This document summarizes a seminar presentation on magnetic refrigeration. It discusses the history of magnetic refrigeration dating back to 1881 when the magneto-caloric effect was discovered. It then provides an overview of how magnetic refrigeration works using the magneto-caloric effect found in solid state refrigerants. The objectives of magnetic refrigeration are to develop more efficient and cost effective small scale hydrogen liquefiers as an alternative to traditional vapor-compression cycles.
This document summarizes a seminar presentation on magnetic refrigeration given by Mr. Hardik N Kothiya. The presentation was given in partial fulfillment of a Bachelor of Engineering degree from the University of Pune, India. The seminar covered the history of magnetic refrigeration, the magneto-caloric effect, how magnetic refrigeration systems work, comparisons to conventional refrigeration, applications, advantages and disadvantages. Key topics included the discovery of the magneto-caloric effect in 1881, the first demonstration of magnetic refrigeration to reach 0.25 K in 1933, and recent developments in room temperature magnetic refrigeration.
The document summarizes Ganesh Pralhad Bharambe's seminar on magnetic refrigeration presented under the guidance of Prof. A. M. Patil. It discusses the basic principles of magnetic refrigeration, the thermodynamic cycle involved, suitable working materials including developments in materials science, and applications of the technology.
This document is a seminar report on magnetic refrigeration submitted for the degree of Bachelor of Technology in Mechanical Engineering. It discusses magnetic refrigeration, which uses the magnetocaloric effect exhibited by solid materials like gadolinium compounds. When these materials are magnetized, their temperature increases due to entropy reduction, and when demagnetized, their temperature decreases due to entropy increase. This effect allows for cooling applications. The report covers the working principle, construction requirements, practical applications and advantages of magnetic refrigeration over conventional vapor compression refrigeration cycles.
seminar on Magnetic Refrigeration - Solid refrigerantVishal Talape
This document discusses magnetic refrigeration, including its working principle, components, advantages, and current state of development. Magnetic refrigeration uses the magnetocaloric effect and works by applying and removing a magnetic field to materials to remove and release heat from target systems. Its potential advantages include higher efficiency and reliability compared to vapor compression refrigeration, without using ozone-depleting refrigerants. However, magnetic refrigeration remains under development due to challenges like initial costs and limited temperature ranges of magnetocaloric materials.
Magnetic refrigeration has been viewed as primarily a cryogenic technology because the necessary high magnetic fields are most easily provided by superconducting magnets.
Introduction to Magnetic RefrigerationSamet Baykul
DATE: 2019.05.12
We have given a lecture to the class in the course of "Refrigeration Systems" in ODTÜ.
● Introduction
● History and Developments
● Physical Phenomenas
● Thermodynamics of Magnetic Refrigeration
● Magnetocaloric Materials
● Future of Magnetic Refrigeration
● Developments
● Usage Areas
● Conclusion
Magnetic refrigeration uses the magnetocaloric effect to achieve cooling through a thermodynamic cycle that involves magnetizing and demagnetizing a material. It was discovered in 1881 and further developed in the 1920s-1930s to achieve temperatures below 1K. Recent research has focused on materials with giant magnetocaloric effects and developing practical refrigerator designs. Magnetic refrigeration offers higher efficiency and lower costs than vapor compression refrigeration, with benefits for the environment and new technologies. Further development is still needed to address challenges like improving magnetocaloric materials and precision moving parts.
This document provides an overview of magnetic refrigeration. It discusses the history and principles of magnetic refrigeration, describing the magnetocaloric effect and the thermodynamic cycle used. The components required for a magnetic refrigerator are outlined. Applications are discussed, along with advantages such as high efficiency and compactness compared to vapor-compression refrigeration. Some challenges are also noted, such as limited temperature changes and availability of materials. In conclusion, while further development is needed, magnetic refrigeration shows promise as an environmentally-friendly cooling technology.
This document summarizes a seminar presentation on magnetic refrigeration given by Mr. Hardik N Kothiya. The presentation was given in partial fulfillment of a Bachelor of Engineering degree from the University of Pune, India. The seminar covered the history of magnetic refrigeration, the magneto-caloric effect, how magnetic refrigeration systems work, comparisons to conventional refrigeration, applications, advantages and disadvantages. Key topics included the discovery of the magneto-caloric effect in 1881, the first demonstration of magnetic refrigeration to reach 0.25 K in 1933, and recent developments in room temperature magnetic refrigeration.
The document summarizes Ganesh Pralhad Bharambe's seminar on magnetic refrigeration presented under the guidance of Prof. A. M. Patil. It discusses the basic principles of magnetic refrigeration, the thermodynamic cycle involved, suitable working materials including developments in materials science, and applications of the technology.
This document is a seminar report on magnetic refrigeration submitted for the degree of Bachelor of Technology in Mechanical Engineering. It discusses magnetic refrigeration, which uses the magnetocaloric effect exhibited by solid materials like gadolinium compounds. When these materials are magnetized, their temperature increases due to entropy reduction, and when demagnetized, their temperature decreases due to entropy increase. This effect allows for cooling applications. The report covers the working principle, construction requirements, practical applications and advantages of magnetic refrigeration over conventional vapor compression refrigeration cycles.
seminar on Magnetic Refrigeration - Solid refrigerantVishal Talape
This document discusses magnetic refrigeration, including its working principle, components, advantages, and current state of development. Magnetic refrigeration uses the magnetocaloric effect and works by applying and removing a magnetic field to materials to remove and release heat from target systems. Its potential advantages include higher efficiency and reliability compared to vapor compression refrigeration, without using ozone-depleting refrigerants. However, magnetic refrigeration remains under development due to challenges like initial costs and limited temperature ranges of magnetocaloric materials.
Magnetic refrigeration has been viewed as primarily a cryogenic technology because the necessary high magnetic fields are most easily provided by superconducting magnets.
Introduction to Magnetic RefrigerationSamet Baykul
DATE: 2019.05.12
We have given a lecture to the class in the course of "Refrigeration Systems" in ODTÜ.
● Introduction
● History and Developments
● Physical Phenomenas
● Thermodynamics of Magnetic Refrigeration
● Magnetocaloric Materials
● Future of Magnetic Refrigeration
● Developments
● Usage Areas
● Conclusion
Magnetic refrigeration uses the magnetocaloric effect to achieve cooling through a thermodynamic cycle that involves magnetizing and demagnetizing a material. It was discovered in 1881 and further developed in the 1920s-1930s to achieve temperatures below 1K. Recent research has focused on materials with giant magnetocaloric effects and developing practical refrigerator designs. Magnetic refrigeration offers higher efficiency and lower costs than vapor compression refrigeration, with benefits for the environment and new technologies. Further development is still needed to address challenges like improving magnetocaloric materials and precision moving parts.
This document provides an overview of magnetic refrigeration. It discusses the history and principles of magnetic refrigeration, describing the magnetocaloric effect and the thermodynamic cycle used. The components required for a magnetic refrigerator are outlined. Applications are discussed, along with advantages such as high efficiency and compactness compared to vapor-compression refrigeration. Some challenges are also noted, such as limited temperature changes and availability of materials. In conclusion, while further development is needed, magnetic refrigeration shows promise as an environmentally-friendly cooling technology.
