Ship Applications Research Articles

Representative application of LNG-fuelled ships: a critical overview on potential ghg emission reductions and economic benefits

The shipping industry is the primary and most significant mode of international cargo transportation. The ship must comply with strict rules regarding reducing greenhouse gas (GHG) emissions as a dominant transportation mode. Liquified Natural Gas (LNG) is the primary alternative fuel option for several shipping companies. In essence, many studies recommend LNG as a transitional and alternative fuel because its emission characteristics are cleaner than other fossil fuels. Several previous investigations have been carried out to develop an action plan for integrating the use of LNG as a ship fuel. However, there have been few discussions on the estimation of GHG emission reduction and the economic efficiency of a representative LNG-fuelled ship. The recent progress on LNG-fuelled ships is systematically reviewed to summarize the pathways and highlight the core technological concepts, technical issues, current LNG-fuelled ship applications, and future outlooks regarding integrating LNG energy resources into ship power systems to measure GHG emission reductions and cost savings estimations. The report will discuss the current development in the maritime sector and the effects of the macroeconomic scale. The result reveals that future research on ship-based LNG energy systems will probably concentrate on integrating new energy source generating strategies with existing ship power systems to improve energy efficiency. Several potential research areas for future outlook were also discussed to anticipate future challenges.

Thermodynamic analysis and assessment of novel ORC- DEC integrated PEMFC system for liquid hydrogen fueled ship application

Proton-exchange membrane fuel cell (PEMFC) and liquid hydrogen are gaining attention as a power generation system and alternative fuel of ship. This study proposes a novel PEMFC system, integrated with the organic Rankine cycle–direct expansion cycle (ORC-DEC), which exploits cold exergy from liquid hydrogen and low temperature waste heat generated by the PEMFC for application in a liquid hydrogen fueled ship. A thermodynamic model of each subsystem was established and analyzed from the economic, energy, and exergy viewpoints. Moreover, parametric analysis was performed to identify the effects of certain key parameters, such as the working fluid in the ORC, pressure exerted by the fuel pump, cooling water temperature of the PEMFC, and the stack current density on the system performance. The results showed that the proposed system could generate 221 kW of additional power. The overall system achieved an exergy and energy efficiency of 43.52 and 40.45%, respectively. The PEMFC system had the largest exergy destruction, followed by the cryogenic heat exchanger. Propane showed the best performance among the several investigated ORC working fluids and the system performance improved with the increase in the cooling water temperature of the PEMFC. The economic analysis showed that the average payback time of ORC-DEC was 11.2 years and the average net present value (NPV) was $295,268 at liquid hydrogen costing $3 to $7, showing the potential viability of the system.

Fault injection and diagnosis of the centrifugal fan

Centrifugal fan is widely used in industry, vehicle and ship application to provide air cycle power. To detect the fan fault at early stage, this paper explores the fault feature in the vibration signal and fault diagnosis method through the fault injection test, where impeller unbalance, rotor unbalance, and bearing fault are involved. Firstly, the fault mechanism is introduced; then, the fault injection methods of the three faults are introduced to obtain the faulty fans; finally, health and fault tests are performed, where the vibration sensors are employed and distributed on the fan in the axial and radial direction. Moreover, the acquired vibration data is analyzed by using time-domain and frequency-domain methods, and further the fault features between health and fault are compared and discussed. The analysis results indicate that the three faults can be detected through the vibration intensity and magnitude comparison at their individual characteristic frequencies in the spectrum.

3D radar stealth composite hierarchical grid structure with extremely broadband absorption performance and effective load bearing

Multifunctional structures with both excellent microwave absorption performance and mechanical properties have attracted great attentions recently due to wide applications in aircraft and ships. In this research, a novel absorption structure was designed and fabricated through molding and interlocking technology by perfectly combining the composite hierarchical grid structure with excellent mechanical properties and extremely broadband 3D absorption metamaterial. The mechanism of structural parameters affecting absorption and mechanical properties of the proposed 3D radar absorption composite hierarchical grid structure (3D-RACHGS) were investigated. The measured result of reflectivity showed that −10 dB absorption bandwidth of 3D-RACHGS achieves 34.8 GHz (2.6–4 GHz, 6.6–40 GHz) with an average reflectivity of −17.4 dB. Further simulation demonstrated that the broadband absorption is attributed to multiple stationary wave modes. The measurement result of out-of-plane compression showed that the specific strength of the 3D-RACHGS achieves 123.5 × 103 m2/s2, which proves its effective load bearing. Failure mechanism map was also constructed to predict the failure mode of the 3D-RACHGS with various structural parameters. The proposed 3D-RACHGS will contribute to the vigorous development of the novel structural absorption materials and have immense potential to be used in new generation multifunctional skin and inlet.

