Vehicle Tank Research Articles

Hydrogen refuelling station calibration with a traceable gravimetric standard

Of all the alternatives to hydrocarbon fuels, hydrogen offers the greatest long-term potential to radically reduce the many problems inherent in fuel used for transportation. Hydrogen vehicles have zero tailpipe emissions and are very efficient. If the hydrogen is made from renewable sources, such as nuclear power or fossil sources with carbon emissions captured and sequestered, hydrogen use on a global scale would produce almost zero greenhouse gas emissions and greatly reduce air pollutant emissions.The aim of this work is to realise a traceability chain for hydrogen flow metering in the range typical for fuelling applications in a wide pressure range, with pressures up to 875 bar (for Hydrogen Refuelling Station - HRS with Nominal Working Pressure of 700 bar) and temperature changes from −40 °C (pre-cooling) to 85 °C (maximum allowed vehicle tank temperature) in accordance with the worldwide accepted standard SAE J2601. Several HRS have been tested in Europe (France, Netherlands and Germany) and the results show a good repeatability for all tests. This demonstrates that the testing equipment works well in real conditions. Depending on the installation configuration, some systematic errors have been detected and explained. Errors observed for Configuration 1 stations can be explained by pressure differences at the beginning and end of fueling, in the piping between the Coriolis Flow Meter (CFM) and the dispenser: the longer the distance, the bigger the errors. For Configuration 2, where this distance is very short, the error is negligible.

Experimental Measurement of Bulk Thermal Conductivity of Activated Carbon with Adsorbed Natural Gas for ANG Energy Storage Tank Design Application

The development of adsorptive natural gas storage tanks for vehicles requires the synthesis of many technologies. The design for an effective Adsorbed Natural Gas (ANG) tank requires that the tank be filled isothermally within a five-minute charge time. The heat generated within the activated carbon is on the order of 150 MJ/m 3 of storage volume. The tank can be effectively buffered using Phase Change Material (PCM) to absorb the heat. The effective design of these tanks requires knowledge of the thermal properties of activated carbon with adsorbed methane. This paper discusses experimental measurements of the thermal conductivity of activated carbon with adsorbed methane. It was found that within the tank the thermal conductivity remains almost constant within the temperature and pressure ranges that ANG tanks will operate.

Analytical methods for the determination of oil carryover from CNG/biomethane refueling stations recovered in a solvent.

Vehicle gas is often compressed to about 200 bar at the refueling station prior to charging to the vehicle's tank. If a high amount of oil is carried over to the gas, it may cause damage to the vehicles; it is therefore necessary to accurately measure oil carryover. In this paper, three analytical methods for accurate quantification of the oil content are presented whereby two methods are based on gas chromatography and one on FTIR. To better evaluate the level of complexity of the matrix, 10 different compressor oils in use at different refueling stations were initially collected and analysed with GC and FTIR to identify their analytical traces. The GC traces could be divided into three different profiles: oils exhibiting some well resolved peaks, oils exhibiting globally unresolved peaks with some dominant peaks on top of the hump and oils exhibiting globally unresolved peaks. After selection of three oils; one oil from each type, the three methods were evaluated with regards to the detection and quantification limits, the working range, precision, trueness and robustness. The evaluation of the three measurement methods demonstrated that any of these three methods presented were suitable for the quantification of compressor oil for samples. The FTIR method and the GC/MS method both resulted in measurement uncertainties close to 20% rel. while the GC/FID method resulted in a higher measurement uncertainty (U = 30% rel.).

Experimental amelioration of flexural behavior under cryogenic conditioning through inter-ply fiber hybridization in FRP composites

Inter-ply fiber hybridization seems to be a very propitious technique to improve the mechanical properties of FRP composites. However, the mechanical response of these hybrid composites under cryogenic conditions has not yet fully explored experimentally. In this research paper, a systematic examination of the flexural behavior of hybrid samples conditioned at ambient temperature, zero, as well as cryogenic conditions has been carried out. In this study, hybrid polymer composites have been pondered by carbon and glass fiber as reinforcement. Fractography of the fractured samples was done by using scanning electron microscopy for featuring failure mechanisms and to validate most of the reasons mentioned in the literature regarding alteration in the properties at each tested condition. These composite materials performance might be governed by polymer relaxation at lower temperatures, matrix cracking, cryogenic hardening, and compressive residual stresses due to the difference in the coefficient of thermal expansion of the fibers and matrix. Fiber hybridization method significantly alleviated the limitations of carbon fiber such as low stain to failure, catastrophic failure, and its cost for the application to cryogenic fuel tanks for space vehicles, support structures of superconducting magnets, etc.

