Showing posts with label body interfacing. Show all posts
Showing posts with label body interfacing. Show all posts
Monday, 5 November 2012
Body Interfacing
Sunday, 2 September 2012
Chemical engineering
Chemical engineering
Chemical engineering is the branch of engineering that deals with physical science (e.g., chemistry and physics), and life sciences (e.g., biology, microbiology and biochemistry) with mathematics and economics, to the process of converting raw materials or chemicals into more useful or valuable forms. In addition, modern chemical engineers are also concerned with pioneering valuable materials and related techniques – which are often essential to related fields such as nanotechnology, fuel cells and biomedical engineering.[1] Within chemical engineering, two broad subgroups include 1) design, manufacture, and operation of plants and machinery in industrial chemical and related processes ("chemical process engineers"); and 2) development of new or adapted substances for products ranging from foods and beverages to cosmetics to cleaners to pharmaceutical ingredients, among many other products ("chemical product engineers").
Etymology
History
Main article: History of chemical engineering
Chemical engineering emerged upon the development of unit operations,
a fundamental concept of the discipline. Most authors agree that Davis
invented unit operations if not substantially developed it.[7] He gave a series of lectures on unit operations at the Manchester Technical School (University of Manchester today) in 1887, considered to be one of the earliest such about chemical engineering.[8] Three years before Davis' lectures, Henry Edward Armstrong taught a degree course in chemical engineering at the City and Guilds of London Institute.
Armstrong's course "failed simply because its graduates ... were not
especially attractive to employers." Employers of the time would have
rather hired chemists and mechanical engineers.[4] Courses in chemical engineering offered by Massachusetts Institute of Technology (MIT) in the United States, Owen's College in Manchester, England and University College London suffered under similar circumstances.[9]New concepts and innovations
By the 1940s, it became clear that unit operations alone was insufficient in developing chemical reactors. While the predominance of unit operations in chemical engineering courses in Britain and the United States continued until the 1960s, transport phenomena started to experience greater focus.[16] Along with other novel concepts, such process systems engineering (PSE), a "second paradigm" was defined.[17][18] Transport phenomena gave an analytical approach to chemical engineering[19] while PSE focused on its synthetic elements, such as control system and process design.[20] Developments in chemical engineering before and after World War II were mainly incited by the petrochemical industry,[21] however, advances in other fields were made as well. Advancements in biochemical engineering in the 1940s, for example, found application in the pharmaceutical industry, and allowed for the mass production of various antibiotics, including penicillin and streptomycin.[22] Meanwhile, progress in polymer science in the 1950s paved way for the "age of plastics".[23]Lag and environmental awareness
The years after the 1950s are viewed{[by whom?] to have lacked major chemical innovations.[24] Additional uncertainty was presented by declining prices of energy and raw materials between 1950 and 1973. Concerns regarding the safety and environmental impact of large-scale chemical manufacturing facilities were also raised during this period. Silent Spring, published in 1962, alerted its readers to the harmful effects of DDT, a potent insecticide[citation needed]. The 1974 Flixborough disaster in the United Kingdom resulted in 28 deaths, as well as damage to a chemical plant and three nearby villages[citation needed]. The 1984 Bhopal disaster in India resulted in almost 4,000 deaths[citation needed]. These incidents, along with other incidents, affected the reputation of the trade as industrial safety and environmental protection were given more focus.[25] In response, the IChemE required safety to be part of every degree course that it accredited after 1982. By the 1970s, legislation and monitoring agencies were instituted in various countries, such as France, Germany, and the United States.[26]Recent progress
Advancements in computer science found applications designing and managing plants, simplifying calculations and drawings that previously had to be done manually. The completion of the Human Genome Project is also seen as a major development, not only advancing chemical engineering but genetic engineering and genomics as well.[27] Chemical engineering principles were used to produce DNA sequences in large quantities.[28] While the application of chemical engineering principles to these fields only began in the 1990s, Rice University researchers see this as a trend towards biotechnology.[29]Concepts
Chemical reaction engineering
Main article: Chemical reaction engineering
Chemical reactions engineering involves managing plant processes and
conditions to ensure optimal plant operation. Chemical reaction
engineers construct models for reactor analysis and design using
laboratory data and physical parameters, such as chemical thermodynamics, to solve problems and predict reactor performance.[30]Plant design
Chemical engineering design concerns the creation of plans and specification, and income projection of plants. Chemical engineers generate designs according to the clients needs. Design is limited by a number of factors, including funding, government regulations and safety standards. These constraints dictate a plant's choice of process, materials and equipment.[31]Process design
Main article: Process design
A unit operation is a physical step in an individual chemical engineering process. Unit operations (such as crystallization, drying and evaporation)
are used to prepare reactants, purifying and separating its products,
recycling unspent reactants, and controlling energy transfer in
reactors.[32]
On the other hand, a unit process is the chemical equivalent of a unit
operation. Along with unit operations, unit processes constitute a
process operation. Unit processes (such as nitration and oxidation) involve the conversion of material by biochemical, thermochemical and other means. Chemical engineers responsible for these are called process engineers.[33]Transport phenomena
Main article: Transport phenomena
Transport phenomena occur frequently in industrial problems. These include fluid dynamics, heat transfer and mass transfer, which mainly concern momentum transfer, energy transfer and transport of chemical species respectively. Basic equations for describing the three transport phenomena in the macroscopic, microscopic and molecular levels are very similar. Thus, understanding transport phenomena requires thorough understanding of mathematics.[34]Applications and practice
Let It Snow, Let It Snow ... CO2
Let It Snow, Let It Snow ... CO2
Could giant chillers at the South Pole freeze our way out of global warming? Some scientists think so.Turning atmospheric carbon dioxide it into snow and burying it underground is a new way to think about capturing harmful CO2. Click to enlarge this image.
