Cargo Hold Research Articles

Design of Cargo Hold Ventilation Electrical System for PCTC

The design of the PCTC cargo compartment ventilation system is an important system in the overall PCTC ship design, which is related to the design of multiple specialties such as general, structure, outfitting, machinery and electrical section. In recent years, the design of the cargo hold ventilation system for PCTC ships has also been constantly changing, improving, and optimizing. This article summarizes and optimizes the current mainstream design schemes for the electrical system of PCTC cargo hold ventilation, taking into account both the construction cost of the shipyard and the operating cost of the shipowner, for reference by relevant designers.

A method for accurate extraction of three-dimensional point cloud feature data in loading test of container ships

The accuracy of container slot dimensions directly affects the efficiency and safety of container loading and unloading. However, traditional methods of container loading tests need to be improved for their long cycles, high costs, and low production efficiency. With the application of three-dimensional laser scanning devices in ship manufacturing, the use of simulated container loading test methods based on point cloud becomes a breakthrough in key technology for container ship construction. This paper presents a multi-objective segmentation method of cargo hold feature point cloud for container ship simulated loading tests. Data preprocessing algorithms are applied to remove noise and pseudo-image, and then a Random Sample Consensus algorithm is used to remove bulkhead and cargo bottom point clouds. Based on the density-based spatial clustering of applications with noise algorithm and the region growing algorithm, an algorithm for multiple segmentation of guide rail and bottom cone point clouds is devised, and a four-plane segmentation of guide rail point clouds is realized. Finally, a method for three-dimensional point cloud data flatness assessment and a Hausdorff distance based method for calculating the guide rail lateral and longitudinal spacing are proposed. These methods are validated through the loading test of a 16,000 TEU container ship.

Numerical Study on the Anti-Sloshing Effect of Horizontal Baffles in a Cargo Hold Loaded with Liquefied Cargo

Sloshing of liquefied bulk granular cargoes weakens the stability of cargo carriers when at sea. Using the horizontal rectangle baffle is a promising way to restrain its sloshing motion. But the location height and optimal baffle area rate to achieve a better anti-sloshing effect should be studied first. The discrete element method was adopted to establish the simulation model, and the direct shear test was used for verification. Through the static tilt tests, the definite relationship between the effects of moisture content on cargo motion and particle friction coefficients was acquired. Then, liquefied cargo motion in a cargo hold without baffles and with one and two pairs of horizontal baffles was simulated. Based on variations in the cargo gravity center offset and the sloshing-induced force on the cargo hold, the anti-sloshing effect of different settings of the baffles was compared. Results show that the baffles have the ability to restrain cargo sloshing, and this is important for sea transportation safety. The anti-sloshing effect is better when the baffle plane is right on the cargo top surface compared to the other location heights. Further, there is an optimal length–width combination, e.g., a single baffle plane with a length of 0.26 L and a width of 0.46 B, at which a better anti-sloshing effect could be achieved with the smallest baffle area rate. This study could be useful for the practical application of horizontal baffles for bulk granular cargo carriers.

Research on temperature distribution in container ship with Type-B LNG fuel tank based on CFD and analytical method

The liquefied natural gas (LNG) fuel tank in a large container ship is loaded with liquid LNG at an ultra-low temperature (-163°C), there is a significant temperature difference in the cargo hold area where the entire fuel tank is located, which will have an important impact on the steel grade design and structural safety of the cargo tank in container ship. This paper develops two heat transfer models using Computational Fluid Dynamics method (CFD method) and an analytical method to analyze the temperature distribution in a large container ship equipped with Type-B LNG fuel tank. These models incorporate the arrangement and heat transfer characteristics of LNG fuel tanks. The temperature field analysis is conducted under typical the environmental conditions specified in the Code for the Construction and Equipment of Ships Transporting Liquefied Gas in Bulk (IGC Code) and the United States Coast Guard Code (USCG Code), based on the CFD method and the analytical method, and the results of temperature field distribution are compared. Additionally, a parametric analysis of the hull temperature field is further carried out, the results show that the thermal conductivity of the insulation layer in LNG storage tanks and the types of the loaded liquid cargo have a limited impact on the final temperature field distribution in hull structure. However, the selection of steel grade in the local structure of the cargo hold, especially in the inner hull part, may lead to significant changes.

