 |
|
Step on the gas — New fuel cell design adds control, reduces complexity
January 17, 2007When Princeton University engineers want to increase the power output of their new fuel cell, they just give it a little more gas - hydrogen gas, to be exact. This simple control mechanism, which varies the flow of hydrogen fuel to control the power generated, was previously thought impossible and is a potentially major development in fuel cell technology.
The secret of their success is a system in which the fuel input itself changes the size of the reaction chamber, and therefore the amount of power produced. The breakthrough design also adds to the understanding of water management in fuel cells - one of the major obstacles to large-scale deployment of the technology in automobiles.
"It's almost so simple that it shouldn't work, but it does," said Jay Benziger, a Princeton professor of chemical engineering. Benziger developed the technique with Claire Woo, who graduated from Princeton in 2006 and is now pursuing a Ph.D. at the University of California, Berkeley. They will publish their findings in the February issue of the journal Chemical Engineering Science.
The first applications of their design are likely to be in small machines such as lawn mowers, the researchers said. The machines would be easy to use, incorporating a design similar to the familiar acceleration systems of cars that use a pedal to increase the flow of fuel and the power output. More important, Benziger said, the use of fuel cells in lawn care equipment would cut down on a major source of greenhouse gases, especially as emissions from these machines are not currently regulated.
At the most basic level, all fuel cells work by combining hydrogen with oxygen in a reaction that generates electricity, water and heat. In the Princeton system, some of the water produced as a by-product collects in a layer at the bottom of the reaction chamber, while the rest drains to an external tank. By varying the height of the water level in the chamber, Benziger and Woo are able to enlarge or shrink the reaction chamber.
For example, an increased flow of hydrogen into the chamber pushes more water out of the system, lowering the water level and increasing the space available for the reaction to take place. Similarly, a decreased flow of hydrogen causes the pressure inside the chamber to drop, drawing some of the water from the tank back into the system and shrinking the reaction chamber.
The water at the bottom of the chamber also serves to maintain the needed humidity for the fuel cell reaction to take place. This patented "auto-humidifying" design demonstrates an innovative use for the water produced during the reaction, which causes problems in most fuel cell designs.
Conventional fuel cells feature a complicated network of serpentine channels to combine the gases, maintain the appropriate humidity levels and eliminate water from the system. Often, droplets of water clog the narrow channels, leading to inefficient and irregular power production. The Princeton system mixes the gases via diffusion in a simple reaction chamber and relies on gravity to drain the water produced.
Benziger and Woo's reaction chamber is effectively sealed by the water at the bottom of the tank. By preventing fuel from leaving the system, this design ensures that the gases remain in the reaction chamber until they combine. Most traditional fuel cells repeatedly run hydrogen and oxygen through an open reaction chamber, converting only about 30 to 40 percent of the fuel at each pass. Since the Princeton system is closed, 100 percent of the fuel can be used with no need for a large and expensive fuel recycling system.
Princeton University, Engineering School
The first applications of their design are likely to be in small machines such as lawn mowers, the researchers said. The machines would be easy to use, incorporating a design similar to the familiar acceleration systems of cars that use a pedal to increase the flow of fuel and the power output. More important, Benziger said, the use of fuel cells in lawn care equipment would cut down on a major source of greenhouse gases, especially as emissions from these machines are not currently regulated.
At the most basic level, all fuel cells work by combining hydrogen with oxygen in a reaction that generates electricity, water and heat. In the Princeton system, some of the water produced as a by-product collects in a layer at the bottom of the reaction chamber, while the rest drains to an external tank. By varying the height of the water level in the chamber, Benziger and Woo are able to enlarge or shrink the reaction chamber.
For example, an increased flow of hydrogen into the chamber pushes more water out of the system, lowering the water level and increasing the space available for the reaction to take place. Similarly, a decreased flow of hydrogen causes the pressure inside the chamber to drop, drawing some of the water from the tank back into the system and shrinking the reaction chamber.
The water at the bottom of the chamber also serves to maintain the needed humidity for the fuel cell reaction to take place. This patented "auto-humidifying" design demonstrates an innovative use for the water produced during the reaction, which causes problems in most fuel cell designs.
Conventional fuel cells feature a complicated network of serpentine channels to combine the gases, maintain the appropriate humidity levels and eliminate water from the system. Often, droplets of water clog the narrow channels, leading to inefficient and irregular power production. The Princeton system mixes the gases via diffusion in a simple reaction chamber and relies on gravity to drain the water produced.
Benziger and Woo's reaction chamber is effectively sealed by the water at the bottom of the tank. By preventing fuel from leaving the system, this design ensures that the gases remain in the reaction chamber until they combine. Most traditional fuel cells repeatedly run hydrogen and oxygen through an open reaction chamber, converting only about 30 to 40 percent of the fuel at each pass. Since the Princeton system is closed, 100 percent of the fuel can be used with no need for a large and expensive fuel recycling system.
Princeton University, Engineering School
Reaction Chamber Current Events and Reaction Chamber News RSSTwo bacteria better than one in cellulose-fed fuel cell
No currently known bacteria that allow termites and cows to digest cellulose, can power a microbial fuel cell and those bacteria that can produce electrical current cannot eat cellulose.
Instant steam takes on MRSA
A method for making instant steam, without the need for electricity, promises to be useful for tackling antibiotic resistant 'superbugs' like MRSA and C. difficile, as well as removing chewing gum from pavements and powering environmentally friendly cars, reports Nina Morgan in Chemistry & Industry, the magazine of the SCI.
Designer gradients speed surface science experiments
Researchers from the National Institute of Standards and Technology (NIST) have demonstrated an elegantly simple technique for synthesizing a wide variety of complex surfaces that vary in a controlled fashion across a test strip.
