Sub-channel flow regime maps in vertical rod bundles with spacer grids

Ren, Qingwen; Zhou, Wen-xiong; Du, Shaowu; Li, Zhongchun; Pan, Liang‐ming

doi:10.1016/j.ijheatmasstransfer.2018.01.133

Cited by 26 publications

(7 citation statements)

References 38 publications

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“…The results presented in this paper have been obtained for a tube bundle geometry containing 15 full cylinders organised in a square array. The tube diameter and array pitch match the experiments of Ren et al [1] and Liu et al [2].…”

Section: Introductionsupporting

confidence: 84%

A Novel Inlet Model for Two-Phase Bubbly Axial Flow Through a Tube Bundle

Moerloose¹,

Paepe²,

Degroote³

2021

14th WCCM-ECCOMAS Congress

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In numerical research about two-phase flow in tube bundles, mainly two trends are distinguishable. On the one hand, some studies start from the assumption that only relatively small bubbles occur in a continuous liquid flow, for which typically Eulerian-Lagrangian modelling is appropriate. This approach is not suitable when modelling flow-induced vibrations in tube bundles, as the most severe vibration conditions are achieved in intermittent, churn or slug flow. On the other hand, some studies focus on accurate numerical modelling of the bubble shape. In that case, it is customary to start from a bubble which is already present inside the domain. However, in order to simulate a sufficiently long flow time which is of interest in the current research, the bubbles should enter the domain through an inlet boundary. In this paper, a new inlet model is proposed which defines a transient inlet boundary condition to be applied in a subsequent Eulerian simulation, more specifically using the Volume-Of-Fluid method. In the first part of this paper, the inlet model is described. The model guarantees the introduction of a userspecified amount of gas during a set time-interval at locations in space and time that are chosen randomly. Subsequently, the model is tested on a 3x5 tube bundle subjected to an axially flowing air/water mixture. The computational time required to complete the inlet model is reported for different values of the most important model parameters. Finally, the computational effort of the new inlet model is compared to that of a simulation with a precursor-domain where bubbles are created by break-up of air jets imposed at the inlet.

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Section: Introductionsupporting

confidence: 84%

A Novel Inlet Model for Two-Phase Bubbly Axial Flow Through a Tube Bundle

Moerloose¹,

Paepe²,

Degroote³

2021

14th WCCM-ECCOMAS Congress

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“…And the presupposed superficial gas and liquid velocities in the test conditions were determined on the purpose of covering a larger range of flow velocities and flow regimes. The flow regime transition lines for gas-liquid flow in rod bundle channel proposed by different researchers were also shown in Figure 5, which includes the global flow regime map proposed by Paranjape et al (2008) based on a plate-type impedance void meter, the theoretical global flow regime transition criteria developed by Liu and Hibiki (2017), and the inner subchannel flow regime map acquired by Ren et al (2018d) based on a sub-channel impedance void meter.…”

Section: Test Conditionsmentioning

confidence: 97%

“…The local superficial gas velocity j g was different because of the different local pressures. The core-peak phase distribution was not so apparent at j l 0.50 m/s, j g 0.19 m/s, which belonged to cap bubbly flow according to the sub-channel flow regime map developed by Ren et al (2018d). Because the void fraction values at the sub-channel centers were larger than those at the adjacent gaps, it was still deemed as the core-peak phase distribution.…”

Section: Superficial Liquid Velocitymentioning

confidence: 97%

“…Moreover, the phase distribution characteristics at the inlet (Port 0 shown in Figure 3) could be referred from Ren et al 2018a. More information about the experimental setup could be found in the authors' previous research (Ren et al, 2018a;Ren et al, 2018b;Ren et al, 2018c;Ren et al, 2018d;Ren et al, 2018e;Liu et al, 2018;Ren et al, 2019;Ye et al, 2019).…”

Section: Experimental Setup Test Loopmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Study on the Transition Characteristics and Criterion From Wall-Peak to Core-Peak Phase Distribution in Vertical Rod Bundles

Ren¹,

Pu²,

Pan

et al. 2021

Front. Energy Res.

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Aiming at understanding the phase distribution characteristics and developing the transition criterion from wall-peak to core-peak phase distribution in a rod bundle channel, air–water two-phase flow experiments were conducted in 5 × 5 rod bundles in the Interfacial Evolution Research Facility at Chongqing University (IERFC). Based on the experimental data, the influences of gas velocity, liquid velocity, mixing vane spacer grid (MVSG), and geometrical size on phase distribution have been analyzed in detail. With the increasing superficial gas velocity and decreasing liquid velocity, the wall-peak phase distribution turned to core-peak. The wall-peak phase distribution was enhanced by an MVSG, and the transition from the transitional phase distribution to the wall-peak phase distribution appeared when the air–water mixture flowed through the MVSG. The gap size was the key factor for the transition of phase distribution in rod bundles. Moreover, the transition criterion from wall-peak to core-peak phase distribution was developed based on present experimental data and the data in the literature, which was also verified based on the limited data. More experiments were recommended to focus on the detailed phase distribution in the rod bundle channel with different geometrical sizes.

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“…After the description of the CFD model in Section 3, the performance of the SBM will be evaluated on a test case containing a square 5-by-3 tube bundle subjected to an axially flowing air/water mixture. The tube diameter and array pitch match the experiments of Ren et al (2018) and Liu et al (2018). A simulation using the boundary condition defined with the SBM is compared to two precursor domain calculations in Section 4.…”

Section: Introductionmentioning

confidence: 94%