Nuha Niawan

List of German inventors and discoverers - german inventors

This is a list of German inventors and discoverers. The following list comprises people from Germany or German-speaking Europe, and also people of predominantly German heritage, in alphabetical order of the surname.

A

Ernst Abbe: Invented the first refractometer, and many other devices. Donated his shares in the company Carl Zeiss to form Carl-Zeiss-Stiftung, still in existence today.
Franz Carl Achard: Developed a process to produce sugar from sugar beet. Built the first factory for the process in 1802.
Robert Adler: Invented a better television remote control.
Konrad Adenauer: Invented soya sausage (1916; "KÃ¶lner Wurst") and, together with Jean and Josef Oebel, [coarse] wholemeal bread (1917; KÃ¶lner Brot).
Georgius Agricola: Named "the father of mineralogy".
Wilhelm Albert: Invented the wire rope 1834.
Kurt Alder: Discovery of the Dielsâ€"Alder reaction, Nobel Prize in Chemistry 1950.
Richard Altmann: Discovery of the Mitochondrion
Alois Alzheimer: Psychiatrist who discovered AlzheimerÂ´s disease, a degeneration of the brain in old age.
Ottomar AnschÃ¼tz: in 1883 he patented a camera with an internal roller blind shutter mechanism, just in front of the photographic plate. Thus the focal-plane shutter in modern recognizable form was born.
Hermann AnschÃ¼tz-Kaempfe: Invented the gyrocompass in 1907.
Manfred von Ardenne: Self-taught researcher, applied physicist and inventor. 600 patents in fields including television and radio, electron microscopy, medical technology, nuclear technology, and plasma physics.
Friedrich Wilhelm August Argelander: catalogued all stars brighter than approximately magnitude 9.5 and north of -2 degrees in the Bonner Durchmusterung, the first large-scale modern star catalogue.
Leo Arons: Mercury-vapor lamp together with Peter Cooper Hewitt.
Leopold Auerbach: Discovery of Plexus myentericus Auerbachi, or Auerbach's plexus.
Max Abraham: Physicist. Worked as Max Planck's assistant for three years. Developed theories on electrons.

B

Walter Baade: astronomer. With Fritz Zwicky, he identified supernovae as a new category of astronomical objects
Karl Ernst von Baer: discovered mammal ovum.
Ralph Baer: Inventor of the first home video game console.
Adolf von Baeyer: Chemist. Synthesized indigo, discovered the phthalein dyes, and investigated polyacetylenes, oxonium salts, nitroso compounds (1869) and uric acid derivatives (1860 and onwards) including the discovery of barbituric acid (1864). Nobel laureate 1905.
Albert Ballin: Father of modern cruise ship travel
Heinrich Band: Developed a musical instrument and called it bandoneÃ³n in 1846. It is used in most tango orchestras until today.
Heinrich Barkhausen: Discovered what is now called the Barkhausen effect, to describe the phenomenon, which is caused by rapid changes of size of magnetic domains in 1919, and Barkhausen stability criterion.
Oskar Barnack: The father of the first mass marketed 35mm camera and Leica.
Heinrich Anton de Bary: Father of Phytopathology, the science of plant diseases and modern Mycology. Coined the word symbiosis in 1879.
Karl Adolph von Basedow: Discovery and description of Graves-Basedow disease
Andreas Friedrich Bauer: first functional steam-powered printing press with his colleague Friedrich Koenig)
Wilhelm Bauer: Inventor and engineer, who built several hand-powered submarines.
Eugen Baumann: He was one of the first people to create polyvinyl chloride (PVC), and, together with Carl Schotten, he discovered the Schotten-Baumann reaction.
Carl Baunscheidt: Inventor of the Lebenswecker ("life awakener") or "artificial leech".
Hans Beck: Inventor of the toy Playmobil.
Georg Bednorz: Physicist, discovered high-temperature superconductivity in ceramics, shared the 1987 Nobel Prize in Physics.
Martin Behaim: Inventor of the first globe of the world (Erdapfel) between 1491 and 1493.
Alexander Behm: Inventor of echo sounding. The patent was granted in 1913.
Fabian Gottlieb von Bellingshausen: Navigator and Explorer. Discovered the land mass of Antarctica on January 28, 1820.
Friedrich Bessel: astronomer; he is credited with being the first to use parallax in calculating the distance to a star.
Hans Bethe: Nuclear physicist and Nobel laureate in physics 1967. During World War II, he was head of the Theoretical Division at the secret Los Alamos laboratory which developed the first atomic bombs.
Emil Adolf von Behring: Discovered the diphtheria antitoxin. It was the world's first cure for a disease (1891). He was awarded history's first Nobel Prize in Physiology of Medicine in 1901.
Melitta Bentz: Inventor of the coffee filter, 1908.
Karl Benz: Father and inventor of the gasoline-powered automobile, 1885, and pioneering founder of automobile manufacturing.
Albrecht Berblinger: Inventor of the spring prosthesis and hang-glider (1811).
Hans Berger: a German neurologist, best known as the inventor of electroencephalography (EEG) (the recording of "brain waves") in 1924, coining the name, and the discoverer of the alpha wave rhythm known as "Berger's wave"
Emil Berliner: He is best known for developing the microphone and disc recording gramophone.
Albert Betz: Betz's law, 1913
Friedrich Bessel: astronom, he is credited with being the first to use parallax in calculating the distance to a star.
Heinz Billing: Computer scientist. He invented the magnetic drum memory and built prototype laser interferometric gravitational wave detector in Garching, Munich.
Gerd Binnig: Physicist. Design of the scanning tunneling microscope (STM) with Heinrich Rohrer. Nobel laureate 1986.
Ludwig Blattner: developed the Blattnerphone, the first magnetic tape recorder (using steel tape) whilst working in Britain in the late 1920s.
Walter Bock: Styrene-butadiene
Max BockmÃ¼hl: He developed Methadone together with German Gustav Ehrhart in 1937 in Germany, working for I.G. Farbenindustrie AG at the Farbwerke Hoechst
Johann Elert Bode: Discovered the Titus-Bode Law
Ludwig BÃ¶lkow: Aeronautical pioneer. Was instrumental in the development of the Me 262, developed a new rotorhead concept for helicopters.
Max Born: Physicist and mathematician. Groundbreaking work in quantum mechanics. Nobel laureate 1954 with Walther Bothe. His Ph.D. student DelbrÃ¼ck, and six of his assistants (Fermi, Heisenberg, Goeppert-Mayer, Herzberg, Pauli, Wigner) went on to win Nobel Prizes. His Ph.D. student J. Robert Oppenheimer led the project to develop the atomic bomb.
Manfred BÃ¶rner: Physicist. Developed the first working fiber-optical data transmission system in 1965. Received a patent for an "electro-optical transmission system utilizing lasers".
Carl Bosch: Chemist and Nobel laureate, discovered the processes of industrial high pressure chemistry.
Robert Bosch: He invented, engineered and launched various innovations for the motor vehicle.
Walther Bothe: Nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born.
Johann Friedrich BÃ¶ttger: He was generally acknowledged as the inventor of European porcelain although more recent sources ascribe this to Ehrenfried Walther von Tschirnhaus. BÃ¶ttger is still credited with developing the manufacture of porcelain in Europe.
Theodor Boveri: described Centrosome.
Karlheinz Brandenburg: Inventor and audio engineer; father of audio compression format MPEG Audio Layer 3, more commonly known as MP3.
Karl Ferdinand Braun: Inventor of the CRT oscilloscope in 1897
Wernher von Braun: The preeminent rocket engineer of the 20th century. Developed the V-2 rocket for Germany. Built Saturn V rocket in USA which put man on the moon.
Korbinian Brodmann: neurologist, Brodmann area in brain
Walter Bruch: PAL, colour encoding system for analogue television
Friedrich Wilhelm Gustav Bruhn: inventor of Taximeter
Ernst BÃ¼chner: Chemist and inventor of BÃ¼chner flask and BÃ¼chner funnel.
Robert Bunsen: Chemist who developed the Bunsen burner, and with Gustav Kirchhoff he discovered caesium (1860) and rubidium (1861).
Wilhelm Busch: Caricaturist, painter and poet; father of comics.
Christian Friedrich Ludwig Buschmann: Pioneer and promoter of the harmonica.
Adolf Busemann: Discovered the effect of swept wing for modern aircraft in 1935.
Adolf Butenandt: Discovered primary female sex hormones. Shared the Nobel Prize in Chemistry with Leopold Ruzicka in 1939.

C

Georg Cantor: Mathematician, discoverer of the set theory (1870s), which has become a fundamental theory in mathematics.
Ernst Boris Chain: biochemist, co-recipient of the Nobel Prize for Physiology or Medicine for his work on penicillin (together with Fleming).
Carl von Clausewitz: The father of modern military theory.
Rudolf Clausius: Mathematician and physicist known for the Second law of thermodynamics.
Justus Claproth: Jurist and inventor of recyclable paper and deinking.
Nicolaus Copernicus: Astronomer, formulated a heliocentric model of the universe which placed the Sun, rather than the Earth, at the centre.
Manfred Curry: German American yachtsman, developed the cam cleat used on sailboats to easily and quickly secure a rope, discoverer of the pseudoscientific phenomenon of "geomagnetic lines" called the Curry Grid.

D

Gottlieb Daimler: Invented the first high-speed internal combustion petrol engine and the first four-wheel automobile, also the first internal combustion motorcycle, the Reitwagen.
Adolf "Adi" Dassler: Sports shoes with and without spikes; founder of Adidas.
Rudolf Dassler: First sport shoes with screw-in shoe spikes, 1949; founder of Puma.
Hans Georg Dehmelt: Physicist. Co-developed the non-magnetic quadrupole mass filter which laid the foundation for what we now call an ion trap. Shared the Nobel Prize in 1989.
Max DelbrÃ¼ck: German American biophysicist. He was awarded the Nobel prize for discovering that bacteria become resistant to viruses (phages) as a result of genetic mutations.
Johann Christoph Denner: Woodwind instrument maker, inventor of the clarinet.
JÃ¼rgen Dethloff: Inventor and engineer, co-inventor of the Smart card (together with Helmut GrÃ¶ttrup).
Johann Friedrich Dieffenbach: Pioneer of skin transplantation and cosmetic surgery.
Ernst Dickmanns: Developer of the first driverless car.
Otto Diels: Dielsâ€"Alder reaction (together with Kurt Alder)
Rudolf Diesel: Inventor of the diesel engine 1893.
Gerhard Domagk: Discovery of what would become the first commercially available antibiotic.
Christian Doppler: Discovered the Doppler effect.
Walter Robert Dornberger: Co-inventor of the V-2 rocket.
Karl Drais: Inventor of the bicycle and typewriter (1821) among other things.
Peter Ferdinand Drucker: Invented the science of modern management.

