Experimental investigation and theoretical modeling of liquid entrainment in a horizontal tee with a vertical-up branch

Welter, Kent; Wu, Qiao; You, Yancheng; Abel, K.; McCreary, D.; Bajorek, Stephen M.; Reyes, J.N.

doi:10.1016/j.ijmultiphaseflow.2004.08.001

Cited by 42 publications

(6 citation statements)

References 11 publications

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“…Most of the above models are for small-sized branches. However, some researchers have found that models used to predict liquid entrainment through small-scale branches are not suitable for large-scale branches (Riemke et al, 2006;Welter et al, 2014). Therefore, we have reason to doubt whether the model used to predict gas entrainment through small-scale branches is suitable for large-scale branches.…”

Section: Introductionmentioning

confidence: 98%

Influence of the Size and the Angle of Branches Connected to the Main Horizontal Pipe on the Onset of Gas Entrainment

et al. 2020

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The influence of the size and the angle of the branch on the onset of gas entrainment is explored in the present study. Since previous studies were performed on small-sized branches and the angles of the branches were specific (0 • or −90 • ), it is difficult to apply them to arbitrary-angled branches. So we conducted a series of experiments in a different direction of −30 • , −45 • , −60 • , and −90 • angles with the main pipe of 80-mm diameter and a branch of 31-mm diameter (T-tube). A new correlation is developed and can predict the most experimental data well within the error range of ±20%. And the new correlation can predict the onset of gas entrainment at arbitrary-angled branch and is not constrained by the angle of branches; that is, it has good versatility. We also gained some meaningful conclusions by analyzing experimental data and the entrainment phenomenon: gas is entrained by a vortex flow, and the size of the branch and the angle of the branch have little effect on the form of entrainment at a given h b /d. The critical Froude number (Fr L ) gradually increases as the angle of the branch changes from −90 • to −30 • . When this is compared with previous models, it can be found that the correlation of the onset of gas entrainment based on small-sized branches is not suitable for large-scale branches. But we have defined a new critical liquid level (h * b ) to successfully expand the scope of application of the correlation.Keywords: T-tube, onset of gas entrainment, size of branch, angle of branch, the onset of phenomenon

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Section: Introductionmentioning

confidence: 98%

Influence of the Size and the Angle of Branches Connected to the Main Horizontal Pipe on the Onset of Gas Entrainment

et al. 2020

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“…According to the different flow structure and liquid carryover mechanism, there are three types of liquid entrainment. The first type is liquid carryover by gas flow in straight tubes [1][2][3][4] and the second type is carryover through T-branches [5][6][7], the third category is the liquid entrainment in a liquid pool [8][9][10]. Liquid entrainment in straight tubes is caused by the shearing effect of the turbulent gas flow on the annular liquid film, while entrainment in the T-branches is caused by the destabilization of the gas-liquid interface under the pressure difference between the main and branch tubes and entrainment in the pool is due to the boiling and bubbling gas flow from the liquid pool.…”

Section: Introductionmentioning

confidence: 99%

“…Liquid entrainment in straight tubes is caused by the shearing effect of the turbulent gas flow on the annular liquid film, while entrainment in the T-branches is caused by the destabilization of the gas-liquid interface under the pressure difference between the main and branch tubes and entrainment in the pool is due to the boiling and bubbling gas flow from the liquid pool. The liquid entrainment problem in straight tubes [1][2][3][4] and T-branches [5][6][7] has received great attention with a large amount of experimental data having been accumulated and well-developed physical or semi-empirical models having been developed. However, there are relatively few studies on pool entrainment.…”

Section: Introductionmentioning

confidence: 99%

Measurement Method and Experimental Analysis of Liquid Entrainment for a Flooded Evaporator of a Water-Cooled Centrifugal Chiller Based on Energy Balance

