Faculty Profile

Stefan Elbel

Mechanical Science and Engineering
Stefan Elbel
Stefan Elbel
Adjunct Assistant Professor, Lecturer
2416 Mechanical Engineering Lab
105 S. Mathews
Urbana Illinois 61801
(217) 244-1531

Primary Research Area

  • Fluid Mechanics & Thermal Sciences

Education

  • Ph.D. in Mechanical Engineering, University of Illinois at Urbana-Champaign, 2007
  • M.Sc. in Mechanical Engineering, University of Illinois at Urbana-Champaign, 2003
  • Diplom-Ingenieur (FH) in Automotive Engineering/Mechatronics, Esslingen University of Applied Sciences (Germany), 2000

Academic Positions

  • Research Assistant Professor, University of Illinois at Urbana-Champaign, Department of Mechanical Science and Engineering, 2016 - date

Other Professional Employment

  • Chief Engineer, Creative Thermal Solutions, Inc. (CTS) in Urbana, IL, 2007 - date

Short Courses

  • Training course on transcritical CO2 technology, Short course for practicing engineers organized by Creative Thermal Solutions, Inc., Urbana, IL September 20-21, 2016
  • Training course on economical design of efficient bottle coolers utilizing carbon dioxide, Short course for practicing engineers organized by Creative Thermal Solutions, Inc., Urbana, IL September 22-25, 2015
  • Latest technology trends in low-charge hydrocarbon refrigeration, Short course for practicing engineers organized by Creative Thermal Solutions, Inc., Urbana, IL January 22-23, 2015
  • Training course on economical design of efficient bottle coolers utilizing carbon dioxide, Short course for practicing engineers organized by Creative Thermal Solutions, Inc., Urbana, IL June 24-27, 2014
  • Economical design of efficient bottle coolers utilizing CO2, Short course for practicing engineers organized by Creative Thermal Solutions, Inc., Urbana, IL June 11-14, 2013
  • CO2 as the refrigerant in bottle coolers, Short course for practicing engineers organized by Creative Thermal Solutions, Inc., Urbana, IL July 6-12, 2012
  • Experience with transcritical CO2 systems and their efficiency improvements, Short Course in Supermarket Refrigeration organized by Creative Thermal Solutions, Inc. and the Air Conditioning and Refrigeration Center at the University of Illinois at Urbana-Champaign, Urbana, IL, USA, February 23-24, 2010
  • Update on natural refrigerants: military environmental control units, Short course(together with J.A. Manzione/US. Army) at Purdue University, West Lafayette, IN, USA, July 12-13, 2008

Other Undergraduate Advising Activities

  • Advisor of winning 2007 University of Illinois Solar Decathlon Thermal Comfort Team

Research Statement

Dr. Elbel is interested in experimental and numerical research in the areas of thermodynamics, fluid mechanics, and heat transfer. His focus is on energy conversion systems with specialization in vapor compression technology using synthetic and natural refrigerants. He conducts both fundamental and applied research on components and systems used in mobile, residential, commercial, and industrial heating and cooling applications.

Dr. Elbel has been researching transcritical carbon dioxide cooling and heating cycles for a large variety of applications for more than 15 years. He has worked extensively on designing and improving refrigerant ejector systems to increase the energy efficiency of vapor compression cycles. His interest in expansion work recovery has been extended to vortex tubes that offer attractive improvement potentials at very low cost. He is also working on waste heat recovery systems that allow the efficient generation of waste heat driven cooling as a promising alternative to absorption cooling systems.

