Faculty Profile

Pega Hrnjak

Mechanical Science and Engineering
 Pega Hrnjak
Pega Hrnjak
Research Professor, Director Air Conditioning and Refrigeration Center
2121 Mechanical Engineering Lab
105 S. Mathews
Urbana Illinois 61801
(217) 244-6377

Other Professional Employment

  • Creative Thermal Solutions. Inc., President 2004-date

Selected Articles in Journals

  • Pottker, G. and P. Hrnjak, 2015, "Experimental investigation of the effect of condenser subcooling in R134a and R1234yf air-conditioning systems with and without internal heat exchanger," International Journal of Refrigeration 50, pp. 104.
  • Jin, S. and P. Hrnjak, 2014, "An Experimentally Validated Model for Predicting Refrigerant and Lubricant Inventory in MAC Heat Exchangers," SAE International Journal of Passenger Cars - Mechanical Systems 7 (2), pp. 769.
  • Zou, Y. and P.S. Hrnjak, 2014, "Single-phase and two-phase flow pressure drop in the vertical header of microchannel heat exchanger," International Journal of Refrigeration 44 , pp. 12.
  • Zou, Y., H. Tuo, and P.S. Hrnjak, 2014, "R-410A maldistribution impact on the performance of MicroChannel evaporator," ASHRAE Transactions 120 (PART 1) , pp. 406.
  • Tuo, H. and P. Hrnjak, 2014, "Effect of venting the periodic reverse vapor flow on the performance of a microchannel evaporator in air-conditioning systems," International Journal of Heat and Mass Transfer 69 , pp. 66.
  • Zou, Y. and P.S. Hrnjak, 2014, "Modeling refrigerant maldistribution in microchannel heat exchangers with vertical headers based on experimentally developed distribution results," Applied Thermal Engineering 64 (1-2) , pp. 172.
  • Zou, Y. and P.S. Hrnjak, 2014, "Effect of oil on R134a distribution in the microchannel heat exchanger with vertical header," International Journal of Refrigeration 40 , pp. 201.
  • Tuo, H. and P. Hrnjak, 2014, "Vapor-liquid separation in a vertical impact T-junction for vapor compression systems with flash gas bypass," International Journal of Refrigeration 40 , pp. 189.
  • Tuo, H. and P. Hrnjak, 2014, "Visualization and measurement of periodic reverse flow and boiling fluctuations in a microchannel evaporator of an air-conditioning system," International Journal of Heat and Mass Transfer 71 , pp. 639.
  • Ren, T. and P. Hrnjak, 2014, "Pressure drop in D shaped cylindrical headers of parallel flow MCHXs: Pressure loss coefficients for single phase flow," Applied Thermal Engineering 65 (1-2), pp. 111.
  • Sethi, A. and Hrnjak, P., 2014, "Oil retention and pressure drop of R1234yf and R134a with POE ISO 32 in suction lines," HVAC and R Research 20 (6) , pp. 703.
  • Zou, Y. and Hrnjak, P.S., 2014, "Effects of fluid properties on two-phase flow and refrigerant distribution in the vertical header of a reversible microchannel heat exchanger - Comparing R245fa, R134a, R410A, and R32," Applied Thermal Engineering 70 (1) , pp. 966.
  • Agarwal R. and P. Hrnjak, 2014, "Effect of sensible heat, condensation in superheated and subcooled region incorporated in unified model for heat rejection in condensers in horizontal round smooth tubes", Applied Thermal Engineering 71 (1) , pp. 378.
  • Tuo, H. and P. Hrnjak, 2013, "Enhancement of vapor-liquid separation in vertical impact T-junctions for vapor compression systems with flash gas bypass," International Journal of Refrigeration 40 , pp. 43.
  • Zou, Y. and P.S. Hrnjak, 2013, "Refrigerant distribution in the vertical header of the microchannel heat exchanger - measurement and visualization of R410A flow," International Journal of Refrigeration 36 (2013), pp. 2196-2208.
  • Zhao, H., S. Elbel, and P. Hrnjak, 2013, "Controlled atmosphere brazing of aluminum heat exchangers," Welding Journal 92 (2), pp. 44-46.