A holistic safety assessment for cargo holds and decks fire & explosion risks under fuzzy Bayesian network approach

Fire and explosion are one of the fatal causalities frequently encountered in maritime transportation. Due to technical or/and human error, fire and explosion can be occurred either in the cargo hold or deck of bulk carriers. According to the EMSA report (2022), fire and explosion causalities were ranked 4th on the top. Fire and explosion accidents onboard may pose hazards for human life and the maritime environment. In this context, performing a comprehensive risk assessment is of paramount importance for safer navigation, cargo operation, and the marine environment. This study aims to assess the risks, including human errors, of fire and explosion accidents in cargo holds and decks of bulk carriers under the fuzzy Bayesian networks (BN) approach. Since BN provides a robust tool for calculating the conditional probability of risk, fuzzy sets deal with uncertainty and ambiguity during expert judgments. The outcomes of the paper are expected to contribute to bulk carrier ship owners, safety superintendents, HSEQ managers, Master, Chief officers, and crew on-board ships to understand basic events that may cause fire and explosion and to improve safety at the operational level.

Smoke Detection with Dual Convolutional Networks From Infrared Frames

In many smoke detection fields, such as fire detection in confined space of aircraft cargo hold, the false alarm rate is still high. In the closed and dark environment of the confined space cabin, the traditional video smoke detection method is difficult to find the fire early because of the limitation of lighting conditions. The advantage of fire detection based on infrared video image is that it does not need lighting conditions and has better performance in dark environment. There is a rapid temperature rise process in the confined space at the beginning of the fire, which is more easily captured by infrared cameras. However, there is little research on infrared frame detection methods in confined space. Therefore, based on the limited space environment of aviation industry, this paper studies the smoke detection problem under the infrared framework, and proposes a high-precision fire and smoke image detection algorithm based on infrared double convolution neural network. By modeling the texture features of neural network and infrared smoke frames, and using video frames as an auxiliary means to increase the number of available training images, the problem of insufficient infrared video data sets is solved. The experimental results show that the detection effect of this method is better than other comparison algorithms in limited space, and the detection false alarm rate is effectively reduced.

Research on Key Technologies for Container Ship Loading Test Based on 3D Laser Scanning

_ Traditional accuracy check methods for cargo hold in container ships rely solely on manual and visual operations, which are time-consuming and resource-intensive. Addressing the challenge of extracting and analyzing key data, such as cell guides and container pedestals, from large-scale point clouds obtained through three-dimensional (3D) laser scanning in container ship trial runs, this paper proposes an algorithmic framework based on 3D laser scanning. Building upon this framework, an improved coordinate-axis filtering RANSAC algorithm is employed to optimize the extraction of cell guide planes. Additionally, an algorithmic process based on Bhattacharyya distance is utilized to automatically extract container pedestal point clouds. Furthermore, a combination of the genetic algorithm and the ICP algorithm is proposed to achieve the fitting of the container pedestal edge contour through point cloud registration. Experimental results demonstrate the consistency between the extracted cell guide and container pedestal data and the actual results, indicating the high practical value of the proposed methodology. Keywords container ship loading test; cargo hold accuracy check; 3D point cloud processing

Reliability Analysis of Crack Growth Occurrence for a Secondary Hull Component due to Vibration Excitation