Research Interests

  • Fundamental and applied research on components and systems used in mobile, residential, commercial, and industrial heating and cooling applications
  • Energy conversion systems with specialization in vapor compression technology using synthetic and natural refrigerants
  • Experimental and numerical research in thermodynamics, fluid mechanics, and heat transfer

Research Topics

  • Fluid Mechanics & Thermal Sciences

Selected Articles in Journals

  • Zhu, J. and S. Elbel, 2016, "A new control mechanism for two-phase ejector in vapor compression cycles for automotive applications using adjustable motive nozzle inlet swirl," SAE Int. J. Passeng. Cars - Mech. Syst. 9(1):44-51.
  • Lawrence, N. and S. Elbel, 2016, "Experimental investigation on the effect of evaporator design and application of work recovery on the performance of two-phase ejector liquid recirculation cycles with R410A," Appl. Therm. Eng., 100:398-411.
  • Elbel, S. and N. Lawrence, 2016, "Review of recent developments in advanced ejector technology," Int. J. Refrig., 62:1-18.
  • Lawrence, N. and S. Elbel, 2015, "Mathematical modeling and thermodynamic investigation of the use of two-phase ejectors for work recovery and liquid recirculation in refrigeration cycles," Int. J. Refrig., 58:41-52.
  • Lawrence, N. and S. Elbel, 2015, "Analysis of two-phase ejector performance metrics and comparison of R134a and CO2 ejector performance," Science and Technology for the Built Environment (formerly HVAC&R Res.), 21:515-525.
  • Brown I.P., G. Sizov, M. Critchley, J. Yin, S. Memory, S. Elbel, C. Bowers, M. Petersen, and P. Hrnjak, 2014, "Design and evaluation of interior permanent magnet compressor motors for commercial transcritical CO2 (R-744) heat pump water heaters," IEEE T. Ind. Appl., 51(1):576-586.
  • Bowers, C.D., D. Wrocklage, S. Elbel, and P. Hrnjak, 2014, "Evaluation of seasonal performance improvements in a 3-Ton air-conditioning heat pump system using a novel design of integrated electronic expansion valves and distributors," ASHRAE Tran., 120(1):1-8.
  • Lawrence N. and S. Elbel, 2014, "Experimental investigation of an alternate two-phase ejector cycle with low-pressure refrigerants R134a and R1234yf," Int. J. Refrig., 38(2): 310-322.
  • Petersen, M., C. Bowers, S. Elbel, and P. Hrnjak, 2013, "Development of high efficiency carbon dioxide commercial heat pump water heater," HVAC&R Res., 19(7): 823-835.
  • Wang, X.F., P.S. Hrnjak, S. Elbel, A.M. Jacobi, and M.G. He, 2013, "Heat transfer performance for a falling-film on horizontal flat tubes," J. Heat Transf., 135(7): 072901.
  • Zhao H., S. Elbel, P. Hrnjak, 2013, "Controlled atmosphere brazing of aluminum heat exchangers," Weld J., 92(2): 44-46.
  • Lawrence, N. and S. Elbel, 2013, "Theoretical and practical comparison of two-phase ejector refrigeration cycles including first and second law analysis," Int. J. Refrig., 36(4): 1220-1232.
  • Wang, X.F., P.S. Hrnjak, S. Elbel, A.M. Jacobi, and M. He, 2012, "Flow modes and mode transitions for falling films on flat tubes," J. Heat Transf., 134(2): 021801.
  • Elbel, S., 2011, "Historical and present developments of ejector refrigeration systems with emphasis on transcritical carbon dioxide air-conditioning applications," Int. J. Refrig., 34(7): 1545-1561.
  • Elbel, S. and P. Hrnjak, 2008, "Experimental validation of a prototype ejector designed to reduce throttling losses encountered in transcritical R744 system operation," Int. J. Refrig., 31(3): 411-422.
  • Elbel, S. and P. Hrnjak, 2004, "Flash gas bypass for improving the performance of transcritical R744 systems that use microchannel evaporators," Int. J. Refrig., 27(7): 724-735.