E

Paul Ehrlich: Scientist in the fields of hematology, immunology, and chemotherapy, and Nobel laureate. Developed an effective treatment against syphilis.
Albert Einstein: Theoretical physicist, key 20th century scientist and cultural icon.
Ludwig Elsbett: Developed new concepts for Diesel engines which drastically enhanced efficiency.
Douglas Engelbart: German American inventor of the computer mouse.
Evaristo Conrado Engelberg: Inventor in 1885 of a machine used to remove the husks from rice and coffee, the Engelberg huller.
Friedrich Engels: He invented together with Karl Marx the economic and sociopolitical worldview Marxism.
Hugo Erdmann: Chemist who discovered, together with his doctoral advisor Jacob Volhard, the Volhard-Erdmann cyclization. In 1898 he was the first who coined the term noble gas (the original noun is Edelgas in German).
Hugo Erfurt: Ingrain wallpaper
Leonhard Euler: Swiss mathematician and physicist. One of the most influential mathematicians of the 18th century.

F

Gerd Faltings: Mathematician known for his work in arithmetic algebraic geometry, Fields Medal in 1986 for proving the Mordell conjecture.
Otto Feick: Wheel gymnastics in 1925.
Wilhelm Emil Fein: Invented the electrically-driven hand drill in 1895.
Adolf Gaston Eugen Fick: Glass Contact lenses
Richard Fiedler: Invented the modern flamethrower in 1901.
Artur Fischer: Invented the (split) wallplug made of plastic in 1958. Fischer held over 1100 patents.
Hermann Emil Fischer: Discoveries in chemistry.
Franz Fischer and Hans Tropsch: Invented a process in 1925 to turn coal into synthesis gas, and still further into liquid hydrocarbons. The process is a key component in modern gas to liquids processes.
Wilhelm Rudolph Fittig: He discovered the pinacol coupling reaction, mesitylene, diacetyl and biphenyl.
Irmgard FlÃ¼gge-Lotz: She worked on what she called "discontinuous automatic control", which laid the foundation for automatic on-off aircraft control systems in jets.
Werner Forssmann: Performed the first human cardiac catheterisation. Shared the Nobel Prize for Medicine 1956
Joseph von Fraunhofer: Discovery of the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope lenses.
Gottlob Frege: He is generally considered to be the father of analytic philosophy. Had influence on Carnap, Russell, and Wittgenstein
Otto Frenzl: Aeronautical pioneer, developed the area rule in 1943, a design technique for airfoils used to reduce an aircraft's drag at transonic and supersonic speeds. Later it was independently developed again by Richard T. Whitcomb in 1952.
Sigmund Freud: Neurologist who became known as the founding father of psychoanalysis.
Nikolaus Friedreich: Discovery of Friedreich-Auerbach disease (together with Leopold Auerbach)
Friedrich FrÃ¶bel: Pedagogue, who laid the foundation for modern education. He created the concept of the kindergarten.
Klaus Fuchs: Theoretical physicist involved with the Manhattan Project; at the same time Soviet spy.
Johann Carl Fuhlrott: Had the insight to recognize the Neanderthal bones for what they were: the remains of a previously unknown type of humans. He (together with Schaafhausen) is considered to be the father of paleoanthropology.

G

Johann Galle: astronom, Discovery of planet Neptune
Hermann Ganswindt: Inventor and spaceflight scientist, whose inventions (such as the dirigible, the helicopter, and the internal combustion engine) are thought to have been ahead of his time.
Johann Carl Friedrich Gauss: German mathematician and physical scientist who contributed significantly to many fields, including number theory, statistics, analysis, differential geometry, geodesy, geophysics, electrostatics, astronomy and optics. Sometimes referred to as "the Prince of Mathematicians".
Hans Geiger: Inventor of the Geigerâ€"MÃ¼ller counter in 1928. It detects the emission of nuclear radiation through the ionization produced in a low-pressure gas in a Geigerâ€"MÃ¼ller tube. Further improved by Walther MÃ¼ller.
Heinrich GeiÃŸler: Inventor of the Geissler tube.
Reinhard Genzel: Astrophysicist, he and his group were the first to track the motions of stars at the centre of the Milky Way and show that they were orbiting a very massive object, probably a supermassive black hole.
Walter Gerlach: Physicist who co-discovered spin quantization in a magnetic field, the Sternâ€"Gerlach effect.
Edmund Germer: Inventor of the neon lamp (Neonlampe).
Max Giese: Inventor of the first concrete pump in 1928.
Heinrich GÃ¶bel: Inventor of Hemmer for Sewing Machines, 1865, Vacuum Pump (Improvement of the Geissler-System of vacuum pumps, 1881 and Electric Incandescent Lamp (sockets to connect the filament of carbon and the conducting wires), 1882
Kurt GÃ¶del: Important discoveries in math and logic, such as the incompleteness theorems

Maria Goeppert-Mayer: Physicist. Nobel laureate in Physics 1963 for proposing the nuclear shell model of the atomic nucleus together with J. Hans D. Jensen. The unit for the two-photon absorption cross section is named the Goeppert-Mayer (GM) unit.
Peter Carl Goldmark: Engineer who was instrumental in developing the long-playing (LP) microgroove 33-1/3 rpm vinyl phonograph disc.
Konrad Grebe: Coal-machine (Kohlenhobel)
Heinrich Greinacher: German-Swiss physicist. He is regarded as an original experimenter and is the developer of the magnetron and the Greinacher multiplier; Cockcroft-Walton-Generator in 1914.
Brothers Grimm: Academic pioneers of philology, linguistics, and storytelling. Worked together on the most comprehensive dictionary of the German language Deutsches WÃ¶rterbuch. Jacob Grimm: Philologist and linguist. Described first what is now known as Grimm's law, the first scientific research into sound change in 1822.
Georg Friedrich Grotefend: Deciphering of cuneiform
Alexander Grothendieck: Mathematician and the central figure behind the creation of the modern theory of algebraic geometry; Fields Medalist (1966).
Helmut GrÃ¶ttrup: smart card (together with JÃ¼rgen Dethloff)
Walter Gropius: Pioneer of modern architecture. Founder of the Bauhaus. First modern industrial building designed in 1910.
Peter GrÃ¼nberg: Physicist. Discovered giant magnetoresistance with Albert Fert. The discovery is used in gigabyte hard disk drives for computers. Nobel laureate 2007.
Heinz Guderian: The father of modern mechanized warfare, inventor of the Blitzkrieg strategy.
Otto von Guericke: Groundbreaking research into air pressure. Invented the vacuum pump in 1650.
Beno Gutenberg: Together with American Charles Francis Richter he invented Richter magnitude scale.
Johannes Gutenberg: Inventor of the technology of printing with movable type in 1439. The first book so printed was the Gutenberg Bible.

H

Fritz Haber: German chemist and Nobel laureate who pioneered synthetic ammonia and chemical warfare.
Theodor W. HÃ¤nsch: Physicist, developed laser-based precision spectroscopy further to determine optical frequency extremely accurately. Nobel laureate in 2005.
Otto Hahn: German chemist and Nobel laureate who pioneered the fields of radioactivity and radiochemistry. Considered to be "the father of nuclear chemistry" and the "founder of the atomic age". Discovered many isotopes, Protactinium and nuclear fission.
Samuel Hahnemann: Physician, best known for creating a system of alternative medicine called homeopathy.
Harald zur Hausen: Virologist, discovered the role of papilloma viruses in the development of cervical cancer. His research made the development of a vaccine against papilloma possible, which will drastically reduce cervical cancer in future. Nobel laureate 2008.
Werner Heisenberg: Theoretical physicist who made fundamental contributions to quantum mechanics. Discovered a particle's position and velocity cannot be known at the same time. Discovered atomic nuclei are made of protons and neutrons.
Wolfgang Helfrich: Co-inventor of Twisted nematic field effect.
Rudolf Hell: Inventor of the first fax machine (Hellschreiber).
Richard Hellmann: Hellmann's (Blue Ribbon) Mayonnaise, 1905.

Hermann von Helmholtz: Discovered the principle of conservation of energy.
Peter Henlein: Inventor of the portable watch.
Friedrich Wilhelm Herschel (William Herschel): Discovered the planet Uranus and infrared radiation among other things.
Heinrich Hertz: Physicist, Discoverer of electromagnetic/radio waves.
Otto Herzog: First use of the Carabiner in mountain climbing which substantially enhanced security for mountaineers.
Victor Francis Hess: Discovered Cosmic rays. Also won the Nobel Prize.
David Hilbert: Influential mathematician who discovered and developed a broad range of fundamental ideas in math.
Albert Hofmann: German-Swiss; Discovered the chemical properties of chitin and lysergic acid diethylamide.
Wilhelm Hofmeister: Discovery of the Alternation of generations
Felix Hoffmann: Isolated acetylsalicylic acid, a painkiller marketed under the name Aspirin (Bayer), 1897. In some English speaking countries marketed under the name disprin.
Herman Hollerith: a German American statistician who developed a mechanical tabulator based on punched cards
Gottlob Honold: Inventor of the spark plug and the modern internal combustion engine, as well as headlights.
Horten brothers: Designed some of the most advanced aircraft of the 1930s and '40s, including the world's first jet-powered flying wing, the Horten Ho 229.
Christian HÃ¼lsmeyer: German inventor of the Telemobilskop, a radio-based detector of remote objects; a 1904 precursor of radar.
Alexander von Humboldt: Naturalist and explorer. His quantitative work on botanical geography was foundational to the field of biogeography.
Wilhelm von Humboldt: Originator of the linguistic relativity hypothesis.
Erich Huzenlaub: Huzenlaub Process for parboiling

I

Ernst Ising: physiscist who developed Ising model.
Otmar Issing: Economist who invented the "pepet pillar" decision algorithm now used by the ECB.