Abstract Ship hull vibration is a significant contributor to fatigue crack growth and the major sources of vibrations are found to be the main engine vibration excitation, the wave-induced springing and whipping loads, and the action of the propeller. In the midship region, wave-induced loads and the main engine are the major contributors, whereas propeller excitation dominates in the aft region of the ship hull. No general method exists to solve all kinds of vibration problems and they need to be evaluated through a cost-by-case approach. The complex and uncertain aspects of hull vibration and fatigue crack growth motivate the need for a reliability-based scheme for assessing the resulting fatigue crack propagation. In the present paper, a probabilistic formulation for the failure probability of the occurrence of crack propagation of a secondary hull component is outlined. A generic cargo hold model is analyzed with engine excitation and wave-induced loading as vibration sources, and a stochastic model for vibration response is outlined. The limit state is formulated as the possible occurrence of fatigue crack growth. The secondary hull component considered is a pipe stack support, which is a supporting component that attaches the cargo pipes to the wall inside a cargo tank. Different initial crack sizes are implemented to evaluate the adequacy of the applied stochastic model for vibration response and the accuracy of the estimated failure probability is assessed.

The Developmentof Software to Automate the Laser Welding of a Liquefied Natural Gas Cargo Tank Using a Mobile Manipulator

The demand for liquefied natural gas (LNG) ships is increasing for various reasons. Despite their enormous size, cargo holds inside freighters transporting LNG have traditionally been constructed by welding to high-quality standards for safety. This process traditionally relies on manual labor or semi-automatic moving devices. In this study, a methodology was designed for robot-based automated laser welding inside large LNG cargo holds. The developed approach offers a practical solution to challenging issues such as the corrugation of the membrane that forms the inner walls of LNG cargo holds and the inter-floor movement of robots. This study analyzes and restructures the work for laser welding using mobile robots inside LNG cargo holds composed of membranes. For realistic constraints, such as inter-floor movement of robots and high-quality welding of membrane corrugations, methods integrated with manual work have been proposed. Additionally, for the overall membrane laser welding of the LNG cargo hold space, an automated method using robots was suggested. The developed methodology has been realized as operational software for the movement of robots for laser welding in LNG cargo holds.

Bulk Grain Cargo Hold Condensation Based on Computational Fluid Dynamics

In order to assess whether condensation will occur on the shipside of a bulk grain cargo hold during transportation at sea, this paper has established a ventilation model for the bulk cargo hold of the ship, and optimized the model according to the characteristics of the solid bulk grain stowed on a moving ship at sea. The temperature field, micro-airflow field and relative humidity field of the bulk grain in a cargo hold are simulated by using fluent software (v.2020). Incorporating the impact of grain moisture exchange, the Equilibrium Relative Humidity (ERH) method is introduced alongside the Dew Point (DP) method to determine the condensation on the shipside of the cargo hold. The results of simulation are in agreement with the practical observation results obtained from an actual ship with a heavy cargo damage claim. Conclusively, this paper finds that the risk of the condensation on the shipside of a bulk grain cargo hold always exists if the inner part of the shipside is directly in contact with the grain. Meanwhile, when the grain temperature near the shipside decreases, the moisture in the cargo hold will migrate to the shipside due to the temperature gradient. Furthermore, the longer the voyage, the more obvious the migration of moisture from the central part of the bulk grain to the shipside, and the greater the risk of condensation.

Numerical Investigation of an Unmanned Aerial Vehicle Launch from Military Transport Aircrafts

Launching a fixed-wing unmanned aerial vehicle (UAV) out of the cargo hold of a flying transport aircraft (TA) is numerically investigated. A numerical tool chain is established to capture the dynamic motion of the UAV during launch, in which the DLR-TAU Code flow solver is coupled with a flight mechanics tool. A parameter study investigates how the UAV launch speed, position, and orientation relative to the loading platform of two different TAs affect its trajectory and aerodynamic behaviors. Furthermore, the influence of the angle of attack of the TA on the UAV trajectory and pitch angle is analyzed. This information will help design a launch mechanism that ensures a safe separation and aerodynamically stable flight after launch.

