Refrigerant distribution in a parallel flow heat exchanger having vertical headers and heated horizontal tubes

Byun, Ho-Won; Kim, N.H.

doi:10.1016/j.expthermflusci.2011.01.011

Cited by 69 publications

(23 citation statements)

References 9 publications

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“…Figure 6 also shows that the impact of flow maldistribution on D is very high and reaches up to 10% when the skew is -1. This finding is similar to the research done by Byun and Kim [9]. …”

Section: Pressure Drop Correlationsupporting

confidence: 82%

“…(c is eliminated in this equation) (9) where  is the normalised mean of the mass flow rate for each circuit From the above equation, the surface area, and difference in enthalpy for both air and refrigerant of each circuit are needed to calculate the normalised mass flow rate of each circuit. It is required to measure the pressure of inlet, outlet and temperature inlet and outlet for each circuit to obtain the difference in enthalpy for refrigerant side.…”

Section: Measurement Of Mass Flow Rate For Each Circuitmentioning

confidence: 99%

“…Moreover, MCHX offers other advantages such as space saving and weight and refrigerant charge [7,8]. Byun and Kim [9] found that R410A maldistribution in MCHX causes the heat transfer performance reduction by 13.4% compared to the even flow distribution. Zou et al [10] investigated the flow distribution in MCHX with R410A and R134a.…”

Section: Introductionmentioning

confidence: 99%

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Analysis on the refrigerant (R32) flow maldistribution of microchannel heat exchanger under superheat and sub-cool

Chng¹,

Chin²,

Tang³

2017

Int. J. Automot. Mech. Eng.

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The aim of this research is to study the impact of statistical moments of probability density function such as mean, standard deviation, skew of R32 flow maldistribution profile on the thermal performance of microchannel heat exchanger under superheat, and subcooling effect. A mathematical model was developed in order to analyse the influence of the statistical moments of probability density function of R32 flow maldistribution on the thermal performance of microchannel heat exchanger under superheat and sub-cooling effect. It was found that the high standard deviation and high negative skew of R32 flow maldistribution profile gave a large impact on the D of microchannel heat exchanger and can achieve up to 10%. Moreover, it was found that the heat transfer performance of microchannel heat exchanger dropped significantly when the sub-cool increases. In short, low standard deviation, high positive skew, and superheat of a flow maldistribution profile is preferred in order to minimize the performance deterioration effect. An experiment was set up to verify the mathematical model. The results from the mathematical model agreed well within 10% of the experimental data. A performance deterioration correlation related to refrigerant maldistribution under superheat and subcool was developed to provide a faster solution to design an even flow distribution heat exchanger. The proposed correlation in this research offers a quicker and simpler way to study the R32 flow maldistribution problem.

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“…Figure 6 also shows that the impact of flow maldistribution on D is very high and reaches up to 10% when the skew is -1. This finding is similar to the research done by Byun and Kim [9]. …”

Section: Pressure Drop Correlationsupporting

confidence: 82%

Section: Measurement Of Mass Flow Rate For Each Circuitmentioning

confidence: 99%

See 1 more Smart Citation

Analysis on the refrigerant (R32) flow maldistribution of microchannel heat exchanger under superheat and sub-cool

Chng¹,

Chin²,

Tang³

2017

Int. J. Automot. Mech. Eng.

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“…Thus, the heat exchanger capacity is usually lower than the case with uniform distribution. Byun and Kim (2011) presented R410A maldistribution in a two-pass outdoor MCHX under heat pump (HP) mode caused the cooling capacity reduced up to 13.4% compared to the uniform distribution case. showed capacity degradation of 30% and 5% for R410A and R134a maldistribution in a two-pass outdoor MCHX under HP mode, respectively.…”

Section: Introductionmentioning

confidence: 99%

Comparison and generalization of R410A and R134a distribution in the microchannel heat exchanger with the vertical header

Hrnjak

2015

Science and Technology for the Built Environment

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This paper explores the effects of fluid properties on two-phase flow in the vertical header and refrigerant distribution into horizontal branch tubes. R410A and R134a are used as the working fluid. Refrigerant enters into the header by five microchannel tubes in the bottom pass and exits through the five microchannel tubes in the top pass representing the flow in the outdoor microchannel heat exchanger of reversible systems under heat pump mode. The difference of fluid properties causes the flow pattern and refrigerant distribution results of R410A and R134a different between each other. Non-dimensional analysis shows that the inertia of R410A is higher than that of R134a. At low qualities, when the flow regime is churn, the higher inertia enables top tubes to receive more liquid so that the distribution of R410A is a little better than that of R134a. At high qualities, when it is likely semiannular, the higher inertia causes more bottom tubes are bypassed by the liquid film of semi-annular flow. It results in worse R410A distribution than R134a, though more liquid reaches the top tubes for R410A. The coefficient of variation of refrigerant distribution is applied in this study to generalize the results of both R410A and R134a at various header geometries and inlet flow conditions. A distribution function is derived for predicting R410A and R134a distribution in future.

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“…However, since the physical properties of air-water two-phase fluid are very different from those of refrigerants, the findings cannot be applied to the header for refrigerants. Byun and Kim [2] tested and visualized the refrigerant distribution in the vertical header made for simulating an actual evaporator. Zou and Hrnjak [3][4][5][6] studied the distribution characteristics of the header with the internal protrusion of 10 flat tubes, where the refrigerant flows from the lower five flat tubes to the upper five flat tubes.…”

Section: Introductionmentioning

confidence: 99%

Refrigerant Distribution Characteristics in Vertical Header of Flat-Tube Heat Exchanger without Internal Protrusion

Endoh¹

2017

JEPE

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A heat exchanger that arranges flat tubes horizontally has a vertical header that distributes the refrigerant to each tube. When the heat exchanger works as an evaporator, differences in flow conditions at each branch, such as the ratio and distribution of vapor and liquid, due to the differences in densities and momentums of vapor and liquid in the two-phase flow make equal distribution difficult. This paper describes the distribution characteristics of a four-branch header that has a rectangular cross-section without the internal protrusion of flat tubes in the case of the inflow of the refrigerant R32 from the bottom of the header by using an equipment that can estimate the distribution ratio of the liquid and vapor phase to each branch. This paper also discusses the distribution characteristics on the basis of the flow visualization in the header. The flow visualization shows that a liquid level that contains vapor phase exists in the header and affects the distribution greatly.

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Refrigerant distribution in a parallel flow heat exchanger having vertical headers and heated horizontal tubes

Cited by 69 publications

References 9 publications

Analysis on the refrigerant (R32) flow maldistribution of microchannel heat exchanger under superheat and sub-cool

Analysis on the refrigerant (R32) flow maldistribution of microchannel heat exchanger under superheat and sub-cool

Comparison and generalization of R410A and R134a distribution in the microchannel heat exchanger with the vertical header

Refrigerant Distribution Characteristics in Vertical Header of Flat-Tube Heat Exchanger without Internal Protrusion

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