MAGNETIC REFRIGERATION

Presented by:Rafi Gouse Basha. Sk(08FE1A0237)

VIGNAN’S LARA INSTITUTE OF TECHNOLOGY & SCIENCE

ContentsHISTORYIntroductionWorking PrincipleRequirementsActivitiesApplicationsMeritsconclusion

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 cycleSteps of thermodynamic cycle -Adiabatic magnetization.

Isomagnetic enthalpic transfer. Adiabatic demagnetization.

Isomagnetic entropic transfer.

WORKING PRINCIPLE

BENEFITSTECHNICAL

High efficiency. Reduced cost. Compactness. Reliability

SOCIO-ECONOMIC

Competition in global market.

Low capital cost. Key factor to

new technologies.

MAGNETIC MATERIALSMagneto 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

REGENERATORSa) Tubes.b) Perforated plates.c) Wire screens.d) 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.

APPLICATIONSLiquefaction 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.

MERITSHigh efficiencyReduced operating costReliability

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.

REFERENCEShttp://en.wikipedia.org/wiki/

Magnetic refrigerationA text book on Refrigeration and

Air conditioning by C P Arora and Domkundwar

A text book on Cryogenic Engineering by Thomas M. Flynn

THANK YOU…