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Yunho Hwang

Research Professor

Research Professor in the field of Alternative Cooling Technologies and Applications, Working Fluid Mixtures, Flow Boiling and Supercritical Heat Transfers, Compact Heat Exchangers, Refrigerant and Oil Distribution, Vapor Compression and Sorption Cycles, Advanced Energy Conversion Systems,...
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experience

Associate Director  
Center for Environmental Energy Engineering, January 2009 to Present

Oversee the day-to-day operations of the center – a world renowned research facility in the study of environmentally responsible, economically feasible distributed energy conversion systems for buildings and transportation.

Research Professor  
University of Maryland, July 1993 to Present

Directing Alternative Cooling Technologies and Applications consortium.

Senior Researcher  
Samsung Electronics, January 1983 to August 1998

RND in HVAC

education

University of Maryland, College  
Ph. D, Mechanical Engineering, Jan, 1993 to Jan, 1997
Dissertation: Comprehensive Investigation of Carbon Dioxide Refrigeration Cycle

University of Maryland, College  
M.S, Mechanical Engineering, Jan, 1993 to Jan, 1995
Thesis: Evaluation of R-22 Alternatives for Heat Pumps

Korea University  
B.E, Mechanical Engineering, Jan, 1979 to Jan, 1983


projects

DOE Ultra-Low Energy Appliance Design Competition  by  Yunho Hwang, John (Jack) Calderone, Jeffrey Sze, Jan Muehlbauer    
January, 2013 - Present
- Collaborated with a team of professors and students to design and build a high efficiency heat pump clothes dryer to be entered in the DOE sponsored Max Tech and Beyond: Ultra-Low Energy Appliance Design Competition - Fabricated a prototype dryer using a vapor compression cycle with vapor injection - Achieved an energy factor of 10.4 lbs of clothes per kWh, a 160% increase over conventional dryers

Certifications

  • ASME Fellow
    ASME 

publications

Integration of variable refrigerant flow and heat pump desiccant systems for the cooling season     
Published by (Applied Thermal Engineering, Vol. 30, no: 8-9, pp. 917-927)
Authors: Yunho Hwang, Tolga N. Aynur, Reinhard Radermacher.  Published January 01, 2010

Integration of variable refrigerant flow and heat pump desiccant systems for the heating season     
Published by (Energy and Buildings, Vol. 42, no. 4, pp. 468-476)
Authors: Yunho Hwang, Tolga N. Aynur, Reinhard Radermacher.  Published January 01, 2010

Field performance measurements of a heat pump desiccant unit in heating and humidification mode     
Published by (Energy and Buildings, Vol. 42, no: 5, pp. 678-683)
Authors: Yunho Hwang, Tolga N. Aynur, Reinhard Radermacher.  Published January 01, 2010

Performance Enhancement of Enhanced Heriingbone Wavy-Fin Round Tube Inclined Heat Exchangers with an     
Published by (ASME 2013 International Mechanical Engineering Congress and Exposition, San Diego, CA.)
Authors: Yunho Hwang, Sahil Popli, Reinhard Radermacher.  Published July 20, 2013

An experimental study has been conducted to evaluate the performance of two herringbone wavy-fin round tube compact heat exchangers working as coolers, with frontal areas of approximately 0.24 m2 each in both dry and wet conditions. Heat exchanger capacity and air-side pressure drop were measured with the heat exchanger angle set at 21° from vertical. Deluge water cooling was achieved by incorporating a water distributor on top of the heat exchanger from which wetting water overflows as thin film over the top leading edge of the heat exchanger fins. A hollow cone nozzle was used for spray cooling. Water was used as a refrigerant, and enters the heat exchanger tubes at 43°C temperature. Ambient air, deluge and spray cooling water were maintained at 28°C temperature, and frontal air velocity was varied from 1.5 m/s to 3.0 m/s. Capacity was significantly enhanced for all heat exchangers using both deluge and spray cooling. However, the air-side pressure drop penalty ratio was much higher for deluge cooling. Furthermore, heat exchanger with hydrophilic coated fins achieved higher capacity enhancement ratios. This study contributes 8 dry cases and 48 wet cases experimental data points of wavy-fin heat exchanger performance. Future studies would aim at obtaining higher capacity enhancement ratios for spray cooling while maintaining air-side pressure drop penalty ratio of 1.0.

Enhancement of Round Tube Heat Exchanger Performance Using Deluge Water Cooling- Paper #2331. 14th I     
Published by (14th International Refrigeration and Air Conditioning Conference, West Lafayette, IN, USA, July, pp.)
Authors: Yunho Hwang, Sahil Popli, Reinhard Radermacher.  Published July 01, 2012

An experimental study has been conducted to evaluate the condenser performance of a compact round-tube louver-fin, each with frontal areas of 0.25 m2 in both dry and wet conditions. Deluge water cooling is achieved by incorporating a perforated bottom plate-type water distributor on top of the round tube heat exchanger. Water is used as a refrigerant, and enters the heat exchanger tubes at 35°C temperature. Ambient air and deluge cooling water are both maintained at 22°C temperature. Heat exchanger capacity and air-side pressure drop are measured with the heat exchanger angle set at 0° and 21° from vertical, with a frontal air velocity of 1.4 m/s and 3.5 m/s without deluge water cooling, and a frontal air velocity of 1.4 m/s with deluge water cooling. For both heat exchangers, the capacity was significantly enhanced with the use of deluge water cooling and with the heat exchanger angle set at 21° from vertical.

Applicability of Entransy Dissipation Based Thermal Resistance for Design Optimization of Two-Phase     
Published by (Applied Thermal Engineering)
Authors: Yunho Hwang, Suxin Qian, Long Huang, private private, Reinhard Radermacher.  Published March 21, 2013

The liquid–vapor two-phase entransy is derived and applied to two-phase heat exchanger optimization studies. Real case studies to optimize a fin-tube condenser and a microchannel condenser are presented. Entransy metric has no advantage over capacity as optimization objective if flow rates are fixed. Entransy metric could be used to optimize air flow rate together with heat transfer area. In air cooled two-phase HXs, entransy metric and entropy metric show little difference in optimization results.