J

J. Hans D. Jensen: Nuclear physicist, proposed the nuclear shell model, shared 1963 Nobel Prize in Physics.
Hugo Junkers: Pioneer of all-metal aircraft construction with the Junkers J 1 (1915â€"16).

K

Donald J. Kessler: Astrophysicist, known for developing the Kessler syndrome.
Hermann Kemper: Invented the magnetic levitation train. Patent granted in 1934.
Johannes Kepler: Discovered the laws of planetary motion.
Wolfgang Ketterle: German-American physicist who developed an "atom laser", amongst other breakthroughs. Nobel laureate 2001.
Erhard Kietz: Pioneer discoverer of video technology.
Gustav Kirchhoff: Discovery of the principles upon which spectroscopy is founded.
Martin Heinrich Klaproth: Discovered the element Uranium.
Klaus von Klitzing: Physicist, known for discovery of the integer quantum Hall effect, 1985 Nobel Prize in Physics.
Ludwig Knorr: Chemist, who together with Carl Paal, discovered the Paal-Knorr synthesis, and the Knorr quinoline synthesis and Knorr pyrrole synthesis.
Robert Koch: Physician, discoverer, inventor and Nobel Prize winner. He became famous for isolating Bacillus anthracis (1877), the Tuberculosis bacillus (1882) and the Vibrio cholera (1883) and for his development of Koch's postulates.
Friedrich Koenig: first functional steam-powered printing press with his colleague Andreas Friedrich Bauer)
Alfred KÃ¶rte and Gustav KÃ¶rte: discovered Gordium, 1900
Franz Kolb: Plasticine
Arthur Korn: Inventor involved in development of the fax machine, specifically the transmission of photographs or telephotography, known as the Bildtelegraph.
Albrecht Kossel: determining the chemical composition of nucleic acids
Max Kramer: Aircraft engineer. Developed the first operational guided bomb in 1942/43. This first smart bomb was radio controlled and joy-stick operated.
Hans Adolf Krebs: discovered two important chemical reactions in the body, namely the urea cycle and the citric acid cycle.
Wilhelm Krische: Galalith
Julius H. Kroehl: Inventor and engineer, who built the first functioning submarine in the world.
Herbert Kroemer: Physicist, shared the Nobel Prize in Physics 2000 for developing semiconductor heterostructures used in high-speed- and opto-electronics.
Werner KrÃ¼ger: Developed the Krueger flap, a lift enhancement device in modern aircraft wings in 1943.
Alfred Krupp: Pioneer in metal casting and metal working process and procedures.
Adam Johann von Krusenstern: Navigator and explorer, led the first Russian expedition to circumnavigate the earth.
Dietrich KÃ¼chemann: Aeronautical pioneer, developed wings for supersonic speed, such as delta wings as used in the Concorde.
Heinz Kunert: Defogger for automobiles

L

Albert Ladenburg: isolated hyoscine
Eugen Langen: Entrepreneur, engineer and inventor, involved in the development of the petrol engine and the Wuppertal monorail.
Paul Langerhans: Islets of Langerhans, Langerhans cells
Max von Laue: Discoveries regarding the diffraction of X-rays in crystals.
Ernst Lecher: He is remembered for developing an apparatusâ€" "Lecher lines"â€"to measure the wavelength and frequency of electromagnetic waves.
Gottfried Wilhelm Leibniz: Philosopher known for discovering the mathematical field of calculus and coherently laying down its basic operations in 1684.
Georg Christoph Lichtenberg: German scientist credited with the development of the electrophorus.
Justus von Liebig: German chemist who made contributions to agricultural and biological chemistry.
Otto Lilienthal: Father of Aviation and first successful aviator. Main discovery was the properties and shape of the wing.
Carl von Linde: Engineer who, among other things, developed refrigeration and gas separation technologies.
Alexander Lippisch: Pioneer of aerodynamics, his most famous design is the Messerschmitt Me 163.
Ernst LitfaÃŸ: free-standing cylindrical advertising column.
Friedrich Loeffler: discovered the organism causing diphtheria (Corynebacterium diphtheriae) and the cause of foot-and-mouth disease (Aphthovirus). His description of the diphtheria bacillus, published in 1884.

M

Georg Hans Madelung: Academic and aeronautical engineer; a participant in the development of the Junkers F.13.
Karl Marx: Political economist and philosopher, who defined the political/economical background of capitalism and discovered the mechanics of Marxism.
J. Heinrich Matthaei: Together with Marshall Nirenberg, they show that a sequence of nucleotide can encode particular amino acid, laying the foundations for deciphering the genetic code.
Wilhelm Maybach: Together with Gottlieb Daimler the first gasoline-powered motorcycle, power-engine boat and later, 1902, the Mercedes car model.
Ottomar von Mayenburg: Inventor of "Chlorodont", the first commercial brand of toothpaste.
Georg Meissner: Discovered Meissner's plexus.
Lise Meitner: Nuclear physicist, who, together with Otto Frisch, provided a theoretical account of nuclear fission.
Julius Lothar Meyer: With Mendeleev he developed the periodic classification of the elements in order of their atomic weight.
Christian Erich Hermann von Meyer: He discovered the Triassic predator Teratosaurus, the earliest bird Archaeopteryx lithographica (1861), the pterosaur Rhamphorhynchus, and the prosauropod dinosaur Plateosaurus
Gregor Mendel: Discoveries in genetics. Mendel demonstrated that the inheritance of certain traits in pea plants follows particular patterns, now referred to as the laws of Mendelian inheritance. First published in 1865.
Ottmar Mergenthaler: Inventor who has been called a second Gutenberg because of his invention of the Linotype machine.
Rudolf MÃ¶ssbauer: physicist, discovered MÃ¶ssbauer effect, shared Nobel Prize in Physics 1961.
Johannes Peter MÃ¼ller: Discoveries in physiology.

N

Thomas Nast: The German American "Father of the American Cartoon".
Walther Nernst: Inventor of the Nernst lamp and Nobel laureate 1920 in Chemistry.
Karl Nessler: Inventor of the permanent wave.
Paul Gottlieb Nipkow: Technician and inventor, the "spiritual father" of the core element of first generation television technology.
Emmy Noether: Mathematician. Groundbreaking contributions to abstract algebra and theoretical physics (Noether's theorem). Considered by many as the most influential woman in the history of mathematics.

O

Hermann Oberth: Pioneer of rocket science and discoverer of the Oberth effect.
Georg Ohm: physicist and mathematician, discoverer of the Ohm's law and Ohm's acoustic law
August Oetker: Pharmacist. He was the first to sell baking powder in small packets to households instead of bakeries (as others before him) and thus made it the popular product we know today.
Hans Joachim Pabst von Ohain: The modern jet engine in 1933, patented in 1936. Frank Whittle had developed a similar concept independently in 1928/1929.
Wilhelm Ostwald: Numerous discoveries and inventions in chemistry and other areas.
Nikolaus August Otto: Inventor of the first internal-combustion engine to efficiently burn fuel directly in a piston chamber.

P

Wolfgang Paul: Physicist. Co-developed the non-magnetic quadrupole mass filter which laid the foundation for what we now call an ion trap. Shared the Nobel Prize in 1989.
Hans von Pechmann: Chemist, renowned for his discovery of diazomethane in 1894. Pechmann condensation and Pechmann pyrazole synthesis.
Rudolf Peierls: nuclear physicist.
Julius Richard Petri: Bacteriologist who is generally credited with inventing the Petri dish while working as assistant to Robert Koch.
Emil Pfeiffer: Discovery of Infectious mononucleosis
Fritz Pfleumer: Inventor of magnetic tape for recording sound. He built the world's first practical tape recorder, called Magnetophon K1.
Max Planck: Physicist, Scientist. He is considered to be the founder of the quantum theory, and one of the most important physicists of the twentieth century.
Robert Wichard Pohl: In 1938, together with Rudolf Hilsch, built first functioning solid-state amplifier using salt as the semiconductor.
Ludwig Prandtl: First to explain the boundary layer and its importance for drag and streamlining in aircraft in 1904. He established and headed the Aerodynamische Versuchsanstalt in GÃ¶ttingen, now Max Planck Institute for Dynamics and Self-Organization. During his tenure the first wind tunnel in Germany was built here, thereby establishing a specific design for wind tunnels (GÃ¶ttingen type).

Q

R

Adolf Rambold: Inventor of modern tea bag.
Johann Philipp Reis: Inventor of the first phone transmitter in 1861, he also invented the term Telephone.
Josef Rodenstock: Founder of Rodenstock, manufacturer of optical systems, ophthalmic lenses and spectacles frames.
Ralf Reski: Moss bioreactor (1998).
Paul Julius Freiherr von Reuter: Communications pioneer.
Fritz Reiche: Was a student of Max Planck and a colleague of Albert Einstein, who was active in, and made important contributions to the early development of quantum mechanics including co-authoring the Thomas-Reiche-Kuhn sum rule.
Hans Reichel: Musical instrument inventor. Inventor of the daxophone and various overtone guitars.
Bernhard Riemann: Mathematician, who made lasting contributions to analysis, number theory, and differential geometry.
Johann Wilhelm Ritter: Physicist and discoverer of Ultraviolet.
Wilhelm Conrad RÃ¶ntgen: Physicist and discoverer of x-rays/RÃ¶ntgen rays (8 November 1895), this earned him the first Nobel Prize in Physics in 1901.
Arthur Rudolph: Rocket engineer who, together with Wernher von Braun, played a key role in the development of the V-2 rocket.
Heinrich Daniel Ruhmkorff: Induction coil
Ernst Ruska: Physicist, developed the first electron microscope in 1933. Nobel laureate 1986.

S

Carl Wilhelm Scheele: Oxygen (although Joseph Priestley published his findings first), identification of molybdenum, tungsten, barium, hydrogen and chlorine
Arthur Scherbius: Developed the mechanical cipher machine Enigma. Patent granted in 1918.
Paul Schlack: Invented Nylon 6.
Friedrich Albert Moritz Schlick: Was a German philosopher, physicist and the founding father of logical positivism and the Vienna Circle.
Heinrich Schliemann: Father of archaeology, among other things he discovered Homeric Troy.
Hugo Schmeisser: Developed the first modern assault rifle StG 44 in 1942.
Bernhard Schmidt: Developed a photographic telescope with minimal optical errors: the Schmidt camera.
Paul Schmidt: Developed since 1928 his idea of a new drive, the "pulsating incineration", also used in the V-1 flying bomb (engine was called "Argus-Schmidtrohr"); pulsejet was a development by Schmidt.
Christian Friedrich SchÃ¶nbein: Professor SchÃ¶nbein is credited with four scientific advances: Ozone, Gun cotton, Collodion and Fuel cell
Johann Lukas SchÃ¶nlein: Professor of medicine, he discovered among other things the parasitic cause of ringworm or favus (Achorion SchÃ¶nleinii).

