MAGNETIC REFRIGERATION Presented by Seminartopics info Dept of

MAGNETIC REFRIGERATION Presented by Seminartopics. info Dept of Mechanical Engg

OBJECTIVE To develop more efficient and costeffective small-scale H 2 liquefiers as an alternative to vapour-compression cycles using magnetic refrigeration (adiabatic magnetization).

CONTENTS Ø Introduction Ø History Ø Basic principle of Magnetic Refrigeration Ø Components Ø Thermodynamic cycle Ø Working Ø Benefits Ø Magnetic materials Ø Regenerators & Superconducting Magnets Ø Active magnetic regenerators (AMR’s) Ø Comparison Ø Activities

INTRODUCTION Magnetic refrigeration is a physical process that exploits the magnetic properties of certain solid materials to produce refrigeration. Magnetic refrigeration is a cooling technology based on the magneto caloric effect. This technique can be used to attain extremely low temperatures (well below 1 Kelvin), as well as the ranges used in common refrigerators, depending on the design of the system.

HISTORY Ø Magneto caloric effect was discovered in pure iron in 1881 by E. Warburg. Ø Debye (1926) & Giauque (1927) proposed a improved technique of cooling via adiabatic demagnetization independently. Ø The cooling technology was first demonstrated experimentally in 1933 by chemist Nobel Laureate William F. Giauque & his colleague Dr. D. P. Mac. Dougall for cryogenic purposes. Ø 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.

Magneto Caloric Effect Ø MCE is a magneto-thermodynamic phenomenon in which a reversible change in temperature of a suitable material is caused by exposing the material to changing magnetic field.

COMPONENTS Ø Magnets. Ø Hot heat exchanger. Ø Cold heat exchanger. Ø Drive. Ø Magneto caloric wheel.

Thermodynamic cycle Steps of thermodynamic cycle ØAdiabatic magnetization. ØIsomagnetic enthalpic transfer. ØAdiabatic demagnetization. ØIsomagnetic entropic transfer.

WORKING PRINCIPLE

BENEFITS TECHNICAL SOCIO-ECONOMIC Ø High efficiency. Ø Reduced cost. Ø Compactness. Ø Reliability Ø Competition in global market. Ø Low capital cost. Ø Key factor to new technologies.

MAGNETIC MATERIALS Gd alloys: Gd 5(Si 2 Ge 2); Gd 5(Si 0. 33 Ge 3. 67); Gd 0. 54 Er 0. 46)N

REGENERATORS a) Tubes. b) Perforated plates. c) Wire screens. d) Particle beds.

SUPER CONDUCTING MAGNETS

AMR’s Ø High heat transfer rate. Ø Low pressure drop of the heat transfer fluid. Ø High magneto caloric effect. Ø Sufficient structural integrity. Ø Low thermal conduction in the direction of fluid flow. Ø Low porosity. Ø Affordable materials. Ø Ease of manufacture.

COMPARISON

CONTD…… Ø Do the same job, but with metallic compounds, not gases. Ø Environmentally friendly alternative to conventional vapor-cycle refrigeration. Ø It eliminates the need of the compressor. Ø Save costs.

ACTIVITIES ( PRESENT & FUTURE ) Ø Development of optimized magnetic refrigerants. ( large magneto caloric effect ) Ø Performance simulations of magnetic refrigerants. Ø Design of a magnetic liquefier.

CONCLUSION Ø Magnetic refrigeration technology could provide a ‘green’ alternative to traditional energy-guzzling gascompression fridges and air conditioners. Ø Computer models have shown 25% efficiency improvement over vapor compression systems. Ø Two advantages to using Magnetic Refrigeration over vapor compressed systems are no hazardous chemicals used and they can be up to 60% efficient.

Promoting energy efficiency THANK YOU…