Refueling Process Research Articles

A novel pump-thermal synergistic pressurization process for an efficient liquid hydrogen refueling station system

The traditional 70 MPa liquid hydrogen (LH2) refueling stations (HRSs) require LH2 pumps with high outlet pressures, leading to high initial investment, energy consumption, and difficulty in developing an LH2 pump meeting requirements. Existing LH2 HRSs using thermal compression eliminate the need for pressurization equipment but result in significant waste due to low-pressure hydrogen venting. Therefore, we have pioneered a novel pump-thermal synergistic pressurization process for an efficient LH2 HRS system. The process utilizes a 45 MPa LH2 pump and an electric heating method, allowing easily controllable heat input. This study constructs a thermodynamic model for this system that includes the dynamic operational processes of all core components. Based on the established model, the outlet parameters of the LH2 pump, characteristic parameters of the pressure vessel, the refueling process, and the operation of the entire system are investigated. By dynamic simulation of the whole HRS system with pump and thermal compression, it is found that the specific energy consumption for hydrogen refueling is reduced to 0.55 kWh/kg, with the pump consuming 0.2 kWh/kg while thermal compression consuming 0.35 kWh/kg. After optimizing control strategies, the cycle venting of the pressure vessel and the residual hydrogen gas after re-heating and pressurization account for only 11.6%, and further utilization through the pump pressurization cycle can achieve high utilization with no residuals. This system effectively reduces the initial investment and energy consumption for LH2 HRSs. It simplifies the structure, facilitating the retrofit of existing stations and promoting the construction and application of HRSs.

Modifikasi Produksi dan Biaya Bahan Bakar Minyak pada Kapal Ciremai

Some of the main research problems are the lack of fuel efficiency use, difficulties in loading and unloading process, the refueling process tardiness and the ships route’s delay of the determined and planned routes that could affect the Ciremai Ship’s On Time Performance (OTP). The research aims to determine and analyze the effect of production and fuel oil cost modifications based on the income of Ciremai Ship and its implications for its financial performance after “Three in One” modification. This research used Descriptive statistical analysis method and hypothesis testing using SmartPLS-3. The research sample was taken from the entire routes of Ciremai Ship over the last four years of 48 months. The secondary research data was taken from the financial reports related to production modifications, fuel oil costs, the income and financial performance of the ship. Research findings show that the production modifications have a direct influence on financial performance while fuel costs and income do not have a direct influence on it. The production modifications do not have a direct effect on income instead fuel costs have a direct effect on income and production modifications do not have an indirect effect on financial performance through income.

Research on Six-Degree-of-Freedom Refueling Robotic Arm Positioning and Docking Based on RGB-D Visual Guidance

The main contribution of this paper is the proposal of a six-degree-of-freedom (6-DoF) refueling robotic arm positioning and docking technology guided by RGB-D camera visual guidance, as well as conducting in-depth research and experimental validation on the technology. We have integrated the YOLOv8 algorithm with the Perspective-n-Point (PnP) algorithm to achieve precise detection and pose estimation of the target refueling interface. The focus is on resolving the recognition and positioning challenges of a specialized refueling interface by the 6-DoF robotic arm during the automated refueling process. To capture the unique characteristics of the refueling interface, we developed a dedicated dataset for the specialized refueling connectors, ensuring the YOLO algorithm’s accurate identification of the target interfaces. Subsequently, the detected interface information is converted into precise 6-DoF pose data using the PnP algorithm. These data are used to determine the desired end-effector pose of the robotic arm. The robotic arm’s movements are controlled through a trajectory planning algorithm to complete the refueling gun docking process. An experimental setup was established in the laboratory to validate the accuracy of the visual recognition and the applicability of the robotic arm’s docking posture. The experimental results demonstrate that under general lighting conditions, the recognition accuracy of this docking interface method meets the docking requirements. Compared to traditional vision-guided methods based on OpenCV, this visual guidance algorithm exhibits better adaptability and effectively provides pose information for the robotic arm.