Research progress on bearing fault diagnosis with localized defects and distributed defects for rolling element bearings

In rotating machinery, rolling elements are the key members of the rolling element bearing (REB), which has tremendous application in automobiles, aerospace, ships, machinery apparatuses, and many more industrial sectors. Bearings are a significant source of various non-linear parameters which strongly affect the whole system. In the last two decades, tremendous research and approaches have been developed, considering the different parameters and faultiness for the proper understanding of the system’s non-linear behavior. This research paper summarizes the literature review on bearing fault diagnosis with localized and distributed defects for rolling element bearings with various non-linear parameters. Artificially-generated defects on the bearing races provides the vibration analysis of the system. These factors like radial clearance, unbalanced force, preload, misalignment, etc. are also considered defects in bearings. Moreover, the literature highlights some significant gaps that should be examined for future research in the condition monitoring of the mechanism.

Multiobjective Optimization Based Framework for Early Stage Design of Modular Multilevel Converter for All-Electric Ship Application

The Medium Voltage DC (MVDC) architecture for All Electric Ships (AES) has the potential to provide superior features compared to traditional 60-HZ AC distribution systems in terms of power density, power quality, and system stability. The MVDC system introduces extensive use of power electronics equipment into the shipboard power system (SPS) design that brings complexity to the system design. These power electronics equipment connect the power sources and load centers to the MVDC bus and play a major role in handling system faults. This paper focuses on developing a framework to determine the volume and failure rate of a Modular Multilevel Converter (MMC) for early stage ship design. Two different methodologies (Taguchi method and a genetic algorithm) were used to determine the best design from a robust set of design options. Once the design parameters have been identified, the Taguchi method forms orthogonal array to explore and evaluate designs. At the end of the design cycle, it identifies the best parameters from a large set of design parameters to achieve lower volume and failure rate. These parameters are used as input to the optimization process. This helps to narrow out the number of inputs for optimization algorithm. The Nondominated Sorting Genetic Algorithm II (NSGA-II) has been integrated with converter design tool to minimize the volume and failure rate of MMC. The results show that the optimization algorithm coupled with Taguchi Method provides the lowest volume and failure rate for MMC. One of the goals of early-stage ship design is to develop preliminary design and evaluation of trade space to narrow it down. This paper is expected to aid early-stage ship design of power electronics converter design for MVDC systems in SPS.

How Government Subsidy Impacts on the Supply Chain Decision for LNG-Fuelled Ships

LNG-fuelled ships help fight environmental pollution induced by fossil fuel. Chinese government has also considered encouraging the shipbuilder’s initiative of producing or introducing LNG-fuelled ships through subsidies. However, rare scholars have concerned the impact of government subsidy on the supply chain decision of LNG-fuelled ships in the existing studies. This study takes green degree and government subsidy into account in the LNG-fuelled ship supply chain of a manufacturer and an owner and studies the pricing, market demand, and supply chain benefits. Our main contributions are considering the correlation between the green degree of LNG ships and government subsidy factors and exploring the influence of government subsidy on supply chain decision-making under decentralized and centralized decision-making by ship manufacturers and owners. The results show that government subsidies are conducive to promoting the whole profit and the market demand in the ship supply chain. Centralized decision generates higher profits than decentralized decisions. In the centralized decision model, government subsidies and the green degree of LNG-fuelled ship are positively correlated with the market demand. In the decentralized decision model, the price of an LNG-fuelled ship charged by shipbuilder when providing subsidies for owners is greater than that when providing subsidies for shipbuilder. Manufacturers and owners should pay attention to the greenness of ships, and the government should adopt appropriate subsidy policies to encourage the production and application of LNG ships.

Fast and stable operation approach of ship solid oxide fuel cell-gas turbine hybrid system under uncertain factors