Molds for Molecules
Molecular imprints in polymers as reaction vessels for pharmaceuticals research Materials with the tiniest of cavities, which can take up other molecules as "guests", play a meaningful role in science and technology. A particularly interesting process for the synthesis of materials with precisely fitted cavities is known as molecular imprinting. This process involves the use of the molecules that are intended as future guests as templates; in their presence, individual building blocks are cross-linked to form a polymer. After the templates are removed, the resulting polymer contains cavities of the desired shape and size, and can be used for the precise separation of substances, as a catalys
New biosensor could save lives by giving faster medical analysis.
Every day accident and emergency units have to treat patients who have taken some sort of drug overdose. To give treatment doctors need to know what the patient has taken. The circumstances can make often this difficult to ascertain quickly. Researchers are developing a new kind of biosensor, which can determine in minutes if a patient's blood contains a particular compound, for example paracetamol. Currently this type of examination needs to be carried out in a laboratory, which is expensive and time consuming. The research is being carried out by Dr Sub Reddy's team at the University of Surrey with funding from the Swindon based Engineering and Physical Sciences Research Council. The se
Electric Nudge toward Self-organization
In search of materials with nonlinear optical properties Window panes and eyeglass lenses that get darker as it gets brighter are especially great in the summer. Their secret lies in optical properties that change as the light intensity changes - nonlinear optical properties. Such materials are also of interest as optoelectronic components. One prerequisite for these unusual optical characteristics is a very orderly microstructure, which can often only be forced upon the materials through expensive techniques. Materials that organize themselves into such microstuctures are therefore quite interesting. Polymeric organic-inorganic hybrid materials, synthesized by Robert Corriu's research team,
More Reaction Chamber Current Events and Reaction Chamber News Articles
 |
Reaction Chamber Alex Monster (Primary Contributor) |
![N"2O"5 hydrolysis on the components of mineral dust and sea salt aerosol: Comparison study in an environmental aerosol reaction chamber [An article from: Atmospheric Environment]](http://ecx.images-amazon.com/images/I/51C4M48N0CL._SL160_.jpg) |
N"2O"5 hydrolysis on the components of mineral dust and sea salt aerosol: Comparison study in an environmental aerosol reaction chamber [An article from: Atmospheric Environment] by P.K. Mogili (Author), P.D. Kleiber (Author), M.A. Young (Author), V Grassian (Author) This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: The kinetics of the heterogeneous hydrolysis of N"2O"5 on some of the major components of mineral dust and sea salt aerosol have been investigated in an environmental aerosol chamber. Gas-phase N"2O"5 undergoes heterogeneous reaction to form HNO"3 on carbonate, clay and oxide minerals. The nitric acid hydrolysis product was promptly detected in the gas phase concomitant with the decay of N"2O"5 over time. The N"2O"5 decay kinetics were measured and analyzed assuming first-order reaction kinetics. When... |
 |
No Reaction by Kenny Chambers |
 |
Catalyst Reaction Chamber () by BD Biosciences Catalyst Reaction Chamber, screw threaded; For GasPak 100 and GasPak 150 Systems |
 |
Reaction Chamber Alex Monster (Primary Contributor) |
|
Catalyst Reaction Chamber, without Charges - Accessory for Anaerobic Systems, BD Diagnostics by BD Designed for the generation of anearobic, microaerophilic (reduced oxygen), or CO2-enriched environments. The BD GasPak 100 and 150 self-contained anaerobic systems consist of one polycarbonate jar (vented or non-vented), lid with O-ring gasket, catalyst reaction chamber, BBL room temperature catalyst charges, one rack, and one tube holder. The BD GasPak 100 system features two catalyst charges; the BD GasPak 150 system features ten charges. These systems use hydrogen and carbon dioxide generator envelopes and do not require a vacuum pump, gas tank, manometer, or pressure reducing valve. The BD GasPak 100 system jar holds up to twelve 100mm (315/16") dishes. The BD GasPak 150 system jar holds up to twelve 150mm (515/16") petri dishes or thirty-six 100mm (315/16") dishes. The BD GasPak... | |
 |
No Reaction Kenny Chambers (Primary Contributor) |
|
|
Gas phase reaction of selected isothiocyanates with OH radicals using a smog chamber-mass analyzer system [An article from: Atmospheric Environment] by R. Sommerlade (Author), P. Ekici (Author), H. Parlar (Author) This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Relative rate constants for the gas phase reaction of methyl isothiocyanate (1), ethyl isothiocyanate (2), allyl isothiocyanate (3), phenyl isothiocyanate (4), 2-methylphenyl isothiocyanate (5), benzoyl isothiocyanate (6), and 4-methoxyphenyl isothiocyanate (7) with OH radicals have been determined at 297+/-2K and 9.21x10^-^2Atm in a 20L smog chamber-coupled online with a quadrupole mass analyzer, in which the concentration of the reaction partners could be determined online every minute. Some of the... |
 |
Third Concerto "Reaction" For Organ, String Orchestra And Timpani (1970/71), Introduction Markus Poschner, Franz Hauk, Anno Kesting The Georgian Chamber Orchestra Ingolstadt (Primary Contributor) |
|
How much can human bodies take?(Higher Education)(Physiologists explore our physical reactions inside a UO environmental chamber): An article from: The Register-Guard (Eugene, OR) by The Register Guard (Publisher) This digital document is an article from The Register-Guard (Eugene, OR), published by The Register Guard on July 5, 2005. The length of the article is 1044 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. Citation Details Title: How much can human bodies take?(Higher Education)(Physiologists explore our physical reactions inside a UO environmental chamber) Publication: The Register-Guard (Eugene, OR) (Newspaper) Date: July 5, 2005 Publisher: The Register Guard Page: d1 Distributed by Thomson... |
| © 2009 BrightSurf.com |