The causes and responses to cargo hold fire accidents in RoRo ships using AcciMap

ABSTRACT The recent string of cargo hold fire incidents on RoRo ships represents one of the most challenging types of ship fire accidents. The densely stowed vehicle cargo loading structure and large volume of RoRo ship cargo holds are factors that complicate firefighting efforts. In addition, vehicle cargoes have a higher likelihood of self-ignition compared to other types of cargo and produce dense smoke when a fire occurs. Combustible materials inside vehicles can also contribute to the spread of fires after they start. Particularly, the recent increase in demand for electric vehicles calls for changes in how we respond to potential cargo hold fires on RoRo ships and heightens the risk of such incidents. In this study, we analyzed major domestic and international RoRo cargo hold fire incidents using AcciMap, a system analysis method. Through this analysis, we identified needs for improved management of vehicle cargo conditions, responses to fixed firefighting systems and system inspections, as well as improvements to fire detection systems. By using a systems analysis approach, we were able to identify areas for improvement needed by ships, ports, governments, shippers, and shipping companies.

A reliability-based design and optimization strategy using a novel MPP searching method for maritime engineering structures

PurposeIn order to solve the problems faced by First Order Reliability Method (FORM) and First Order Saddlepoint Approximation (FOSA) in structural reliability optimization, this paper aims to propose a new Reliability-based Design Optimization (RBDO) strategy for offshore engineering structures based on Original Probabilistic Model (OPM) decoupling strategy. The application of this innovative technique to other maritime structures has the potential to substantially improve their design process by optimizing cost and enhancing structural reliability.Design/methodology/approachIn the strategy proposed by this paper, sequential optimization and reliability assessment method and surrogate model are used to improve the efficiency for solving RBDO. The strategy is applied to the analysis of two marine engineering structure cases of ship cargo hold structure and frame ring of underwater skirt pile gripper. The effectiveness of the method is proved by comparing the original design and the optimized results.FindingsIn this paper, the proposed new RBDO strategy is used to optimize the design of the ship cargo hold structure and the frame ring of the underwater skirt pile gripper. According to the results obtained, compared with the original design, the structure of optimization design has better reliability and stability, and reduces the risk of failure. This optimization can also better balance the relationship between performance and cost. Therefore, it is recommended for related RBDO problems in the field of marine engineering.Originality/valueIn view of the limitations of FORM and FOSA that may produce multiple MPPs for a single performance function, the new RBDO strategy proposed in this study provides valuable insights and robust methods for the optimization design of offshore engineering structures. It emphasizes the importance of combining advanced MPP search technology and integrating SORA and surrogate models to achieve more economical and reliable design.

Study on fuel cold energy utilization of large ammonia powered ship

Taking large ammonia powered container ship as the research object, a set of liquid ammonia cold energy cascade comprehensive utilization system is designed. The system mainly includes low temperature cargo hold system, high temperature cargo hold system and marine air conditioning system. Aspen HYSYS software is used to simulate the system scheme. Based on the utilization rate of cold energy in the low temperature cargo hold system, the maximum of liquid ammonia flow fraction under different operating conditions was determined, and the cold energy utilization system exergy efficiency was calculated. In the 75% working condition of the ship, when the flow fraction was 40%, the whole cold energy utilization system exergy efficiency was 34.42%, in this way, the effective utilization of liquid ammonia cold energy is realized.