Otto Schoetensack: Named the Homo heidelbergensis.
Otto Schott: Inventor of borosilicate glass. Donated his shares in the company Carl Zeiss to form Carl-Zeiss-Stiftung, still in existence today.
Walter H. Schottky: Played a major early role in developing the theory of electron and ion emission phenomena, invented the screen-grid vacuum tube and the pentode.
Marx Schwab: Silversmith, invented coining with the screw press around 1550.
Theodor Schwann: Discovery of properties of cells in animals.
Karl Schwarzschild: astronom, Schwarzschild metric, Deriving the Schwarzschild solution, Schwarzschild radius
Alois Senefelder: He invented the printing technique of lithography in 1796.
Friedrich SertÃ¼rner: First to isolate morphine from the opium poppy in 1803/1804, discovering morphine.
Philipp Franz von Siebold: Physician and naturalist, detailed description and collection of the Japanese flora and fauna. Introduced Western medicine to Japan and opened a medical school.
Ernst Werner von Siemens: Dynamo, pointer telegraph that used a needle to point to the right letter, first electric elevator, trolleybus.
Friedrich Soennecken: Invented Hole punch and ring binder.
Arnold Sommerfeld: Theoretical physicist who pioneered developments in atomic and quantum physics.
Johannes Stark: Discovery of the Doppler effect in canal rays and the splitting of spectral lines in electric fields" (the latter is known as the Stark effect).
Jack Steinberger: German-American-Swiss physicist, co-discovered the muon neutrino, shared 1988 Nobel Prize in Physics.
Georg Wilhelm Steller: Chief naturalist on Vitus Bering's expedition during which Alaska was discovered (1741) and pioneer of Alaskan Natural History. Steller's sea cow (now extinct) was named after him.
Otto Stern: Nobel laureate; contributed to the discovery of spin quantization in the Sternâ€"Gerlach experiment with Walther Gerlach in 1922.
Heinrich StÃ¶lzel: Developed the valve for brass instruments which is used today in 1818. Friedrich BlÃ¼hmel had made a similar development independently at the same time.
Horst Ludwig StÃ¶rmer: German-American physicist. Shared the Nobel Prize in 1998 for the discovery of a new form of quantum fluid with fractionally charged excitations.
Levi Strauss: The German American father of blue jeans.
Ernst Stromer: Discovery and Describing of Aegyptosaurus, Bahariasaurus, Carcharodontosaurus, and the largest known theropod, Spinosaurus aegyptiacus. Stromer also described the giant crocodilian Stomatosuchus.

T

Ehrenfried Walther von Tschirnhaus: He is considered to have been the inventor of European porcelain.
Oscar Troplowitz: He invented adhesive tape, Leukoplast.

U

Dietrich "Diedrich" Uhlhorn: Engineer, mechanic and inventor, who invented the first mechanical tachometer (1817), between 1817 and 1830 inventor of the Presse MonÃ©taire (level coin press known as Uhlhorn Press) which bears his name.

V

Abraham Vater: Professor of anatomy; Ampulla of Vater.
Richard Vetter: Developed the most fuel efficient condensing boiler for heating systems in 1980. Used in many houses in Europe.
Rudolf Virchow: "Father of modern pathology"; numerous discoveries in the area of medicine.
Hans Vogt: Invented sound-on-film (idea 1905) together with Jo Engl and Joseph Massolle, first sound-on-film for the public on 17 September 1922 in Filmtheater Alhambra, Berlin, Germany.
Woldemar Voigt (often: Waldemar Voigt): Physicist, who taught at the Georg August University of GÃ¶ttingen. He worked on crystal physics, thermodynamics and electro-optics. He discovered the Voigt effect in 1898.
Waldemar Voigt (aerospace engineer): Chief designer at Messerschmitt's Oberammergau offices and pioneer of the Me 163 and Me 264, project leader of the development of Me P. 1101, Me P. 1106, Me P. 1110, Me P. 1111, Me P. 1112 and Me P. 1116.
Jacob Volhard: Chemist who discovered, together with his student Hugo Erdmann, the Volhardâ€"Erdmann cyclization.

W

Martin WaldseemÃ¼ller: Cartographer, used the name "America" on his map Universalis Cosmographia in honour of the Florentine explorer Amerigo Vespucci. The map was drawn at St-Die in 1507 and it was the first time "America" was used on a map.
Otto Wallach: Chemist who researched, amongst others, alicyclic compounds. Nobel Prize in Chemistry 1910.
Hellmuth Walter: Engineer who pioneered research into rocket engines and gas turbines.
Felix Wankel: Inventor of the Rotary Motor.
Max Weber: Discovered the mass effects of capitalism and modernity.
Wilhelm Eduard Weber: Inventor of the first electromagnetic telegraph together with Carl Friedrich Gauss.
Alfred Wegener: He is most notable for proposing continental drift in 1912
Wilhelm Weinberg: Hardyâ€"Weinberg principle
Gustav WeiÃŸkopf: Aviation pioneer, designer and builder of early aircraft and engines, is reported to be the first flying a powered aircraft in 1901
Rainer Weiss: born in Berlin, American physiscist who invented laser interferometric gravitational wave detectors.
Johan Wilcke: Inventor of the electrophorus
Hugo Winckler: Discovery of Hattusa
Clemens Alexander Winkler: Chemist who discovered the element germanium in 1886.
August WÃ¶hler: Investigated fatigue phenomena in the behavior of materials
Friedrich WÃ¶hler: The first to synthesize urea. WÃ¶hler is regarded as a pioneer in organic chemistry.
Heinrich WÃ¶hlk: Contact lenses in PMMA
Theodor Wulf: Cosmic ray (together with Austrian Victor Hess)

X

Y

Z

Hermann Zapf: Pioneer of computer typography and creator of many well-known typefaces.
Carl Zeiss: Pioneered glass casting and allied procedures and processes for high quality optics.
Ferdinand Graf von Zeppelin (1838â€"1917): Inventor of the airship named after him. Start of the airship LZ1 in 1900.
Karl Zimmer: Discovered the effects of ionizing radiation on DNA in 1935.
Konrad Zuse: Inventor of the first functional program-controlled Turing-complete computer in 1941, and the first high-level programming language PlankalkÃ¼l in 1942.

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A potato chip (American English) or crisp (British English) is a thin slice of potato that has been deep fried, baked, kettle-cooked, or popped until crunchy. Potato chips are commonly served as a snack, side dish, or appetizer. The basic chips are cooked and salted; additional varieties are manufactured using various flavorings and ingredients including herbs, spices, cheeses, artificial flavours and additives. More generally, crisps and chips include savory snack products made from not just potato, but also corn, tapioca, banana, or other cereals, root vegetables, and fruits.

Potato chips are a predominant part of the snack food and convenience food market in Western countries. The global potato chip market generated total revenues of US$16.49 billion in 2005. This accounted for 35.5% of the total savory snacks market in that year ($46.1 billion).

History

The earliest known recipe for potato chips is in William Kitchiner's cookbook The Cook's Oracle, first published in 1817, which was a bestseller in England and the United States. The 1822 edition's version of recipe 104 is called "Potatoes fried in Slices or Shavings" and reads "peel large potatoes, slice them about a quarter of an inch thick, or cut them in shavings round and round, as you would peel a lemon; dry them well in a clean cloth, and fry them in lard or dripping". Early recipes for potato chips in the United States are found in Mary Randolph's Virginia House-Wife (1824), and in N.K.M. Lee's Cook's Own Book (1832), both of which explicitly cite Kitchiner.

Nonetheless, a legend associates the creation of potato chips with Saratoga Springs, New York, decades later. By the late 19th century, a popular version of the story attributed the dish to George Crum, a half-black, half-Native American cook at Moon's Lake House, who was trying to appease an unhappy customer on August 24, 1853. The customer kept sending his French-fried potatoes back, complaining that they were too thick. Frustrated, he sliced the potatoes razor thin, fried them until crisp and seasoned them with extra salt. To Crum's surprise, the customer loved them. They soon became called "Saratoga Chips", a name that persisted into at least the mid-20th century. A version of this story popularized in a 1973 national advertising campaign by St. Regis Paper Company, which manufactured packaging for chips, said that Crum's customer was Cornelius Vanderbilt. Crum was renowned as a chef and by 1860 owned his own lakeside restaurant, Crum's House.

In the 20th century, potato chips spread beyond chef-cooked restaurant fare and began to be mass-produced for home consumption. The Dayton, Ohio-based Mike-sell's Potato Chip Company, founded in 1910, identifies as the "oldest potato chip company in the United States". New England-based Tri-Sum Potato Chips, founded in 1908 as the Leominster Potato Chip Company, in Leominster, Massachusetts claim to be America's first potato chip manufacturer. Chips sold in markets were usually sold in tins or scooped out of storefront glass bins and delivered by horse and wagon. The early potato chip bag was wax paper with the ends ironed or stapled together. At first, potato chips were packaged in barrels or tins, which left chips at the bottom stale and crumbled.

Laura Scudder, an entrepreneur in Monterey Park, California, started having her workers take home sheets of wax paper to iron into the form of bags, which were filled with chips at her factory the next day. This pioneering method reduced crumbling and kept the chips fresh and crisp longer. This innovation, along with the invention of cellophane, allowed potato chips to become a mass-market product. Today, chips are packaged in plastic bags, with nitrogen gas blown in prior to sealing to lengthen shelf life, and provide protection against crushing.

Traditional chips were made by the "batch-style" process, where all chips are fried all at once at a low temperature and continuously raked to prevent them from sticking together. Industrial advance resulted in a shift to production by a "continuous-style" process, running chips through a vat of hot oil and drying them in a conveyor process. Consumer desire for original style chips resulted in the introduction of traditionally made "kettle-style" chips in the 2000s (known as hand-cooked in the UK/Europe).

Flavored chips

In an idea originated by the Smiths Potato Crisps Company Ltd, formed in 1920, Frank Smith packaged a twist of salt with his chips in greaseproof paper bags, which were sold around London.

