Browse College of Engineering by Author "Hrnjak, P.S."

  • Hrnjak, P.S.; Miller, N.R.; Rodarte, E. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 1997-12)

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  • Fei, P.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2004-01)
    This research is focused on the experimental analysis and numerical simulation of adiabatic developing two-phase refrigerant flow in manifolds including the inlet tube after the expansion device. The two-phase flow ...

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  • Xia, Y.; Hrnjak, P.S.; Jacobi, A.M. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2006-12)
    The thermal-hydraulic behavior of folded-louvered-fin, microchannel heat exchangers is explored under conditions of air-side frosting, defrosting, and refrosting. The temperature distribution within a two-dimensional composite ...

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  • Park, C.Y.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2007-01)
    Carbon dioxide (CO2) has been seriously considered as an alternate refrigerant for HCFC and HFC fluids, due to the increasing interest of environmentally safe refrigerants in air-conditioning and refrigeration systems. ...

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  • Nino, V.G.; Hrnjak, P.S.; Newell, T.A. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2002-10)
    Aluminum multi-port microchannel tubes are currently utilized in automotive air conditioners for refrigerant condensation. Recent research activities are directed toward developing other air conditioning and refrigeration ...

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  • Hoehne, M.R.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2004-01)

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  • Traeger, K.M.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2005-06)
    This thesis focuses on microchannel heat exchangers, and the methods used to try and reduce the charge contained in them. First, four condensers were designed and manufactured with the same air side characteristics and same ...

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  • Boewe, D.E.; McEnaney, R.P.; Park, Y.C.; Yin, J.M.; Bullard, C.W.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 1999-07)

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  • Richter, M.R.; Bullard, C.W.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2001-06)
    In the first part of this report, experimental results are presented comparing a prototype R744 system with a commercially available R410A system in heating mode. When the heating capacity of the two systems is matched at ...

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  • Litch, A.D.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 1999-08)

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  • Zilly, J.; Jang, J.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2003-03)
    Enhanced tubes have been commonly used in heat exchangers for 30 years. Modern micro-fin tubes play a significant role in high-efficiency refrigerators and air conditioners with their significantly enhanced heat ...

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  • Jang, J.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2004-06)

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  • Miller, N.R.; Hrnjak, P.S.; Rodarte, E. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 1998-11)

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  • Rasmussen, B.P.; Shah, R.; Musser, A.B.; Alleyne, Andrew G.; Bullard, C.W.; Hrnjak, P.S.; Miller, N.R. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2002-10)
    This thesis details the efforts to develop a dynamic model of a transcritical vapor compression system suitable for multivariable control design purposes. The modeling approach is described and the developed models are ...

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  • Carlson, D.M.; Hrnjak, P.S.; Bullard, C.W. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2001-06)
    Frost deposition across a typical eight-row deep refrigeration display case heat exchanger was studied under varying conditions of face velocity, refrigerant temperature glide, and absolute humidity. The heat exchanger, ...

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  • Verma, P.; Bullard, C.W.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2002-10)
    A simulation model for predicting the performance of a display case under frosting conditions has been developed. An experimentally validated heat exchanger simulation model for a secondary refrigerant was extended to ...

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  • Uribe, T.; Bullard, C.W.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2003-12)
    The purpose of this project is to explore the system design implications of compressor rapid cycling. An earlier project yielded promising results for a typical 2-ton residential split system. It showed that cycle periods ...

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  • Shah, R.; Alleyne, Andrew G.; Bullard, C.W.; Rasmussen, Bryan P.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2003-08)
    The focus of this research is on the development of a dynamic modeling capability for subcritical vapor compression systems with one or more evaporators. The modeling methodology is developed with the multiple objectives ...

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  • Ilic, S.M.; Bullard, C.W.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2001-12)
    Effects of compressor on/off cycle times shorter than typical a/c heat exchanger thermal time constant (~1 min) were examined as a method of cooling capacity regulation. Short compressor on/off cycle times enable the ...

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  • Yin, J.M.; Bullard, C.W.; Hrnjak, P.S. (Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign., 2001-05)
    This document summarizes the evolution of the design of a 10 kW split system residential heat pump, to operate with R744 on the transcritical cycle. It is the first such prototype to be designed, and will be used for ...

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