This document discusses magnetic refrigeration. It begins by introducing magnetic refrigeration and the magnetocaloric effect. It then explains the thermodynamic cycle of magnetic refrigeration, which involves adiabatic magnetization, isomagnetic heat transfer, adiabatic demagnetization, and isomagnetic entropy transfer. Common working materials like gadolinium and its alloys are mentioned. Advantages discussed include being more environmentally friendly than vapor-compression refrigeration by avoiding hazardous chemicals and ozone-depleting refrigerants.
Introduction to Magnetic RefrigerationSamet Baykul
DATE: 2019.06
We have given a lecture to the class in the course of "Refrigeration Systems" in ODTÜ.
Refrigeration technology has an important role over various areas such as medicine, food, manufacturing, and it is a very important element for a comfortable life for the society. It directly affects the people’s life by permiting to store the medicines and foods for long times, manufacturing with very high accuracy, air conditioning applications, etc.
Although refrigeration technology have lots of benefits which has been mentioned above, conventional vapor compression/expansion systems have some weaknesses. Refrigerant fluids that are used in the traditional cooling/refrigeration applications have important effects over the global warming and ozone depletion. To be able to overcome these disadvantages of the refrigeration applications, new thecnologies which does not use harmful matirals such as traditional refrigerants are investigated. One of these developing technologies is magnetic refrigeration systems.
Magnetic refrigeration systems are commonly used in the low temperature applications and it also has usage in air conditioning applications, aerospace technologies and telecommunication technologies.
Magnetic refrigeration has lots of advantages such that:
1. It uses very small amount of energy compared to compressor work inlet of a similar size vapor compression/expansion system.
2. It is highly more compact and makes less noise than the traditional systems.
3. It has a lower operating and maintenance cost.
4. It is environment friendly and does not cause the global warming or ozone depletion.
Although the magnetic refrigeration has lots of benefits which have been described above, because of its high initial cost and need of the very rare materials in the system, it is not very common recent days, however, it has a high potential for the future.
This document discusses magnetic refrigeration, which uses the magnetocaloric effect to provide cooling. It works by applying and removing a magnetic field from magnetocaloric materials, causing their temperature to change. The document outlines the components, thermodynamic cycle steps, requirements, examples of prototypes, advantages like efficiency and sustainability, and challenges like initial costs. It also covers potential applications like household refrigeration and compares magnetic refrigeration to current technologies under development.
The document summarizes a seminar on magnetic refrigeration presented by Ganesh Pralhad Bharambe. It discusses the basic principles of using magnetocaloric effects to generate cooling, describing the thermodynamic cycle of adiabatic magnetization, isomagnetic enthalpic transfer, adiabatic demagnetization, and isomagnetic entropic transfer. It also covers potential working materials for magnetic refrigeration like gadolinium alloys, and developments in materials science to improve efficiency, such as amorphous alloys and nanostructured composites.
The document discusses magnetic refrigeration, which uses magneto caloric materials to produce refrigeration through magnetic fields. The objective is to develop more efficient small-scale hydrogen liquefiers using this technique. Magnetic refrigeration offers benefits over traditional vapor-compression cycles like higher efficiency, reduced costs, compactness and reliability. Current activities involve developing optimized magnetic refrigerants and designing a magnetic liquefier. Magnetic refrigeration could provide a more efficient and environmentally friendly alternative to traditional gas-compression refrigeration systems.
This document summarizes a presentation on magnetic refrigeration. It introduces the magnetocaloric effect where certain magnetic materials experience a temperature change when exposed to a changing magnetic field. It then describes how magnetic refrigeration works by using this effect to remove heat from a substance, replacing the gas compression/expansion process with magnetizing and demagnetizing the magnetic material. Finally, it discusses suitable magnetic materials, the advantages of magnetic refrigeration over conventional refrigeration like higher efficiency and being environmentally friendly, and potential applications of the technology.
Magnetic refrigeration is a non-conventional refrigeration method that uses the magnetocaloric effect and works through a thermodynamic cycle. It has applications in industries like air conditioning, refrigeration plants, and food storage. Magnetic refrigeration could provide greater efficiency than conventional refrigeration and reduce national power consumption due to its higher performance and lower cost permanent magnetic materials.
This document discusses magnetic refrigeration, which provides cooling through the magnetocaloric effect. It begins by introducing magnetic refrigeration and the magnetocaloric effect. It then covers the basic principles and mechanism of magnetic refrigeration, including the thermodynamic cycle and components required. Potential magnetocaloric materials are discussed. Applications for magnetic refrigeration include household appliances, buildings, transportation, food storage, and electronics cooling. Benefits include higher efficiency and lower environmental impact compared to traditional refrigeration. Further research is still needed to improve temperature changes and develop stronger permanent magnets for widespread commercial use.
The magnetic refrigeration at room temperature is an emerging technology that has
attracted the interest of researchers around the world (Bouchekara, 2008). Such a technology
applies the magnetocaloric effect which was first discovered by Warburg (Bohigas, 2000;
Zimm, 2007).
The document summarizes the working principles of magnetic refrigeration systems. It begins with an introduction to different refrigeration methods and outlines the advantages of magnetic refrigeration over conventional vapor compression systems. It then describes the key concepts of magnetocaloric effect and magnetic refrigeration cycles. Specifically:
1) Magnetic refrigeration utilizes the magnetocaloric effect where applying/removing a magnetic field causes certain materials to heat up/cool down. This replaces the need for compressors and refrigerants.
2) The document explains the temperature changes associated with magnetizing/demagnetizing magnetocaloric materials like gadolinium and illustrates the temperature-entropy diagram of magnetic refrigeration cycles.
3) It provides an overview of
What Is Magnetic refrigeration
he magnetocaloric effect (MCE, from magnet and calorie) is a magneto-thermodynamic phenomenon in which a temperature change of a suitable material is caused by exposing the material to a changing magnetic field. This is also known by low temperature physicists as adiabatic demagnetization. In that part of the refrigeration process, a decrease in the strength of an externally applied magnetic field allows the magnetic domains of a magnetocaloric material to become disoriented from the magnetic field by the agitating action of the thermal energy (phonons) present in the material. If the material is isolated so that no energy is allowed to (re)migrate into the material during this time, (i.e., an adiabatic process) the temperature drops as the domains absorb the thermal energy to perform their reorientation. The randomization of the domains occurs in a similar fashion to the randomization at the curie temperature of a ferromagnetic material, except that magnetic dipoles overcome a decreasing external magnetic field while energy remains constant, instead of magnetic domains being disrupted from internal ferromagnetism as energy is added.
One of the most notable examples of the magnetocaloric effect is in the chemical element gadolinium and some of its alloys. Gadolinium's temperature increases when it enters certain magnetic fields. When it leaves the magnetic field, the temperature drops. The effect is considerably stronger for the gadolinium alloy (Gd
5Si
2Ge
2).[8] Praseodymium alloyed with nickel (PrNi
5) has such a strong magnetocaloric effect that it has allowed scientists to approach to within one milliKelvin, one thousandth of a degree of absolute zero.[9]
Exergy analysis of magnetic refrigerationManoj maurya
The document discusses magnetic refrigeration and exergy analysis of magnetic refrigeration cycles. It explains the magnetocaloric effect and how magnetic fields can be used to achieve cooling via adiabatic demagnetization. Key equations presented include those relating the magnetocaloric effect to changes in magnetic field and temperature. The document also summarizes the reversible Brayton refrigeration cycle used in magnetic refrigeration and equations for the exergy efficiency and exergy destroyed. Major breakthroughs in 1997 that accelerated progress in the field are noted. In closing, the summary states that magnetic refrigeration provides an effective and efficient cooling method and has improved significantly since initial work in the 1920s-1930s.