Corbis
What if you could build a giant refrigeration unit near the South Pole, pulling harmful carbon dioxide out of the Earth’s atmosphere, turning it into snow and burying it underground. Wind turbines would power the chiller plants, converting CO2 from a heat-trapping atmospheric gas to a solid as a way of slowing down climate change.
Of all the greenhouse gases, CO2 is the "control knob" of climate change. There's currently too much of it in our atmosphere, and the more of it that there is, the greater the effects of warming.
It sounds far-fetched, but researchers at Purdue University have put together a plan on how such a device would work.
“It’s kind of a novel idea and it’s going to take a lot of refrigeration units and a lot of cost,” said Ernest Agee, professor earth and planetary sciences at Purdue and author of the paper appearing in the Journal of Applied Meteorology and Climatology.
ANALYSIS: The Sun Can't Save Us From Global Warming
hackers
VIDEO: All About Climate Change: From Glacial Melt to Endangered Tigers
Water vapor turns to snow around 32 degrees Fahrenheit, but CO2 doesn’t switch from gas to solid until it gets down to a chilly -220 degrees Fahrenheit (133 Kelvin). The ambient air temperature in Antarctica can often reach -100 F, which gives the chilling process a head start. But to transform the planet’s atmospheric CO2 into snow, it would take an estimated 446 individual refrigeration units that use a closed-loop liquid nitrogen process. The units would be powered by 16 1,200-megawatt wind turbines. That’s a lot of power.
Agee says the idea came to him during a discussion about Mars’ south polar ice cap, which was found to consist of CO2 by the Mars Global Surveyor and Odyssey missions.
He says Antarctica’s coastline would be the best place to put the chiller plants and the turbines since the coast gets blasts of high-powered winds that cascade down from the higher South Polar ice cap toward the ocean. The CO2 snow would be stored in insulated landfills. The winds can power the turbines, while excess heat from the chillers and electricity from the turbines can be harnessed to keep Antarctic research stations warm and dry.
Russell Donnelly, a University of Oregon physicist, is intrigued with Agee’s idea.“It’s quite exciting,” Donnelly said. “It’s certainly thinking big.”
ANALYSIS: Can Geoengineering Stop Global Warming?enlarge
Donnelly is pushing his own, slightly different idea of chilling carbon dioxide. He wants to install chillers at coal-burning power plants to remove C02 from smokestacks. “You look at the hot gases of a stack, it would look impossible,” Donnelly said. “But you can cool them off with water sprays and down to room temperature without spending much money. Then if you start to refrigerate, you need to put just enough refrigeration to get the job done.”
Donnelly and colleagues published a paper in the July 12 issue of the journal Physical Review E that spells out how he would build such a device.
He said the electricity would cost 25 percent more to produce, “but you would have an environmentally-friendly power plant.”
Carbon sequestration schemes are not new. Utilities have been looking at burying excess CO2 beneath the ground or in deep wells or algae ponds for years, but efforts have not paid off because of the high associated costs.
Richard Branson’s Virgin Earth Challenge is offering $25 million to any company or group that can sequester a billion tons of CO2 from the atmosphere per year. That’s the same amount that Agee says he can pull using his Antarctic chiller system, although he did not enter the contest.
Eleven finalists were chosen in November 2011, but no winners yet.
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