The design and development of the cryogenic compressed gas refueling system

As a new economical, efficient and feasible high density hydrogen storage method, cryogenic compressed hydrogen has been widely explored by scholars in recent years. In this paper, a new cryogenic compressed hydrogen refueling system based on liquid nitrogen cooling is proposed on the basis of the existing high pressure hydrogenation station at normal temperature. The main operating modes of the system include precooling, refueling and standby mode. During the refueling process, it can generate cryogenic compressed hydrogen at 80K temperature and 35MPa pressure, with a mass flow rate of 1kg/min. Additionally, when the cryogenic compressed hydrogen tank requires refueling at high temperatures, the system can provide precooling to reduce hydrogen loss and increase the refueling speed. To validate the feasibility of key equipment and the proposed system, helium gas is used as the working medium for testing. The construction of the cold box, compressor, and cryogenic tank have been completed, and the system is expected to undergo commissioning in the near future.

Analysis of Gaseous Hydrogen Refueling Process to Develop Thermodynamic Model

Analysis of Gaseous Hydrogen Refueling Process to Develop Thermodynamic Model

A Study on the Thermal Behavior of Series and Parallel Connection Methods in the Process of Hydrogenation of Ship-Borne Hydrogen Storage Cylinder

As a subdivision of the hydrogen energy application field, ship-borne hydrogen fuel cell systems have certain differences from vehicle or other application scenarios in terms of their structural type, safety, environmental adaptability, and test verification. The connection method of the ship-borne hydrogen storage cylinder (SHSC) is very important for the hydrogen fuel cell ship, and the structural parameters of the SHSC are particularly important in the hydrogen refueling process. To ensure the safe and reliable operation of the hydrogen-powered ship, research on the filling of the SHSC under different connection modes was carried out during refueling. In our study, a thermal flow physical model of the SHSC was established to research the hydrogen refueling process of the series and parallel SHSCs. The influence of series and parallel modes of the SHSCs on the hydrogen refueling process was explored, and the evolution law of the internal flow field, pressure, and temperature of series and parallel SHSCs under different filling parameters was analyzed by numerical simulation. Our results confirmed the superiority of the parallel modular approach in terms of thermal safety during refueling. The results can supply a technical basis for the future development of hydrogen refueling stations and ship-board hydrogenation control algorithms.

Numerical simulation and environmental impact assessment of oil vapor diffusion in surrounding residential areas before/after vapor recovery at petrol stations

ABSTRACT Oil vapor emitted during refueling process has caused serious issues of air pollution, especially the environmental impact in surrounding residential areas. Most petrol stations have installed oil vapor recovery systems, but some stations did not properly maintain or switch on them. With the increasing emphasis on ecological environmental protection, it is more crucial to investigate the internal mechanism of vapor-air mass transfer. In this study, a computational fluid dynamic (CFD) model was developed and verified to analyze the effects of wind speed, vehicles number, and residential layout on oil vapor diffusion in residential areas. Simultaneously, the effectiveness of oil vapor recovery was assessed by comparing contamination before and after recovery. Results indicate that wind speed greatly affects the area and location of excess emission areas (EEAs). As the wind speed increases from 2 m/s to 4 m/s, highest concentration, distance to buildings and width of EEAs decreases by 49.1%, 43.8%, and 33.3%, respectively, and EEAs disappear at the wind speed of 6 m/s. Vehicles number has a more significant effect on the symmetry of EEAs, and EEAs become gradually symmetrical as the number increases from 3 to 12. Further, the enclosure layout proves to be an effective layout for protecting residential air, with a minimum concentration of 0.18 mg/m3. Notably, the effectiveness of oil vapor recovery is remarkable, with a purification rate of 98.5%. These findings can offer a valuable guidance for controlling air pollution in residential areas and enhancing the environmental protection level of petroleum enterprises.