Magnetic refrigeration is a cooling technology that uses the magnetocaloric effect to attain low and refrigerator temperatures. It was discovered in the 1930s by Weiss, Piccard, Debye, and Giaque through the observation that applying or removing a magnetic field to certain materials causes a temperature change. The magnetocaloric effect is a magneto-thermodynamic phenomenon in which the temperature of a suitable material changes with exposure to a changing magnetic field. Gadolinium alloys are commonly used as they heat up in a magnetic field.
This presentation discusses magnetic and nuclear cooling techniques. Magnetic cooling uses the magnetocaloric effect where applying or removing a magnetic field from certain materials causes a temperature change. The process involves magnetizing a material, transferring heat away, demagnetizing to cool the material, and transferring the cold to the target. Very low temperatures below 1K can be achieved using nuclear demagnetization which exploits the magnetic dipoles of atomic nuclei. This technique allows cooling to temperatures as low as 0.001K and is useful for experimental applications. Magnetic and nuclear refrigeration provide advantages over conventional cooling like reduced energy costs and avoiding ozone-depleting refrigerants.
It is a technolgy by which we can produce cooling Effect Using MAgnets and Magnetic Materials......
For any other enquiry u can contact me on +919540278218....
and can join my Page www.facebook.com/engineeringindia
Adiabatic de-magnetization, process by which the removal of a magnetic field from certain materials serves to lower their temperature. Milli Kelvin temperatures could be achieved.
This application note illustrates the use and advantages of dielectric heating, which as the name implies, is used for materials that are non-conducting. The essential advantage of dielectric heating is that the heat is generated within the material to be heated. In comparison with more conventional heating techniques (hot air, infrared, et cetera) in which the material is heated via the outer surface, dielectric heating is much more rapid. This is because electrical insulating materials, i.e. the domain of dielectric heating, are usually also poor conductors of heat.
Other interesting characteristics of radio frequency and microwave heating are the high power density and the potential for selectively heating materials. However, dielectric heating is an expensive technique and its application is generally limited to the heating of products with high added value, or to products that cannot be heated by other means.
Magnetic refrigeration is a technology that has proven to
be environmentally safe. Computer models have shown
25% efficiency improvement over vapor compression
systems.
This document summarizes research on magnetic refrigeration. It describes the development of magnetic refrigeration technology over time, including early experiments in the late 19th century and key advances in the late 20th century. It then discusses several studies that have designed and tested different types of magnetic refrigeration devices, including reciprocating and rotating systems, and investigated how to optimize performance by studying various design and operating parameters. The document focuses on a study in Iraq that constructed the first magnetic refrigerator in the country to experimentally investigate its performance and the effects of different operational parameters.
This presentation discusses thermoelectric effects on magnetic nanostructures and their application in magnetic refrigeration. It explains that magnetic refrigeration is based on the magnetocaloric effect and the varying magnetic entropy of magnetic materials. Magnetic refrigeration has advantages over traditional vapor compression cycles, including lower costs, less electricity usage, no compressor or refrigerant gases. While initial investment is higher for magnetic refrigeration, it provides safer, more environmentally friendly cooling. The goal is to develop efficient magnetic refrigeration technology for standard home refrigerators.
This short document does not contain any meaningful information to summarize. It consists of formatting characters without any words or sentences of substance. In 3 sentences or less, there is no essential information that can be extracted from the given text to create a useful summary.
Bhargav S is seeking a challenging and responsible position in a professionally managed organization. He has a BE in Mechanical Engineering from B G S Institute of Technology with an aggregate of 75.77% until the 6th semester. He has technical skills in MS Office, ANSYS, Solid Edge, and CATIA V5 sketcher. His hobbies include playing cricket and volleyball, watching TV, and listening to music.
This document discusses magnetic refrigeration. It begins by introducing magnetic refrigeration and the magnetocaloric effect. It then explains the thermodynamic cycle of magnetic refrigeration, which involves adiabatic magnetization, isomagnetic heat transfer, adiabatic demagnetization, and isomagnetic entropy transfer. Common working materials like gadolinium and its alloys are mentioned. Advantages discussed include being more environmentally friendly than vapor-compression refrigeration by avoiding hazardous chemicals and ozone-depleting refrigerants.
Introduction to Magnetic RefrigerationSamet Baykul
DATE: 2019.06
We have given a lecture to the class in the course of "Refrigeration Systems" in ODTÜ.
Refrigeration technology has an important role over various areas such as medicine, food, manufacturing, and it is a very important element for a comfortable life for the society. It directly affects the people’s life by permiting to store the medicines and foods for long times, manufacturing with very high accuracy, air conditioning applications, etc.
Although refrigeration technology have lots of benefits which has been mentioned above, conventional vapor compression/expansion systems have some weaknesses. Refrigerant fluids that are used in the traditional cooling/refrigeration applications have important effects over the global warming and ozone depletion. To be able to overcome these disadvantages of the refrigeration applications, new thecnologies which does not use harmful matirals such as traditional refrigerants are investigated. One of these developing technologies is magnetic refrigeration systems.
Magnetic refrigeration systems are commonly used in the low temperature applications and it also has usage in air conditioning applications, aerospace technologies and telecommunication technologies.
Magnetic refrigeration has lots of advantages such that:
1. It uses very small amount of energy compared to compressor work inlet of a similar size vapor compression/expansion system.
2. It is highly more compact and makes less noise than the traditional systems.
3. It has a lower operating and maintenance cost.
4. It is environment friendly and does not cause the global warming or ozone depletion.
Although the magnetic refrigeration has lots of benefits which have been described above, because of its high initial cost and need of the very rare materials in the system, it is not very common recent days, however, it has a high potential for the future.
This document discusses magnetic refrigeration, which uses the magnetocaloric effect to provide cooling. It works by applying and removing a magnetic field from magnetocaloric materials, causing their temperature to change. The document outlines the components, thermodynamic cycle steps, requirements, examples of prototypes, advantages like efficiency and sustainability, and challenges like initial costs. It also covers potential applications like household refrigeration and compares magnetic refrigeration to current technologies under development.
The document summarizes a seminar on magnetic refrigeration presented by Ganesh Pralhad Bharambe. It discusses the basic principles of using magnetocaloric effects to generate cooling, describing the thermodynamic cycle of adiabatic magnetization, isomagnetic enthalpic transfer, adiabatic demagnetization, and isomagnetic entropic transfer. It also covers potential working materials for magnetic refrigeration like gadolinium alloys, and developments in materials science to improve efficiency, such as amorphous alloys and nanostructured composites.
