# Quantitative Analysis of Leakage Consequences of LNG Ship-to-Ship Bunkering Based on CFD

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## Abstract

**:**

## 1. Introduction

## 2. Numerical Calculation Model

#### 2.1. Governing Equations

^{3}; t is time, s; u

_{j}is the velocity vector in the j direction, m/s; x

_{j}is the length coordinate in the j direction, m; Γφ is the diffusion coefficient; S

_{φ}is the source term.

^{2}/s

^{2}; ε is the turbulent dissipation rate, m

^{2}/s

^{3}; β

_{v}is the bulk porosity; β

_{j}is the surface porosity in the j direction; μ

_{eff}is the effective viscosity of the fluid, Pa·s; P

_{k}is the generation term of the turbulent kinetic energy, N; P

_{ε}is the generation term of the turbulent dissipation rate, N; σ

_{k}and σ

_{ε}are the Prandtl–Schmidt numbers; C

_{2}= 1.92 is the model constant.

#### 2.2. Leakage Model

#### 2.2.1. Gas-Phase Leakage

^{2}; P

_{1}is the leakage pressure, Pa; P

_{2}is the ambient pressure, Pa; r is the gas adiabatic index; M is the molar mass of gas, g/mol; R = 8314 is the gas constant, J/(kmol·K); T is the pipe gas temperature, K; C

_{0}is the leakage port diffusion coefficient.

#### 2.2.2. Liquid-Phase Leakage

^{2}; ρ is the liquid density, kg/m

^{3}; P

_{0}is the ambient pressure, Pa; g is the gravitational acceleration; h

_{L}is the distance between the leak and the liquid level, m; C

_{0}is the leakage port diffusion coefficient.

_{sat}is the saturated vapor pressure of the liquid, Pa; R is the gas constant, J/(kmol·K); T

_{L}is the liquid temperature, K.

#### 2.3. Diffusion Model

_{g}is the ground roughness; λ

_{g}is the ground thermal conductivity; α

_{g}is the ground thermal diffusion coefficient; t

_{gw}is the time from the start of leakage of the liquid to contact with the ground; ω is the albedo; ε

_{g}and ε

_{p}are the emission coefficients of the surrounding gas and liquid pool, respectively; σ is the Stefan–Boltzmann constant.

#### 2.4. Physical and Computational Models

^{3}LNG bunker vessel are detailed in Table 1 and the main scale parameters of 14,800 TEU series dual-fuel container carriers are displayed in Table 2. Based on these parameters, 3D models were established using the FLACS software, as shown in Figure 1 and Figure 2. The model of the hose connection between the two vessels is shown in Figure 3. As can be seen from Figure 2, each bay position on the container vessel is 12.2 m 40 wide, with a gap of 1.2 m between bays. BAY2–BAY22 are located before the bow building, BAY22–BAY26 are located either side of the bow building, BAY26 is the bay position at which the bunkering station is located, BAY26–BAY70 lie between the bow building and the stern building, and BAY74–BAY86 are located after the stern building. There are 16 large container deep-water berths in Yantian Port. The total length of the inlet channel from the mouth of Dapeng Bay to the Yantian Port area is about 26 km, with a channel depth of 17.4 m and a channel width of 400 m. A three-dimensional model based on the FLACS satellite map of Yantian Port II is shown in Figure 4.

#### 2.5. Initial and Boundary Conditions

## 3. Quantitative Analysis of Leakage Consequences

#### 3.1. Leakage from Gas-Phase Hose

#### 3.2. Leakage from Liquid-Phase Hose

#### 3.3. Leakage at the Bunkering Station Flange Joints of Bunker Vessel

#### 3.4. Leakage at the Bunkering Station Flange Joints of Receiving Vessel

## 4. Results and Discussion

## 5. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

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**Figure 7.**Scenario 1 Spread of combustible vapor cloud under no-load conditions: (