Modeling and Influence Factors Analysis of Refueling Emissions for Plug-In Hybrid Electric Vehicles

Abstract Vehicle fuel evaporative emissions are an important source of volatile organic compounds (VOCs), causing serious pollution to the environment. Plug-in hybrid electric vehicles (PHEVs) often use high-pressure fuel tank to seal the fuel vapor generated by running loss (RL), hot soak loss (HSL), and diurnal breathing loss (DBL) in the fuel tank, resulting in increased refueling emissions. With the widespread use of PHEVs, the issue of refueling emissions cannot be ignored. In this study, according to the working characteristics of PHEV, the refueling process is divided into depressurization phase and refueling phase, and a mathematical model is established for the fuel vapor emission process. The mathematical model is solved and calculated by using matlab, and compared with the experimental results. The error between experimental and calculated results of refueling emissions is only 2.45%, indicating that the established mathematical model can accurately predict the refueling emissions of PHEVs. The refueling emission experiment activities are carried out, and the influencing factors of PHEV refueling emission are discussed, including initial pressure, ambient temperature, and refueling temperature. The effect of the temperature difference between ambient temperature and refueling temperature on refueling emissions is discussed for the first time, and it is found that refueling temperature has a more significant impact on refueling emissions compared with ambient temperature. When refueling temperature increases to 303 K and 313 K compared to 293 K, refueling emission mass increases by 31.97% and 69.88% respectively.

Enhanced stability of aerial refueling process of UAV based on fuzzy PID

This essay aims to study UAV(Unmanned Aerial Vehicle) aerial refueling technology, and by understanding the control analysis of aerial UAV refueling by comparing multiple R&D(Research And Development) teams, a more practical and feasible method is obtained, that is, through the discussion and design of UAV motion modeling, UAV trajectory tracking control system, fuzzy PID(proportion integral derivative) controller design, etc., the purpose of UAV aerial refueling is finally achieved, and the time of UAV is increased to enhance the stability and durability of UAV in air operation.

Performance optimization design of wide-body aircraft pressure refueling system

In order to reduce the wide body aircraft refueling process time-cost and improve the airport operation efficiency, pressure refueling system design strategy was innovated. The shutoff valves’ operation sequence in refueling process was optimized. The diameter of the orifices on the pressure refueling system fuel line was designed. Pressure refueling performance was simulated and analyzed at different scenarios. The results show that it can improve the pressure refueling system performance at different scenarios by optimizing the pressure refueling process strategy design including optimizing the fuel line orifice design and optimizing the wing tank inner side shut-off valve operation sequence.

Paradox of Book and Claim for Carbon Emission Reduction in Maritime Operations Management: Mathematical Models and Numerical Experiments

In recent years, the maritime industry’s carbon emissions have garnered increasing attention, leading to the proposal of various policy measures aimed at mitigating emissions and fostering a green and sustainable maritime sector. Among these measures, the book and claim mechanism, which allows shippers to access low or zero-emission bunkering by purchasing such fuels without physically participating in the refueling process, has emerged as a crucial catalyst for fuel conversion within the maritime industry. While book and claim has gained widespread recognition and facilitated the sale of clean fuels by some bunker suppliers, there has been limited research focused on evaluating its practical efficacy. Thus, we construct two distinct Mixed-Integer Linear Programming (MILP) models—one with the inclusion of the book and claim mechanism and one without—and conduct an analytical comparison of optimal decisions made by bunker suppliers and shippers under different model scenarios. Through numerical experiments, we have uncovered a noteworthy insight: with book and claim, bunker suppliers may set higher prices to maximize total profits due to various price sensitivities among shippers towards clean fuels, thus promoting low-price-sensitive shippers to purchase clean fuels while making it challenging for high-price-sensitive shippers to do so. Consequently, when compared to a scenario without book and claim, the total quantity of clean fuels purchased by shippers in the presence of book and claim may decrease, giving rise to a paradox where the implementation of book and claim inadvertently increases societal carbon emissions. This underscores the imperative for policymakers to conduct comprehensive market research, understand different shippers’ price sensitivities towards clean fuels, and make scientifically sound decisions when considering the implementation of the book and claim mechanism.