The document discusses magnetic refrigeration, which uses magneto caloric materials to produce refrigeration through magnetic fields. The objective is to develop more efficient small-scale hydrogen liquefiers using this technique. Magnetic refrigeration offers benefits over traditional vapor-compression cycles like higher efficiency, reduced costs, compactness and reliability. Current activities involve developing optimized magnetic refrigerants and designing a magnetic liquefier. Magnetic refrigeration could provide a more efficient and environmentally friendly alternative to traditional gas-compression refrigeration systems.
This document summarizes a presentation on magnetic refrigeration. It introduces the magnetocaloric effect where certain magnetic materials experience a temperature change when exposed to a changing magnetic field. It then describes how magnetic refrigeration works by using this effect to remove heat from a substance, replacing the gas compression/expansion process with magnetizing and demagnetizing the magnetic material. Finally, it discusses suitable magnetic materials, the advantages of magnetic refrigeration over conventional refrigeration like higher efficiency and being environmentally friendly, and potential applications of the technology.
Magnetic refrigeration is a non-conventional refrigeration method that uses the magnetocaloric effect and works through a thermodynamic cycle. It has applications in industries like air conditioning, refrigeration plants, and food storage. Magnetic refrigeration could provide greater efficiency than conventional refrigeration and reduce national power consumption due to its higher performance and lower cost permanent magnetic materials.
This document discusses magnetic refrigeration, which provides cooling through the magnetocaloric effect. It begins by introducing magnetic refrigeration and the magnetocaloric effect. It then covers the basic principles and mechanism of magnetic refrigeration, including the thermodynamic cycle and components required. Potential magnetocaloric materials are discussed. Applications for magnetic refrigeration include household appliances, buildings, transportation, food storage, and electronics cooling. Benefits include higher efficiency and lower environmental impact compared to traditional refrigeration. Further research is still needed to improve temperature changes and develop stronger permanent magnets for widespread commercial use.
The magnetic refrigeration at room temperature is an emerging technology that has
attracted the interest of researchers around the world (Bouchekara, 2008). Such a technology
applies the magnetocaloric effect which was first discovered by Warburg (Bohigas, 2000;
Zimm, 2007).
The document summarizes the working principles of magnetic refrigeration systems. It begins with an introduction to different refrigeration methods and outlines the advantages of magnetic refrigeration over conventional vapor compression systems. It then describes the key concepts of magnetocaloric effect and magnetic refrigeration cycles. Specifically:
1) Magnetic refrigeration utilizes the magnetocaloric effect where applying/removing a magnetic field causes certain materials to heat up/cool down. This replaces the need for compressors and refrigerants.
2) The document explains the temperature changes associated with magnetizing/demagnetizing magnetocaloric materials like gadolinium and illustrates the temperature-entropy diagram of magnetic refrigeration cycles.
3) It provides an overview of
What Is Magnetic refrigeration
he magnetocaloric effect (MCE, from magnet and calorie) is a magneto-thermodynamic phenomenon in which a temperature change of a suitable material is caused by exposing the material to a changing magnetic field. This is also known by low temperature physicists as adiabatic demagnetization. In that part of the refrigeration process, a decrease in the strength of an externally applied magnetic field allows the magnetic domains of a magnetocaloric material to become disoriented from the magnetic field by the agitating action of the thermal energy (phonons) present in the material. If the material is isolated so that no energy is allowed to (re)migrate into the material during this time, (i.e., an adiabatic process) the temperature drops as the domains absorb the thermal energy to perform their reorientation. The randomization of the domains occurs in a similar fashion to the randomization at the curie temperature of a ferromagnetic material, except that magnetic dipoles overcome a decreasing external magnetic field while energy remains constant, instead of magnetic domains being disrupted from internal ferromagnetism as energy is added.
One of the most notable examples of the magnetocaloric effect is in the chemical element gadolinium and some of its alloys. Gadolinium's temperature increases when it enters certain magnetic fields. When it leaves the magnetic field, the temperature drops. The effect is considerably stronger for the gadolinium alloy (Gd
5Si
2Ge
2).[8] Praseodymium alloyed with nickel (PrNi
5) has such a strong magnetocaloric effect that it has allowed scientists to approach to within one milliKelvin, one thousandth of a degree of absolute zero.[9]
Exergy analysis of magnetic refrigerationManoj maurya
The document discusses magnetic refrigeration and exergy analysis of magnetic refrigeration cycles. It explains the magnetocaloric effect and how magnetic fields can be used to achieve cooling via adiabatic demagnetization. Key equations presented include those relating the magnetocaloric effect to changes in magnetic field and temperature. The document also summarizes the reversible Brayton refrigeration cycle used in magnetic refrigeration and equations for the exergy efficiency and exergy destroyed. Major breakthroughs in 1997 that accelerated progress in the field are noted. In closing, the summary states that magnetic refrigeration provides an effective and efficient cooling method and has improved significantly since initial work in the 1920s-1930s.
Magnetic refrigeration is a cooling technology that uses the magnetocaloric effect to attain low and refrigerator temperatures. It was discovered in the 1930s by Weiss, Piccard, Debye, and Giaque through the observation that applying or removing a magnetic field to certain materials causes a temperature change. The magnetocaloric effect is a magneto-thermodynamic phenomenon in which the temperature of a suitable material changes with exposure to a changing magnetic field. Gadolinium alloys are commonly used as they heat up in a magnetic field.
This presentation discusses magnetic and nuclear cooling techniques. Magnetic cooling uses the magnetocaloric effect where applying or removing a magnetic field from certain materials causes a temperature change. The process involves magnetizing a material, transferring heat away, demagnetizing to cool the material, and transferring the cold to the target. Very low temperatures below 1K can be achieved using nuclear demagnetization which exploits the magnetic dipoles of atomic nuclei. This technique allows cooling to temperatures as low as 0.001K and is useful for experimental applications. Magnetic and nuclear refrigeration provide advantages over conventional cooling like reduced energy costs and avoiding ozone-depleting refrigerants.
It is a technolgy by which we can produce cooling Effect Using MAgnets and Magnetic Materials......
For any other enquiry u can contact me on +919540278218....
and can join my Page www.facebook.com/engineeringindia
Adiabatic de-magnetization, process by which the removal of a magnetic field from certain materials serves to lower their temperature. Milli Kelvin temperatures could be achieved.
This application note illustrates the use and advantages of dielectric heating, which as the name implies, is used for materials that are non-conducting. The essential advantage of dielectric heating is that the heat is generated within the material to be heated. In comparison with more conventional heating techniques (hot air, infrared, et cetera) in which the material is heated via the outer surface, dielectric heating is much more rapid. This is because electrical insulating materials, i.e. the domain of dielectric heating, are usually also poor conductors of heat.
Other interesting characteristics of radio frequency and microwave heating are the high power density and the potential for selectively heating materials. However, dielectric heating is an expensive technique and its application is generally limited to the heating of products with high added value, or to products that cannot be heated by other means.
Magnetic refrigeration is a technology that has proven to
be environmentally safe. Computer models have shown
25% efficiency improvement over vapor compression
systems.
This document summarizes research on magnetic refrigeration. It describes the development of magnetic refrigeration technology over time, including early experiments in the late 19th century and key advances in the late 20th century. It then discusses several studies that have designed and tested different types of magnetic refrigeration devices, including reciprocating and rotating systems, and investigated how to optimize performance by studying various design and operating parameters. The document focuses on a study in Iraq that constructed the first magnetic refrigerator in the country to experimentally investigate its performance and the effects of different operational parameters.