**a**) Top view; (

**b**) Side view.

**Figure 8.**Scenario 1 Range of combustible vapor cloud dispersion under laden conditions: (

**a**) Top view; (

**b**) Side view.

**Figure 10.**Scenario 2 Range of combustible vapor cloud dispersion under ballast conditions: (

**a**) Top view; (

**b**) Side view.

**Figure 11.**Scenario 2 Range of combustible vapor cloud dispersion under laden conditions: (

**a**) Top view; (

**b**) Side view.

**Figure 12.**Illustration of the location of a flange joint leak at the bunkering station of the bunker vessel.

**Figure 13.**Scenario 3 Range of combustible vapor cloud dispersion under ballast conditions: (

**a**) Top view; (

**b**) Side view.

**Figure 14.**Scenario 3 Range of combustible vapor cloud dispersion under laden conditions: (

**a**) Top view; (

**b**) Side view.

**Figure 15.**Schematic diagram of the location of a flange joint leak at the bunkering station of the receiving vessel.

**Figure 16.**Scenario 4 Spread of combustible vapor cloud under no-load conditions: (

**a**) Top view; (

**b**) Side view.

**Figure 17.**Scenario 4 Range of combustible vapor cloud dispersion under laden conditions: (

**a**) Top view; (

**b**) Side view.

Main Parameters | Value | ||||
---|---|---|---|---|---|

Overall length × width × depth | 119.30 × 19.8 × 11 m | ||||

Laden draught | 6.475 m | ||||

Ballast draft | 4.264 m | ||||

Laden Displacement | 11,109 t | ||||

Ballast discharge | 6729 t | ||||

No.1–No.2 Type C Independent Liquid Cargo Hold | 4100 m^{3}/4100 m^{3} | ||||

Tubes | Interface form | Caliber (“) | Quantity (single side) | Distance to tail plumb line (m) | Distance from baseline (m) |

Liquid Phase Tubes | Flange | 8 | 2 | 86.4/83.4 | 16.03 |

Gas phase tubes | Flange | 8 | 1 | 84.9 | 16.03 |

Range of flat sections of the hull | Laden (m) | Ballast (m) | |||

Distance from stern plumb line to the rear intersection point of parallel mid-body/waterline | 9.00 | 21.46 | |||

Distance between parallel mid-body/waterline forward intersection and bow and stern plumb lines | 80.07 | 75.50 |

Main Parameters | Value | ||||
---|---|---|---|---|---|

Overall length × width × depth | 366 × 51 × 29.85 m | ||||

Design draught | 14.524 m | ||||

Structural draft | 16.024 m | ||||

Ballast draft | 8.27 m | ||||

Design Draft Displacement | 180,331 t | ||||

Ballast Draft Displacement | 90,279 t | ||||

Type B Independent Liquid Cargo Tank | 12,000 m^{3} | ||||

Liquid Cargo Tank Evaporation Rate BOR | 0.17% | ||||

LNG bunkering station interface | spread pattern L-V-L | ||||

Tubes | Interface form | Caliber (“) | Quantity (single side) | Distance to tail plumb line (m) | Distance from baseline (m) |

Liquid Phase Tubes | Flange | 8 | 2 | 231.55/235.75 | 32.448 |

Gas phase tubes | Flange | 12 | 1 | 233.75 | 32.448 |

Range of flat sections of the hull | Design draft (m) | Ballast draft | |||

Distance from stern plumb line to the rear intersection point of parallel mid-body/waterline | 57.20 | 120.28 | |||

Distance between parallel mid-body/waterline forward intersection and bow and stern plumb lines | 265.88 | 247.01 |

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**MDPI and ACS Style**

Kong, X.; Jiao, W.; Xiang, W.; Wang, Q.; Cao, J.; Han, L.
Quantitative Analysis of Leakage Consequences of LNG Ship-to-Ship Bunkering Based on CFD. *Energies* **2023**, *16*, 4631.
https://doi.org/10.3390/en16124631

**AMA Style**

Kong X, Jiao W, Xiang W, Wang Q, Cao J, Han L.
Quantitative Analysis of Leakage Consequences of LNG Ship-to-Ship Bunkering Based on CFD. *Energies*. 2023; 16(12):4631.
https://doi.org/10.3390/en16124631

**Chicago/Turabian Style**

Kong, Xiangyu, Wenling Jiao, Weidong Xiang, Qiang Wang, Jiaolong Cao, and Lianfu Han.
2023. "Quantitative Analysis of Leakage Consequences of LNG Ship-to-Ship Bunkering Based on CFD" *Energies* 16, no. 12: 4631.
https://doi.org/10.3390/en16124631