Analysis of Refueling Behavior Models for Hydrogen-Fuel Vehicles: Markov versus Generalized Poisson Modeling

This paper presents an analysis of two methodologies that can be used to predict refueling behavior. Both models aim to provide insights into hydrogen-fuel vehicle users’ refueling patterns and behaviors. The first model leverages probabilistic transitions between refueling states to simulate and predict the refueling behavior of hydrogen vehicle users. In contrast, the GP-1 model employs Gaussian processes to capture the underlying patterns and uncertainties in hydrogen-fuel vehicle refueling behavior, taking into consideration additional factors such as weather conditions and the time of the year. The model demonstrates statistical significance and accuracy in predicting trips while identifying the insignificance of precipitation and high ambient temperatures. The methodologies, findings, strengths, and limitations of the two models were tested and compared to identify their relevant contributions. By contrasting their methodologies and evaluating their predictive performance, using performance metrics such as accuracy, precision, and recall values, this study provides valuable insights into the strengths and limitations of each approach. Limitations include assuming a stationary refueling process and excluding external factors and limitations related to data availability, as well as the absence of a specific focus on hydrogen-fuel vehicles. By understanding the differences and similarities between these two models, this paper aims to provide a unique perspective on gaps and further requirements for accurate prediction and modeling of refueling behavior to guide policymakers, infrastructure planners, and stakeholders in making informed decisions regarding the design and optimization of hydrogen refueling infrastructure.

Analysis of energy saving potential of an asynchronous refueling process for liquid hydrogen station

Liquid hydrogen station shows a great advantage in the future larger market of fuel cell vehicles. However, the energy-saving potential of the liquid hydrogen station remains underexplored. Therefore, a novel asynchronous refueling process (HRP-as) to refuel the vehicle and the high-pressure storage system is proposed based on a conventional synchronous hydrogen refueling process (HRP-s). Moreover, the imperfect compression of the liquid pump and different initial storage pressure are considered. Accordingly, the thermodynamic models of both processes were established, and the evolution of critical parameters was analyzed. Results indicate that the electricity consumption of the liquid pump rises along with the initial storage pressure increase. Compared to the HRP-s, HRP-as exhibits the ability to achieve electricity savings of up to 9.5% within the restrictions of pump capacity and total refueling time. Therefore, HRP-as provides an excellent option for liquid station design without extra expenditure.

Cryogenic cold energy recovery in liquid hydrogen refueling station with double-pipe heat exchanger

Recovering the cryogenic cold energy of liquid hydrogen (LH2) for precooling high-pressure hydrogen gas before refueling can significantly reduce the electricity and energy consumption of liquid hydrogen refueling stations. Existing methods, such as blending, require continuous cryogenic pump operation and are not suitable for various operating conditions. This work proposes a novel method to recover LH2 cryogenic cold energy using a double-pipe heat exchanger, which can decouple the compression and refueling process and meet the fluctuating demand for the cryogenic cold energy required by the hydrogen dispenser. The lumped parameter method and temperature partition method were adopted to design the heat exchanger structure. Numerical simulations of a 2D axisymmetric swirl model were done to verify the accuracy of the temperature partition method applied to high-pressure cryogenic hydrogen. Due to the low temperature of LH2, the secondary refrigerant dichloromethane (CH2Cl2) risks freezing. Comparing the outer wall surface temperature of the inner pipe with the CH2Cl2 freezing point temperature, the optimal anti-freezing condition is that the outer pipe nominal diameter should be selected as 0.032 m and CH2Cl2 mass flow rate should be at least 1.72 kg s−1. Recovery efficiency can reach over 75.39% without freezing.

Experimental Comparison of Hydrogen Refueling with Directly Pressurized vs. Cascade Method

This paper presents a comparative analysis of two hydrogen station configurations during the refueling process: the conventional “directly pressurized refueling process” and the innovative “cascade refueling process.” The objective of the cascade process is to refuel vehicles without the need for booster compressors. The experiments were conducted at the Hydrogen Research and Fueling Facility located at California State University, Los Angeles. In the cascade refueling process, the facility buffer tanks were utilized as high-pressure storage, enabling the refueling operation. Three different scenarios were tested: one involving the cascade refueling process and two involving compressor-driven refueling processes. On average, each refueling event delivered 1.6 kg of hydrogen. Although the cascade refueling process using the high-pressure buffer tanks did not achieve the pressure target, it resulted in a notable improvement in the nozzle outlet temperature trend, reducing it by approximately 8 °C. Moreover, the overall hydrogen chiller load for the two directly pressurized refuelings was 66 Wh/kg and 62 Wh/kg, respectively, whereas the cascading process only required 55 Wh/kg. This represents a 20% and 12% reduction in energy consumption compared to the scenarios involving booster compressors during fueling. The observed refueling range of 150–350 bar showed that the cascade process consistently required 12–20% less energy for hydrogen chilling. Additionally, the nozzle outlet temperature demonstrated an approximate 8 °C improvement within this pressure range. These findings indicate that further improvements can be expected in the high-pressure region, specifically above 350 bar. This research suggests the potential for significant improvements in the high-pressure range, emphasizing the viability of the cascade refueling process as a promising alternative to the direct compression approach.

