Search Results - "HRNJAK, P. S"

Refrigerant 134a liquid flow through micro-scale short tube orifices with/without phase change by Tu, X., Hrnjak, P.S., Bullard, C.W.

“…The paper presents the results of experiments when R134a was flowing through micro-orifices with diameters of 31.0 and 52.0 μm, and length-to-diameter ratio of…”
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Experimental results of transcritical CO2 heat pump for residential application by RICHTER, M. R, SONG, S. M, YIN, J. M, KIM, M. H, BULLARD, C. W, HRNJAK, P. S

“…This paper describes experiments comparing a commercially available R410A heat pump and prototype R744 (carbon dioxide) system in heating mode. The R744 system…”
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Air-side performance evaluation of three types of heat exchangers in dry, wet and periodic frosting conditions by Zhang, Ping, Hrnjak, P.S.

“…The performances of three types of heat exchangers that use the louver fin geometry: (1) parallel flow parallel fin with extruded flat tubes heat exchanger (PF…”
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Air-side performance of a parallel-flow parallel-fin (PF 2) heat exchanger in sequential frosting by Zhang, Ping, Hrnjak, P.S.

“…The thermal-hydraulic performance in periodic frosting conditions is experimentally studied for the parallel-flow parallel-fin heat exchanger, henceforth…”
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Single-Phase Pressure Drop Measurements in a Microchannel Heat Exchanger by Yin, J. M., Bullard, C. W., Hrnjak, P. S.

“…Single-phase pressure drops inside the complex headers and parallel circuits of a microchannel heat exchanger were measured systematically, for the purpose of…”
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Effect of some geometric parameters on performance of PF2 heat exchangers in periodic frosting by PING ZHANG, HRNJAK, P. S

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Heat flux variation between neighboring channels in compact minichannel heat exchangers by Khovalyg, D., Hrnjak, P.S., Jacobi, A.M.

“…•Evidence of non-uniform heat flux q distribution between parallel minichannels.•The difference in q between the leading and the trailing channel can be up to…”
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Experimental investigation of thermal contact resistance in plain-fin-and-tube evaporators with collarless fins by ElSherbini, A.I., Jacobi, A.M., Hrnjak, P.S.

“…The thermal contact resistance between fins and tubes in a plain-fin heat exchanger has been studied. The test coils have aluminum fins and tubes with no…”
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Thin-film resistance sensor for measuring liquid mass fraction in super-heated refrigerant by Shannon, M.A., Leicht, T.M., Hrnjak, P.S., Miller, N.R., Khan, F.A.

“…A microfabricated thin-film resistance (TFR) sensor is presented for measuring the liquid mass fraction (LMF) of refrigerant in the evaporator exits of…”
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R-744 gas cooler model development and validation by Yin, Jian Min, Bullard, Clark W., Hrnjak, Predrag S.

“…A first principles-based model was developed for a transcritical CO2 gas cooler, using a finite element method. The model uses published correlations for…”
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Evaporator performance enhancement by pulsation width modulation (PWM) by Wang, X., Tang, K., Hrnjak, P.S.

“…•Effects of pulsating flow on heat transfer performance and pressure drop in an air-refrigerant evaporator have been explored.•Pulsating flow has enhanced…”
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Two-Phase Flow Visualization of R134A in a Multiport Microchannel Tube by Niño, Victor G., Hrnjak, Predrag S., Newell, Ty A.

“…Results are presented from a flow visualization investigation of a multiport microchannel tube using R134a, a medium pressure refrigerant. The study covers…”
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CO2 and R410A flow boiling heat transfer, pressure drop, and flow pattern at low temperatures in a horizontal smooth tube by PARK, C. Y, HMJAK, P. S

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Frost, defrost, and refrost and its impact on the air-side thermal-hydraulic performance of louvered-fin, flat-tube heat exchangers by Xia, Y., Zhong, Y., Hrnjak, P.S., Jacobi, A.M.

“…The thermal-hydraulic performance under conditions of an initial frost growth on the air-side surface, and for subsequent ‘refrosting’ after a defrost period…”
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Detection of liquid mass fraction at the evaporator exit of refrigeration systems by Hrnjak, Pega S, Shannon, Mark A, Leicht, Todd M, Miller, Norman R

“…The article presents four methods of detecting droplets in the stream of superheated vapor at the evaporator exit of refrigeration systems: (a) an energy…”
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Experimental Results of Transcritical CO sub(2) Heat Pump for Residential Application by Richter, M R, Song, S M, Yin, J M, Kim, M H, Bullard, C W, Hrnjak, P S

“…The performance of a commercially available R410 heat pump and a prototype carbon dioxide-based R744 system was compared for the residential heating mode. The…”
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Experimental results of transcritical CO 2 heat pump for residential application by Richter, M.R., Song, S.M., Yin, J.M., Kim, M.H., Bullard, C.W., Hrnjak, P.S.

“…This paper describes experiments comparing a commercially available R410A heat pump and prototype R744 (carbon dioxide) system in heating mode. The R744 system…”
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Design and evaluation of interior permanent magnet compressor motors for commercial transcritical CO2 (R-744) heat pump water heaters by Brown, I. P., Critchley, M. W., Yin, J., Memory, S. B., Elbel, S. W., Bowers, C. D., Petersen, M., Hrnjak, P. S., Sizov, G. Y.

“…This paper describes the design and experimental evaluation of two high efficiency interior permanent magnet (IPM) motors for use in a commercial transcritical…”
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Control Strategies for Transcritical R744 Systems by McEnaney, R. P., Hrnjak, P. S.

“…This paper presents one possible control strategy for a transcritical R744 automotive air conditioning system. The controller is developed for systems using…”
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Flow-Regime-Based Model for Pressure Drop Predictions in Microchannels by Niño, Victor G., Jassim, Emad W., Hrnjak, Predrag S., Newell, Ty A.

“…A flow-regime-based pressure drop model is developed to correlate experimental data in the intermittent and annular flow regime. For the intermittent region,…”
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