This presentation discusses thermoelectric effects on magnetic nanostructures and their application in magnetic refrigeration. It explains that magnetic refrigeration is based on the magnetocaloric effect and the varying magnetic entropy of magnetic materials. Magnetic refrigeration has advantages over traditional vapor compression cycles, including lower costs, less electricity usage, no compressor or refrigerant gases. While initial investment is higher for magnetic refrigeration, it provides safer, more environmentally friendly cooling. The goal is to develop efficient magnetic refrigeration technology for standard home refrigerators.
This short document does not contain any meaningful information to summarize. It consists of formatting characters without any words or sentences of substance. In 3 sentences or less, there is no essential information that can be extracted from the given text to create a useful summary.
Bhargav S is seeking a challenging and responsible position in a professionally managed organization. He has a BE in Mechanical Engineering from B G S Institute of Technology with an aggregate of 75.77% until the 6th semester. He has technical skills in MS Office, ANSYS, Solid Edge, and CATIA V5 sketcher. His hobbies include playing cricket and volleyball, watching TV, and listening to music.
Magnetocaloric effect and magnetic field-induced martensitic transformation i...Universidad de Oviedo
One of the challenges of modern societies consists in to increase the equipment energy efficiency, whereby reducing the energy consumption. In this sense, the magnetic solid-state refrigeration technology based on the magnetocaloric effect (MCE), attracts an enormous interest because of its potential to substitute the conventional liquid-gas refrigerant systems due to, among other advantages, its superior efficiency (up to 60% of Carnot's cycle) [1,2]. However, to be commercially competitive, this technology still needs cheap materials with enhanced refrigerant properties. Among the potential materials, metamagnetic shape memory alloys (mainly, Heusler-type Ni-Mn-based alloys) occupy a unique place because, alongside the shape memory effect and superelasticity, they exhibit large magnetocaloric effect due to the sharp change of the magnetization associated to the magnetostructural martensitic transformation (MT) [4].
We will present our recent studies of both the magnetocaloric effect and the influence of magnetic field on MT in metamagnetic Ni-Mn-In alloys doped by Cu and Cr. This doping mode allows a fine tuning of both the MT temperature around the room temperature (278-315 K) and magnetization drop at MT. The adiabatic MCE measurements have been performed using in-house made set-up [3]. An application of 1.9 T magnetic field results in a maximum inverse adiabatic temperature change of ~ -2 K caused by magnetic field-induced MT. Besides, the austenite phase undergoes a ferro-to-paramagnetic transition to which a direct adiabatic temperature change of almost the same amplitude as for inverse effect is associated. Furthermore, MT moves to lower temperatures (around 40 K for Cu-doped alloy) in magnetic fields up to 10 T accompanied by a decrease of the transformation entropy change.
References:
1. M.-H. Phan and S.-C. Yu, J. Magn. Magn. Mater. 308, 325 (2007).
2. V. Franco, J.S. Blázquez, B. Ingale, and A. Conde, Annu. Rev. Mater. Res. 42, 305 (2012).
3. V.A. Chernenko et al., J. Magn. Magn. Mater. 324, 3519 (2012).
4. P. Álvarez-Alonso et al., Key Eng. Mater. 644, 215–218 (2015).
USAT Certified Coach Dave Jimenez did a tailored presentation at TriShop in Plano, TX on Monday, June 22, 2015 for athletes planning on racing Ironman 70.3 Buffalo Springs in Lubbock, TX on June 28, 2015.
In this presentation, Dave helps plan your logistics and race strategy to have your best 70.3 yet. Dave covered important things to do the days leading up to the event, race morning, the weather and how it may impact your approach to the race, the swim, bike and run courses including strategies about how to race the course and have efficient transitions.
The document is copyrighted to Six Apart, Ltd. and contains repeated copyright notices and blank lines. It notes that server performance and environment are subject to change and includes partner and copyright information.
SURVEY AND DESIGN OF A HEADLIGHT CIRCUIT TO REDUCE POWER CONSUMPTIONIAEME Publication
All the components in an automobile are powered by internal combustion engines and thereby reducing its mechanical efficiency. Battery in an automobile is charged with an internal combustion engine with the conversion of mechanical to electrical energy by an alternator also known as generator. Most of the people often forget to turn off their light in the morning which reduces mechanical efficiency of an engine.
El glaucoma es una enfermedad de los ojos causada por un aumento de la presión intraocular que puede llevar a la pérdida de la vista. Existen dos tipos principales: glaucoma de ángulo cerrado y glaucoma de ángulo abierto. Los factores de riesgo incluyen la edad, antecedentes familiares de glaucoma, y ascendencia africana o asiática. La prevención requiere exámenes regulares de la vista y el seguimiento del tratamiento médico.
This document provides an overview of maglev and hyperloop transportation technologies. It discusses how maglev trains use magnetic levitation to float above a guideway, with two main types being electromagnetic suspension (EMS) and electrodynamic suspension (EDS). The hyperloop concept proposes using linear induction motors and air bearings in low pressure tubes to enable passenger or cargo capsules to travel at faster-than-airline speeds. Key components of a hyperloop system include the low pressure tube, capsules for passengers/cargo, propulsion via linear accelerators along the tube, and an air bearing suspension system to support the capsules with minimal friction.
In this PPT you know about the SELF HEALING technology in spacecrafts
This technology is still under research in NASA.
This technology can be also implement on Aircrafts.So it is very simple concept it includes some basic knowledge about Composites materials and its properties.
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aseminar report on magnetic refrigeration
1. 1
A
Seminar
On
“MAGNETIC REFRIGERATION”
By
MR. HARDIK N KOTHIYA
Under The Guidance Of
Prof. J. R. MAHAJAN
Submitted In Partial Fulfillment of the Requirement For
Bachelor of Engineering (Mechanical) Degree
of
University of Pune
Department of Mechanical Engineering
Late G.N. Sapkal College of Engineering,
Anjaneri, Nashik-422212
2013-2014
2. 2
Kalyani Charitable Trust’s
Late G. N. Sapkal College of Engineering
Sapkal Knowledge Hub, Kalyani Hills, Anjaneri, Trimbakeshwar Road,
Nashik – 422 212, Maharashtra State, India
CERTIFICATE
This is to certify that Mr. HARDIK N KOTHIYA has successfully
completed his Seminar on the topic “MAGNETIC REFRIGERATION”,
under the able guidance of Prof. J. R. MAHAJAN towards the partial
fulfillment of Third Year of Mechanical Engineering as laid down by
University of Pune during academic year 2013-14.
Prof. Prof. T.Y. Badgujar
[Seminar Guide] [ H.O.D. Mechanical ]
Dr. Basavaraj S. Balapgol
[Examiner] Principal
3. 3
CONTENT
ACKNOWLEDGEMENT
ABSTRACT
INDEX
Sr.
No.
Description Page
No.