The potato chip remained otherwise unseasoned until an innovation by Joe "Spud" Murphy, the owner of the Irish crisps company Tayto, who in the 1950s developed a technology to add seasoning during manufacture. After some trial and error, Murphy and his employee Seamus Burke produced the world's first seasoned chips: Cheese & Onion and Salt & Vinegar. Companies worldwide sought to buy the rights to Tayto's technique.

The first flavored chips in the United States, barbecue flavor, were being manufactured and sold by 1954. In 1958, Herr's was the first company to introduce barbecue-flavored potato chips in Pennsylvania.

Nomenclature

Little consistency exists in the English-speaking world for names of fried potato slices, thick or thin. American and Canadian English use "chips" for the above-mentioned dish â€" this term is also used (but not universally) in other parts of world, and sometimes "crisps" for the same made from batter.

In the United Kingdom and Ireland, "crisps" are potato chips which are eaten cold, whilst "chips" are similar to french fries (as in "fish and chips") and are served hot. In Australia, some parts of South Africa, New Zealand, India, the general West Indies especially in Barbados, both forms of potato product are simply known as "chips", as are the larger "home-style" potato crisps. In the north of New Zealand, they are known as "chippies", but are marketed as "chips" throughout the country. In Australia and New Zealand, sometimes the distinction is made between "hot chips" (fried potatoes) and "chips" or "potato chips". In Bangladesh, they are generally known as "chip" or "chips", and much less frequently as "crisps" (pronounced "kirisp") and locally, alu bhaja (for their similarity to the native potato bhajji).

In German-speaking countries (Austria, Germany: "Kartoffelchips"; Switzerland: "Pommes Chips") and in countries of the former SFR Yugoslavia, fried thin potato slices are known as "chips" (locally pronounced very similar to the actual English pronunciation), with a clear distinction from french fries. In Brazil, "home-style" potato chips are known as batatas portuguesas ("Portuguese potatoes") if their sides are relatively smooth and batatas prussianas ("Prussian potatoes") if their sides show a wafer biscuit-like pattern, whilst American-like industrial uniform potato chips made from a fried potato purÃ©e-based dough are known as "batata chips" ("potato chips"), or just "chips".

Health concerns

A big concern about the nutrition of potato chips is that because they are usually made with salt, they contain substantial levels of sodium. This had been linked to health issues such as high blood pressure, and potato chips' taste appeal caused people to overeat and become obese. Researchers at Queen Mary, University of London in 2004 noted, though, that a small "bag of ready-salted crisps" contains less salt than a serving of "Special K, All-Bran, Golden Grahams, Cheerios, Shreddies, and every brand of cornflakes on sale in the UK."

Some potato chip companies have responded to the criticism by investing in research and development to modify existing recipes and create health-conscious products. Kettle Foods was founded in 1978 and currently sells only trans fatâ€"free products, including potato chips. PepsiCo research shows that about 80% of salt on chips is not sensed by the tongue before being swallowed. Frito-Lay spent $414 million in 2009 on product development, including development of salt crystals that would reduce the salt content of Lay's potato chips without adversely affecting flavor.

Also, the option of unsalted chips is available, e.g. the longstanding British brand Salt 'n' Shake, whose chips are not seasoned, but instead include a small salt sachet in the bag, such that the chips can be salted as much or as little as the purchaser would like.

Regional varieties

In Canada, seasonings include dill pickle, jalapeÃ±o, ketchup, barbecue, all dressed, sour cream and onion, and salt and vinegar. In 2006, Lay's introduced wasabi chips in Toronto and Vancouver, but no longer offers them. Loblaw, Canada's largest food retailer, offers several unusual flavors under its President's Choice brand, including poutine, maple bacon, Jamaican jerk chicken, Greek feta and olive, ballpark hot dog, and barbeque baby back ribs.
In Hong Kong, the two prominent potato chips are the spicy "Ethnican" variety by Calbee, and barbecue by Jack'n Jill. Lay's are also popular in Hong Kong.
In Ireland the two main flavors are cheese and onion, and salt and vinegar. However in Ireland, the word "Tayto" is synonymous with potato chips after the Tayto brand and can be used to describe all varieties of chips, including those not produced by Tayto. Owing to the dominance of Tayto in the Irish market, the word has become a genericized trademark. Hunky Dorys and King crisps are other popular Irish brands.
In Germany, only two flavors were traditionally available, red paprika (paprika, sometimes also called ungarisch) and ready salted (gesalzen). These are still by far the most common and popular types, but some vendors started to offer a number of other flavors such as sour cream & onion, cheese, oriental, or more exotic seasonings like "chakalaka", "currywurst", "pommes" (french fries), "Rot-weiss" (red and white - french fries with tomato ketchup and mayonnaise). Potato chips made from ground potatoes are called Stapelchips rather than Kartoffelchips for legal reasons.
In Colombia, lemon, chicken, chorizo, and sirloin steak with mushroom sauce flavored potato chips are sold.

In Japan, flavors include nori and shiyo, consommÃ©, wasabi, soy sauce and butter, garlic, plum, barbecue, pizza, mayonnaise, and black pepper. Chili, scallop with butter, teriyaki, takoyaki and yakitori chip flavors are also available. Major manufacturers are Calbee, Koikeya and Yamayoshi. Chips are called potato chips, or simply "potato" (ãƒãƒ†ãƒˆ).
The market in the United Kingdom is dominated by Walkers, which holds 58% of the British crisp market. Walkers is known for its wide variety of potato chips. The three main flavors are ready salted, cheese and onion, and salt and vinegar; however, other examples are prawn cocktail (which were incorrectly described in the media as being subject to an EU directive banning them), Worcester sauce, roast chicken, steak and onion, smoky bacon, lamb and mint, ham and mustard, barbecue, BBQ rib, tomato ketchup, sausage and ketchup, pickled onion, Branston pickle, and Marmite. More exotic flavors are Thai sweet chili, roast pork and creamy mustard sauce, lime and Thai spices, chicken with Italian herbs, sea salt and cracked black pepper, sea salt and chardonnay wine vinegar, sea salt and cider vinegar, spicy and aromatic curry, turkey and bacon, caramelized onion and sweet balsamic vinegar, Stilton and cranberry, mango chili, and special flavors such as American cheeseburger and English r oast beef and Yorkshire pudding. Kettle Foods Ltd's range of thick-cut crunchy potato chips include gourmet flavors: Mexican limes with a hint of chilli, salsa with mesquite, buffalo mozzarella tomato and basil, mature cheddar with Adnams Broadside Beer, Soulmate cheeses, and onion. McCoys Crisps are also popular in the UK. In the north of England, Seabrook Potato Crisps are popular, but they are much less common in the south. Tayto is a popular brand in Northern Ireland.
In the United States, popular potato chip flavorings include sour cream and onion, dill pickle, barbecue, ranch dressing, salt and vinegar, cheddar, and lemon-lime. In the Gulf South, Zapp's Potato Chips of Gramercy, Louisiana, manufactures kettle-fried chips with regional flavors such as Crawtator, Cajun dill, Voodoo, and Creole onion.
Pennsylvania leads the U.S. in chip production and has been dubbed "the Potato Chip Capital" by several sources. Pennsylvania-based companies producing potato chips include Utz Quality Foods, Herr's Snacks, Snyder's of Hanover, Wise Foods, Middleswarth Potato Chips, Dieffenbach's Potato Chips, Hartley's Potato Chips, Gibbles Foods, Stehman's Potato Chips, and Charles Chips.
In New Mexico, jerky shops offer locally made chips (often kettle-cooked) flavored with local red or green chile, or a combination of the two (known as "Christmas").

Similar foods

Another type of potato chip, notably the Pringles and Lay's Stax brands, is made by extruding or pressing a dough made from dehydrated potatoes into the desired shape before frying. This makes chips that are uniform in size and shape, which allows them to be stacked and packaged in rigid tubes. In America, the official term for Pringles is potato crisps, but they are rarely referred to as such. Conversely, Pringles may be termed potato chips in Britain, to distinguish them from traditional "crisps". Munchos, another brand that uses the term potato crisps, has deep air pockets in its chips that give it a curved shape, though the chips themselves resemble regular bagged chips.

An additional variant of potato chips exists in the form of "potato sticks", also called shoestring potatoes. These are made as extremely thin (2 to 3Â mm) versions of the popular French fry, but are fried in the manner of regular salted potato chips. A hickory-smoke-flavored version is popular in Canada, going by the vending machine name "Hickory Sticks". Potato sticks are typically packaged in rigid containers, although some manufacturers use flexible pouches, similar to potato chip bags. Potato sticks were originally packed in hermetically sealed steel cans. In the 1960s, manufacturers switched to the less expensive composite canister (similar to the Pringles container). Reckitt Benckiser was a market leader in this category under the Durkee Potato Stix and French's Potato Sticks names, but exited the business in 2008. In 2014, French's reentered the market.

A larger variant (about 1Â cm thick) made with dehydrated potatoes is marketed as Andy Capp's Pub Fries, using the theme of a long-running British comic strip, which are baked and sold in a variety of flavors. Walkers make a similar product (using the Smiths brand) called "Chipsticks" which are sold in ready-salted and salt and vinegar flavors.

Some companies have also marketed baked potato chips as an alternative with lower fat content. Additionally, some varieties of fat-free chips have been made using artificial, and indigestible, fat substitutes. These became well known in the media when an ingredient many contained, Olestra, was linked in some individuals to abdominal discomfort and loose stools.

Americans' appetite for crispy snacks gave birth to the packaged, flavored corn chips, with such brands as Fritos, CC's, and Doritos dominating the market. "Swamp chips" are similarly made from a variety of root vegetables, such as parsnips, rutabagas, and carrots. Japanese-style variants include extruded chips, like products made from rice or cassava. In South Indian snack cuisine, an item called happla in Kannada/vadam in Tamil, is a chip made of an extruded rice-sago or multigrain base that has been around for many centuries.

Many other products might be called "crisps" in Britain, but would not be classed as "potato chips" because they are not made with potato or are not chipped (for example, Wotsits, Quavers, Skips, Hula Hoops, and Monster Munch).