Articles in Conference Proceedings

  • Elbel, S. and P. Hrnjak, 2016, "Natural refrigerants for light commercial applications: a fair comparison of the pros & cons of CO2 and propane," 12th IIR Gustav Lorentzen Conference on Natural Refrigerants, Edinburgh, UK, August 21-24, Paper 1099.
  • Lawrence, N. and S. Elbel, 2016, "Experimental comparison of the performance of a CO2 ejector cycle for transcritical and subcritical operation," 12th IIR Gustav Lorentzen Conference on Natural Refrigerants, Edinburgh, UK, August 21-24, Paper 1085.
  • Lawrence, N. and S. Elbel, 2016, "Numerical modeling of the off-design performance of a transcritical CO2 two-phase ejector cycle," 12th IIR Gustav Lorentzen Conference on Natural Refrigerants, Edinburgh, UK, August 21-24, Paper 1084.
  • Lawrence, N. and S. Elbel, 2016, "Experimental study on control methods for transcritical CO2 two-phase ejector systems at off-design conditions," 12th IIR Gustav Lorentzen Conference on Natural Refrigerants, Edinburgh, UK, August 21-24, Paper 1083.
  • Lawrence, N. and S. Elbel, 2016, "Implementation of a two-phase ejector cycle for R744 glass door merchandisers," 12th IIR Gustav Lorentzen Conference on Natural Refrigerants, Edinburgh, UK, August 21-24, Paper 1082.
  • Visek, M., S. Elbel, P. Hrnjak, B. Hoaglan, C. Tang, and D. Smith, 2016, "Conversion of platelet incubator refrigeration system to R600a and performance optimization," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2615.
  • Wujek, S.S., W.L. Staats, Elbel S.W., J.P. Koplow, H.A. Kariya, and P.S. Hrnjak, 2016, "Method for determining air side convective heat transfer coefficient using infrared thermography," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2587.
  • Wenzel, M., S. Elbel, and P. Hrnjak, 2016, "Design, build-up, and commissioning of 350 kW refrigeration test facility for experimental investigation of large cold chain equipment," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2580.
  • Visek, M., S. Elbel, and P. Hrnjak, 2016, "Conversion of cold beverage dispenser￿s refrigeration system to R744 refrigerant," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2556.
  • Zhao, H., S. Raghunandanan, S. Elbel S., and P. Hrnjak, 2016, "A study of microchannel heat exchanger performance associated with the manufacturing process," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2545.
  • Musser, A., P. Hrnjak, and S. Elbel, 2016, "Internal heat exchanger performance quantification and comparison testing methods including exploration of the effects of location of measurements and oil in circulation," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2453.
  • Elbel, S., M. Duggan, T. LaGrotta, S. Raj, and P. Hrnjak, 2016, "Accelerated fatigue testing of aluminum refrigeration press fittings for HVAC & R applications," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2438.
  • Elbel, S., M. Visek, and P. Hrnjak, 2016, "A fair comparison of CO2 and propane used in light commercial applications featuring natural refrigerants," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2429.
  • Zhu, J. and S. Elbel, 2016, "Modeling of initially subcooled flashing vortex flow in the nozzle for possible applications in the control of ejector cooling cycles," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2368.
  • Lawrence, N. and S. Elbel, 2016, "Numerical study on the design of microchannel evaporators for ejector refrigeration cycles," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2092.
  • Zhu, J. and S. Elbel, 2016, "A new control mechanism for two-phase ejector in vapor compression cycles using adjustable motive nozzle inlet vortex," 16th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, Paper 2076.
  • Elbel S., 2016, "Natural, low-GWP refrigerants for light commercial refrigeration: examples of successfully converted applications using R290, R600a and R744," Presentation at ASHRAE 2016 Annual Conference, St. Louis, MO, USA, June 26-29.
  • Elbel, S. and C. Tang, 2016, "Conversion of platelet incubator to hydrocarbon refrigerant," ATMOsphere America, Chicago, IL, USA, June 16-17.
  • Zhao, H., S. Elbel, and P. Hrnjak, 2016, "Influence of surface morphology on wetting behaviors of Zn-Al filler metal on aluminum matrix composite," L￿ 2016 - 11th International Conference on Brazing, High Temperature Brazing and Diffusion Bonding, Aachen, Germany, June 7-9.
  • Zhu, J. and S. Elbel, 2016, "Vortex tube heat booster to improve performance of heat driven cooling cycles for automotive applications," SAE World Congress, Detroit, MI, USA, April 12-14, Paper 2016-01-0245.
