Experimental study on condensation heat transfer inside a single circular minichannel

Matkovič, Marko; Cavallini, Alberto; Col, Davide Del; Rossetto, Luisa

doi:10.1016/j.ijheatmasstransfer.2008.11.013

Cited by 179 publications

(79 citation statements)

References 23 publications

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“…Local heat transfer coefficients for refrigerants R134a and R32 obtained from the measurement of local heat flux and saturation and wall temperatures within a single horizontal circular 0.96 mm i.d. minichannel at mass fluxes in the range 100 kg m -2 s -1 < G < 1200 kg m -2 s -1 were reported by Matkovic et al [6] and Cavallini et al [7]. Heat transfer coefficients during condensation of R134a over the mass flux range 150 kg m -2 s -1 < G < 750 kg m -2 s -1 were measured for three horizontal circular multiport minichannels (0.5 mm < D < 1.5 mm) by Bandhauer at al.…”

Section: Introductionsupporting

confidence: 54%

“…As an example, the local heat transfer coefficients predicted by Wang and Rose [11] at 100 kg m -2 s -1 < G < 1300 kg m -2 s -1 do not depend on mass flux for a large portion of the channel length; several experimental data sets for both circular and non-circular minichannels, however, show a strong dependence on mass flux [6,8,9,18,19]. All reported numerical results in the present work are compared to the experimental data of Matkovic et al [6]. ).…”

Section: Introductionmentioning

confidence: 93%

“…In the experimental apparatus used by Matkovic et al [6], refrigerant R134a is cooled with water which does not ensure that the saturation-to-wall temperature difference is constant along the test section. The saturation-to-wall temperature difference ranges between 6.1 K and 13.1 K for the experimental data reported in Error!…”

Section: Validation Against Experimental Datamentioning

confidence: 99%

“…As an example, the measurements by Matkovic et al [6], except for the lowest mass flux (G = 100 kg m -2 s -1 ), do not show significant differences from the trends expected for macroscale tubes: all experimental data at mass fluxes higher than 100 kg m -2 s -1 could be predicted within 15% by the Cavallini et al [10] empirical correlation, which was developed from a database for macroscale tubes (3 mm < D < 8 mm). Even if selected empirical correlations can predict specific experimental results with reasonable accuracy (see [4,5]), an established predictive model is unavailable, and a more complete understanding of the two-phase flow and heat transfer process in minichannels is needed for the design and optimization of heat exchangers.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The importance of turbulence during condensation in a horizontal circular minichannel

Riva

Col

Garimella

et al. 2012

International Journal of Heat and Mass Transfer

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117

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Section: Introductionsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 93%

Section: Validation Against Experimental Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The importance of turbulence during condensation in a horizontal circular minichannel

Riva

Col

Garimella

et al. 2012

International Journal of Heat and Mass Transfer

Self Cite

117

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“…In mini-and microchannels, body forces such as gravity and buoyancy decrease in significance and surface tension increases in importance [10][11][12][13][14][15]. Condensation heat transfer coefficients typically increase with increasing mass flux and steam quality [7,8,12,13,16,17], except at low qualities [4,18].…”

Section: Introductionmentioning

confidence: 99%

Combined Visualization and Heat Transfer Measurements for Steam Flow Condensation in Hydrophilic and Hydrophobic Mini-Gaps

Chu

Derby

2016

Journal of Heat Transfer

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Condensation enhancement was investigated for flow condensation in mini-channels. Simultaneous flow visualization and heat transfer experiments were conducted in 0.952-mm diameter mini-gaps. An open loop steam apparatus was constructed for a mass flux range of 50-100 kg/m 2 s and steam quality range of 0.2-0.8, and validated with single-phase experiments. Filmwise condensation was observed in the hydrophilic minigap; pressure drop and heat transfer coefficients were compared to the (Kim and Mudawar, 2013, "Universal Approach to Predicting Heat Transfer Coefficient for Condensing Mini/Micro-Channel Flow," Int. J. Heat Mass Transfer, 56(1-2), pp. 238-250) correlation and prediction was very good; the mean absolute error (MAE) was 20.2%. Dropwise condensation was observed in the hydrophobic mini-gap, and periodic cycles of droplet nucleation, coalescence, and departure were found at all mass fluxes. Snapshots of six typical sweeping cycles were presented, including integrated flow visualization quantitative and qualitative results combined with heat transfer coefficients. With a fixed average steam quality ( x ¼ 0.42), increasing mass flux from 50 to 75 to 100 kg/m 2 s consequently reduced average sweeping periods from 28 to 23 to 17 ms and reduced droplet departure diameters from 13.7 to 12.9 to 10.3 lm, respectively. For these cases, condensation heat transfer coefficients increased from 154,700 to 176,500 to 194,800 W/m 2 K at mass fluxes of 50, 75, and 100 kg/m 2 s, respectively. Increased mass fluxes and steam quality reduced sweeping periods and droplet departure diameters, thereby reducing liquid thickness and increasing heat transfer coefficients.

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Experimentelle Bestimmung von Wärmeübergang und Druckverlust in Multiportflachrohren

Bastuck

Piesche

Mitrovic³

2015

Chemie Ingenieur Technik

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Präsentiert werden Messungen zum Wärmeübergang und Druckverlust an drei glatten Multiportflachohren mit kleinen hydraulischen Durchmessern < 1 mm bei einphasiger Strömung (Heptan) und Strömung mit Kondensation (Kältemittel R134a). Die für die Untersuchungen aufgebauten Prüfstände sind mit innovativen Messaufbauten für die Bestimmung der entstehenden Kondensatmenge und für die Erfassung der Kältemittel-und Rohrwandtemperatur ausgestattet. Die Messwerte für das Rohr mit dem kleinsten hydraulischen Durchmesser zeigen, dass die Annahme einer Leistungssteigerung bei Verkleinerung des hydraulischen Durchmessers nicht unbegrenzt gilt.Heat transfer and pressure drop data of three smooth multiport minichannels featuring hydraulic diameters > 1 mm are presented. Experiments were conducted under single phase convection of heptane and under convection of condensing R134a. Two specifically designed testing facilities feature a novel measurement setup to register the amount of condensate generated and to measure the temperatures of the refrigerant and minichannel wall. The results for the smallest minichannel geometrie show that the assumption of an increasing heat transfer rate with decrasing hydraulic diameter is not generally valid.

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Experimental study on condensation heat transfer inside a single circular minichannel

Cited by 179 publications

References 23 publications

The importance of turbulence during condensation in a horizontal circular minichannel

The importance of turbulence during condensation in a horizontal circular minichannel

Combined Visualization and Heat Transfer Measurements for Steam Flow Condensation in Hydrophilic and Hydrophobic Mini-Gaps

Experimentelle Bestimmung von Wärmeübergang und Druckverlust in Multiportflachrohren

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