MAGNETIC REFRIGERATION 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

WORKING PRINCIPLE

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.

SUPER CONDUCTING MAGNETS

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.

COMPARISON

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

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