  • Lawrence, N. and S. Elbel, 2016, "Performance improvements of R744 glass door merchandiser using low-cost two-phase ejector," 4th IIR Conference on Sustainability and the Cold Chain, Auckland, New Zealand, April 7-9.
  • Lawrence, N. and S. Elbel, 2016, "Experimental investigation of control strategies for off-design operation of a transcritical CO2 two-phase ejector refrigeration system for the cold chain," 4th IIR Conference on Sustainability and the Cold Chain, Auckland, New Zealand, April 7-9.
  • Zhu, J. and S. Elbel, 2015, "Fresh look at vortex tubes and their potential use as expansion device in automotive vapor compression systems," SAE 2015 Thermal Management Systems Symposium, Troy, MI, USA, September 29 - October 1.
  • Padilla Fuentes, Y., P. Hrnjak, and S. Elbel, 2015, "High-efficiency, low-cost glass door merchandisers using transcritical carbon dioxide," 24th IIR International Congress of Refrigeration, Yokohama, Japan, August 16-22, Paper 305.
  • Padilla Fuentes, Y., P. Hrnjak, and S. Elbel, 2015, "Low-charge propane refrigeration system technology for single and multi-door bottle coolers," 24th IIR International Congress of Refrigeration, Yokohama, Japan, August 16-22, Paper 303.
  • Zhu, J. and S. Elbel, 2015, "Vortex tube heat booster to improve performance of heat driven cooling cycles," 24th IIR International Congress of Refrigeration, Yokohama, Japan, August 16-22, Paper 299.
  • Elbel, S., S. Wujek, and P. Hrnjak, 2015, "Waste heat driven cooling by vapor jet ejector," 24th IIR International Congress of Refrigeration, Yokohama, Japan, August 16-22, Paper 297.
  • Lawrence, N. and S. Elbel, 2015, "Study on the use of ejectors for capacity modulation and performance improvement in CO2 commercial refrigeration systems," 24th IIR International Congress of Refrigeration, Yokohama, Japan, August 16-22, Paper 195.
  • Lawrence, N. and S. Elbel, 2015, "Experimental investigation of two-phase ejector liquid recirculation cycles with R410A," 24th IIR International Congress of Refrigeration, Yokohama, Japan, August 16-22, Paper 194.
  • Lawrence, N. and S. Elbel, 2015, "Numerical investigation of evaporator design in the ejector refrigeration cycle with R134a and CO2," 24th IIR International Congress of Refrigeration, Yokohama, Japan, August 16-22, Paper 193.
  • Lawrence, N. and S. Elbel, 2015, "Numerical investigation of the effect of microchannel evaporator design on the performance of two-phase ejector automotive air conditioning cycles," SAE World Congress, Detroit, MI, USA, April 21-23, Paper 2015-01-0362.
  • Zhao H., S. Elbel, and P. Hrnjak, 2015, "An investigation on thermal integrity of brazed heat transfer devices," Proceedings of the 6th International Brazing and Soldering Conference (IBSC), Long Beach, CA, April 19-22.
  • Zhao, H., S. Elbel, and P. Hrnjak, 2015, "Low temperature controlled atmosphere brazing of aluminum matrix composite," Proceedings of the 6th International Brazing and Soldering Conference (IBSC), Long Beach, CA, April 19-22.
  • Padilla Fuentes, Y., S. Elbel, and P. Hrnjak, 2014, "Extremely low refrigerant charge beverage display cooler technology using propane," 11th IIR Gustav Lorentzen Conference on Natural Refrigerants, Hangzhou, China, August 31 - September 2, Paper 98.
  • Lawrence, N. and S. Elbel, 2014, "Review and analysis of the effect of ejector geometry on the performance of two-phase CO2 ejectors," 11th IIR Gustav Lorentzen Conference on Natural Refrigerants, Hangzhou, China, August 31 - September 2, Paper 53.
  • Lawrence, N. and S. Elbel, 2014, "Numerical investigation of two-phase ejector liquid recirculation cycles with natural refrigerants," 11th IIR Gustav Lorentzen Conference on Natural Refrigerants, Hangzhou, China, August 31 - September 2, Paper 52.
  • Elbel, S., Y. Padilla Fuentes, C. Bowers, and P. Hrnjak, 2014, "Successful conversion and validation of glass door merchandisers using transcritical R744," 11th IIR Gustav Lorentzen Conference on Natural Refrigerants, Hangzhou, China, August 31 - September 2, Paper 44.
  • Zhu, J., M. Mohiuddin, and S. Elbel, 2014, "Vortex tubes used as expansion device in vapor compression systems, 11th IIR Gustav Lorentzen Conference on Natural Refrigerants," Hangzhou, China, August 31 - September 2, Paper 43.
  • Lawrence, N.and S. Elbel, 2014, "Experimental and numerical study on the performance of R410A liquid recirculation cycles with and without ejectors," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2187.