Huang

Zhang

et al. 2021

Applied Sciences

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Liquid entrainment in a flooded evaporator has an important impact on the performance and safety of a water-cooled centrifugal chiller. In this paper, two methods for measuring the liquid entrainment factor in the evaporator of a centrifugal chiller based on energy balance are proposed. Method 1 involves only the heat exchange capacity of the evaporator and Method 2 involves both evaporator and condenser. The applicable conditions of the methods are discussed. Experimental measurements on the flooded evaporator of a single-stage water-cooled centrifugal chiller with refrigerant R134a show that, for a system with good thermal balance, there is little difference in the entrainment factor values obtained by the two methods. Method 2 was found to have slightly higher measurement accuracy, compared to Method 1. The uncertainty propagation analysis shows that for method two, the inlet and outlet water temperatures of the evaporator and condenser, motor input power, motor efficiency, transmission power loss and compressor suction and discharge temperatures are important factors. The experimental results show that the variation of the evaporator entrainment factor with refrigerant charge amount is different for different cooling capacity. At 700 and 800 refrigeration ton (RT), the entrainment factor of the test evaporator increases with the increase of refrigerant charge and the growth rate gradually accelerates. For the chiller tested, when the entrainment factor reaches 0.89% and 1.02%, respectively, at 700 ton and 800 ton, the rapid increase of the entrainment factor leads to a significant decrease in the coefficient of performance (COP) during the charging process. Based on the analysis of the experimental results, it is recommended that the maximum entrainment factor for efficient operation of the centrifugal chiller should be controlled within 1%.

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“…Wang et al (2011) and Smoglie et al (1987) assessed the entrainment onset of small branch pipes with horizontal, vertical upward and vertical downward directions by ignoring the viscosity and surface tension of the fluid. Furthermore, , Cho and Jeun (2004), Cho and Jeun (2007), and Welter et al (2004) also made outstanding contributions to the study on the onset of liquid entrainment. Lu et al (2018) have conducted a study on large branch pipe (D = 80 mm, d = 56 mm) with different angles.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Different Branch Angles and Different Branch Pipe Sizes on the Onset Law of Liquid Entrainment

Shen

Liu

et al. 2020

Front. Energy Res.

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The T-junction has been extensively employed in nuclear power plant systems. To ensure the normal operation of nuclear power plant, the onset point of T-junction liquid entrainment requires in-depth studies. Existing studies have been conducted on the onset point of liquid entrainment, whereas most of them are for small branch pipes. This study primarily discussed the onset law of large branch pipe. Moreover, the effects of branch angle and size on the onset point of liquid entrainment were analyzed by comparing it with other branch pipe sizes in this study. This study demonstrated that the effect of branch angle on the onset point of entrainment complies with that of other sizes, i.e., because that the decrease in the inertial force in the vertical direction acting on the liquid phase by the gas phase with the decrease in the angle, hence, the onset requires larger Fr g under the identical h b with the decrease in the angle between the branch pipe and the horizontal direction. Moreover, by comparing the onset point law of liquid entrainment exhibiting different branch pipe sizes, the effect of branch pipe size on the onset was reported in this study that the smaller branch pipe requires the greater gas velocity in the presence of onset. We found that there is different flow resistance of different sizes of branch pipe, small branch has larger flow resistance, in order to remedy the flow resistance, the gas dynamic head decreases, thereby causing the Bernoulli effect weaker; the onset of liquid entrainment requires larger V 3g .

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Experimental investigation and theoretical modeling of liquid entrainment in a horizontal tee with a vertical-up branch

Cited by 42 publications

References 11 publications

Influence of the Size and the Angle of Branches Connected to the Main Horizontal Pipe on the Onset of Gas Entrainment

Influence of the Size and the Angle of Branches Connected to the Main Horizontal Pipe on the Onset of Gas Entrainment

Measurement Method and Experimental Analysis of Liquid Entrainment for a Flooded Evaporator of a Water-Cooled Centrifugal Chiller Based on Energy Balance

The Effect of Different Branch Angles and Different Branch Pipe Sizes on the Onset Law of Liquid Entrainment

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