Distribution of two-phase annular flow at header–channel junctions

Lee, Jun Kyoung; Lee, Sang Yong

doi:10.1016/s0894-1777(03)00042-6

Cited by 86 publications

(33 citation statements)

References 1 publication

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“…The evaluation methods for the distribution performance employed by previous researchers can be categorized into three types: (a) First, instead of using refrigerant as a working fluid, either an air-water or a nitrogen-water mixture, are used. The flow rates of the gas and liquid are measured, respectively, at every branch tube after the distributor (1) . This method is relatively simple to test due to the simplicity of the separation of the gas-liquid phase.…”

Section: Previous Test Methodsmentioning

confidence: 99%

Performance Evaluation and Optimization of A Refrigerant Distributor for Air Conditioner

Yoshioka

Kim

Kasai

2008

JTST

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Refrigerant mal-distribution in a distributor located at the inlet of a heat exchanger used for an air conditioning system plays an important role in the heat exchanger performance. Distribution performance in the distributor is greatly affected by the flow conditions as well as the geometrical parameters of the distributor. To clarify the distribution characteristics, it is essential to know flow rates of both liquid and vapor states at every branch tube after distribution. This paper proposes a relatively simple test method, which enables to measure the inlet quality and the flow rate of refrigerant at every branch of the distributor. By using the proposed evaluation method, optimization on the geometrical parameters of the distributor was conducted to reduce the refrigerant mal-distribution. It was confirmed that the optimized distributor was able to reduce the mal-distribution of the refrigerant over branches despite the flow condition changes. By the flow visualization of the refrigerant in the distributor, it was observed that certain amount of liquid refrigerant remained and swayed unstably at the bottom of the distributor. It is supposed that the liquid refrigerant behavior in the distributor great affects the distribution performance.

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Section: Previous Test Methodsmentioning

confidence: 99%

Performance Evaluation and Optimization of A Refrigerant Distributor for Air Conditioner

Yoshioka

Kim

Kasai

2008

JTST

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“…An empirical model was developed to describe phase split in the header. Lee et al (2004) examined the distribution of air-water twophase annular flow in a vertical heat exchanger header. The effect of tube protrusion was examined and the most uniform distribution could be achieved by adjusting the depth of protrusion.…”

Section: Introductionmentioning

confidence: 99%

Quantification of liquid refrigerant distribution in parallel flow microchannel heat exchanger using infrared thermography

Hrnjak

2015

Applied Thermal Engineering

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This paper presents a method to quantify the distribution of liquid refrigerant mass flow rate in parallel flow microchannel heat exchanger from the infrared images. Quantification is achieved by building the relationship between the liquid mass flow rate through each microchannel tube and the air side capacity calculated from the infrared measurement of the wall temperature. After being implemented in a heat exchanger model, the quantification method is validated against experimental data. This method can be used for several types of heat exchangers: evaporators, condensers etc., also it can be applied to various heat exchanger designs: different inlet/outlet locations, different flow configurations etc.

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“…The thermal performance of the evaporator is greatly affected by the flow distribution characteristics of the multi-pass channel, and a uniform distribution of liquid to all the branches is desirable to the evaporator. Therefore, the two-phase flow distribution in multi-pass channels has been a major problem in development of compact heat exchangers, and many studies have been conducted on this subject in real refrigerant flow system [2][3][4][5][6][7][8][9] or in isothermal air-water flow system [10][11][12][13][14][15][16][17]. Recently, an extensive review of researches on the gas-liquid flow distributions in T-junctions and multi-pass channels was published by Lee et al [18].…”

Section: Introductionmentioning

confidence: 99%

Gas-Liquid Flow Distributions in Multipass Channels with Vertical Upward Branches

Razlan¹,

Goshima²,

Hirota³

et al. 2011

TOTPJ

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The gas-liquid flow distributions in multi-pass channels that simulate a compact evaporator used for an automobile air-conditioning system was examined experimentally. The test channel had a horizontal header with a square cross section of 20mm × 20mm and a length of 255mm, and ten upward branches with a length of 200mm were connected to it. Experiments were conducted in an isothermal air-water flow system. Special attention was directed to influences of (i) flow-inlet condition at the header entrance (stratified-flow inlet and mist-flow inlet), (ii) pressure condition at the branch outlets (uniform backpressure and non-uniform backpressure) and (iii) pressure-loss characteristics of branches (flat tubes and multi-port tubes) on the gas-liquid distribution characteristics. In addition to the gas-liquid distributions to branches, the pressure distributions in the headers were measured to make clear the pressure condition in a real evaporator. It was found that the outlet pressure condition of branches exerts great influence on the gas-liquid distributions to branches in the channel with flat tube branches, but it has only minor influence in the channel with multiport tube branches. The flow-inlet condition at the header entrance has significant influence on the gas-liquid distribution, and the uniformity of the liquid distribution to branches is improved under the mist-flow inlet condition. The pressure in the headers showed uniform distributions in the longitudinal direction, suggesting that the uniform backpressure condition at the branch outlets is appropriate for reproducing the flow in a real compact evaporator with multi-pass channels.

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Distribution of two-phase annular flow at header–channel junctions

Cited by 86 publications

References 1 publication

Performance Evaluation and Optimization of A Refrigerant Distributor for Air Conditioner

Performance Evaluation and Optimization of A Refrigerant Distributor for Air Conditioner

Quantification of liquid refrigerant distribution in parallel flow microchannel heat exchanger using infrared thermography

Gas-Liquid Flow Distributions in Multipass Channels with Vertical Upward Branches

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