Experimental investigation of adverse effect of frost formation on microchannel evaporators, part 1: Effect of fin geometry and environmental effects

Moallem, Ehsan; Hong, Tommy; Cremaschi, Lorenzo; Fisher, Daniel E.

doi:10.1016/j.ijrefrig.2012.09.009

Cited by 46 publications

(8 citation statements)

References 11 publications

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“…Similar results were observed for other samples (Moallem et al 2013). The location of the camera was in the center of the 6-in.-long sample.…”

Section: Visual Observationssupporting

confidence: 87%

“…The effect of various surface temperatures and geometries were previously published in previous work (Moallem et al 2013). In this section, a new set of frost correlations were developed and verified against experimental data.…”

Section: Frost Empirical Correlation Scope and Fundamentalsmentioning

confidence: 97%

“…As a result, the effect of geometry modification was coupled with the effect of surface temperature change. To isolate and study the effect of surface temperature, a new methodology was developed by the authors that measured and controlled the fin surface temperature independently and isolated its effects from the geometry effects (Moallem et al 2013). The experimental data of authors' previous work are used in the present study.…”

Section: Introductionmentioning

confidence: 99%

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Developing empirical correlations for frost thickness and air face velocity degradation for microchannel heat exchangers used in heat pump applications under frosting conditions

et al. 2013

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This study experimentally investigated the frost growth on louvered folded fins in outdoor microchannel heat exchangers used in air-source heat pump systems. The effects of surface temperature and fin geometries on the performance of the microchannel heat exchangers under frosting condition were studied. Seven fin samples with various fin widths, fin heights, and fin densities and a louver angle of approximately 30 • were tested in controlled laboratory conditions that replicated those of actual heat pump systems in the winter season. The fin surface temperature was experimentally measured with the novel methodology developed in the present study. Experimental data of local frost thickness, air pressure drop across the coils, time of frost-defrost cycles, and heat transfer rates were recorded for heat exchangers operating in actual transient frosting conditions. Data showed that frosting time and frost growth rates depended mainly on the local fin surface temperature. A set of empirical correlations were developed to predict the frost thickness on the fin leading edge and the reduction of air face velocity due to air pressure drop across the frosted coil during frosting operation. The correlations were compared against experimental data of frost collected in the present study, and satisfactory agreement was achieved. The frost thickness correlation and air face velocity correlations aid in the calculation of the instantaneous air-side Reynolds numbers during frosting operation of the fin samples. These are critical for predicting the heat transfer rates of the microchannel coils in quasi-steady-state frosting operating conditions.

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“…Similar results were observed for other samples (Moallem et al 2013). The location of the camera was in the center of the 6-in.-long sample.…”

Section: Visual Observationssupporting

confidence: 87%

Section: Frost Empirical Correlation Scope and Fundamentalsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Developing empirical correlations for frost thickness and air face velocity degradation for microchannel heat exchangers used in heat pump applications under frosting conditions

et al. 2013

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“…On the other hand, due to the diffusion of water vapour molecules, the density of frost layer increases continuously. From a qualitative point of view there is a good agreement between the numerical results and experimental observations [18]; however, there is no quantitative comparison. In the second case, the FPI (Fins Per Inch) increased from 10.6 to12.7 while the face area ( ) of the section was constant.…”

Section: Frosting On a Plate-fin Evaporatormentioning

confidence: 74%

Numerical Simulation of Frost Formation on a Plate-Fin Evaporator

Afrasiabian¹,

Iliev²,

Lazzari³

et al. 2018

World Congress on Momentum, Heat and Mass Transfer

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In the present paper, the Eulerian-granular model is adopted, to predict the frost growth on one channel of a plate-fin evaporator. A proper mass transfer model and modified frosting criteria are used to simulate the frost formation process. First, the model is validated with experimental data obtained under various operating conditions. The numerical predictions for the frost thickness and density are in good agreement with available experimental data. Furthermore, a parametric analysis is carried out to study the impact of the geometrical parameters of a three-dimensional plate-fin evaporator. A qualitative comparison shows a good agreement between the numerical data and experimental observations reported in the literature. One interesting outcome emerging from this study is that the distance between refrigerant tubes can play an important role in the frosting time.

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“…Also, they found that relative humidity had no effect on heat transfer and pressure drop for the larger fin pitches. Recent studies have focused on the effects of fin geometry, test operating, surface coating, and frosting phenomena on the fin and tube of the micro-channel heat exchanger, which is important to the development of heat pump systems [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Air-side performance of a micro-channel heat exchanger in wet surface conditions

et al. 2017

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The effects of operating conditions on the air-side heat transfer, and pressure drop of a micro-channel heat exchanger under wet surface conditions were studied experimentally. The test section was an aluminum micro-channel heat exchanger, consisting of a multi-louvered fin and multi-port mini-channels. Experiments were conducted to study the effects of inlet relative humidity, air frontal velocity, air inlet temperature, and refrigerant temperature on air-side performance. The experimental data were analyzed using the mean enthalpy difference method. The test run was performed at relative air humidity's ranging between 45% and 80%; air inlet temperature ranges of 27, 30, and 33 o C, refrigerant-saturated temperatures ranging from 18 to 22 o C, and Reynolds numbers between 128 and 166. The results show that the inlet relative humidity, air inlet temperature, and the refrigerant temperature had significant effects on heat transfer performance and air-side pressure drop. The heat transfer coefficient and pressure drop for the micro-channel heat exchanger under wet surface conditions are proposed in terms of the Colburn factor and Fanning factor.

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Experimental investigation of adverse effect of frost formation on microchannel evaporators, part 1: Effect of fin geometry and environmental effects

Cited by 46 publications

References 11 publications

Developing empirical correlations for frost thickness and air face velocity degradation for microchannel heat exchangers used in heat pump applications under frosting conditions

Developing empirical correlations for frost thickness and air face velocity degradation for microchannel heat exchangers used in heat pump applications under frosting conditions

Numerical Simulation of Frost Formation on a Plate-Fin Evaporator

Air-side performance of a micro-channel heat exchanger in wet surface conditions

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