Kumara (sweet potato) chips are eaten in Korea, New Zealand, and Japan; parsnip, beetroot, and carrot crisps are available in the United Kingdom. India is famous for a large number of localized 'chips shops', selling not only potato chips, but also other varieties such as plantain chips, tapioca chips, yam chips, and even carrot chips. Plantain chips, also known as chifles or tostones, are also sold in the Western Hemisphere from Canada to Chile. In the Philippines, banana chips can be found sold at local stores. In Kenya, chips are made from arrowroot and casava. In the United Kingdom, Sweden, Finland, and Australia, a new variety of Pringles made from rice has been released and marketed as lower in fat than its potato counterparts.

Production

Process of making chips

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A refrigerator (colloquially fridge) is a popular household appliance that consists of a thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room. Refrigeration is an essential food storage technique in developed countries. The lower temperature lowers the reproduction rate of bacteria, so the refrigerator reduces the rate of spoilage. A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum temperature range for perishable food storage is 3 to 5Â Â°C (37 to 41Â Â°F). A similar d evice that maintains a temperature below the freezing point of water is called a freezer. The refrigerator replaced the icebox, which had been a common household appliance for almost a century and a half. For this reason, a refrigerator is sometimes referred to as an icebox in American usage.

The first cooling systems for food involved using ice. Artificial refrigeration began in the mid-1750s, and developed in the early 1800s. In 1834, the first working vapor-compression refrigeration system was built. The first commercial ice-making machine was invented in 1854. In 1913, refrigerators for home use were invented. In 1923 Frigidaire introduced the first self-contained unit. The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s. Home freezers as separate compartments (larger than necessary just for ice cubes) were introduced in 1940. Frozen foods, previously a luxury item, became commonplace.

Freezer units are used in households and in industry and commerce. Commercial refrigerator and freezer units were in use for almost 40 years prior to the common home models. Most households use the freezer-on-top-and-refrigerator-on-bottom style, which has been the basic style since the 1940s. A vapor compression cycle is used in most household refrigerators, refrigeratorâ€"freezers and freezers. Newer refrigerators may include automatic defrosting, chilled water and ice from a dispenser in the door.

Domestic refrigerators and freezers for food storage are made in a range of sizes. Among the smallest is a 4Â L Peltier refrigerator advertised as being able to hold 6 cans of beer. A large domestic refrigerator stands as tall as a person and may be about 1Â m wide with a capacity of 600Â L. Refrigerators and freezers may be free-standing, or built into a kitchen. The refrigerator allows the modern household to keep food fresh for longer than before. Freezers allow people to buy food in bulk and eat it at leisure, and bulk purchases save money.

History

Refrigeration technology

Before the invention of the refrigerator, icehouses were used to provide cool storage for most of the year. Placed near freshwater lakes or packed with snow and ice during the winter, they were once very common. Natural means are still used to cool foods today. On mountainsides, runoff from melting snow is a convenient way to cool drinks, and during the winter one can keep milk fresh much longer just by keeping it outdoors. The word "refrigeratory" was used at least as early as the 17th century

The history of artificial refrigeration began when Scottish professor William Cullen designed a small refrigerating machine in 1755. Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled, absorbing heat from the surrounding air. The experiment even created a small amount of ice, but had no practical application at that time.

In 1805, American inventor Oliver Evans described a closed vapor-compression refrigeration cycle for the production of ice by ether under vacuum. In 1820, the British scientist Michael Faraday liquefied ammonia and other gases by using high pressures and low temperatures, and in 1834, an American expatriate to Great Britain, Jacob Perkins, built the first working vapor-compression refrigeration system. It was a closed-cycle device that could operate continuously. A similar attempt was made in 1842, by American physician, John Gorrie, who built a working prototype, but it was a commercial failure. American engineer Alexander Twining took out a British patent in 1850 for a vapor compression system that used ether.

The first practical vapor compression refrigeration system was built by James Harrison, a British journalist who had emigrated to Australia. His 1856 patent was for a vapor compression system using ether, alcohol or ammonia. He built a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong, Victoria, and his first commercial ice-making machine followed in 1854. Harrison also introduced commercial vapor-compression refrigeration to breweries and meat packing houses, and by 1861, a dozen of his systems were in operation.

The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as "aqua ammonia") was developed by Ferdinand CarrÃ© of France in 1859 and patented in 1860. Carl von Linde, an engineering professor at the Technological University Munich in Germany, patented an improved method of liquefying gases in 1876. His new process made possible the use of gases such as ammonia (NH₃), sulfur dioxide (SO₂) and methyl chloride (CH₃Cl) as refrigerants and they were widely used for that purpose until the late 1920s.

Domestic refrigerator

In 1913, refrigerators for home and domestic use were invented by Fred W. Wolf of Fort Wayne, Indiana with models consisting of a unit that was mounted on top of an ice box. In 1914, engineer Nathaniel B. Wales of Detroit, Michigan, introduced an idea for a practical electric refrigeration unit, which later became the basis for the Kelvinator. A self-contained refrigerator, with a compressor on the bottom of the cabinet was invented by Alfred Mellowes in 1916. Mellowes produced this refrigerator commercially but was bought out by William C. Durant in 1918, who started the Frigidaire Company to mass-produce refrigerators. In 1918, Kelvinator Company introduced the first refrigerator with any type of automatic control. The absorption refrigerator was invented by Baltzar von Platen and Carl Munters from Sweden in 1922, while they were still students at the Royal Institute of Technology in Stockholm. It became a worldwide success and was commercialized by Electrolux. Other pioneers in cluded Charles Tellier, David Boyle, and Raoul Pictet. Carl von Linde was the first to patent and make a practical and compact refrigerator.

These home units usually required the installation of the mechanical parts, motor and compressor, in the basement or an adjacent room while the cold box was located in the kitchen. There was a 1922 model that consisted of a wooden cold box, water-cooled compressor, an ice cube tray and a 9-cubic-foot (0.25Â m³) compartment, and cost $714. (A 1922 Model-T Ford cost about $450.) By 1923, Kelvinator held 80 percent of the market for electric refrigerators. Also in 1923 Frigidaire introduced the first self-contained unit. About this same time porcelain-covered metal cabinets began to appear. Ice cube trays were introduced more and more during the 1920s; up to this time freezing was not an auxiliary function of the modern refrigerator.

The first refrigerator to see widespread use was the General Electric "Monitor-Top" refrigerator introduced in 1927, so-called because of its resemblance to the gun turret on the ironclad warship USS Monitor of the 1860s. The compressor assembly, which emitted a great deal of heat, was placed above the cabinet, and enclosed by a decorative ring. Over a million units were produced. As the refrigerating medium, these refrigerators used either sulfur dioxide, which is corrosive to the eyes and may cause loss of vision, painful skin burns and lesions, or methyl formate, which is highly flammable, harmful to the eyes, and toxic if inhaled or ingested. Many of these units are still functional today, after requiring little more service than a replacement start relay or thermostat if at all. These cooling systems cannot legally be recharged with the hazardous original refrigerants if they leak or break down.

The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s and provided a safer, low-toxicity alternative to previously used refrigerants. Separate freezers became common during the 1940s; the popular term at the time for the unit was a deep freeze. These devices, or appliances, did not go into mass production for use in the home until after World War II. The 1950s and 1960s saw technical advances like automatic defrosting and automatic ice making. More efficient refrigerators were developed in the 1970s and 1980s, even though environmental issues led to the banning of very effective (Freon) refrigerants. Early refrigerator models (from 1916) had a cold compartment for ice cube trays. From the late 1920s fresh vegetables were successfully processed through freezing by the Postum Company (the forerunner of General Foods), which had acquired the technology when it bought the rights to Clarence Birdseye's successful fresh freezing methods.< /p>

The first successful application of frozen foods occurred when General Foods heiress Marjorie Merriweather Post (then wife of Joseph E. Davies, United States Ambassador to the Soviet Union) deployed commercial-grade freezers in Spaso House, the US Embassy in Moscow, in advance of the Daviesâ€™ arrival. Post, fearful of the USSR's food processing safety standards, fully stocked the freezers with products from General Foods' Birdseye unit. The frozen food stores allowed the Davies to entertain lavishly and serve fresh frozen foods that would otherwise be out of season. Upon returning from Moscow, Post (who resumed her maiden name after divorcing Davies) directed General Foods to market frozen product to upscale restaurants.

Home freezers as separate compartments (larger than necessary just for ice cubes), or as separate units, were introduced in the United States in 1940. Frozen foods, previously a luxury item, became commonplace.

Freezer

Freezer units are used in households and in industry and commerce. Food stored at or below âˆ'18Â Â°C (0Â Â°F) is safe indefinitely. Most household freezers maintain temperatures from âˆ'23 to âˆ'18Â Â°C (âˆ'9 to 0Â Â°F), although some freezer-only units can achieve âˆ'34Â Â°C (âˆ'29Â Â°F) and lower. Refrigerators generally do not achieve lower than âˆ'23Â Â°C (âˆ'9Â Â°F), since the same coolant loop serves both compartments: Lowering the freezer compartment temperature excessively causes difficulties in maintaining above-freezing temperature in the refrigerator compartment. Domestic freezers can be included as a separate compartment in a refrigerator, or can be a separate appliance. Domestic freezers are generally upright units resembling refrigerators or chests (upright units laid on their backs). Many modern upright freezers come with an ice dispenser built into their door. Some upscale models include thermostat displays and controls, and sometimes flatscreen televisions as well.

Commercial and domestic refrigerators

Commercial refrigerator and freezer units, which go by many other names, were in use for almost 40 years prior to the common home models. They used gas systems such as ammonia (R-717) or sulfur dioxide (R-764), which occasionally leaked, making them unsafe for home use. Practical household refrigerators were introduced in 1915 and gained wider acceptance in the United States in the 1930s as prices fell and non-toxic, non-flammable synthetic refrigerants such as Freon-12 (R-12) were introduced. However, R-12 damaged the ozone layer, causing governments to issue a ban on its use in new refrigerators and air-conditioning systems in 1994. The less harmful replacement for R-12, R-134a (tetrafluoroethane), has been in common use since 1990, but R-12 is still found in many old systems today.

A common commercial refrigerator is the glass fronted beverage cooler. These type of appliances are typically designed for specific re-load conditions meaning that they generally have a larger cooling system. This ensures that they are able to cope with a large throughput of drinks and frequent door opening. As a result, it is common for these types of commercial refrigerators to have energy consumption of >4 kWh/day.