Study on the Crashworthiness Performance of A Cargo Hold Support Column of A Civil Aircraft

With the continuous development of China’s general aviation industry, there are urgent requirements for research on aircraft crashworthiness to provide better safety for aircraft occupants. According to the results of long-term crash investigations, if crash safety design is taken into account at the earliest stages of aircraft design, most accidents will become viable or partially survivable, which can greatly improve the survival rate of aircraft passengers after an accident. In this paper, the design criteria and design methods for crash resistance technology of aircraft cargo uphold pillars are studied, and the crash simulation analysis of a certain type of aircraft is analyzed. First, a feasible design method and optimization principle are formulated according to the specific characteristics of a certain type of aircraft; Then, the crash resistance characteristics of a certain type of aircraft are analyzed, and the finite element model of the fuselage and cargo uphold pillars structure is established based on the three-dimensional electronic prototype of the aircraft. By the crash conditions specified in the relevant specifications, a mechanical simulation study of the aircraft is carried out, and the results are analyzed. Finally, constructive comments are given based on the simulation results. The reliability of the design is verified using simulation analysis, which provides a reference for the simulation and analysis of the anti-crash design of the aircraft cargo uphold pillars structure.

Long-term approach for assessment of sloshing loads in LNG carrier, part II: Grouping method

Assessing the sloshing loads has been a significant issue in designing the cargo containment system (CCS) of a liquefied natural gas carrier (LNGC). The sloshing problem contains numerous physical and technical uncertainties. The long-term approach has been suggested to reduce the possible uncertainties, but it has not been a feasible option owing to the incalculable number of experimental cases. Daewoo Shipbuilding and Marine Engineering Co., Ltd., Hyundai Heavy Industry Co., Ltd., Samsung Heavy Industry Co., Ltd., Korean Register, and Seoul National University conducted extensive sloshing model tests for the 174 K S-LNGC. To consider the long-term approach, Part I describes the differences between short- and long-term approaches based on the guidelines of different classification societies. To address the significant number of experimental conditions required for the long-term approach, a grouping method is investigated (Part II). Although this grouping method is typically used in practical design, it has not been validated, and its applicability is yet to be determined. In Part II, the sea states are classified using 16 different grouping methods. The long-term exceedance probabilities and pressures are obtained individually and then compared with the results obtained from fully considering all sea states. After performing the general sloshing model test of the shipbuilding industry, the sloshing impact pressure of a liquefied natural gas cargo model is measured via 6DoF irregular simulations, where the upper section of the cargo hold structure is considered. Long-term pressures are locally and globally investigated and compared among 16 different sea states and all the sea states. Based on the results, the best grouping method is suggested for the long-term approach.

Thermodynamic qualification of knitted spacer fabrics for use as insulation box insert in the context of refrigerated transport containers in the logistics sector

Temperature-sensitive products such as refrigerated and frozen goods pose particular challenges for logistics. Against the background of the mobility shift towards electric vehicles and the current challenges of temperature-stable transport in the field of pharmaceutical, esp. vaccine logistics in the context of the SARS-CoV-2 pandemic, new, energy-efficient vehicle equipment is needed to maintain cold chains. Known refrigeration concepts are designed to cool the entire cargo hold. In addition, the goods cannot be removed from the vehicle while maintaining the cold chain. An insulating effect of containers is typically achieved by using foamed polystyrene (Styrofoam). On the one hand, these structures have a very good insulating effect, but on the other hand, they cannot be reduced in volume during recirculation and are problematic with regard to recycling. The aim of the research presented here is therefore to develop a knitted box that is designed as a volume-reducible, rigid but foldable box. This can be used as a supplement to existing transport container systems and therefore can be inserted in the transport container. The knitted box performs as insulation when the transported goods are actively cooled inside the box, which is more sustainable and flexible than recent insulation solutions. Knitted fabrics, especially spacer fabrics, have advantageous thermo-physical properties for this application due to their structural design. In the course of a research project, various spacer fabrics were tested for their thermo-physical suitability as insulation materials. It was found that knitted predetermined folding lines represent an insulation gap. Based on this, a new structure was developed which, due to its structural design, compensates for cold or thermal bridges at vertices and edges of the box. The results show that the knitted corrugated structure insulates better than the knitted spacer fabrics with predetermined folding lines. A thermal imaging camera was used to identify critical points for heat transfer.