1 Introduction 7
2 History 8
3 Refrigeration 9
3.1 Magnetic Refrigeration 9
4 Objective Of Magnetic Refrigeration 10
5 Magneto-caloric Effect 10
6 Working Of Magnetic Refrigeration 12
6.1 Magnetic Refrigeration System 12
6.2 Refrigerator’s Configuration 13
7 Comparison Between Magnetic Refrigeration
& Conventional Refrigeration
14
8 Components 16
9 Application 17
9.1 A Rotary AMR Liquefier 17
9.2 Future Application 17
10 Techinical Benefits 18
11 Advantages 18
12 Disadvantages 19
13 Current & Future Uses 20
14 Conclusion 21
15 Reference 21
4. 4
FIGURE INDEX
FIGURE NO. TITLE PAGE NO.
2.1 Emil Warburg Gabriel 8
5.1 Magneto-Caloric Effect 11
5.2 Process of Magneto-Caloric Effect 11
6.1 Flow Process Diagram A 12
6.2 Flow Process Diagram B 13
7.1
Comparison Between Magnetic
Refrigeration & Conventional Refrigeration
14
7.2
Refrigeration Cycle For Conventional Gas
Compression & Magnetic Refrigeration
15
8.1 Components 16
9.1 A Rotary AMR Liquefier 17
5. 5
ACKNOWLEDGEMENT
I take this opportunity to express our deep sense of gratitude and respect towards
our guide MR. J. R. MAHAJAN, Department of Mechanical Engineering, Late G N
Sapkal College Of Engineering , NASHIK. I am very much indebted to his for the
generosity, expertise and guidance; I have received from him while collecting data on this
seminar and throughout our studies. Without his support and timely guidance, the
completion of my seminar would have seemed a far fetched dream. In this respect I find
ourselves lucky to have his as our guide. He has guided us not only with the subject
matter, but also taught us the proper style and technique of working and presentation. It is
a great pleasure for me to express my gratitude towards those who are involved in the
completion of my seminar report. I whole-heartedly thank to our HOD Mr. T. Y.
BADGUJAR for their guidance. I am also indebted to all Sr. Engineers and others who
gave me their valuable time and guidance. The various information and sources I used
during my report completion find place in my report.
I am also grateful to Senior Seminar Coordinators respected sir’s.
HARDIK N KOTHIYA
III year, VSem
Deptt. Of Mechanical Engineering (L.G.N.S.COE, Nashik) Magnetic Refrigeration
6. 6
ABSTRACT
The objective of this effort is to study the Magnetic Refrigeration which uses
solid materials as the refrigerant. These materials demonstrate the unique property known
as magneto caloric effect, which means that they increase and decrease in temperature
when magnetized/demagnetized. This effect has been observed for many years and was
used for cooling near absolute zero. Recently materials are being developed which have
sufficient temperature and entropy change to make them useful for a wide range
temperature applications.
Magnetic refrigeration is an emerging technology that exploits the magneto-
caloric effect found in solid state refrigerants. The combination of solid-state refrigerants,
water based heat transfer fluids and high efficiency leads to environmentally desirable
products with minimal contribution to global warming. Among the numerous application
of refrigeration technology air conditioning applications provide the largest aggregate
cooling power and use of the greatest quantity of electric energy.
7. 7
1. INTRODUCTION
Refrigeration is the process of removing heat from matter which may be a solid,
a liquid, or a gas. Removing heat from the matter cools it, or lowers its temperature. In
the mechanical refrigeration a refrigerant is a substance capable of transferring heat that it
absorbs at low temperatures and pressures to a condensing medium; in the region of
transfer, the refrigerant is at higher temperatures and pressures. By means of expansion,
compression, and a cooling medium, such as air or water, the refrigerant removes heat
from a substance and transfers it to the cooling medium.
Our society is highly dependent on reliable cooling technology. Refrigeration is
critical to our health and the global economy. Consumer application includes air
conditioning, food preservation, air dehumidification, beverage dispensing and ice
making without refrigerant ion the food supply wood still be seasonal and limited to
locally produced non-perishable items.
Modern refrigeration is almost entirely based on a compression/ expansion
refrigeration cycle. It is a mature, reliable & relatively low cost technology. Over the
years ,all parts of a conventional refrigerator were considerably improved due to extended
research and development efforts. Furthermore, some liquids used as refrigerants are
hazardous chemicals, while other eventually escape into the environment contributing
towards ozone layer depletion and global warming and therefore, conventional
refrigeration ultimately promotes deleterious trends in the global climate.
Magnetic refrigerator, which has advantages in refrigeration efficiency,
reliability, low noise and environmental friendliness with respect to the conventional gas
refrigerators, is becoming a promising technology to replace the conventional technique.
The development of the magnetic material, magnetic refrigeration cycles, magnetic field
and the refrigerator of room temperature magnetic refrigeration is introduced.
8. 8
2. HISTORY
Fig. 2.1 Emil Warburg Gabriel
The effect was discovered in pure iron in 1881 by E. Warburg. Originally, the
cooling effect varied between 0.5 to 2 K/T. Major advances first appeared in the late
1920s when cooling via adiabatic demagnetization was independently proposed by two
scientists: Debye (1926) and Giauque(1927).
The process was demonstrated a few years later when Giauque and MacDougall
in 1933 used it to reach a temperature of 0.25 K. Between 1933 and 1997, a number of
advances in utilization of the MCE for cooling occurred.
This cooling technology was first demonstrated experimentally by chemist Nobel
Laureate William F. Giauque and his colleague Dr. D.P. MacDougall in 1933 for
cryogenic purposes (they reached 0.25 K) In 1997, the first near room temperature proof
of concept magnetic refrigerator was demonstrated by Prof. Karl A. Gschneidner, Jr. by
the Iowa State University at Ames Laboratory. This event attracted interest from
scientists and companies worldwide that started developing new kinds of room
temperature materials and magnetic refrigerator designs.
Refrigerators based on the magneto caloric effect have been demonstrated in
laboratories, using magnetic fields starting at 0.6 T up to 10 teslas. Magnetic fields above
2 T are difficult to produce with permanent magnets and are produced by a
superconducting magnet (1 tesla is about 20,000 times the Earth's magnetic field).
9. 9
3.REFRIGERATION
Refrigeration is the process of removing heat from an enclosed space, or from a
substance, and moving it to a place where it is unobjectionable. The primary purpose of
refrigeration is lowering the temperature of the enclosed space or substance and then
maintaining that lower temperature. The term cooing refers generally to any natural or
artificial process by which heat is dissipated. The process of artificially producing
extreme cold temperatures is referred to as cryogenics. Cold is the absence of heat, hence
in order to decrease a temperature, one “removes heat", rather than "adding cold." In
order to satisfy the Second Law of Thermodynamics, some form of work must
be performed to accomplish this. This work is traditionally done by mechanical work but
can also be done by magnetism, laser or other means.
3.1 MAGNETIC REFRIGERATION
Magnetic refrigeration, or adiabatic demagnetization, is a cooling technology
based on the magneto caloric effect, an intrinsic property of magnetic solids. The
refrigerant is often a paramagnetic salt, such as cerium magnesium nitrate. The active
magnetic dipoles in this case are those of the electron shells of the paramagnetic atoms.
A strong magnetic field is applied to the refrigerant, forcing its various magnetic
dipoles to align and putting these degrees of freedom of the refrigerant into a state of
lowered entropy. A heat sink then absorbs the heat released by the refrigerant due to its
loss of entropy. 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.