  • Zou, Y. and P.S. Hrnjak, 2013, "Experiment and visualization on R134a upward flow in the vertical header of microchannel heat exchanger and its effect on distribution," International Journal of Heat and Mass Transfer 62 (1) , pp. 124-134.
  • Tuo, H. and P. Hrnjak, 2013, "New approach to improve performance by venting periodic reverse vapor flow in microchannel evaporator," International Journal of Refrigeration 36 (2013), pp. 2187-2195.
  • Tuo, H. and P. Hrnjak, 2013 "Effect of the header pressure drop induced flow maldistribution on the microchannel evaporator performance," International Journal of Refrigeration 36 (2013), pp. 2176-2186 .
  • Petersen, M., C. Bowers, S. Elbel, and P. Hrnjak, 2013, "Development of high-efficiency carbon dioxide commercial heat pump water heater," HVAC and R Research 19 (7), pp. 823-835.
  • Tuo, H. and P. Hrnjak, 2013, "Periodic reverse flow and boiling fluctuations in a microchannel evaporator of an air-conditioning system - Visualization and quantification," International Journal of Refrigeration 36 (4) , pp. 1263-1275.
  • Tuo, H. and P. Hrnjak, 2013, "Effect of venting the periodic reverse vapor flow on the performance of a microchannel evaporator in air-conditioning systems," International Journal of Heat and Mass Transfer 69 , pp. 66-76.
  • Tuo, H. and P. Hrnjak, 2013, "Periodic Reverse Flow and Boiling Fluctuations in a Microchannel Evaporator of an R134a Mobile Air-Conditioning System," SAE International Journal of Materials and Manufacturing 6 (3).
  • Li, H. and P. Hrnjak, 2013, "Effect of lubricant on two-phase refrigerant distribution in microchannel evaporator," SAE International Journal of Materials and Manufacturing 6 (3).
  • Kondou, C. and P. Hrnjak, 2013, "Heat rejection in condensers close to critical point-de-superheating, condensation in superheated region, and condensation of two-phase fluid," Heat Transfer Engineering, 34 ( 14 ) pp. 1180 - 1190, 2013.
  • Jin, S. and P. Hrnjak, 2013, "Refrigerant and lubricant distribution in MAC system," SAE International Journal of Passenger Cars - Mechanical Systems, 6 (2).
  • Wang, X.F., P.S. Hrnjak, S. Elbel, A.M. Jacobi, and M.G. He, "Heat transfer performance for a falling-film on horizontal flat tubes, Journal of Heat Transfer," 135 (7), art. no. 072901, 2013.
  • Zou, Y. and P.S. Hrnjak, 2013, "Experiment and visualization on R134a upward flow in the vertical header of microchannel heat exchanger and its effect on distribution," International Journal of Heat and Mass Transfer. 62 (1) pp. 124 - 134
  • Tuo, H. and P.S. Hrnjak, 2013, "New approach to improve performance by venting periodic reverse vapor flow in MC evaporator," 2013 IJR, in print.
  • Tuo, H. and P.S. Hrnjak, 2013, "Periodical reverse flow and boiling fluctuations in a microchannel evaporator of an air-conditioning system," International Journal of Refrigeration, Volume 36, Issue 4, June, Pages 1263-1275.
  • Tuo, H., Hrnjak, P. 2013, "Flash gas bypass in mobile air conditioning system with R134a," (2012) International Journal of Refrigeration, 35 (7), pp. 1869-1877.
  • Tuo, H. and P. Hrnjak, 2012, "Experimental Study of Refrigerant Two Phase Separation in a Compact Vertical T-Junction,"￿ ASHRAE Transactions, 118:1.
  • 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," Journal of Heat Transfer, 2012, 134 (2), art. no. 021801.
  • Tuo, H., A. Bielskus, and P. Hrnjak, 2012, "An Experimentally Validated Model of Refrigerant Distribution in a Parallel Microchannel Evaporator," ASHRAE Transactions, 118:1.
  • Tuo, H., A. Bielskus, and P. Hrnjak, 2012, ￿Experimentally Validated Model of Refrigerant Distribution in a Parallel Microchannel Evaporator,￿ SAE International Journal of Materials and Manufacturing, 5(2), pp.365-374.
  • Tuo, H. and P. Hrnjak, 2012, ￿Flash Gas Bypass in Mobile Air Conditioning System with R134a,￿ International Journal of Refrigeration, in Press.
  • Kondou, C. and P. Hrnjak, "Condensation From Superheated Vapor Flow of R744 And R410A At Subcritical Pressures in a Horizontal Smooth Tube," International Journal of Heat and Mass Transfer, 55:11-12, 2779-2791, 2012.
  • Li, B., S. Peuker, P.S. Hrnjak, and A.G. Alleyne, 2011, "Refrigerant mass migration modeling and simulation for air conditioning systems," Applied Thermal Engineering, 31 (10), pp. 1770-1779.
  • Tuo, H., A. Bielskus, and P. Hrnjak, ￿Effect of Flash Gas Bypass on the Performance of R134a Mobile Air-Conditioning System with Microchannel Evaporator,￿ SAE International Journal of Materials and Manufacturing, 4(1), pp. 231-239, 2011.
  • Li, B., S. Peuker, P. Hrnjak, and A. Alleyne, ￿Evaluation of Transient Refrigerant Migration Modeling Approach on Automotive Air Conditioning Systems,￿ SAE International Journal of Materials and Manufacturing, 4(1), pp. 864-874, 2011.
  • Oh, J.-T., A.S. Pamitran, K.-I. Choi, P. Hrnjak, ￿Experimental Investigation on Two-Phase Flow Boiling Heat Transfer of Five Refrigerants in Horizontal Small Tubes Of 0.5, 1.5 and 3.0 Mm Inner Diameters,￿ International Journal of Heat and Mass Transfer, 54 (9-10), pp. 2080-2088, 2011.
  • Kondou, C. and P. Hrnjak, ￿Heat Rejection from R744 Flow Under Uniform Temperature Cooling in a Horizontal Smooth Tube Around the Critical Point,￿ International Journal of Refrigeration, 34 (3), pp. 719-731, 2011.
  • Li, B., S. Peuker, P. S. Hrnjak, and A. G. Alleyne, "Refrigerant Mass Migration Modeling and Simulation for Air Conditioning Systems," Applied Thermal Engineering, 31 (10), 1770-1779, 2011.
  • Park, C.Y and P.S. Hrnjak, ￿Pure NH3 and CO2 Heat Transfer and Pressure Drop in Horizontal Smooth Tubes for NH3 Two-Stage And NH3/CO2 Cascade Refrigeration Systems: A Review,￿ International Journal of Air-Conditioning and Refrigeration, 18 (2), pp. 85-100, 2010.
  • Hrnjak, P.S., "Issues in Two Phase Flow Distribution in Microchannel Heat Exchangers, KGH - Air conditioning, Heating and Refrigeration," (in Serbian: Problematika raspodele dvofaznih tokova u mikrokanalnim razmenjivac￿ima toplote) vol. 39, No. 1, pp. 63-74, 2010.
  • Zhang, P. and P.S. Hrnjak, ￿Effect of Some Geometric Parameters on Performance of PF2 Heat Exchangers in Periodic Frosting,￿ International Journal of Refrigeration 33 (2), pp. 334-346, 2010.
  • Hrnjak, P.S. and S. H. Hong, ￿Effect of Return Bend and Entrance on Heat Transfer in Thermally Developing Laminar Flow in Round Pipes of Some Heat Transfer Fluids with High Prandtl Numbers,￿ Journal of Heat Transfer 132 (6), pp. 1-12, 2010.
  • Zhang, P. and P.S. Hrnjak, "Air-side Performance of a Parallel-flow Parallel-fin (PF2) Heat Exchanger in Sequential Frosting," International Journal of Refrigeration 33 (6), pp. 1118-1128, 2010.
  • Pamitran, A. S.,K.-I. Choi, J.-T. Oh, and P. Hrnjak, "Characteristics of Two-phase Flow Pattern Transitions and Pressure Drop of Five Refrigerants in Horizontal Circular Small Tubes," International Journal of Refrigeration, 33:3, 578-588, May 2010.
  • Park, C.Y. and P.S. Hrnjak, "Flow Condensation Heat Transfer and Pressure Drop in Multi-Port Microchannels at Low Temperatures," International Journal of Refrigeration 32 (6), pp. 1129-1139, 2009.
  • Pamitran, A. S., K.-I. Choi, J.-T. Oh, and P. Hrnjak, "Experimental Investigation of Flow Boiling Heat Transfer of R-410A and R-134a in Horizontal Small Tubes," Korean Journal of Air-Conditioning and Refrigeration Engineering V. 21 N. 12 , pp. 1141~1146, 2009.6.
  • Choi, K.-I., A. S. Pamitran, J.-T. Oh, P. Hrnjak, and C. Y. Park, "Effect on Flow Boiling Heat Transfer of Minichannel Diameter for R-410A," 설비공학논문집 제21권 제12호, 12,663-670, 2009.
  • Peuker, S. and P.S. Hrnjak, ￿Transient Refrigerant Migration and Oil Distribution of an R134a Automotive A/C System,￿ SAE International Journal of Passenger Cars - Mechanical Systems 2 (1), pp. 714-724, 2009.
  • Wujek, S.S. and P.S. Hrnjak, ￿Using Density to Calculate the Oil Circulation Ratio of a PAG Oil in R134A,￿ SAE International Journal of Materials and Manufacturing 1 (1), pp. 362-368, 2009.
  • Hrnjak, P. S., J. Manzione, D. Adams, D. Garski, and S. Collier, ￿EXITOSA CONVERSI￿ A R744 EN UNA UNIDAD DE CONTROL MEDIOAMBIENTAL," Frio-Calor-Aire Acondicionado, September 2009, (Based on #125 conference publication)
  • Elbel, S. and P. S. Hrnjak ￿REFRIGERACI￿ CON EYECTOR EN APLICACIONES DE AIRE ACONDICIONADO VISI￿ GENERAL DE LA EVOLUCI￿ DE DESARROLLOS,￿ Frio-Calor-Aire Acondicionado, Jul/August 2009 (based on #123 conference publication)
  • Park, C.Y., and P.S. Hrnjak, ￿CONDENSACI￿, TRANSMISI￿ DE CALOR Y CA￿A DE PRESI￿ DEL NH3 EN EL INTERIOR DE UN TUBO LISO, Frio-Calor-Aire Acondicionado, January 2009 (Based on #40)
  • Park, C. Y. and P. S. Hrnjak, ￿Flow Boiling Heat Transfer, Pressure Drop, and Flow Pattern for CO2 in a 3.5 mm Horizontal Smooth Tube,￿ Journal of Heat Transfer, 131, 091501-1, 2009.
  • Zhang, P. and P. S. Hrnjak, ￿Air-side Performance Evaluation of Three Types of Heat Exchangers in Dry, Wet and Periodic Frosting Conditions,￿ International Journal of Refrigeration, 32:5, 911-921, 2009.
  • Kim, Y. J., J. Jang, P. S. Hrnjak, and M. S. Kim, ￿Condensation Heat Transfer of Carbon Dioxide Inside Horizontal and Vertical Pressure Smooth and Microfin Tubes at Low Temperatures,￿ Journal of Heat Transfer, 131:2, 2009.
  • Kim, Y. J. , J. Jang, P. S. Hrnjak, and M. S. Kim, ￿Adiabatic Horizontal and Vertical Pressure Drop of Carbon Dioxide Inside Smooth and Microfin Tubes at Low Temperatures,￿ Journal of Heat Transfer, 130:11, 111001-1-111001-10, November 2008.
  • Park, C. Y. and P. S. Hrnjak, ￿Experimental and Numerical Study on Microchannel and Round-Tube Condensers in a R410A Residential Air-Conditioning System,￿ International Journal of Refrigeration, 31:5, 822-831, 2008.
  • Park, C.Y. and P. S. Hrnjak, ￿NH3 In-Tube Condensation Heat Transfer and Pressure Drop in a Smooth Tube,￿ International Journal of Refrigeration, 31:4, 643-651, June 2008.
  • Hrnjak, P.S. and A. D. Litch, ￿Microchannel Heat Exchangers for Charge Minimization in Air-Cooled Ammonia Condensers and Chillers,￿ International Journal of Refrigeration, 31:4, 658-668, 2008.
  • Elbel, S. W. and P. S. Hrnjak, ￿Experimental Validation of a Prototype Ejector Designed to Reduce Throttling Losses Encountered in Transcritical R744 System Operation,￿ International Journal of Refrigeration, 31:3, 411-422, 2008.
  • Hrnjak, P. S. and X. Tu, ￿Single Phase Pressure Drop in Microchannels,￿ International Journal of Heat and Fluid Flow, 28:1, 2-14, 2007.
  • Park, C.Y. and P. S. Hrnjak, ￿CO2 and R410A Flow Boiling Heat Transfer, Pressure Drop, and Flow Pattern at Low Temperatures in a Horizontal Smooth Tube,￿ International Journal of Refrigeration, 30:1, 166-178, 2007.
  • Hrnjak, P. S. and X. Tu, ￿Single Phase Pressure Drop in Microchannels,￿ International Journal of Heat and Fluid Flow, 28:1, 2-14, Feb 2007.
  • Park, C.Y. and P. S. Hrnjak, ￿Effect of Heat Conduction Through the Fins of a Microchannel Serpentine Gas Cooler of Transcritical CO2 System,￿ International Journal of Refrigeration, 389-397, 2007.
  • Park, C.Y. and P. S. Hrnjak, ￿CO2 and R410A Flow Boiling Heat Transfer, Pressure Drop, and Flow Pattern at Low Temperatures in a Horizontal Smooth Tube,￿ International Journal of Refrigeration, 166-178, 2007.
  • Field, B. S. and P. S. Hrnjak, "Adiabatic Two-Phase Pressure Drop of Refrigerants in Small Channels," Heat Transfer Engineering, 28:8, 1-11, 2007.
  • Hrnjak, P. S. ￿Carbon Dioxide Systems￿ HVAC&R Research 12:1, 1-2 Jan 2006.
  • Xia, Y, Y. Zhong, P. S. Hrnjak, and A. M. Jacobi, ￿Frost, Defrost, and Refrost and Its Impact on the Air-Side Thermal-Hydraulic Performance of Louvered-Fin, Flat Tube Heat Exchangers,￿ International Journal of Refrigeration, 29:7, 1066-179, 2006.
  • Ni￿V. G., E. W. Jassim, P. S. Hrnjak, and T. A. Newell, ￿Flow-Regime-Based Model for Pressure Drop Predictions in Microchannels,￿ International Journal of HVAC&R Research, 12:1, 17-34, 2006.
  • Tu, X., P. S. Hrnjak, and C. W. Bullard, ￿Refrigerant 134a Liquid Flow Through Micro-Scale Short Tube Orifices with/with Phase Change,￿ Experimental Thermal and Fluid Science, 30:3, 253-262, 2006.
  • McEnaney, R. and P. S. Hrnjak, ￿Clutch Cycling Mode of Compressor Capacity Control of Transcritical R744 systems compared to R134a systems,￿ Society of Automotive Engineering Journal of Passenger Cars ￿ Mechanical Systems,￿ 2005-01-2033.
  • Park, C. Y. and P Hrnjak, ￿Flow Boiling Heat Transfer of CO2 at Low Temperatures in a Horizontal Smooth Tube,￿ ASME Journal of Heat Transfer, 127:12, 1305-1312, 2005.
  • Xia, Y, P. S. Hrnjak, and A. M. Jacobi, ￿The Air-Side Thermal-Hydraulic Performance of Louvered-Fin, Flat-Tube Heat Exchangers with Sequential Frost-Growth Cycles,￿ ASHRAE Transactions, 111:1, 487-495, 2005.
  • Richter, M. R., S. M. Song, J. M. Yin, M. H. Kim, C. W. Bullard, and P. S. Hrnjak, ￿Experimental Results of Transcritical CO2 Heat Pump for Residential Application,￿ Energy, 28:10, 1005-1019, 2005.
  • Elbel, S. and P. S. Hrnjak ￿Flash Gas Bypass for Improving the Performance of Transcritical R744 Systems that Use Microchannel Evaporators,￿ International Journal of Refrigeration, 27:7, 724-735, 2004.
  • ￿Microchannel Heat Exchangers￿, KGH, 2004
  • Hrnjak, P. S., ￿Flow Distribution Issues in Parallel Flow Heat Exchangers,￿ ASHRAE Transactions, 110:1, 301-306, 2004.
  • Hrnjak, P. S., ￿Developing Adiabatic Two-phase Flow in Headers ￿ Distribution Issue in Parallel Flow Microchannel Heat Exchangers,￿ Heat Transfer Engineering, 25:3, 61-68, 2004.
  • ElSherbini, A. I., A. M. Jacobi, and P. S. Hrnjak, ￿Experimental Investigation of Thermal Contact Resistance in Plain-fin-and-tube Evaporators with Collarless Fins,￿ International Journal of Refrigeration, 26:5, 527-536., 2003.
  • Tu, X., P. S., Hrnjak, and C. W. Bullard, ￿Refrigerant 134a Liquid Flow through Micro-Scale Short Tube Orifices with/without Phase Change,￿ Experimental Heat Transfer and Fluid Flow, 30, 253-262, 2003.
  • Tu, X. and P. S. Hrnjak, ￿Pressure Drop and Visualization of R134a Two-phase Flow in a Rectangular Microchannel,￿ Transactions of ASHRAE, 109:1, 703-710, 2003.
  • Giannavola, S. M., J. M. Yin, C. W. Bullard, and P. S. Hrnjak, ￿Contribution of Heat Exchangers in Improved Performance of New Generation Automotive Air Conditioning System with R744,￿ Transactions of ASHRAE, 109:1, 542-554, 2003.
  • Nino, V. G., P. S. Hrnjak, and T. A. Newell, ￿Two-phase Flow Visualization of R134a in a Multiport Microchannel Tube,￿ Heat Transfer Engineering, 24:1, 41-52, 2003.
  • Bullard, C. W. and P. S. Hrnjak, ￿Research in Transcritical R744 at ACRC, University of Illinois at Urbana-Champaign,￿ J. Soc. Air Conditioning and Refrig. Engrs. of Korea, 31:7, 32-52, 2002.
  • Song, S., C. W. Bullard, and P. S. Hrnjak, ￿Frost Deposition and Refrigerant Distribution in Microchannel Heat Exchangers,￿ Transactions of ASHRAE, 108:2, 944-953, 2002.
  • Yin, J. M., C. W. Bullard, and P. S. Hrnjak, ￿Single-phase Pressure Drop Measurements in a Microchannel Heat Exchanger,￿ Journal of Heat Transfer Engineering, 23:4, 3-12, 2002.
  • Bullard, C. W., J. M. Yin, and P. S. Hrnjak, ￿Compact Counterflow Gas Cooler for R744,￿ Transactions of ASHRAE, 108:1, 487-491, 2002.
  • Yin, J. M., C. W. Bullard, and P. S. Hrnjak, ￿R-744 Gas Cooler Model Development and Validation,￿ International Journal of Refrigeration, 24, 692-701, 2001.
  • Hrnjak, P. S. and Y. Mao, ￿Defrost Issues in Indirectly Refrigerated Display Cases,￿ ASHRAE Transactions, 107:1, 466-472, 2001.
  • Fang, X., D., C. W. Bullard, and P. S. Hrnjak, ￿Modeling and Analysis of Gas Coolers,￿ ASHRAE Transactions, 107:1, 4-13, 2001.
  • Fang, X., D., C. W. Bullard, and P. S. Hrnjak, ￿Heat Transfer and Pressure Drop of Gas Coolers,￿ ASHRAE Transactions, 107:1, 255-266, 2001.
  • Singh, G. M., P. S. Hrnjak, and C. W. Bullard, ￿Flow of Refrigerant R134a through Orifice Tubes,￿ International Journal of HVAC&R Research, V.7 No. 3, 245-262, July 2001.
  • Hrnjak, P. S., M. A. Shannon, T. M. Leicht, and N. R. Miller, ￿Detection of Liquid Mass Fraction at the Evaporator Exit of Refrigeration Systems,￿ International Journal of Thermal Sciences, 40, 773-786, 2001.
  • McEnaney, R. P. and P. S. Hrnjak, ￿Control Strategies for Transcritical R744 Systems,￿ Journal of Passenger Cars, 109:6, 1711-1720, 2001.
  • Drozdek, J., J. Chappel, C. Cusano, P. S. Hrnjak, N. R. Miller, and T. A. Newell, ￿Methods for Detection of Lubrication Failure Applied to a Swashplate Compressor,￿ Journal of Passenger Cars, 109:6, 1553-1557, 2001.
  • Stoecker, W. F., P. S. Hrnjak, and C. A. Infante Ferreira, ￿Application of Ammonia and CO2 in Supermarkets,￿ Koude and Luchtbehandeling, 94:8, 17-20, 2001.
  • Yin, J. M., C. W. Bullard, and P. S. Hrnjak, ￿R-744 Gas Cooler Model Development and Validation,￿ International Journal of Refrigeration, 24, 692-701, 2001.
  • Boewe, D. E., C. W. Bullard, J. M. Yin, and P. S. Hrnjak, ￿Contribution of Internal Heat Exchanger to Transcritical R744 Cycle Performance,￿ International Journal of HVAC&R Research, 7:2, 155-168, 2001.
  • Shannon, M. A., T. M. Leicht, P. S. Hrnjak, N. R. Miller, and F. A. Kahn, ￿Thin-Film Resistance Sensor for Measuring Liquid Mass Fraction in Super-Heated Refrigerant,￿ Sensors and Actuators A, 88, 164-177, 2001.
  • Rodarte, E., G. Singh, N. R. Miller, and P. S. Hrnjak, ￿Sound Attenuation In Tubes Due to Visco-Thermal Effects,￿ Journal of Sound and Vibration, 231:5, 1221-1242, 2000.
  • Rodarte, E., G. Singh, N. R. Miller, and P. S. Hrnjak, ￿Refrigerant Expansion Noise Propagation through Downstream Tube Walls,￿ Journal of Passenger Cars, 108:6, 2224-2234, 1999.
  • Peixoto, R. A. and P. S. Hrnjak, ￿Elimina￿ de CFCs na Refrigera￿ de Supermercados,￿ Abrava, Sao Paolo, Brazil, 50-58, March/April 1998.
  • Rodarte, E., N. Miller, and P. S. Hrnjak, ￿Acoustic Resonance in Plate Heat Exchangers,￿ International Journal of Refrigeration, 21:8, 626-638, 1998.
  • Vujic, S., M. Markoski, and P. S. Hrnjak, ￿On Generalization of Test Results for Air Coolers with Moisture Extraction,￿ KGH, 4, Belgrade, Yugoslavia (in Serbocroatian), 1983.

Research Honors

  • 2013 Fellow SAE, Society of Automotive Engineers
  • 2012 Academician - Academy of Engineering Sciences AINS Serbia
  • 2012 J&E Hall Medal, IoR (Institute of Refrigeration, London f. 1899) This single annual award recognizes the most noteworthy practical contribution to the science of refrigeration.
  • 2011 Gustav Lorentzen Medal, IIR (International Institute of Refrigeration, Paris f. 1908). The prize is awarded every four years to one person with outstanding and original achievements in academic or industrial research, innovation or development, in all fields of refrigeration, thus promoting creativity and renewal.
  • Fellow ASHRAE, American Society of Heating, Refrigeration and Air Conditioning Engineers
  • 2008 The Ritter von Rittinger award. The highest international award in the air conditioning, heat pump and refrigeration field by IEA. This award highlights outstanding contributions to the advancement of international collaboration in research, policy development and applications for energy-efficient heat pumping technologies. It is awarded every three years. The Rittinger award is named for Peter Ritter von Rittinger who is credited with the design and installation of the first energy-conserving heat pump system at a salt works in Upper Austria in 1855.
  • 2004-2005 Environmental Excellence in Weapon System Acquisition (EEWSA) Award - US Army. The award is the Army￿s highest honor for outstanding environmental stewardship during the acquisition of weapon systems that will support the nation￿s military objectives.