Desain Sistem Pendeteksi Plat Kendaraan Untuk Pengisian BBM Menggunakan Metode K-Nearest Neighbor (KNN)

This study aims to design and develop a vehicle plate detection system for refueling. Applications built using the K-Nearest Neighbor (KNN) method, this method is used to classify vehicle plates. This research will use the OpenCV module in the python programming language to recognize vehicle plates and carry out the pre-processing, segmentation, feature extraction, and classification stages of vehicle Image data. This system will utilize the K-Nearest Neighbor (KNN) method such as edge detection, perspective transformation, and pattern recognition to achieve optimal results. The test results show that the system is able to recognize with high accuracy various types of vehicle license plates under different lighting conditions and viewing angles, thus a system can be created and determined for each license plate to only be refueled once a day. When the vehicle has never been filled on that day, the system will display a green light which means refueling can be done. Whereas for vehicles that have filled in on that day, the system will display a red light which means the vehicle cannot fill up so it must wait the next day after the system is reset. This system will be able to accurately and real-time detect and identify the vehicle plates used in the refueling process. Therefore, the design of this system is expected to be the basis for increasing efficiency in the refueling industry as well as providing a basis for the development of further research in this field.

Influence of Different Refueling Temperatures and Refueling Rates on Refueling Emission

With the increase of automobiles on hand in China, automobile refueling emissions, as an important part of volatile organic compounds (VOC), have been paid more and more attention. Frequent refueling is related to the fuel vapor concentration and operation safety of the gas stations. Reducing refueling emissions can improve fuel vapor recovery efficiency and reduce fuel waste in gas stations. Therefore, the research on refueling emissions test began to attract attention. However, due to the long pre-processing time of the refueling test, the occupation of the laboratory, and the complicated operation of testers, most studies in China focus on the numerical simulation of a simplified refueling model or the impact analysis of refueling emission of the local fuel system, and there are fewer studies on refueling emission of the whole automobile. This paper aims to analyze the influence of automobile refueling emissions on the environment more scientifically and reduce the fuel vapor loss in refueling more reasonably. The influence of different refueling temperatures and refueling rates on the refueling emission of the whole automobile was investigated. The research showed that automobile refueling emissions increased with the refueling temperature increasing. When the refueling temperature increased to a certain extent, fuel splashing occurred in refueling. When the refueling temperatures are 10°C, 30°C, and 40°C, the refueling emissions of vehicles equipped with ORVR system are 0.92 times, 3.08 times, and 8.29 times than the standard refueling temperature (20°C). In actual refueling, it was recommended to adopt the refueling temperature of 20°C. The refueling emissions decreased first and then increased with the refueling rate. The refueling emissions with the increase in refueling rate were lower than that with the decrease in refueling rate. When the refueling rate is 7L/min, 27L/min, 47L/min, the refueling emissions of vehicles equipped with the ORVR system are 13 times, 1.25 times, and 1.75 times that of the standard refueling rate (37L/min). Too high a refueling rate could lead to fuel splashing; therefore, a refueling rate of 37 L/min was recommended. Compared with ordinary gasoline vehicles and gasoline vehicles equipped with the ORVR system, it can be seen that vehicles equipped with the ORVR system can reduce refueling emissions by 99%. According to an industry report, 12320.4386t gasoline can be saved throughout the year if all vehicles are installed with the ORVR system in 2017 in Yunnan province. It will save 39.3730t and 149.6174t gasoline, when the gas station chooses a refueling temperature of 20 °C throughout the year, compared with the refueling temperature of 30°C and 40°C. And using a refueling rate of 37 L/min can save 4.7248t and 14.1743t gasoline, compared with the refueling rates of 27 L/min and 47 L/min throughout the year. Therefore, it is recommended that China continue to promote the installation of the ORVR system. In the actual refueling process, it is recommended to choose a lower refueling temperature and slower refueling rates to save energy.