  • Lawrence, N. and S. Elbel, 2014, "Analysis and comparison of two-phase ejector performance metrics for R134a and CO2 ejectors," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2188.
  • Elbel, S., Y. Padilla Fuentes, C. Bowers, and P. Hrnjak, 2014, "Successful design, implementation, and validation of transcritical R744 technology for beverage display coolers," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2192.
  • Mohiuddin, M. and S. Elbel, 2014, "A fresh look at vortex tubes used as expansion device in vapor compression systems," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2193.
  • Bowers, C.D., D. Wrocklage, S. Elbel, and P. Hrnjak, 2014, "Improvements in refrigerant flow distribution using an expansion valve with integrated distributor," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2369.
  • Bowers, C.D., G. Baker, S. Elbel, and P. Hrnjak, 2014, "Accelerated thermal cycling test for heat exchangers used in reversible heat pump," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2363.
  • Padilla, F. Y., S. Elbel, and P. Hrnjak, 2014, "Extremely low refrigerant charge beverage display cooler technology using propane," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2458.
  • Zhao, H., S. Elbel, and P. Hrnjak, 2014, "Influence of surface morphology on wetting behaviors of liquid metal during aluminum heat exchanger fabrication," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2461.
  • Benanti, T.L., E.T. Hessell, R.A. Urrego, S.S. Wujek, C.D. Bowers, and S. Elbel, 2014, "Effects of refrigerant-lubricant combinations on the energy efficiency of a convertible split-system residential air-conditioner," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2499.
  • Wujek, S.S., M.J. McCready, G. Mozurkewich, W.F. Schneider, and S. Elbel, 2014, "Experimental and modeling improvements to a co-fluid cycle utilizing ionic liquids and carbon dioxide," 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2501.
  • Zhao, H., S. Elbel, and P. Hrnjak, 2014, "Wetting behaviors of Al based filler metals on aluminum matrix composites," International Conference on Brazing, Soldering and Special Joining Technologies, Beijing, China, June 9-13.
  • Bowers, C., D. Wrocklage, S. Elbel, and P. Hrnjak, 2014, "Evaluation of seasonal performance improvements in a 3-ton residential heat pump system using a novel design of integrated electronic expansion valves and distributors," poster presentation at the 11th IEA Heat Pump Conference, Montreal, Canada, May 12-16.
  • Lawrence, N. and S. Elbel, 2014, "Comparison of CO2 and R134a Two-Phase Ejector Performance for Use in Automotive Air Conditioning Applications," SAE World Congress, Detroit, MI, USA, April 8-10, Paper 2014-01-0689.
  • Bowers, C., M. Petersen, S. Elbel, and P.S. Hrnjak, 2014, "Nueva generaci￿e calentadores de agua comerciales por bomba de calor utilizando di￿o de carbono y diferentes enfoques de mejora," Spanish translation of Bowers C., Petersen M., Elbel S., Hrnjak P., 2012, Next generation commercial heat pump water heater using carbon dioxide using different improvement approaches, 10th IIR Gustav Lorentzen Conference on Natural Working Fluids, Delft, The Netherlands, June 25-27, Paper 181, published in February 2014 issue of Frio-Calor-Aire Acondicionado.
  • Bowers, C., D. Wrocklage, S. Elbel, and P. Hrnjak, 2014, "Evaluation of seasonal performance improvements in a 3-ton residential heat pump system using a novel design of integrated electronic expansion valves and distributors," Presentation at ASHRAE 2014 Winter Conference, New York, NY, USA, January 18-24.
  • Elbel, S., 2013, "Successful Design and Implementation of Transcritical CO2 Technology for Beverage Display Coolers," Presentation at ASHRAE 2013 Annual Conference, Denver, CO, June 23-26
  • Lawrence, N., and S. Elbel, 2013, "Experimental and analytical investigation of two-phase ejector air-conditioning cycles using low-pressure refrigerants R134a and R1234yf, SAE World Congress," Detroit, MI, USA, April 16-18, Paper 2013-01-1495
  • Bowers, C.D., S. Elbel, M. Petersen, and P.S. Hrnjak, 2013, "Mejoras en el rendimiento de los calentadores de agua comerciales de bomba de calor, que utilizan di￿o de carb￿ Spanish translation of Bowers, C.D., S. Elbel, M. Petersen, and P.S. Hrnjak, 2011, "Performance improvements in commercial heat pump water heaters using carbon dioxide," 23rd IIR International Congress of Refrigeration, Prague, Czech Republic, August 21-26, Paper 211, published in February 2013 issue of Frio-Calor-Aire Acondicionado
