Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. Space Industry and Business News .




TECH SPACE
New NIST screening method identifies 1,200 candidate refrigerants to combat global warming
by Staff Writers
Washington DC (SPX) Sep 21, 2012


To help industry find refrigerant fluids with low global warming potential (GWP), NIST researchers screened 56,203 compounds and identified 1,234 candidates for further study. Credit: Kazakov/NIST.

Researchers at the National Institute of Standards and Technology (NIST) have developed a new computational method for identifying candidate refrigerant fluids with low "global warming potential" (GWP) - the tendency to trap heat in the atmosphere for many decades - as well as other desirable performance and safety features.

The NIST effort is the most extensive systematic search for a new class of refrigerants that meet the latest concerns about climate change. The new method was used to identify about 1,200 promising, low-GWP chemicals* for further study among some 56,000 that were considered. Only about 60 of these have boiling points low enough to be suitable for common refrigeration equipment, an indication of how difficult it is to identify usable fluids.

The ongoing NIST project is a response to U.S. industry interest in a new generation of alternative refrigerants that already are required for use in the European Union.

The refrigerants now used in cars and homes are mainly hydrofluorocarbons (HFCs). They were adopted a generation ago in the effort to phase out chlorofluorocarbons (CFCs), which deplete the stratospheric ozone layer. An example is R-134a (1,1,1,2-tetrafluoroethane), which replaced ozone-depleting chemicals in automobile air conditioners and home refrigerators. R-134a now is being phased out in Europe because HFCs remain in the atmosphere for many years, yielding a high GWP.

A compound's GWP is defined as the warming potential of one kilogram of the gas relative to one kilogram of carbon dioxide. R-134a has a GWP of 1,430, much higher than the GWP of 150 or less now mandated for automotive use in Europe.

Promising low-GWP chemicals include fluorinated olefins, which react rapidly with atmospheric compounds and thus will not persist for long periods.

"What industry is trying to do is be prepared, because moving from a GWP in the thousands or tens of thousands to a GWP of 150 is an enormous challenge, both economically and technologically," says NIST chemist Michael Frenkel. "We decided to leverage the tools NIST has been developing for the last 15 years to look into the whole slew of available chemicals."

The affected industry is huge: The U.S. air conditioning, heating and refrigeration equipment manufacturing industry ships about $30 billion in goods annually, according to the U.S. Bureau of the Census.

NIST has extensive experience evaluating alternative refrigerants, having previously helped the refrigeration industry find replacements for CFCs.**

The new NIST method estimates GWP by combining calculations of a compound's radiative efficiency (a measure of how well it absorbs infrared radiation) and atmospheric lifetime, both derived from molecular structure. Additional filtering is based on low toxicity and flammability, adequate stability, and critical temperature (where the compound's liquid and gas properties converge) in a desirable range.

The method was applied to 56,203 compounds and identified 1,234 candidates for further study. The method, which was validated against available literature data, is accurate and fast enough for virtual screening applications. The approach is similar to the large-scale virtual screening and computational design methods for discovering new pharmaceuticals.

The screening is the initial stage of a larger study funded by the U.S. Department of Energy. The next step will be to further narrow down the candidates to a couple dozen suitable for detailed investigation in refrigeration cycle modeling.

A. Kazakov, M.O. McLinden and M. Frenkel. Computational design of new refrigerant fluids based on environmental, safety, and thermodynamic characteristics. Industrial and Engineering Chemistry Research. Article ASAP, Publication Date (Web): September 4, 2012. DOI: 10.1021/ie3016126; See 2007 NIST Tech Beat article, "NIST Releases Major Update of Popular REFPROP Database,".

.


Related Links
National Institute of Standards and Technology (NIST)
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





TECH SPACE
International team of physicists makes discovery about temperature in convection
Santa Barbara CA (SPX) Sep 19, 2012
An international team of physicists is working to ascertain more about the fundamental physical laws that are at work in a process known as convection, which occurs in a boiling pot of water as well as in the turbulent movement of the liquid outer core of the Earth. The team's new finding specifies the way that the temperature of a gas or liquid varies with the distance from a heat source ... read more


TECH SPACE
iPhone 5 rollout draws big crowds worldwide

Using a laser to 'see' the smallest world

YouTube seeking education video 'gurus'

Angling for gold

TECH SPACE
Hughes Awarded Custom SATCOM Solutions Contract by GSA

4 SOPS begins testing newest AEHF satellite

SES Government Solutions Awarded Custom Satellite Solutions Contract in the US

Boeing Chosen for US Government's COMSATCOM Services Acquisition Program

TECH SPACE
Fueling underway with the Galileo satellites for next Soyuz launch from French Guiana

SpaceX, NASA Target Oct. 7 Launch For Resupply Mission To Space Station

Failure Review Oversight Board Establishes Proton Return to Flight Schedule

HISPASAT chooses Arianespace to launch its Amazonas 4A and AG1 satellites

TECH SPACE
China launches another 2 navigation system satellites

Improved positioning indoors

ITT Exelis announces new capability in GPS interference, detection and geolocation

Countdown: a month to go to Galileo's next launch

TECH SPACE
Indian air force to buy French fighters

Japan's ANA says to order 11 more Dreamliners

New airport system facilitates smoother take-offs and landings

US selling Indonesia eight Apache helicopters

TECH SPACE
Single-atom writer a landmark for quantum computing

Supercomputer breakthrough for Australian team

Radiation-Enabled Computer Chips Could Lead to Low-Cost Security Imaging Systems

Memristors based on transparent electronics offer technology of the future

TECH SPACE
Knight Foundation invests to accelerate data projects

First Images from SPOT 6 Satellite

Apple fans complain of missing landmarks in new map system

Pioneering UK project to improve land carbon intelligence accuracy and reliability

TECH SPACE
Measuring mercury levels: Nano-velcro detects water-borne toxic metals

Indonesian lives risked on 'world's most polluted' river

Oil spill ship's officers deported from New Zealand

Chemical use inflicts mounting bill on poor countries: UN




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement