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Pega Hrnjak
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Proceedings Papers

Effect of Comfort Constraints on Cycle Efficiencies

Matthew Richter, Clark Bullard, Pega Hrnjak
Proc. ASME. IMECE2001, Advanced Energy Systems, 275-286, November 11–16, 2001
Paper No: IMECE2001/AES-23633
DOI: https://doi.org/10.1115/IMECE2001/AES-23633
View Paper titled, Effect of Comfort Constraints on Cycle Efficiencies
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Topics: Cycles, Air flow, Climate, Heating and cooling, Refrigerants, Stress
Journal Articles

Heat Transfer Coefficient, Pressure Gradient, and Flow Patterns of R1234yf Evaporating in Microchannel Tube

Houpei Li, Pega Hrnjak
Journal: Journal of Heat Transfer
Article Type: Research-Article
J. Heat Transfer. April 2021, 143(4): 042501.
Paper No: HT-19-1251
DOI: https://doi.org/10.1115/1.4049635
Published Online: February 23, 2021
View Article titled, Heat Transfer Coefficient, Pressure Gradient, and Flow Patterns of R1234yf Evaporating in Microchannel Tube
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Topics: Flow (Dynamics), Heat transfer coefficients, Microchannels, Pressure gradient, Vapors, Heat flux, Pressure drop, Heat transfer, Evaporation, Pressure
Includes: Supplementary data
Journal Articles

Phase Separation in Vertical Header of Microchannel Condensers—A Mechanistic Model

Jun Li, Pega Hrnjak
Journal: Journal of Fluids Engineering
Article Type: Research-Article
J. Fluids Eng. January 2020, 142(1): 011303.
Paper No: FE-19-1128
DOI: https://doi.org/10.1115/1.4044285
Published Online: October 4, 2019
View Article titled, Phase Separation in Vertical Header of Microchannel Condensers—A Mechanistic Model
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Topics: Condensers (steam plant), Drops, Flow (Dynamics), Microchannels, Phase separation, Separation (Technology), Vapors, Pressure drop
Journal Articles

Parametric Study and Improvement of Phase Separation in Intermediate Headers of Microchannel Condensers

Jun Li, Pega Hrnjak
Journal: Journal of Fluids Engineering
Article Type: Research-Article
J. Fluids Eng. January 2020, 142(1): 011304.
Paper No: FE-19-1141
DOI: https://doi.org/10.1115/1.4044480
Published Online: October 4, 2019
View Article titled, Parametric Study and Improvement of Phase Separation in Intermediate Headers of Microchannel Condensers
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Topics: Condensers (steam plant), Drops, Flow (Dynamics), Microchannels, Phase separation, Separation (Technology), Vapors, Refrigerants
Proceedings Papers

Parametric Study and Improvement of Phase Separation in Intermediate Headers of Microchannel Condensers

Jun Li, Pega Hrnjak
Proc. ASME. IMECE2018, Volume 7: Fluids Engineering, V007T09A015, November 9–15, 2018
Paper No: IMECE2018-88438
DOI: https://doi.org/10.1115/IMECE2018-88438
View Paper titled, Parametric Study and Improvement of Phase Separation in Intermediate Headers of Microchannel Condensers
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Topics: Condensers (steam plant), Microchannels, Phase separation, Separation (Technology), Vapors, Flow (Dynamics), Air conditioning, Engineering prototypes, Fluids, Heat transfer
Proceedings Papers

Phase Separation in Vertical Header of Microchannel Condensers: A Mechanistic Model

Jun Li, Pega Hrnjak
Proc. ASME. FEDSM2018, Volume 3: Fluid Machinery; Erosion, Slurry, Sedimentation; Experimental, Multiscale, and Numerical Methods for Multiphase Flows; Gas-Liquid, Gas-Solid, and Liquid-Solid Flows; Performance of Multiphase Flow Systems; Micro/Nano-Fluidics, V003T20A003, July 15–20, 2018
Paper No: FEDSM2018-83311
DOI: https://doi.org/10.1115/FEDSM2018-83311
View Paper titled, Phase Separation in Vertical Header of Microchannel Condensers: A Mechanistic Model
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Topics: Condensers (steam plant), Microchannels, Phase separation, Vapors, Separation (Technology), Compression, Design, Drops, Energy conversion, Engineering prototypes
Proceedings Papers

Effect of Inclination on Heat Transfer in Large Flattened-Tube Steam Condensers

William A. Davies, Yu Kang, Pega Hrnjak, Anthony M. Jacobi
Proc. ASME. IMECE2017, Volume 6: Energy, V006T08A035, November 3–9, 2017
Paper No: IMECE2017-70332
DOI: https://doi.org/10.1115/IMECE2017-70332
View Paper titled, Effect of Inclination on Heat Transfer in Large Flattened-Tube Steam Condensers
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Topics: Condensers (steam plant), Heat transfer, Steam, Visualization, Aluminum, Condensation, Drainage, Fins, Porosity, Power stations
Proceedings Papers