  • Elbel, S. and N. Lawrence, 2012, "Investigation of automotive ejector air-conditioning cycles," Presentation at SAE 2012 Thermal Management Systems Symposium, Scottsdale, AZ, October 31 - November 1
  • Brown, I.P., M.W. Critchley, J. Yin, S.B. Memory, S.W. Elbel, C.D. Bowers, M. Petersen, P.S. Hrnjak, and G.Y. Sizov, 2012, "Design and evaluation of interior permanent magnet compressor motors for commercial transcritical CO2 (R-744) heat pump water heaters," 2012 IEEE Energy Conversion Congress and Exposition (ECCE), Raleigh, NC, USA, September 15-20, pp. 2790-2797
  • Zhao, H., S. Elbel, and P. Hrnjak, 2012, "Capillary flow of liquid metal occurring in micro-channel heat exchanger fabrication," 14th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 16-19, Paper 2498
  • Bowers, C.D., H. Mai, S. Elbel, and P. Hrnjak, 2012, "Refrigerant distribution effects on the performance of microchannel evaporators," 14th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 16-19, Paper 2173
  • Petersen, M., C.D. Bowers, S. Elbel, and P. Hrnjak, 2012, "Development of high efficiency carbon dioxide commercial heat pump water heater," 14th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 16-19, Paper 2168
  • Elbel, S., C.D. Bowers, M. Reichle, J.M. Cristiani, and P. Hrnjak, 2012, "Vapor jet ejector used to generate free waste heat driven cooling in military environmental cooling units," 14th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 16-19, Paper 2164
  • Elbel, S., C. Bowers, H. Zhao, S. Park, P. Hrnjak, 2012, "Development of microclimate cooling systems for increased thermal comfort of individuals," 14th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 16-19, Paper 2149
  • Lawrence, N. and S. Elbel, 2012, "Experimental and analytical investigation of automotive ejector air-conditioning cycles using low-pressure refrigerants," 14th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 16-19, Paper 2118
  • Bowers, C., M. Petersen, S. Elbel, and P. Hrnjak, 2012, "Next generation commercial heat pump water heater using carbon dioxide using different improvement approaches," 10th IIR Gustav Lorentzen Conference on Natural Working Fluids, Delft, The Netherlands, June 25-27, Paper 181
  • Elbel, S., M. Reichle, C. Bowers, and P. Hrnjak, 2012, "Integration of a two-phase ejector into a compact, lightweight unitary-type air-conditioner using R744 for energy efficient operation in hot climates," 10th IIR Gustav Lorentzen Conference on Natural Working Fluids, Delft, The Netherlands, June 25-27, Paper 180
  • Bowers, C., S. Elbel, and M. Reichle, 2012, "Research, development, and demonstration of co-generation ejector and modified organic Rankine cycle environmental control systems," Interagency Advanced Power Group, Mechanical Working Group Meeting, Arlington, VA, USA, May 1-3
  • Zhao, H., S. Elbel, P. Hrnjak, 2012, "Controlled atmosphere brazing of microchannel heat exchangers for mini-cooling systems," Proceedings of the 5th International Brazing and Soldering Conference (IBSC), Las Vegas, NV, April 22-25, pp. 183-187
  • Wang, X.F., P.S. Hrnjak, S. Elbel, A.M. Jacobi, and M.G. He, 2011, "Heat transfer performance for a falling-film on horizontal flat tubes," ASME 2011 International Mechanical Engineering Congress and Exposition (IMECE), Denver, CO, USA, November 11-17, v 10, Parts A and B, pp. 43-50
  • Elbel, S., C.D. Bowers, H. Zhao, S. Park, P. Hrnjak, 2011, "Development and analysis of miniature vapor compression cooling technology," 23rd IIR International Congress of Refrigeration, Prague, Czech Republic, August 21-26, Paper 244
  • Bowers, C.D., S. Elbel, M. Petersen, and P.S. Hrnjak, 2011, "Performance improvements in commercial heat pump water heaters using carbon dioxide," 23rd IIR International Congress of Refrigeration, Prague, Czech Republic, August 21-26, Paper 211
  • Elbel, S., J.A. Manzione, S.J. Collier, and P. Hrnjak, 2011, "Acondicionador de aire del tipo unidad compacta ligera utilizando R744 transcr￿co y dise￿ para funcionar con eficiencia energ￿ca en climas calurosos," Spanish translation of Elbel S., J.A. Manzione, S.J. Collier, and P. Hrnjak, 2010, "Compact, lightweight unitary-type air-conditioner using transcritical R744 designed for energy efficient operation in hot climates," 9th IIR Gustav Lorentzen Conference on Natural Working Fluids, Sydney, Australia, April 12-14, Paper 1, published in February 2011 issue of Frio-Calor-Aire Acondicionado
