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VIGNAN’S LARA INSTITUTE OF TECHNOLOGY & SCIENCE. MAGNETIC REFRIGERATION. Presented by: Rafi Gouse Basha. Sk ( 08FE1A0237 ). Contents. HISTORY Introduction Working Principle Requirements Activities Applications Merits conclusion. HISTORY.
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VIGNAN’S LARA INSTITUTE OF TECHNOLOGY & SCIENCE MAGNETIC REFRIGERATION Presented by: Rafi Gouse Basha. Sk (08FE1A0237)
Contents • HISTORY • Introduction • Working Principle • Requirements • Activities • Applications • Merits • conclusion
HISTORY • Magneto caloric effect was discovered in pure iron in 1881 by E. Warburg. • Debye (1926) & Giauque (1927) proposed a improved technique of cooling via adiabatic demagnetization independently. • The cooling technology was first demonstrated experimentally in 1933 by chemist Nobel Laureate William F. Giauque & his colleague Dr. D. P. MacDougall for cryogenic purposes. • In 1997, Prof. Karl A. Gschneidner, Jr. by the Iowa State University at Ames Laboratory, demonstrated the first near room temperature proof of concept magnetic refrigerator.
Introduction • Magnetic refrigeration is a cooling technology based on the magneto caloric effect. • Invented by Emil Warburg in 1880 • Used to attain cryogenic temperatures well below 1o K with the help of magnetic fields
Magneto Caloric EffecT • Magneto caloric effect is the basic principle on which the cooling is achieved. • Magneto caloric effect is a magneto-thermodynamic phenomenon in which a reversible change in temperature of a suitable material is caused by exposing the material to a changing magnetic field • This is called adiabatic demagnetisation .
COMPONENTS • Magnets. • Hot heat exchanger. • Cold heat exchanger. • Drive. • Magneto caloric wheel.
Thermodynamic cycle Steps of thermodynamic cycle - • Adiabatic magnetization. • Isomagnetic enthalpic • transfer. • Adiabatic demagnetization. • Isomagnetic entropic • transfer.
BENEFITS TECHNICAL • High efficiency. • Reduced cost. • Compactness. • Reliability SOCIO-ECONOMIC • Competition in global market. • Low capital cost. • Key factor to new technologies.
MAGNETIC MATERIALS Magneto caloric effect is an intrinsic property of a substance Gadolinium and its alloys are the best materials available for magnetic refrigeration They can reach ultra low temperatures
REGENERATORS Tubes. Perforated plates. Wire screens. Particle beds.
ACTIVE MAGNETIC REGENERATORS • A regenerator that undergoes cyclic heat transfer operations and magneto caloric effect is called Active Magnetic Regenerator • It should be designed to possess: high heat transfer rate high magneto calorific effect affordable materials ease of manufacture
ACTIVE MAGNETIC REGENERATORS • High heat transfer rate. • Low pressure drop of the heat transfer fluid. • High magneto caloric effect. • Sufficient structural integrity. • Low thermal conduction in the direction of fluid flow. • Low porosity. • Affordable materials. • Ease of manufacture.
CONTD…… • Do the same job, but with metallic compounds, not gases. • Environmentally friendly alternative to conventional vapor-cycle refrigeration. • It eliminates the need of the compressor. • Save costs.
ACTIVITIES ( PRESENT & FUTURE ) • Development of optimized magnetic refrigerants. ( large magneto caloric effect ) • Performance simulations of magnetic refrigerants. • Design of a magnetic liquefier.
APPLICATIONS • Liquefaction purposes in the case of hydrogen, nitrogen and helium • Also focuses on many future applications like magnetic household refrigeration,cooling in transportation,cooling electronic circuits etc.
MERITS • High efficiency • Reduced operating cost • Reliability
CONCLUSION • Magnetic refrigeration technology could provide a ‘green’ alternative to traditional energy-guzzling gas-compression fridges and air conditioners. • Computer models have shown 25% efficiency improvement over vapor compression systems. • Two advantages to using Magnetic Refrigeration over vapor compressed systems are no hazardous chemicals used and they can be up to 60% efficient.
REFERENCES • http://en.wikipedia.org/wiki/Magnetic refrigeration • A text book on Refrigeration and Air conditioning by C P Arora and Domkundwar • A text book on Cryogenic Engineering by Thomas M. Flynn