Oil Effects on In-Tube Evaporation of CO 2 by Altering Flow Regime and Properties

Pega Hrnjak, Seongho Kim
Proc. ASME. HT2013, Volume 2: Heat Transfer Enhancement for Practical Applications; Heat and Mass Transfer in Fire and Combustion; Heat Transfer in Multiphase Systems; Heat and Mass Transfer in Biotechnology, V002T04A012, July 14–19, 2013
Paper No: HT2013-17838
DOI: https://doi.org/10.1115/HT2013-17838
View Paper titled, Oil Effects on In-Tube Evaporation of CO 2 by Altering Flow Regime and Properties
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Topics: Carbon dioxide, Evaporation, Flow (Dynamics), Heat transfer, Boiling, Flux (Metallurgy), Heat transfer coefficients, Vapors, Visualization, Heat
Proceedings Papers

A Mechanistic Model of Two-Phase Pressure Drop in Microchannels

Brandon S. Field, Pega Hrnjak
Proc. ASME. IMECE2011, Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B, 411-419, November 11–17, 2011
Paper No: IMECE2011-64269
DOI: https://doi.org/10.1115/IMECE2011-64269
View Paper titled, A Mechanistic Model of Two-Phase Pressure Drop in Microchannels
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Topics: Microchannels, Pressure drop, Flow (Dynamics), Microchannel flow, Fluids, Refrigerants, Bubbly flow, Slug flows, Surface tension, Two-phase flow
Journal Articles

Flow Boiling Heat Transfer, Pressure Drop, and Flow Pattern for C O 2 in a 3.5 mm Horizontal Smooth Tube

Chang Yong Park, Pega Hrnjak
Journal: Journal of Heat Transfer
Article Type: Research Papers
J. Heat Transfer. September 2009, 131(9): 091501.
DOI: https://doi.org/10.1115/1.2909079
Published Online: June 19, 2009
View Article titled, Flow Boiling Heat Transfer, Pressure Drop, and Flow Pattern for C O 2 in a 3.5 mm Horizontal Smooth Tube
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Topics: Boiling, Flow (Dynamics), Heat transfer, Heat transfer coefficients, Pressure drop, Temperature, Carbon dioxide
Proceedings Papers

Visualization of Two-Phase Refrigerant and Refrigerant-Oil Flow in a Microchannel

Brandon S. Field, Pega Hrnjak
Proc. ASME. IMECE2007, Volume 8: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A and B, 1647-1656, November 11–15, 2007
Paper No: IMECE2007-43471
DOI: https://doi.org/10.1115/IMECE2007-43471
View Paper titled, Visualization of Two-Phase Refrigerant and Refrigerant-Oil Flow in a Microchannel
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Topics: Flow (Dynamics), Microchannels, Refrigerants, Visualization, Fluids, Slug flows, Temperature, Vapors, Bubbles, Flow visualization
Proceedings Papers

Developing Adiabatic Two Phase Flow in Headers

Pega Hrnjak
Proc. ASME. ICMM2003, 1st International Conference on Microchannels and Minichannels, 207-214, April 24–25, 2003
Paper No: ICMM2003-1022
DOI: https://doi.org/10.1115/ICMM2003-1022
View Paper titled, Developing Adiabatic Two Phase Flow in Headers
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Topics: Fluids, Heat exchangers, Microchannels, Two-phase flow
Proceedings Papers

Experimental Investigation of Single-Phase Flow Pressure Drop Through Rectangular Microchannels

Xiao Tu, Pega Hrnjak
Proc. ASME. ICMM2003, 1st International Conference on Microchannels and Minichannels, 257-267, April 24–25, 2003
Paper No: ICMM2003-1028
DOI: https://doi.org/10.1115/ICMM2003-1028
View Paper titled, Experimental Investigation of Single-Phase Flow Pressure Drop Through Rectangular Microchannels
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Topics: Flow (Dynamics), Microchannels, Pressure drop, Friction, Reynolds number, Surface roughness, Fluids, Testing, Turbulence, Vapors
Proceedings Papers

Adiabatic Two-Phase Pressure Drop of Refrigerants in Small Channels

Brandon S. Field, Pega Hrnjak
Proc. ASME. ICNMM2006, ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels, Parts A and B, 1173-1180, June 19–21, 2006
Paper No: ICNMM2006-96200
DOI: https://doi.org/10.1115/ICNMM2006-96200
View Paper titled, Adiabatic Two-Phase Pressure Drop of Refrigerants in Small Channels
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Topics: Pressure drop, Refrigerants, Flow (Dynamics), Surface tension, Fluids, Kinetic energy, Reynolds number, Vapors