  • Zhao, H., S. Elbel, and P. Hrnjak, 2010, "Development of novel compact heat exchanger using aluminum brazing technology," AWS 37th International Brazing and Soldering Symposium, Atlanta, GA, November 3.
  • Zhao, H., S. Elbel, and P. Hrnjak, 2010, "The potential of open cell aluminum foams as fin structures for CAB brazed heat exchangers," AFC-Holcroft￿s 14th Annual Aluminum Brazing Invitational Seminar, Novi, MI, USA, October 27-29
  • Wang, X., P.S. Hrnjak, S. Elbel, A.M. Jacobi, and M. He, 2010, "Flow patterns and mode transitions for falling-film on flat tubes," 13th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 12-15, Paper 2461
  • Elbel, S. and P. Hrnjak, 2010, "Design, build-up, and performance investigation of a 35 kW (10 Ton) military environmental control unit using transcritical R744 technology," 13th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 12-15, Paper 2205
  • Zhao, H., S. Elbel, P. Hrnjak, 2010, "Transport phenomena involved in controlled atmosphere brazing of microchannel Al heat exchanger," 13th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 12-15, Paper 2046
  • Elbel S., J.A. Manzione, S.J. Collier, and P. Hrnjak, 2010, "Compact, lightweight unitary-type air-conditioner using transcritical R744 designed for energy efficient operation in hot climates," 9th IIR Gustav Lorentzen Conference on Natural Working Fluids, Sydney, Australia, April 12-14, Paper 1
  • Elbel, S. and P. Hrnjak, 2009, "Refrigeraci￿on eyector en aplicaciones de aire acondicionado visi￿eneral de la evoluci￿esarrollos hist￿os y actuales," Spanish translation of Elbel, S. and P. Hrnjak, 2008, "Ejector refrigeration: an overview of historical and present developments with an emphasis on air conditioning applications," 12th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2350, published in July/August 2009 issue of Frio-Calor-Aire Acondicionado
  • Elbel, S., 2008, "Next generation ECU," Presentation given at the c-dig Meeting at CETIAT/CETHIL, Lyon, France, November 3-4
  • Elbel, S. and P. Hrnjak, 2008, "Ejector refrigeration: an overview of historical and present developments with an emphasis on air conditioning applications," 12th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 14-17, Paper 2350
  • Elbel, S. and P. Hrnjak, 2007, "Experimental investigation of transcritical CO2 ejector system performance," 22nd IIR International Congress of Refrigeration, Beijing, China, August 21-26, Paper ICR07-E1-72
  • Elbel, S. and P. Hrnjak P., 2007, "Experimental validation of a prototype ejector with integrated high-side pressure control designed to reduce throttling losses encountered in transcritical CO2 system operation," Presentation given at the VDA Alternative Refrigerant Winter Meeting at Saalfelden, Austria, February 14-15, www.vda-wintermeeting.de
  • Elbel, S. and P. Hrnjak, 2006, "A thermodynamic property chart as a visual aid to illustrate the interference between expansion work recovery and internal heat exchange," 11th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 17-20, Paper R165
  • Elbel, S. and P. Hrnjak, 2006, "Experimental validation and design study of a transcritical CO2 prototype ejector system," 7th IIR Gustav Lorentzen Conference on Natural Working Fluids, Trondheim, Norway, May 28-31, Paper 149
  • Elbel, S. and P. Hrnjak, 2006, Experiments and modeling of ejector systems, Presentation given at the c-dig Meeting at Purdue University, West Lafayette, IN, USA, March 16-17
  • Elbel, S. and P. Hrnjak, 2006, "Development of a prototype refrigerant ejector used as expansion device in a transcritical CO2 system," Presentation given at the VDA Alternative Refrigerant Winter Meeting at Saalfelden, Austria, February 15-16, www.vda-wintermeeting.de
  • Memory S., J. Yin, S. Collier, M. Gunter, P. Hrnjak, S. Peuker, S. Elbel, J. Manzione, N. Schultz, and J. Dolney, 2005, "Using R744 (CO2) to cool an up-armored M1114 HMMWV," Vehicle Thermal Management Systems Conference and Exhibition (VTMS7) at Toronto, Canada, May 10-12, Paper 2005-01-2024
  • Elbel S., and P. Hrnjak, 2004, "Flash gas bypass in transcritical R744 systems using microchannel evaporators," Presentation given at the c-dig Meeting at the University of Illinois at Urbana-Champaign, Urbana, IL, USA, October 7-8
  • Elbel S.W. and P.S. Hrnjak, 2004, "Effect of internal heat exchanger on performance of transcritical CO2 systems with ejector," 10th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, July 12-15, Paper R166

