoparticles of that element. They are then subjected to another series of processes to produce the desired shape and filter out unwanted particles.

Because of their shape and size, nanorods interact with light, electricity and magnetic fields differently. They display highly coveted optical, electronic and other properties not found in macroscopic materials.

MIT News: Bending Light To Cloak Objects Lead To Better Electron Transfer For Thermoelectric Devices

A new approach that allows objects to become “invisible” has now been applied to an entirely different area: letting particles “hide” from passing electrons, which could lead to more efficient thermoelectric devices and new kinds of electronics.

Diagram shows the 'probability flux' of electrons, a representation of the paths of electrons as they pass through an 'invisible' nanoparticle. While the paths are bent as they enter the particle, they are subsequently bent back so that they re-emerge from the other side on the same trajectory they started with — just as if the particle wasn't there.
Image courtesy Bolin Liao et al.

The concept — developed by MIT graduate student Bolin Liao, former postdoc Mona Zebarjadi (now an assistant professor at Rutgers University), research scientist Keivan Esfarjani, and mechanical engineering professor Gang Chen — is described in a paper in the journal Physical Review Letters.

Quantum Effects in Cold Atom Physics Through Pre-Thermalization Are More Than Expected

On an atom chip (top), clouds of ultracold atoms (red) are created. They are allowed to interfere, creating an ordered matter-wave interference pattern (bottom).
Credit: Vienna University of Technology

Absolute zero is measured at 0 kelvins. The 3rd law of thermodynamics dictate that it is impossible to cool down an object to exactly 0 kelvins. Since cold is the absence of heat, absolute zero would mean that there is no heat left in the object or system. In 2003, MIT Researchers achieved the lowest temperature which is .45 nK (nano kelvin) or 4.5 x 10-10 K or 0.00000000045 K.

Ultracold atoms are atoms that are maintained at temperatures close to absolute zero. The study that uses ultracold atoms in relation to fundamental quantum phenomena is called Cold Atom Physics. Applications for this technology range from quantum computers, and quantum simulators to ultra-high-precision atomic clocks and quantum metrology.

One of the basic underlying phenomenon of cold atom physics is the Boss-Einstein Condensate (BEC). This is a new state of mater that forms in very low temperatures. When atoms are cooled down to very low temperatures, they start to behave in wave like properties, as the temperature keeps going down, they start to merge and behave like one singular wave like particle. This was predicted by Satyendra Nath Bose and Albert Einstein in 1924–25 and was successfully produced and observed in 1995.

Ultracold atoms reveal surprising new quantum effects

Every day we observe systems thermalizing: Ice cubes in a pot of hot water will melt and will never remain stable. The molecules of the ice and the molecules of the water will reach thermal equilibrium, ending up at the same temperature. Well-ordered ice crystals turn into a disordered liquid.

Experiments at the Vienna Center for Quantum Science and Technology (VCQ) at the Vienna University of Technology have shown that in the quantum world the transition to thermal equilibrium is more interesting and more complicated than assumed so far.

Basics of Thermodynamics And MIT News: Efficient Heat Dissipation

Thermodynamics

Thermodynamics is the branch of science that studies the relationships of heat, work, energy, and pressure.

In thermodynamics, it studies the interaction in relation to two kinds of systems: an isolated system and an open system. In an isolated system, material and energy of an object cannot exchange with its environment. In an open system, material and energy can exchange with its environment. Both this systems are precisely defined regions or spaces under study. Everything else outside the system is known as the surroundings.

A boundary separates the system and the surroundings. This is simply a surface surrounding the system or volume of interest. Anything that passes across the boundary that effects a change in the internal energy needs to be accounted for in the energy balance equation.

Laws of Thermodynamics

There are four laws that govern the behavior of energy and the passing of energy in thermodynamics. These are:

The Zeroth law: When 2 systems are in thermal equilibrium with a third system, these 2 systems are in thermal equilibrium with each other. Simply, if 2 objects have the same temperature with one other object, these two objects have the same temperature with each other.

• There is no heat flow between objects of the same temperature.

The 1st Law of Thermodynamics: This is also known as the law of conservation of energy. It states that the total energy in an isolated system never changes.

• Energy cannot be created or destroyed, it can only be transferred.

The 2nd Law of Thermodynamics: This law states that the entropy of an isolated system always increases or remains constant over time. Entropy as used in this law can be defined as disorder. An example of the 2nd law in action are ubiquitous in nature; ice melting, fires burning down, a battery running out of electrical charge, etc.

