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R 1BJ07ME408 Department of Mechanical engineering Department of Mechanical engineering SRI BHAGAWAN MAHAVEER JAIN COLLEGE OF ENGINEERING 1 department of mechancal engineering CONTENTS: : CONTENTS: Introduction to refrigeration Methods of refrigeration Magnetic refrigeration Principle of Magnetic refrigeration Thermodynamic cycle Working materials Advantages of Magnetic refrigeration 2 department of mechanical engineering Introduction to refrigeration : Introduction to refrigeration Refrigeration is the process of removing heat from an enclosed space, or from a substance. The primary purpose of refrigeration is lowering the temperature of the enclosed space or substance and then maintaining that lower temperature. 3 department of mechancal engineering Methods of refrigeration : Methods of refrigeration Non-cyclic refrigeration Cyclic refrigeration Vapor cycle Vapor compression refrigeration Vapor absorption refrigeration Gas cycle Thermoelectric refrigeration Magnetic refrigeration Other methods 4 department of mechancal engineering Magnetic refrigeration : Magnetic refrigeration Magnetic refrigeration is a cooling technology based on the magneto caloric effect A strong magnetic field is applied to the refrigerant 5 department of mechancal engineering Slide 6: A heat sink then absorbs the heat released by the refrigerant Thermal contact with the heat sink is then broken so that the system is insulated, and the magnetic field is switched off This increases the heat capacity of the refrigerant, thus decreasing its temperature below the temperature of the heat sink. 6 department of mechancal engineering Principle of Magnetic refrigeration : : Principle of Magnetic refrigeration : Mageto calorific effect is the basic principle on which the cooling is achieved. All magnets bears a property called Currie effect i.e. If a temperature of magnet is increased from lower to higher range at certain temperature magnet looses the magnetic field. 7 department of mechancal engineering Slide 8: Currie temperature. Depends on individual property of each material As Energy input to the magnet is increased the orientation of the magnetic dipoles in a magnet starts loosing orientation. And vice a versa at Currie temperature as magnet looses energy to the media it regains the property. 8 department of mechancal engineering Thermo dynamic cycle : Thermo dynamic cycle 9 department of mechancal engineering Slide 10: Adiabatic magnetization Isomagnetic enthalpic transfer Adiabatic demagnetization Isomagnetic entropic transfer Steps of thermodynamic cycle - 10 department of mechancal engineering Adiabatic magnetization : Adiabatic magnetization The increasing external magnetic field (+H) causes the magnetic dipoles of the atoms to align The net result is that the item heats up (T + ΔTad) department of mechancal engineering 11 Isomagnetic enthalpic transfer : Isomagnetic enthalpic transfer This added heat can then be removed by a fluid like water or helium The magnetic field is held constant to prevent the dipoles from reabsorbing the heat department of mechancal engineering 12 Adiabatic Demagnetization : Adiabatic Demagnetization The substance is returned to another adiabatic (insulated) condition so the total entropy remains constant thermal energy causes the domains to overcome the field, and thus the sample cools department of mechancal engineering 13 Isomagnetic entropic transfer : Isomagnetic entropic transfer The magnetic field is held constant to prevent the material from heating back up The material is placed in thermal contact with the environment being refrigerated department of mechancal engineering 14 Slide 15: 15 department of mechancal engineering Working Materials : Working Materials Magneto caloric effect is an intrinsic property of magnetic solid. Ease of application and removal of magnetic effect is most desired propery of material. It is individual characteristics and strongly depends on : Curie temperature Degree of freedom for magnetic dipoles during ordering and randomization of particals. 16 department of mechancal engineering Slide 17: The originally suggested refrigerant was a paramagnetic salt, such as cerium magnesium nitrate. Gadolinium and its alloys are the best material available today for magnetic refrigeration 17 department of mechancal engineering Advantages of Magnetic Refrigeration : Advantages of Magnetic Refrigeration MG do not use hazardous or environmentally damaging chemicals Purchase cost may be high, but running costs are 20% less than the conventional chillers Ozone depleting refrigerants are avoided in this system, hence it more eco-friendly department of mechancal engineering 18 Conclusion : Conclusion Magnetic refrigerator is best suitable refrigerator compare to other department of mechancal engineering 19 References : References 1. Zimm, C., et. al. 2007. “Design and initial performance of a magnetic refrigerator with a rotating permanent magnet.” 2nd International Conference on Magnetic Refrigeration at Room Temperature. 2. ADL. 1999. “Opportunities for energy savings in the residential and commercial sectors with high-efficiency electric motors.” Final Report for the U.S. Department of Energy, Office of Building Technology, State and Community Programs. http://tinyurl.com/34e5gg (or www.eere.energy.gov/buildings/info/documents/pdfs/doemotor2_2_00.pdf). 3. IIR. 2005. Proceedings of the 1st International Conference on Magnetic Refrigeration at Room Temperature. 4. IIR. 2007. Proceedings of the 2nd International Conference on Magnetic Refrigeration at Room Temperature. 5. Brück, E. 2005. “Developments in magneto caloric refrigeration.” Journal of Physics D: Applied Physics 38(7):R381–R391. department of mechancal engineering 20 Thanking you : Thanking you 21 department of mechancal engineering You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.