This work focuses on investigating the adaptability of solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system for ship application under uncertain factors. The effect of rapids, wind and waves on the performance of ship SOFC-GT is analyzed. In addition, a novel control system combining fuzzy logic theory, temperature feedforward and coordination factor on-line adjustment is proposed to address the problem of load disturbances caused by uncertain factors. The results show that the proposed operation strategy can shorten the thermal response time inside fuel cell stacks by almost 49.97%, meanwhile, reducing the maximum temperature changing rate at the electrochemically active tri-layer cell composed of anode, electrolyte, and cathode (PEN structure) by around 17.86%. Moreover, the reasonable matching between air flow and fuel flow is an essential prerequisite to ensure the safe and efficient operation of ship SOFC-GT. While the SOFC-GT is working at full load, the results indicate that the fuel to air ratio cannot exceed 2.56✕10−2 g/g. Finally, an application scenario of the 5000-ton river-to-sea cargo ship sails from Nanjing Port to Yangshan Port (Eastern China) is conducted to analyze the operation characteristics of ship SOFC-GT under uncertain factors. Two set of 1000 kW SOFC-GT systems with the electrical efficiency of 64.66% is designed for the target ship, the results conclude that the operation strategy of each SOFC-GT system supports 50% load is beneficial in reducing the power tracking time and SOFC temperature overshoot. The average electrical efficiency of 61.45% and 61.04% are achieved in winter and summer typical days respectively in the whole voyage.

Application and Development of Selective Catalytic Reduction Technology for Marine Low-Speed Diesel Engine: Trade-Off among High Sulfur Fuel, High Thermal Efficiency, and Low Pollution Emission

In recent years, the International Maritime Organization (IMO), Europe, and the United States and other countries have set up different emission control areas (ECA) for ship exhaust pollutants to enforce more stringent pollutant emission regulations. In order to meet the current IMO Tier III emission regulations, an after-treatment device must be installed in the exhaust system of the ship power plant to reduce the ship NOx emissions. At present, selective catalytic reduction technology (SCR) is one of the main technical routes to resolve excess NOx emissions of marine diesel engines, and is the only NOx emission reduction technology recognized by the IMO that can be used for various ship engines. Compared with the conventional low-pressure SCR system, the high-pressure SCR system can be applied to low-speed marine diesel engines that burn inferior fuels, but its working conditions are relatively harsh, and it can be susceptible to operational problems such as sulfuric acid corrosion, salt blockage, and switching delay during the actual ship tests and ship applications. Therefore, it is necessary to improve the design method and matching strategy of the high-pressure SCR system to achieve a more efficient and reliable operation. This article summarizes the technical characteristics and application problems of marine diesel engine SCR systems in detail, tracks the development trend of the catalytic reaction mechanism, engine tuning, and control strategy under high sulfur exhaust gas conditions. Results showed that low temperature is an important reason for the formation of ammonium nitrate, ammonium sulfate, and other deposits. Additionally, the formed deposits will directly affect the working performance of the SCR systems. The development of SCR technology for marine low-speed engines should be the compromise solution under the requirements of high sulfur fuel, high thermal efficiency, and low pollution emissions. Under the dual restrictions of high sulfur fuel and low exhaust temperature, the low-speed diesel engine SCR systems will inevitably sacrifice part of the engine economy to obtain higher denitrification efficiency and operational reliability.

Performance Evaluation of KBH4 as Energy Carrier for Shipping Applications

AbstractNon‐fossil fuels are urgently needed for maritime and inland shipping applications to mitigate the sector's adverse impact on the global climate. This study investigates the performance of potassium borohydride (KBH4) as an alternative, carbon‐free energy carrier on the basis of detailed process simulations of the overall energy storage cycle in Aspen Plus®. After optimizing the individual on‐board and off‐board process steps, the feasibility of installing a KBH4‐based energy supply system on board of an inland‐waterway cargo vessel is evaluated and critical process steps are highlighted along with current research challenges.

Combined cold supply system for ship application based on low GWP refrigerants - Thermo-economic and ecological analyses

The withdrawal of popular high-GWP refrigerants will significantly affect maritime industry. Refrigeration and air conditioning systems currently used on ships are not ready to fulfil future limitations. Therefore, there is a need for system, which will operate with low-GWP refrigerants and at the same time will be efficient and reliable in difficult environmental conditions. This paper explains the concept of a cold supply system, in which refrigeration/freezing plant rejects heat not to a seawater but to a chilled water, produced by the air conditioning unit. Configuration of single stage compression with internal heat exchanger and HFO refrigerant was used in the air conditioning system, while in the refrigeration/freezing plant, two-stage compression trans-critical booster with R744 as refrigerant. Comparative thermodynamic analyses of presented concept with other configurations of thermodynamic cycles and refrigerants were performed. They were carried out in wide range of seawater temperature values and incorporated efficiency characteristics of compressors produced by a well-known manufacturers. Results confirmed ability of described system to improve energy efficiency in comparison with separated and currently used on ships cold supply systems, especially in hot climate. Economic and ecological analyses of proposed concept exhibited an additional benefit - positive environmental impact.