Because few materials exhibit the needed properties at room temperature, applications
have so far been limited to cryogenics and research.
10. 10
4. OBJECTIVES OF MAGNETIC REFRIGERATION
To develop more efficient and cost effective small scale H2 liquefiers as an
alternative to vapor-compression cycles using magnetic refrigeration. With the help of
magnetic refrigeration our objective is to solve the problem of hydrogen storage as it
ignites on a very low temperature. Hydrogen Research Institute (HRI) is studying it
with the help of magnetic refrigeration. We provide the cooling for the hydrogen storage
by liquefying it.
The hydrogen can be liquefied at a low temperature and the low temperature is
achieved with the help of magnetic refrigeration. Thus, the magnetic refrigeration also
provides a method to store hydrogen by liquefying it. The term used for such a device is
magnetic liquefier.
5. MAGNETO CALORIC EFFECT
The Magneto caloric effect (MCE, from magnet and calorie) 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 also
known as adiabatic demagnetization by low temperature physicists, due to the
application of the process specifically to affect a temperature drop. In that part of the
overall refrigeration process, a decrease in the strength of an externally applied magnetic
field allows the magnetic domains of a Chosen (magneto caloric) material to become
disoriented from the magnetic field by the agitating Action of the thermal energy
(phonons) present in the material. If the material is isolated so that no energy is allowed
to (e) migrate into the material during this time (i.e. an adiabatic process), the temperature
drops as the domains absorb the thermal energy to perform their reorientation.
One of the most notable examples of the magneto caloric effect is in the chemical
element gadolinium and some of its alloys. Gadolinium's temperature is observed to
increase when it enters certain magnetic fields. When it leaves the magnetic field, the
11. 11
temperature returns to normal. The effect is considerably stronger for the gadolinium
alloy Gd5 (Si2Ge2). Praseodymium alloyed with nickel (Pr Ni 5) has such a strong
magneto caloric effect that it has allowed scientists to approach within one thousandth of
a degree of absolute zero. Magnetic Refrigeration is also called as Adiabatic
Magnetization.
Fig. 5.1 Magneto-Caloric Effect
Fig. 5.2 Process of Magneto-Caloric Effect
12. 12
1. WORKING OF MAGNETIC REFRIGERATION SYSTEM
6.1 Magnetic Refrigeration system : -
Consists of two beds containing spherical powder of Gadolinium with water
being usedas the heat transfer fluid. The magnetic field for this system is 5 Wb/m2,
providing a temperature span of 38 K. The process flow diagram for the magnetic
refrigeration system is shown in Fig.
Fig. 6.1 Flow process diagram A
A mixture of water and ethanol serves as the heat transfer fluid for the system.
The fluid first passes through the hot heat exchanger, which uses air to transfer heat to the
atmosphere. The fluid then passes through the copper plates attached to the no
magnetized cooler-magneto caloric beds and loses heat. A fan blows air over this cold
fluid into the freezer to keep the freezer temperature at approximately 0°F. The heat
transfer fluid then gets heated up to 80°F, as it passes through the copper plates adjoined
by the magnetized warmer magneto caloric beds, where it continues to cycle around the
loop. However, the magneto caloric beds simultaneously move up and down, into and out
of the magnetic field. The temperature of the refrigerator section is kept around 39°F.
6.2 Refrigerator Configuration :-
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The typical household refrigerator has an internal volume of 165-200 litres,
where the freezer represents approximately 30% of this volume. Freezers are designed to
maintain at temperature of 0°F. Refrigerators maintain a temperature of 39°F. The
refrigerator will be insulated with polyurethane foam, one of the most common forms of
insulation available. The refrigerator is kept cool by forcing cold air from the freezer into
the refrigerator by using a small fan.
Fig. 6.2 Flow process diagram B
The control system for maintaining the desired internal temperatures consists of
two thermostats with on/off switches. The freezer thermostat regulates the temperature by
turning the compressor off when the temperature gets below 0°F. A second thermostat
regulates the fan that cools the refrigerator to 39°F. To maintain a frost-free environment
in the freezer, a defrost timer will send power to a defrost heater on the coils for a fifteen
minute time period every eight hours. In the first six minutes, the walls of the freezer will
be defrosted. The water will then drain into a pan at the base of the refrigerator. The next
nine minutes involve the safety factor of not reaching a temperature in the freezer that is
too high. Also, a safety thermostat keeps the liquid water from freezing as it drains.
The heat transfer fluid for the magnetic refrigeration system is a liquid alcohol
water mixture. The mixture used in the design consists of 60 % ethanol and 40 % water.
This mixture has a freezing point of –40°F, assuring that the mixture does not freeze at
operating temperatures. This heat transfer fluid is cheaper than traditional refrigerants
and also eliminates the environmental damage produced from these refrigerants.
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7. COMPARISON BETWEEN MAGNETIC REFRIGERATION
AND CONVENTIONAL REFRIGERATION
Fig. 7.1 Comparison between Magnetic Refrigeration and Conventional Refrigeration
In Figure 2 the four basic steps of a conventional gas compression/ Expansion
refrigeration process are shown. These are a compression of a gas, extraction of heat,
Expansion of the gas, and injection of heat. The two Process steps extraction of heat and
expansion are Responsible for a cooling process in two steps. The main Cooling usually
occurs through the expansion of the gas.
The steps of a magnetic refrigeration process are Analogous. By comparing a
with b, in Figure.2 one can see That instead of compression of a gas, a magnetocaloric
Material is moved into a magnetic field and that instead of Expansion it is moved out of
the field. As explained in the Previous section, these processes change the temperature Of
the material and heat may be extracted, respectively Injected just as in the conventional
process. There are Some differences between the two processes. The heat Injection and
rejection in a gaseous refrigerant is a rather Fast process, because turbulent motion
15. 15
transports heat Very fast. Unfortunately, this is not the case in the solid Magneto-caloric
materials. Here, the transport mechanism For heat is slow molecular diffusion. Therefore,
at present fi Ligree porous structures are considered to be the best Solution to overcome
this problem. The small distances From the central regions of the material to an adjacent
fluid Domain, where a heat transport fluid captures the heat and Transports it out of the
material, are ideal to make the Magnetic cooling process faster. Furthermore, the not very
Large adiabatic temperature differences of magneto-caloric Materials will require more
often a design of cascade or Regenerative magnetic refrigerators than in conventional
Refrigerators and hence require additional heat transfer Steps. In the is the conventional
gas compression Process is driven by continuously repeating The four different basic
processes shown and is the Magnetic refrigeration cycle comparison. Compression is
Replaced by adiabatic magnetization and expansion by Adiabatic demagnetization.
Fig. 7.2 Refrigeration cycles for conventional gas compression and magnetic
refrigeration
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8. COMPONENTS
Components required for construction :-
Fig. 8.1 Components
1. Magnets : -
Magnets are the main functioning element of the magnetic refrigeration.
Magnets provide the magnetic field to the material so that they can lose or gain the heat to
the surrounding and from the space to be cooled respectively.
2. Hot Heat Exchanger : -
The hot heat exchanger absorbs the heat from the material used and gives off to
the surrounding. It makes the transfer of heat much effective.