Thermodynamic and heat transfer models for refueling hydrogen vehicles: Formulation, validation and application

Compression is currently the preferred storage technology for hydrogen vehicles due to its quick refueling process and relatively simple design. However, the temperature rise associated with fast filling must be controlled to ensure its safe operation. This article discusses general heat transfer models based on the mass and energy balance equations for the refueling process of the compressed hydrogen storage tank. Depending on the way of treating the geometric structure of the storage tank, three general lumped parameter models of single-zone (hydrogen), dual-zone (hydrogen and tank wall) and triple-zone (hydrogen, tank wall liner and shell) are built. The general single-zone and dual-zone models are reduced to some special cases which have been published. Under adiabatic and diathermic conditions, four models, including single-zone, dual-zone single-temperature (hydrogen temperature), dual-zone dual-temperature (hydrogen and tank wall temperatures) and triple-zone triple-temperature (hydrogen, tank wall liner and tank wall shell temperatures), are implemented using Matlab/Simulink™ to simulate the hydrogen refueling process under corresponding conditions. Analytical solutions of single-zone and dual-zone lumped parameter models are derived. The temperature rises of the compressed hydrogen storage tank are described by comparing the analytical solution with the numerical solution. The proposed general models were applied to estimate the final hydrogen temperature and mass, the SOC, the refueling time, and the precooling hydrogen temperature, reviewed and summarized in this article. The analytical solutions of the heat transfer during hydrogen refueling can provide theoretical guidance for improving the refueling efficiency and enhancing refueling safety.

Study on the methodology for evaluating the filling quality of type III hydrogen storage cylinders

With the development of refueling technology, the filling speed, the state of charge (SOC), and the overall experience of the refueling process have received increasing attention. However, a comprehensive evaluation of filling quality needs to be further proposed. Based on the standard k-ϵ model and the National Institute of Standards and Technology Real Gas Model, the effects of refueling parameters for type III hydrogen storage cylinders on hydrogen temperature and SOC were analyzed by numerical simulations of the structured grid model. An analytical model for predicting SOC with four parameters was developed, with the indicators of mass flow rate, initial pressure, inlet hydrogen temperature, and ambient temperature. A filling quality index considering six parameters is proposed. This work offers roadmaps for adjusting the working conditions of hydrogenation stations. The evaluation of the filling quality presented provides a set of novel theoretical solutions to improving the filling quality of hydrogen cylinders.

Features of applying safeguards to Optimized Floating Power Unit spent nuclear fuel handling

After the Floating Power Unit Akademik Lomonosov with the KLT-40S reactor plant had been successfully commissioned, the next step for ROSATOM was to develop optimized floating power units (OFPU). OFPUs powered by the RITM reactor plant are an export-oriented product, and they designed to operate on sites outside Russia. OFPU engineering solutions are based upon the practical design and operation experience in nuclear-powered icebreakers and upon problem solving to assure safety for operation of nuclear plants under severe northern conditions. At the nuclear fuel enrichment lower than 20%, the refueling interval for the OFPU may be up to 10 years depending on Loadings. The RITM reactor refueling process has a number of differences compared to the refueling process of other nuclear power plants fitted with water-cooled water-moderated power reactors. RITM plants have never been placed under the IAEA Safeguards, and capabilities and features of applying the IAEA Safeguards to such plants require an additional analysis. The developed operation model assumes that the OFPU be operated on a deployment site for a long period, and all fuel handling operations will be done at a specialized facility in the Russian Federation (RF). This paper is discussing the major fuel handling features in the life cycle of the OFPU fitted with RITM-200M—these are the critical features in terms of the IAEA Safeguards. Also, the paper is providing the designers’ perspective on solving the key non-proliferation problems through adapting the Safeguards approaches with account of the OFPU technical features.