Computational Galerkin Finite Element Method for Thermal Hydrogen Energy Utilization of First Grade Viscoelastic Hybrid Nanofluid Flowing Inside PTSC in Solar Powered Ship Applications

Parabolic trough solar collectors (PTSCs) are commonly used in solar thermal implementations to achieve high-temperatures. The current investigation looks at entropy formation and the effect of nano solid particles on a parabolic trough surface collector (PTSC) mounted aboard a solar-powered ship (SPS). The non-Newtonian first grade viscoelastic type, as well as a porous medium and Darcy-Forchheimer effects, were utilised in the current study. The flowing of PTSC was created by a non-linear stretching sheet, and the changing thermal conductivity, heat source, and viscous dissipation effects were used to calculate the heat flux in the thermal boundary layer. To convert partial differential equations (PDEs) into solvable ordinary differential equations (ODEs) with boundary-constraints, a similarity transformation strategy was used. The boundary-constraints and PDEs have been reduced to a set of non-linear ODEs (ordinary differential equations). To reach the approximated solution of ODEs, the Galerkin finite element method (G-FEM) is used. As working fluids, copper-sodium alginate (Cu-SA) and molybdenum disulfide-copper/sodium alginate (MoS2-Cu/SA) hybrid nanofluids were used. According to the findings, the permeability factor diminished the Nusselt number whilst boosting the skin friction factor. Furthermore, overall entropy variance throughout the domain was increased for flow speeds using the Reynolds number, and viscosity changes were tracked using the Brinkman number. When compared to MoS2-Cu/SA, using Cu-SA nanofluid boosted thermal efficiency by 1.3–18.8%.

Design of a High-Durability X-Band Patch Antenna with a CPW Feeding Network Based on a Durability Evaluation Analysis

In this paper, we propose a high-durability X-band patch antenna with a coplanar waveguide (CPW) feeding network that can directly connect the upper antenna and the lower transmitting receiver modules without additional cabling. To improve the durability of the antenna, both the sub miniature push-on (SMP) connector and the feed-pin are separated through the CPW layer. This separated structure can minimize the deterioration of the antenna performance when the unwanted movement of the SMP connector occurs from external shocks. To verify the design feasibility, the reflection coefficient and radiation patterns of the proposed antenna are measured in a full anechoic chamber. The reflection coefficient of the proposed antenna is −27 dB at 10 GHz, and the operating frequency bandwidth (|Γ| < −10 dB) is 4.7% (9.82~10.29 GHz) in X-band. The proposed antenna has a maximum gain of 5.7 dBi at the bore-sight direction. In addition, the durability evaluations of the proposed design according to unwanted SMP connector movements provoked by external shocks are investigated using Monte Carlo simulations. The results demonstrate that the proposed high-durability antenna design is suitable for military ship applications that involve exposure to various external shocks.

Robust Ship Detection in Infrared Images through Multiscale Feature Extraction and Lightweight CNN.

The sophistication of ship detection technology in remote sensing images is insufficient, the detection results differ substantially from the practical requirements, mainly reflected in the inadequate support for the differentiated application of multi-scene, multi-resolution and multi-type target ships. To overcome these challenges, a ship detection method based on multiscale feature extraction and lightweight CNN is proposed. Firstly, the candidate-region extraction method, based on a multiscale model, can cover the potential targets under different backgrounds accurately. Secondly, the multiple feature fusion method is employed to achieve ship classification, in which, Fourier global spectrum features are applied to discriminate between targets and simple interference, and the targets in complex interference scenarios are further distinguished by using lightweight CNN. Thirdly, the cascade classifier training algorithm and an improved non-maximum suppression method are used to minimise the classification error rate and maximise generalisation, which can achieve final-target confirmation. Experimental results validate our method, showing that it significantly outperforms the available alternatives, reducing the model size by up to 2.17 times while improving detection performance be improved by up to 5.5% in multi-interference scenarios. Furthermore, the robustness ability was verified by three indicators, among which the F-measure score and true–false-positive rate can increase by up to 5.8% and 4.7% respectively, while the mean error rate can decrease by up to 38.2%.