3. Cold Heat Exchanger :-
The cold heat exchanger absorbs the heat from the space to be cooled and gives
it to the magnetic material. It helps to make the absorption of heat effective.
4. Drive : -
Drive provides the right rotation to the heat to rightly handle it. Due to this heat
flows in the right desired direction.
5. Magneto caloric Wheel : -
It forms the structure of the whole device. It joins both the two magnets to work properly.
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9. APPLICATIONS
9.1 A rotary AMR liquefier :-
The Cryofuel Systems Group is developing an AMR refrigerator for the purpose
of liquefying natural gas. A rotary configuration is used to move magnetic material into
and out of a superconducting magnet. This technology can also be extended to the
liquefaction of hydrogen.
Fig. 9.1 A Rotary AMR liquefier
9.2 Future Applications:-
In general, at the present stage of the development of magnetic refrigerators with
permanent magnets, hardly any freezing applications are feasible. These results, because
large temperature spans occur between the heat source and the heat sink. Such are used
for freezing, e.g. in cooling plants in the food industry or in large marine freezing
applications. Some of the future applications are:
1. Magnetic household refrigeration appliances
2. Magnetic cooling and air conditioning in buildings and houses
3. Central cooling system
4. Refrigeration in medicine
5. Cooling in food industry and storage
6. Cooling in transportation
7. Cooling of electronics
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10. TECHNICAL BENEFITS
2. High efficiency: - As the magneto caloric effect is highly reversible, the thermo
dynamic efficiency of the magnetic refrigerator is high. It is somewhat 50% more
than Vapor Compression cycle.
3. Reduced operating cost: - As it eliminates the most inefficient part of today’s
refrigerator i.e. comp. The cost reduces as a result.
4. Compactness: - It is possible to achieve high energy density compact device. It is
due to the reason that in case of magnetic refrigeration the working substance is a
solid material (say gadolinium) and not a gas as in case of vapor compression
cycles.
5. Reliability: - Due to the absence of gas, it reduces concerns related to the emission
into the atmosphere and hence is reliable one.
11. ADVANTAGES
1. Environmental friendly: - Conventional refrigerator use refrigerant that contains
CFC or HCFC, which have been linked to Ozone depletion and global warming.
Some refrigerant like ammonia are toxic and inflammable.
2. Low running and operating cost:-There is no compressor in magnetic
refrigerator, which is most inefficient and costlier part. This leads in less energy
consumption and hence low running cost.
3. Higher efficiency:-Because it eliminates the need to expand and compressed the
liquid, magnetic refrigerator consume less energy and can operate at 60%
efficiency.
4. Wide temperature span: - Operating temperature of magnetic refrigerator can
easily be changed over a wide range from about 30 k to 290 k without losing the
magneto-caloric effect.
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5. Reliability: - High energy density and more compact device, less moving parts as
compared to traditional system hence more reliable.
6. Quite operation: - This refrigerator unit is substantially quite than traditional
refrigeration system.
12. DISADVANTAGES
On the other hand, some disadvantages include:
1. The initial investment is more as compared with conventional refrigeration.
2. The magneto caloric materials are rare earth materials hence their availability also
adds up an disadvantage in MAGNETIC REFRIGERATION.
GMCE materials need to be developed to allow higher frequencies of rectilinear
and rotary magnetic refrigerators.
3. Protection of electronic components from magnetic fields. But notice that they
are static, of short range and may be shielded
4. Permanent magnets have limited field strength. Electromagnets and
superconducting magnets are (too) expensive.
5. Temperature changes are limited. Multi-stage machines lose efficiency through
the heat transfer between the stages.
6. Moving machines need high precision to avoid magnetic field reduction due to
gaps between the magnets and the magneto caloric material.
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13. CURRENT AND FUTURE USES
There are still some thermal and magnetic hysteresis problems to be solved for
these first-order phase transition materials that exhibit the MCE to become really useful;
this is a subject of current research. A useful review on magneto caloric materials
published in 2005 is entitled "Recent developments in magneto caloric materials" by Dr.
Karl A. Gschneidner, .This effect is currently being explored to produce better
refrigeration techniques, especially for use in spacecraft. This technique is already used to
achieve cryogenic temperatures in the laboratory setting (below 10K). As an object
displaying MCE is moved into a magnetic field, the magnetic spins align, lowering the
entropy. Moving that object out of the field allows the object to increase its entropy by
absorbing heat from the environment and disordering the spins. In this way, heat can be
taken from one area to another. Should materials be found to display this effect near room
temperature, refrigeration without the need for compression may be possible, increasing
energy efficiency.
In addition, magnetic refrigeration could also be used in domestic refrigerators.
In 2006, a research group led by Karl Sandeman at the University of Cambridge made a
new alloy, composed of cobalt, manganese, silicon and germanium that can be used for
magnetic refrigeration. This has made the use of the expensive material gadolinium
redundant, and made the creation of domestic magnetic refrigerators possible. The use of
this technology for domestic refrigerators though is very remote due to the high efficiency
of current Vapor-compression refrigeration in the range of 60% of Carnots efficiency.
Gas molecules are responsible for heat transfer, they absorb heat in the inner side of the
refrigerator by expanding and release this heat in the outside by condensing. The work
provided to do this work is a cheap and highly efficient compressor, driven by an electric
motor that is more than 80% efficient. This technology could eventually compete with
other cryogenic heat pumps for gas liquefaction purposes.
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14. CONCLUSION
If we say future perspectives of room temperature Magnetic Refrigeration; It can
be seen from the earlier Description that main progresses have been made in America.
However, with the continual phasic progresses of Room temperature magnetic
refrigeration, the whole world Has accelerated in the research. Nevertheless, it is notable
that main work is concentrated On investigations of magnetic materials, lack of
Experimental explorations of magnetic refrigerator. From The former results achieved by
researchers, it can be seen. At the end of this study we can say;
1. It is a technology that has proven to be environmentally safe.
2. In order to make the magnetic refrigerator commercially Viable, scientists need to
know how to achieve larger temperature swings and also permanent magnets
which can produce strong magnetic fields of order 10 tesla.
3. There are still some thermal and magnetic hysteresis problems to be Solved for
the materials that exhibit the MCE to become really useful.
4. Magnetic materials available for room Temperature magnetic refrigeration are
mainly Gd, Gdsige alloys, mn as-like materials, perovskite like Materials,
5. Materials under development for room Temparature magnetic refrigeration are
La(fexsi1-X)13 and La(Fe0.88Si0.12)13Hy
6. Excellent behavior of regeneration and heat Transfer is required It can be use
household refrigerator, central Cooling systems, room air conditioners and
Supermarket refrigeration applications.
7. This technology must be universalized worldwide.
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15. REFERENCES
1. http://en.wikipedia.org/wiki/Magnetic_refrigeration
2. http://www.scribd.com/doc/19537314/Magnetic-Refrigeration
3. Lounasmaa, experimental principles and methods, academic press
4. Richardson and Smith, experimental techniques in condensed matter physics at low
temperature, Addison Wesley (2003)
5. A text book on cryogenic engineering by V.J.Johnson
6. “Refrigeration and Air conditioning” by Arora and Domkundwar
7. Magnetic Refrigeration, ASHRAE Journal (2007), by John Dieckmann, Kurt Roth and
James Brodrick