PROPOSED DESIGN CRITERIA FOR A BILGE PUMPING SYSTEM: A CASE STUDY OF LARGE BULK CARRIER

In this study, the bilge pumping performance was investigated using the actual bilge pumping arrangement of a 180K class bulk carrier, and it was assumed that the No. 1 cargo hold was fully flooded. As a result of the calculation, the mean water velocity at bilge main could not satisfy the 2m/s requirement while discharging all the accumulated water from the flooded No. 1 cargo hold with the actual arrangement installed on the 180K class bulk carrier. As a result of the calculation by modified arrangement, it was found that the 2 m/s requirement could be satisfied when a pipe smaller than the required internal diameter according to the rule requirements of classification societies was applied to the bilge main under the same pump conditions. In addition, it was found that the flow rate of the pump should be increased by at least 40% when piping acceptable for the rule requirements of classification societies was applied to the bilge main. The bilge pumping system of 180K bulk carriers may be similar for every ship, and in our opinion, urgent modifications and repair are necessary for consideration of the characteristics of bulk carriers with a relatively high risk of flooding. According to the GBS structure, the rule requirements of classification societies regarding bilge pumping system should comply with the intended purpose of SOLAS Regulation II-1/35-1. It is proposed to revise SOLAS Regulation II-1/35-1 by applying the concept of Performance-Based Standard (PBS) in order to secure the performance of the bilge pumping system by applying a pipe smaller than the required internal diameter according to the rule requirement of classification societies. In particular, it is proposed that SOALS Regulation II-1/35-1.3.9, the requirement for the required internal diameter of bilge main, should be deleted so that any size pipe can be used if the bilge pumping performance can satisfy the 2 m/s requirement. Finally, “2 m/s Criterion” is proposed only design criteria to fulfill the intended purpose of the 2 m/s requirement of SOLAS.

Long-term approach for assessment of sloshing loads in LNG carrier, Part I: Comparison of Short- and Long-term approaches

To assess the long-term sloshing loads of a liquefied natural gas carrier, Daewoo Shipbuilding and Marine Engineering Co., Ltd., Hyundai Heavy Industry Co., Ltd, Samsung Heavy Industry Co., Ltd. (SHI), Korean Register, and Seoul National University conducted a series of joint industrial experiments using a six-degree-of-freedom irregular sloshing model test. SHI provides a 174 K S-LNGC and its cargo hold information. To consider the numerous test conditions of the long-term approach, the present study focuses on the upper regions of the cargo hold structure, and feasible operating scenarios are assumed. A total of 3870 h at a real scale are simulated based on 387 sailing conditions. Extensive experimental results of sloshing loads are analyzed based on different guidelines suggested by different maritime classification societies. Part I of this study provides an assessment of sloshing loads based on a comparison of short- and long-term approaches distinguished by the guidelines, and the possible reference values are presented. A practical solution for the long-term approach will be discussed in Part II.

An integrated group entropy-weighted interval type-2 fuzzy weighted aggregated sum product assessment (WASPAS) method in maritime transportation

This study aims to provide an integrated decision-making approach in maritime transportation problems. The duty of hatch cover is to prevent the ingress of water into the cargo hold and protect the goods from being damped and damaged. Hence, it has the considerable role in productivity of maritime transportation systems. Since each hatch cover has distinguished properties with respect to criteria than the others, the hatch cover selection problem (HCSP) can be considered as a multi-criteria decision-making (MCDM) problem. In this paper, interval type-2 fuzzy sets (IT2FSs) are first used to weight criteria and evaluations of hatch covers with respect to criteria. In addition, an integrated group Shannon entropy- based weighted aggregated sum product assessment (WASPAS) approach is applied to solve the HCSP using the limit distance mean (LDM) in which the interval type-2 fuzzy Shannon entropy approach is used to determine the objective weights and then they are integrated with the subjective weights. On the other hand, in order to demonstrate the effectiveness and practicability of the proposed method, it is fulfilled in a real case study and the ranked results are compared with the others.