• The 2nd law is the reason why heat always transfers from a relatively higher temperature to an object that is lower.

The 3rd Law of Thermodynamics: The 3rd law states that it is impossible to cool an object down to a temperature of absolute zero. It can also be stated in terms of heat; it is impossible to remove all the heat from a physical system.

• The lowest possible limit on temperature is absolute zero. Temperature can never be lower than this in the whole universe. In quantitative terms, absolute zero can be measured as 0 Kelvin (K), -273.15 Celsius (C), or -459.67 Fahrenheit(F),
• In 2003, MIT Researchers achieved the lowest temperature which is .45 nK (nano kelvin) or 4.5 x 10^-10 K or 0.00000000045 K

These laws dictate how heat, energy, and pressure behave within a thermodynamic system.

Heat Transfer

As with the laws of thermodynamics, the transfer of heat between one object to another is defined by these. Heat is transferred from one object to another through one of four fundamental modes:

• Conduction or diffusion: The transfer of energy between objects that are in physical contact
• Convection: The transfer of energy between an object and its environment, due to fluid motion
• Radiation: The transfer of energy to or from a body by means of the emission or absorption of electromagnetic radiation
• Advection: The transfer of energy from one location to another as a side effect of physically moving an object containing that energy

Better surfaces could help dissipate heat

Cooling systems that use a liquid that changes phase — such as water boiling on a surface — can play an important part in many developing technologies, including advanced microchips and concentrated solar-power systems. But understanding exactly how such systems work, and what kinds of surfaces maximize the transfer of heat, has remained a challenging problem. Now, researchers at MIT have found that relatively simple, microscale roughening of a surface can dramatically enhance its transfer of heat. Such an approach could be far less complex and more durable than approaches that enhance heat transfer through smaller patterning in the nanometer (billionths of a meter) range.

The new research also provides a theoretical framework for analyzing the behavior of such systems, pointing the way to even greater improvements. The work was published this month in the journal Applied Physics Letters, in a paper co-authored by graduate student Kuang-Han Chu, postdoc Ryan Enright and Evelyn Wang, an associate professor of mechanical engineering.

Application of Nanotechnology and Thermodynamics in Measuring Devices

The fundamental factor in science research is in measuring data. Technology has significantly evolved the measuring process. The more data that can be measured, the more insights and observation can be gathered. Most measurement devices are electronic in nature. Some use light, some heat, and others use nanotechnology.

Atomic force microscope cantilever tips with integrated heaters are widely used to characterize polymer films in electronics and optical devices, pharmaceuticals, paints, and coatings. These heated tips are also used in research labs to explore new ideas in nanolithography and data storage, and to study fundamentals of nanometer-scale heat flow. Until now, however, no one has used a heated nano-tip for electronic measurements.

"We have developed a new kind of electro-thermal nanoprobe," according to William King, a College of Engineering Bliss Professor in the Department of Mechanical Science and Engineering at the University of Illinois at Urbana-Champaign. "Our electro-thermal nanoprobe can independently control voltage and temperature at a nanometer-scale point contact. It can also measure the temperature-dependent voltage at a nanometer-scale point contact."

"Our goal is to perform electro-thermal measurements at the nanometer scale," according to Patrick Fletcher, first author of the paper, "Thermoelectric voltage at a nanometer-scale heated tip point contact," published in the journal Nanotechnology. "Our electro-thermal nanoprobe can be used to measure the nanometer-scale properties of materials such as semiconductors, thermoelectrics, and ferroelectrics."

Video: Next-generation system design using micro- and nano-scale functional materials

The electro-thermal probes are different than thermal nanoprobes typically used in King's group and elsewhere. They have three electrical paths to the cantilever tip. Two of the paths carry heating current, while the third allows the nanometer-scale electrical measurement. The two electrical paths are separated by a diode junction fabricated into the tip. While the cantilever design is complex, the probes can be used in any atomic force microscope.

In addition to Fletcher, co-authors of the paper include Byeonghee Lee, and William King. The research was performed in the Nanoengineering laboratory as well as the Micro and Nanotechnology Laboratory and the Materials Research Laboratory at the University of Illinois.
The paper is available online at doi:10.1088/0957-4484/23/3/035401
The research was sponsored by the Office of Naval Research and the Air Force Office of Scientific Research.

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