Tuesday, January 26, 2016: 11:15 AM-12:45 PM
Fundamentals and Applications
Chair:
Omar Abdelaziz, Ph.D., Oak Ridge National Laboratory
Technical Committee: 01.01 Thermodynamics and Psychrometrics
Cooling technology requirements have moved beyond our basic needs for comfort and food safety, and their new development should meet extra requirements, such as compliance to new efficiency standards and legal codes on refrigerant. ASHRAE members have demonstrated a lot of development in these aspects for vapor compression technology, but what is happening to other alternatives? In this seminar, the new breakthroughs of three alternative cooling technologies—electrocaloric cooling, magnetocaloric refrigeration and elastocaloric cooling—are explored for their potentials to meet the new challenges. The presentations also cover their theories and experimental results, including potential commercial development.
1 Electrocaloric Cooling: Present Advances and Future Perspectives
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Omar Abdelaziz, Ph.D., Oak Ridge National Laboratory |
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Qiming Zhang, Ph.D., Penn State University |
Electrocaloric effect (ECE) is the ability of a dielectric to change its temperature and entropy as an electric field is applied and released. It provides an effective means to realize solid-state cooling devices that are environmentally benign and potentially highly energy efficient. Recent breakthroughs are presented in ferroelectric materials exhibiting giant electrocaloric effect, where an adiabatic temperature change DT > 40 oC has been obtained in several nano-structured ferroelectrics. EC cooling devices based on these new materials, as well as challenges and future perspectives are discussed.
2 Magnetocaloric Refrigeration, Potentials, State of the Art and Challenges
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Ayyoub Mehdizadeh Momen, Ph.D., Oak Ridge National Laboratory |
ORNL is collaborating with GEA on developing the world's first magnetocaloric refrigerator. The technology could yield energy savings of 25% over baseline vapor compression systems. A drastic upgrade in refrigerator design using magnetocaloric materials (MCM) eliminates the need for refrigerants but creates new challenges ― one is how to transfer heat to or from the solid MCM material using a heat transfer fluid. In this presentation, the basics of magnetocaloric refrigeration and the performance potential will be discussed, followed by describing state of art systems. The technical challenges and potential solutions for this emerging technology will also be reviewed.
3 Testing Results of Compressive Elastocaloric Cooling Prototype
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Yunho Hwang, Ph.D., University of Maryland |
Elastocaloric cooling has been recognized as a potential alternative and supplementary technology to the state-of-the-art vapor compression cooling systems. It is based on the elastocaloric effect found in shape memory alloys associated with the solid-solid martensitic phase transformation induced by stress. The fundamental thermodynamics of the martensitic phase change process will be introduced. Elsatocaloric cooling material following the single stage Brayton cycle and the system design will be presented. With the commercially available nickel-titanium tubes, we will demonstrate two compressive elastocaloric cooling prototypes developed in University of Maryland. Experimental test results and potential performance improvement methods will be presented.