Process design of onboard membrane carbon capture and liquefaction systems for LNG-fueled ships

This study proposes an onboard membrane carbon capture and liquefaction system for LNG-fueled ships to satisfy the IMO’s 2050 greenhouse gas reduction targets. The exhaust gas from a natural gas ship has a low CO2 fraction (∼3%) and high O2 fraction (∼16%) compared to the flue gas from power plants. Herein, considering the above distinguishing features, a membrane carbon capture and liquefaction system has been proposed that is energy efficient and compact for the application of ships. To ascertain the performance of the proposed membrane-based system, it is compared to an amine-based onboard system in terms of energy consumption and major equipment size. This work evaluates four process configurations by varying the number of membrane stages and associated liquefaction processes at different CO2/N2 selectivity and CO2 permeance. The results show that energy consumption (3.98 GJe/tLCO2) is higher than the amine-based system (3.07 GJe/tLCO2) at the CO2/N2 selectivity of 50, but it can be decreased to 3.14 and 2.82 (GJe/tLCO2) with an improved selectivity of 100 and 150, respectively. The major equipment size decreases to 54%, 28%, and 20% of the amine-based system when the permeance is 1000, 2000, and 3000 GPU, respectively. The results indicate that the new onboard membrane carbon capture and liquefaction system can be a competitive solution for the IMO’s greenhouse gas reduction targets for 2050.

Structural Assessment of Printed Circuit Heat Exchangers in Supercritical CO2 Waste Heat Recovery Systems for Ship Applications

Structural Assessment of Printed Circuit Heat Exchangers in Supercritical CO2 Waste Heat Recovery Systems for Ship Applications

Design and Economic Analysis of a Small Modular Pressurized Water-Cooled Reactor Core for Application in Commercial Ships

Design and Economic Analysis of a Small Modular Pressurized Water-Cooled Reactor Core for Application in Commercial Ships

Thermal Characterization of Coolant Maxwell Type Nanofluid Flowing in Parabolic Trough Solar Collector (PTSC) Used Inside Solar Powered Ship Application

Parabolic trough solar collectors (PTSCs) are generally utilized to reach high temperatures in solar-thermal applications. The current work investigates entropy production analysis and the influence of nano solid particles on a parabolic trough surface collector (PTSC) installed within a solar powered ship (SPS). For the current investigation, the non-Newtonian Maxwell type, as well as a porous medium and Darcy–Forchheimer effects, were used. The flow in PTSC was produced by a nonlinear stretching surface, and the Cattaneo–Christov approach was used to assess the thermal boundary layer’s heat flux. Similarity transformation approach has been employed to convert partial differential equations into solvable ordinary differential equations allied to boundary conditions. Partial differential and the boundary conditions have been reduced into a group of non-linear ordinary differential equations. A Keller-box scheme applied to solve approximate solutions of the ordinary differential equations. Single-walled carbon nanotubes -engine oil (SWCNT-EO) and Multiwalled carbon nanotubes/engine oil (MWCNT-EO) nanofluids have been utilized as working fluid. According to the findings, the magnetic parameter led to a reduction in the Nusselt number, as well as an increment in skin friction coefficient. Moreover, total entropy variance over the domain enhanced for flow rates through Reynolds number and viscosity fluctuations were monitored by using Brinkman number. Utilizing SWCNT-EO nanofluid increased the thermal efficiency between 1.6–14.9% in comparison to MWCNT-EO.

Maritime Digital Twin architecture

Abstract Digital Twins (DTs) play an important role in current digitalization trends across industries. As maritime markets are particularly affected by recent global tendencies such as increasing delivery costs or political pressure for decarbonization, DT solutions could provide important support for shipbuilding and shipping companies to master recent and upcoming challenges. This paper provides a brief insight into the current state of the maritime industry and shows possible use-cases for DT Ship applications throughout the entire product lifecycle. To further advance the general understanding of DTs and their implementation, the concept of a Maritime Digital Twin Architecture (MDTA) is proposed to structure practical DT features.

Techno-economic and Environmental Comparison of Internal Combustion Engines and Solid Oxide Fuel Cells for Ship Applications

In order to quantify the economic and environmental impact of technology selection in ship power systems, four different battery-supported hybrid configurations including diesel and gas combustion engines, as well as natural gas fueled solid oxide fuel cells (SOFCs) are modeled and analyzed. The investigations include component investments, maintenance and operational costs, as well as the components’ and fuels’ carbon footprints, operational greenhouse gases and other relevant emissions. Dynamic energy system models are used to derive economically optimal system designs for an appropriate technology comparison in a cruise ship case study. The assessment is conducted for a cruise ship case study with technology parameters for the near future and 2050. Results indicate that the auxiliary power system based on diesel combustion is inferior both economically and environmentally compared to SOFCs or gas combustion engines. While latter are the most cost efficient, SOFC application provides an environmental improvement without the need for a new fuel such as hydrogen. In a final outlook for the year 2050, SOFCs economically overtake gas combustion engines on the condition that their investment costs decrease and synthetic fuels are introduced to the market as a low emission solution.