Styles of refrigerators

In the early 1950s most refrigerators were white, but from the mid-1950s through present day designers and manufacturers put color onto refrigerators. In the late-1950s/early-1960s, pastel colors like turquoise and pink became popular, brushed chrome-plating (similar to stainless finish) was available on some models from different brands. In the late 1960s and throughout the 1970s, earth tone colors were popular, including Harvest Gold, Avocado Green and almond. In the 1980s, black became fashionable. In the late 1990s stainless steel came into vogue, and in 2009, one manufacturer introduced multi-color designs.

Production by country

General technical explanation

A vapor compression cycle is used in most household refrigerators, refrigeratorâ€"freezers and freezers. In this cycle, a circulating refrigerant such as R134a enters a compressor as low-pressure vapor at or slightly below the temperature of the refrigerator interior. The vapor is compressed and exits the compressor as high-pressure superheated vapor. The superheated vapor travels under pressure through coils or tubes that make up the condenser; the coils or tubes are passively cooled by exposure to air in the room. The condenser cools the vapor, which liquefies. As the refrigerant leaves the condenser, it is still under pressure but is now only slightly above room temperature. This liquid refrigerant is forced through a metering or throttling device, also known as an expansion valve (essentially a pin-hole sized constriction in the tubing) to an area of much lower pressure. The sudden decrease in pressure results in explosive-like flash evaporation of a portion (typically about half) of the liquid. The latent heat absorbed by this flash evaporation is drawn mostly from adjacent still-liquid refrigerant, a phenomenon known as auto-refrigeration. This cold and partially vaporized refrigerant continues through the coils or tubes of the evaporator unit. A fan blows air from the refrigerator or freezer compartment ("box air") across these coils or tubes and the refrigerant completely vaporizes, drawing further latent heat from the box air. This cooled air is returned to the refrigerator or freezer compartment, and so keeps the box air cold. Note that the cool air in the refrigerator or freezer is still warmer than the refrigerant in the evaporator. Refrigerant leaves the evaporator, now fully vaporized and slightly heated, and returns to the compressor inlet to continue the cycle.

Domestic refrigerators are extremely reliable because the moving parts and fluids are sealed from the atmosphere for life, with no possibility of leakage or contamination. In comparison, mechanically-driven refrigeration compressors, such as those in automobile air conditioning, inevitably leak fluid and lubricant past the shaft seals. This leads to a requirement for periodic recharging and, if ignored, possible compressor failure.

An absorption refrigerator works differently from a compressor refrigerator, using a source of heat, such as combustion of liquefied petroleum gas, solar thermal energy or an electric heating element. These heat sources are much quieter than the compressor motor in a typical refrigerator. A fan or pump might be the only mechanical moving parts; reliance on convection is considered impractical.

The Peltier effect uses electricity to pump heat directly; refrigerators employing this system are sometimes used for camping, or in situations where noise is not acceptable. They can be totally silent (if a fan for air circulation is not fitted) but are less energy-efficient than other methods.

Other uses of an absorption refrigerator (or "chiller") include large systems used in office buildings or complexes such as hospitals and universities. These large systems are used to chill a brine solution that is circulated through the building.

Many modern refrigerator/freezers have the freezer on top and the refrigerator on the bottom. Most refrigerator-freezersâ€"except for manual defrost models or cheaper unitsâ€"use what appears to be two thermostats. Only the refrigerator compartment is properly temperature controlled. When the refrigerator gets too warm, the thermostat starts the cooling process and a fan circulates the air around the freezer. During this time, the refrigerator also gets colder. The freezer control knob only controls the amount of air that flows into the refrigerator via a damper system. Changing the refrigerator temperature will inadvertently change the freezer temperature in the opposite direction. Changing the freezer temperature will have no effect on the refrigerator temperature. The freezer control may also be adjusted to compensate for any refrigerator adjustment.

This means the refrigerator may become too warm. However, because only enough air is diverted to the refrigerator compartment, the freezer usually re-acquires the set temperature quickly, unless the door is opened. When a door is opened, either in the refrigerator or the freezer, the fan in some units stops immediately to prevent excessive frost build up on the freezer's evaporator coil, because this coil is cooling two areas. When the freezer reaches temperature, the unit cycles off, no matter what the refrigerator temperature is. Modern computerized refrigerators do not use the damper system. The computer manages fan speed for both compartments, although air is still blown from the freezer.

A few manufacturers offer dual compressor models. These models have separate freezer and refrigerator compartments that operate independently of each other, sometimes mounted within a single cabinet. Each has its own separate compressor, condenser and evaporator coils, insulation, thermostat, and door. Typically, the compressors and condenser coils are mounted at the top of the cabinet, with a single fan to cool them both.

This design, where no air passes between the two compartments, provides for more appropriate humidity levels and much tighter temperature control in each compartment. It also requires much less energy to operate, since each compressor & coolant system can be optimized for a specific temperature range. Further, opening the door of one compartment does not affect the temperature of the air or humidity level in the other compartment. Thus, it avoids many of the disadvantages of the much more common single compressor designs described above, although at a higher initial cost and increased system noise. Manufacturers of such designs argue that the increased cost is compensated over time due to reduced energy use and less food waste due to reduced spoilage.

Alternatives to the vapor-compression cycle not in current use include:

Features

Newer refrigerators may include:

Automatic defrosting
A power failure warning that alerts the user by flashing a temperature display. It may display the maximum temperature reached during the power failure, and whether frozen food has defrosted or may contain harmful bacteria.
Chilled water and ice from a dispenser in the door. Water and ice dispensing became available in the 1970s. In some refrigerators, the process of making ice is built-in so the user doesn't have to manually use ice trays. Some refrigerators have water chillers and water filtration systems.
Cabinet rollers that lets the refrigerator roll out for easier cleaning
Adjustable shelves and trays
A status indicator that notifies when it is time to change the water filter
An in-door ice caddy, which relocates the ice-maker storage to the freezer door and saves approximately 60 litres (2Â cuÂ ft) of usable freezer space. It is also removable, and helps to prevent ice-maker clogging.
A cooling zone in the refrigerator door shelves. Air from the freezer section is diverted to the refrigerator door, to cool milk or juice stored in the door shelf.
A drop down door built into the refrigerator main door, giving easy access to frequently used items such as milk, thus saving energy by not having to open the main door.
A Fast Freeze function to rapidly cool foods by running the compressor for a predetermined amount of time and thus temporarily lowering the freezer temperature below normal operating levels. It is recommended to use this feature several hours before adding more than 1Â kg of unfrozen food to the freezer. For freezers without this feature, lowering the temperature setting to the coldest will have the same effect.

Early freezer units accumulated ice crystals around the freezing units. This was a result of humidity introduced into the units when the doors to the freezer were opened condensing on the cold parts, then freezing. This frost buildup required periodic thawing ("defrosting") of the units to maintain their efficiency. Manual Defrost (referred to as Cyclic) units are still available. Advances in automatic defrosting eliminating the thawing task were introduced in the 1950s, but are not universal, due to energy performance and cost. These units used a counter that only defrosted the freezer compartment (Freezer Chest) when a specific number of door openings had been made. The units were just a small timer combined with an electrical heater wire that heated the freezer's walls for a short amount of time to remove all traces of frost/frosting. Also, early units featured freezer compartments located within the larger refrigerator, and accessed by opening the refrigerator door, and t hen the smaller internal freezer door; units featuring an entirely separate freezer compartment were introduced in the early 1960s, becoming the industry standard by the middle of that decade. These older freezer compartments were the main cooling body of the refrigerator, and only maintained a temperature of around âˆ'6Â Â°C (21Â Â°F), which is suitable for keeping food for a week.

In the early 1950s, the butter conditioner's patent was filed and published by the inventor Nave Alfred E. This feature was supposed to "provide a new and improved food storage receptacle for storing butter or the like which may quickly and easily be removed from the refrigerator cabinet for the purpose of cleaning." Because of the high interest to the invention, companies in UK, New Zealand, and Australia started to include the feature into the mass fridge production and soon it became a symbol of the local culture. However, not long after that it was removed from production as according to the companies this was the only way for them to meet new ecology regulations and they found it inefficient to have a heat generating device inside a fridge.

Later advances included automatic ice units and self compartmentalized freezing units.

An increasingly important environmental concern is the disposal of old refrigeratorsâ€" initially because freon coolant damages the ozone layerâ€"but as older generation refrigerators wear out, the destruction of CFC-bearing insulation also causes concern. Modern refrigerators usually use a refrigerant called HFC-134a (1,1,1,2-Tetrafluoroethane), which does not deplete the ozone layer, instead of Freon. A R-134a is now becoming very uncommon in Europe. Newer refrigerants are being used instead. The main refrigerant now used is R-600a, or isobutane. This refrigerant is naturally occurring, and has a smaller effect on the atmosphere if released. There have been reports of refrigerators exploding if the refrigerant leaks gas in the presence of a spark.

Disposal of discarded refrigerators is regulated, often mandating the removal of doors; children playing hide-and-seek have been asphyxiated while hiding inside discarded refrigerators, particularly older models with latching doors. Since 2 August 1956, under U.S. federal law, refrigerator doors are no longer permitted to latch so they cannot be opened from the inside. Modern units use a magnetic door gasket that holds the door sealed but allows it to be pushed open from the inside. This gasket was invented, developed and manufactured by Max Baermann (1903-1984) of Bergisch Gladbach/Germany.

Types of domestic refrigerators

Domestic refrigerators and freezers for food storage are made in a range of sizes. Among the smallest is a 4Â L Peltier refrigerator advertised as being able to hold 6 cans of beer. A large domestic refrigerator stands as tall as a person and may be about 1Â m wide with a capacity of 600Â L. Some models for small households fit under kitchen work surfaces, usually about 86Â cm high. Refrigerators may be combined with freezers, either stacked with refrigerator or freezer above, below, or side by side. A refrigerator without a frozen food storage compartment may have a small section just to make ice cubes. Freezers may have drawers to store food in, or they may have no divisions (chest freezers).

Refrigerators and freezers may be free-standing, or built into a kitchen.