Invited Lectures

  • Improvement of cooling capacity and COP through the use of two-phase ejectors in transcritical CO2 automotive air-conditioning systems (in German)
  • Technology developments in air-conditioning and refrigeration
  • Emerging component and system technologies for HVAC&R
  • Recent technology developments in HVAC & refrigeration
  • Electrically driven automotive air-conditioning systems: potentials, challenges and major differences in comparison to conventional technology (in German)
  • The next decade: a US perspective of expected technology trends in air-conditioning and refrigeration
  • Historical and present developments of ejector refrigeration systems with emphasis on transcritical carbon dioxide air-conditioning applications

Professional Societies

  • American Society of Mechanical Engineers (ASME)
  • International Institute of Refrigeration (IIR)
  • American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)
  • Society of Automotive Engineers (SAE)

Teaching Honors

  • List of Teachers Ranked as Excellent, University of Illinois at Urbana-Champaign (Fall 2015)
  • List of Teachers Ranked as Excellent, University of Illinois at Urbana-Champaign (Fall 2014)
  • List of Teachers Ranked as Excellent, University of Illinois at Urbana-Champaign (Spring 2012)

Research Honors

  • Eurammon Natural Refrigeration Award (2009)
  • IIR Willis H. Carrier Young Researcher's Award (2007)
  • IIR Gustav Lorentzen Conference Best Paper Award (2006)
  • US Army Award for Environmental Excellence (2005)

Public Service Honors

  • Recognition Award from the Society of Automotive Engineers (2005)

Other Honors

  • Dr.-Ing. H.C.F. Porsche AG Award of Excellence (2000)
  • Award of Excellence from Verein der F￿rer der Fachhochschule Esslingen (2000)
  • Behr GmbH & Co Award of Excellence (2000)