Compressor refrigerators are by far the most common type; they make a noticeable noise.
Absorption refrigerators or thermo-electric Peltier units are used where quiet running is required; Peltier coolers are used in the smallest refrigerators as they have no bulky mechanism.
Compressor and Peltier refrigerators are powered by electricity. Absorption units can be designed to get power from any heat source. A noticeable difference between the two types is the absence of refrigerant with Peltier coolers (these use a different method of cooling). But Peltier coolers use more electricity because they are thermodynamically inefficient.
Oil, gas (natural gas or propane) and dual power gas/electricity units are also available (typically found in RV's).
Solar refrigerators and Thermal mass refrigerators are designed to reduce electrical consumption. Solar refrigerators have the added advantage that they do not use refrigerants that are harmful to the environment or flammable. Typical solar designs are absorption refrigerators that use ammonia as the working gas, and employ large mirrors to concentrate sufficient sunlight to reach the temperature required to free gaseous ammonia from the solvent. Most thermal mass refrigerators are designed to use electricity intermittently. As these units are heavily insulated, cooling load is limited primarily to heat introduced by new items to be refrigerated, and ambient air transfer when the unit is open. Very little power is therefore required if opened infrequently. Refrigeration units for commercial and industrial applications can be made in various size, shape or style to fit customer needs.

Other specialised cooling mechanisms may be used for cooling, but have not been applied to domestic refrigerators.

Magnetic refrigerators are refrigerators that work on the magnetocaloric effect. The cooling effect is triggered by placing a metal alloy in a magnetic field.
Acoustic refrigerators are refrigerators that use resonant linear reciprocating motors/alternators to generate a sound that is converted to heat and cold using compressed helium gas. The heat is discarded and the cold is routed to the refrigerator.

Energy efficiency

In a house without air-conditioning (space heating and/or cooling) refrigerators consumed more energy than any other home device. In the early 1990s a competition was held among the major manufacturers to encourage energy efficiency. Current US models that are Energy Star qualified use 50% less energy than the average models made in 1974. The most energy-efficient unit made in the US consumes about half a kilowatt-hour per day (equivalent to 20 W continuously). But even ordinary units are quite efficient; some smaller units use less than 0.2 kWh per day (equivalent to 8 W continuously). Larger units, especially those with large freezers and icemakers, may use as much as 4Â kWÂ·h per day (equivalent to 170 W continuously). The European Union uses a letter-based mandatory energy efficiency rating label instead of the Energy Star; thus EU refrigerators at the point of sale are labelled according to how energy-efficient they are.

For US refrigerators, the Consortium on Energy Efficiency (CEE) further differentiates between Energy Star qualified refrigerators. Tier 1 refrigerators are those that are 20% to 24.9% more efficient than the Federal minimum standards set by the National Appliance Energy Conservation Act (NAECA). Tier 2 are those that are 25% to 29.9% more efficient. Tier 3 is the highest qualification, for those refrigerators that are at least 30% more efficient than Federal standards. About 82% of the Energy Star qualified refrigerators are Tier 1, with 13% qualifying as Tier 2, and just 5% at Tier 3.

Besides the standard style of compressor refrigeration used in normal household refrigerators and freezers, there are technologies such as absorption refrigeration and magnetic refrigeration. Although these designs generally use a much larger amount of energy compared to compressor refrigeration, other qualities such as silent operation or the ability to use gas can favor these refrigeration units in small enclosures, a mobile environment or in environments where unit failure would lead to devastating consequences.

Many refrigerators made in the 1930s and 1940s were far more efficient than most that were made later. This is partly attributable to the addition of new features, such as auto-defrost, that reduced efficiency. Additionally,after World War 2, refrigerator style became more important than efficiency. This was especially true in the 1970s, when side-by-side models with ice dispensers and water chillers became popular. However, the reduction in efficiency also arose partly from reduction in the amount of insulation to cut costs. Because of the introduction of new energy efficiency standards, refrigerators made today are much more efficient than those made in the 1930s; they consume the same amount of energy while being three times as large.

The efficiency of older refrigerators can be improved by defrosting (if the unit is manual defrost) and cleaning them regularly, replacing old and worn door seals with new ones, adjusting the thermostat to accommodate the actual contents (a refrigerator needn't be colder than 4Â Â°C (39Â Â°F) to store drinks and non-perishable items) and also replacing insulation, where applicable. Some sites recommend you clean condenser coils every month or so on units with coils on the rear. It has been proven that this does very little for improving efficiency, however, the unit should be able to "breathe" with adequate spaces around the front, back, sides and above the unit. If the refrigerator uses a fan to keep the condenser cool, then this must be cleaned, at the very least, yearly.

Frost-free refrigerators or freezers use electric fans to cool the appropriate compartment. This could be called a "fan forced" refrigerator, whereas manual defrost units rely on colder air lying at the bottom, versus the warm air at the top to achieve adequate cooling. The air is drawn in through an inlet duct and passed through the evaporator where it is cooled, the air is then circulated throughout the cabinet via a series of ducts and vents. Because the air passing the evaporator is supposedly warm and moist, frost begins to form on the evaporator (especially on a freezer's evaporator). In cheaper and/or older models, a defrost cycle is controlled via a mechanical timer. This timer is set to shut off the compressor and fan and energize a heating element located near or around the evaporator for about 15 to 30 minutes at every 6 to 12 hours. This melts any frost or ice build up and allows the refrigerator to work normally once more. It is believed that frost free units have a l ower tolerance for frost, due to their air-conditioner like evaporator coils. Therefore, if a door is left open accidentally (especially the freezer), the defrost system may not remove all frost, in this case, the freezer (or refrigerator) must be defrosted.

If the defrosting system melts all the ice before the timed defrosting period ends, then a small device (called a defrost limiter) acts like a thermostat and shuts off the heating element to prevent too large a temperature fluctuation, it also prevents hot blasts of air when the system starts again, should it finish defrosting early. On some early frost-free models, the defrost limiter also sends a signal to the defrost timer to start the compressor and fan as soon as it shuts off the heating element before the timed defrost cycle ends. When the defrost cycle is completed, the compressor and fan are allowed to cycle back on.

Frost-free refrigerators, including some early frost free refrigerator/freezers that used a cold plate in their refrigerator section instead of airflow from the freezer section, generally don't shut off their refrigerator fans during defrosting. This allows consumers to leave food in the main refrigerator compartment uncovered, and also helps keep vegetables moist. This method also helps reduce energy consumption, because the refrigerator is above freeze point and can pass the warmer-than-freezing air through the evaporator or cold plate to aid the defrosting cycle.

Regarding total life-cycle costs, many governments offer incentives to encourage recycling of old refrigerators. One example is the Phoenix refrigerator program launched in Australia. This government incentive picked up old refrigerators, paying their owners for "donating" the refrigerator. The refrigerator was then refurbished, with new door seals, a thorough cleaning and the removal of items, such as the cover that is strapped to the back of many older units. The resulting refrigerators, now over 10% more efficient, were then distributed to low income families.

Effect on lifestyle

The refrigerator allows the modern family to keep food fresh for longer than before. The most notable improvement is for meat and other highly perishable wares, which needed to be refined to gain anything resembling shelf life. (On the other hand, refrigerators and freezers can also be stocked with processed, quick-cook foods that are less healthy.) Refrigeration in transit makes it possible to enjoy foodstuffs from distant places.

Dairy products, meats, fish, poultry and vegetables can be kept refrigerated in the same space within the kitchen (although raw meat should be kept separate from other foodstuffs for reasons of hygiene).

Freezers allow people to buy food in bulk and eat it at leisure, and bulk purchases save money. Ice cream, a popular commodity of the 20th century, could previously only be obtained by traveling to where the product was made and eating it on the spot. Now it is a common food item. Ice on demand not only adds to the enjoyment of cold drinks, but is useful for first-aid, and for cold packs that can be kept frozen for picnics or in case of emergency.

Temperature zones and ratings

Some refrigerators are now divided into four zones to store different types of food:

âˆ'18Â Â°C (0Â Â°F) (freezer)
0Â Â°C (32Â Â°F) (meat zone)
5Â Â°C (41Â Â°F) (cooling zone)
10Â Â°C (50Â Â°F) (crisper)

The capacity of a refrigerator is measured in either liters or cubic feet. Typically the volume of a combined refrigerator-freezer is split with 1/3rds to 1/4th of the volume allocated to the freezer although these values are highly variable.

Temperature settings for refrigerator and freezer compartments are often given arbitrary numbers by manufacturers (for example, 1 through 9, warmest to coldest), but generally 3 to 5Â Â°C (37 to 41Â Â°F) is ideal for the refrigerator compartment and âˆ'18Â Â°C (0Â Â°F) for the freezer. Some refrigerators must be within certain external temperature parameters to run properly. This can be an issue when placing units in an unfinished area, such as a garage. European freezers, and refrigerators with a freezer compartment, have a four star rating system to grade freezers.

[âˆ—] Â : min temperature = âˆ'6Â Â°C (21Â Â°F). Maximum storage time for (pre-frozen) food is 1 week
[âˆ—âˆ—] Â : min temperature = âˆ'12Â Â°C (10Â Â°F). Maximum storage time for (pre-frozen) food is 1 month
[âˆ—âˆ—âˆ—] Â : min temperature = âˆ'18Â Â°C (0Â Â°F). Maximum storage time for (pre-frozen) food is between 3 and 12 months depending on type (meat, vegetables, fish, etc.)
[âˆ—âˆ—âˆ—âˆ—]Â : min temperature = âˆ'18Â Â°C (0Â Â°F). Maximum storage time for pre-frozen or frozen-from-fresh food is between 3 and 12 months

Although both the three and four star ratings specify the same storage times and same minimum temperature of âˆ'18Â Â°C (0Â Â°F), only a four star freezer is intended for freezing fresh food, and may include a "fast freeze" function (runs the compressor continually, down to as low as âˆ'26Â Â°C (âˆ'15Â Â°F)) to facilitate this. Three (or fewer) stars are used for frozen food compartments that are only suitable for storing frozen food; introducing fresh food into such a compartment is likely to result in unacceptable temperature rises. This difference in categorisation is shown in the design of the 4-star logo, where the "standard" three stars are displayed in a box using "positive" colours, denoting the same normal operation as a 3-star freezer, and the fourth star showing the additional fresh food/fast freeze function is prefixed to the box in "negative" colours or with other distinct formatting.

Most European refrigerators include a moist cold refrigerator section (which does require (automatic) defrosting at irregular intervals) and a (rarely frost free) freezer section.

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Refrigerator - Inventor Of Refrigerator

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Commercial and domestic refrigerators

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Production by country

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Types of domestic refrigerators

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