ПРИМЕНЕНИЕ МЕТОДОВ ЧИСЛЕННОГО МОДЕЛИРОВАНИЯ ПРИ ЭКCПЕРИМЕНТАЛЬНОЙ ОТРАБОТКЕ ЗАБОРНЫХ УСТРОЙСТВ ЦЕНТРАЛЬНОГО ТИПА

At the design of intakes of fuel tanks of launch vehicles in engineering practice, empirical and semi-empirical dependences are used for the determination of main parameters of the movement of liquid. However, the received from skilled data, empirical dependencies are applicable for a limited circle of tasks in which conditions (initial and boundary) are similar to for what these dependencies were received. Therefore, the calculated parameters of intakes it has to be validated by the results of experimental working off. Experimental working off intakes at hydrodynamic stands is, as a rule, carried out on natural tanks and their large-scale models (skilled designs) in terrestrial conditions. For confirmation of similarity of hydrodynamic processes, experimental working off the large-scale models is carried out on several skilled designs of different scales and several model liquids. Now, with the development of computer facilities and numerical methods of the solution of the differential equations of the movement of liquid, there was an opportunity to replace almost universal use of empirical dependences with more exact computing experiment. It, in some cases, allows reducing the quantity of the used skilled designs, terms of carrying out experimental working off, and, as a result, material expenses. The article presents results of the experimental definition of the static hydraulic rest of a component of fuel in skilled designs of a tank of the first step of carrier rockets with the central selection of a component and numerical modeling on mathematical 3D and 2D models of skilled designs (similar scale) are considered. The authors developed the calculated and experimental method of verification of results of numerical modeling allowing them to conduct necessary researches with the demanded accuracy. The offered approach allows improving the existing traditional method of experimental working off of intakes, already at the initial stage of development to optimize their parameters, to reduce the volume of necessary experimental working off and to lower time and material expenditure on its carrying out.

Sub-zero Temperature Dependence of Tensile Response of Friction Stir Welded Al-Cu-Li (AA2198) Alloy

Mechanical properties at ambient and cryogenic temperatures of Al-Cu-Li alloy are required for design and fabrication of liquid hydrogen and liquid oxygen tanks of satellite launch vehicles. In the present work, bead-on-sheet, friction stir welding was carried out with three different rotation speeds. The yield and strain hardening behaviors of the welds were evaluated in temperature range of 20 K to 298 K. Both yield stress and strain hardening ability in the specimen increased with decrease in testing temperature. The dependence of yield stress on temperature was modeled on the basis of thermally activated dislocation mobility, while that of strain hardening was modeled on the temperature dependence of dynamic recovery rate parameter. The recovery parameter followed an Arrhenius-type relationship with temperature. The model parameters determined from the experimental data were further used to simulate the stress–strain curves at different sub-zero temperatures for the friction stir welds.

Comparative Evaluation of the Accuracy and Robustness of Various Information Processing Algorithms from Tripled Measuring Channels

Using the example of a three-channel system for measuring the level of filling of tanks of launch vehicles, we perform a comparative assessment of the accuracy and robustness of various algorithms for processing measurement information received from three measuring channels of the same type. We consider various processing algorithms of three equal-precision measurements: finding the arithmetic mean of three equal-precision measurements and a majority choice of three equal-precision measurements. For these algorithms, the probability density function of the measurement errors and confidence limits of the measurement error are found using the assumption of uniform or normal laws of the error distribution of three equally accurate measurements. A generalized algorithm for processing redundant information is proposed. The essence of the generalized algorithm is the addition of three equally accurate measurements taking into account individual weighting factors. Weight coefficients are selected based on the values of three equally accurate measurements: the minimum and maximum values are assigned the same weighting coefficient, and the median is assigned a coefficient which normalizes the sum of the three weighting factors to one. For a generalized algorithm by means of simulation modeling, the confidence limits of the measurement error are determined depending on the selected weighting factors. The robustness of the considered processing algorithms is evaluated for three equally accurate measurements performed on three measuring channels identical in design, with a random perturbation applied to one of the channels. Recommendations on the selection of weights for three equal measurements are given. For the fuel level measurement system under consideration, it is justified to use an algorithm for processing measurement information based on a majority choice of three equally accurate measurements.

Effects of Filler Wires on the Microstructure and Mechanical Properties of 2195-T6 Al-Li Alloy Spray Formed by TIG Welding.

The main purpose of this work was to investigate the microstructure and mechanical properties of spray-formed 2195-T6 Al-Li alloy welding joints produced by tungsten inert gas (TIG) with Al-Cu and Al-Si-Cu filler wires, so that they can be better used in space vehicle tanks. The porosity analysis indicates that the porosity area of the weld seam with the Al-Si-Cu filler wire is approximately 7.989 times larger than that of the Al-Cu filler wire. Furthermore, the microstructure and microhardness results indicate that the Al/Cu eutectic near the fusion line distributes more at the grain boundaries, while more dispersed Al2Cu phase is found inside the grain, which improves the strength of the joint when using Al-Cu filler wire. However, when using the Al-Si-Cu filler wire, more Si, Cu, and Ti elements are segregated at the grain boundaries, forming a brittle-hard network Al/Cu/Ti eutectic, which reduces the performance of the joint. Additionally, the tensile strength and elongation of the weld joint are about 68.6% and 89.9% of the base metal (BM) when using the Al-Cu filler wire, and can approach the level of friction stir welding (FSW). However, the tensile strength and elongation are only about 56.8% and 39.9%, respectively, of the BM in the weld joint when using the Al-Si-Cu filler wire. Lastly, the fractures both occur on the fusion line and the fracture morphology of the weld joint shows that it is a mixed fracture mode dominated by plastic fracture when using Al-Cu filler wire, while it is mainly a quasi-cleavage fracture mode when using Al-Si-Cu filler wire. Therefore, the joint strength when using Al-Si-Cu filler wire with high strength matching is not as good as that of Al-Cu filler wire with low strength matching.

Composite spherical shells at large deflections. Asymptotic analysis and applications

The asymptotic method for spherical shells at large deflections was developed in the case of composite shell subject to external pressure. Reissner’s equations describing axially symmetric deformation of deep shells with arbitrary deflections and rotation angles were considered as initial ones. They were significantly simplified and asymptotic formulae for deformation energy, external pressure and stresses depending on deflection amplitude were obtained. The energy barrier criterion was applied for the composite shell for estimation of the shell metastability. Formula for design buckling pressure was derived for composite shells. It improves the significantly more conservative NASA SP-8032 recommendations. The full inversion of the shell was studied as well. Asymptotic formulae were obtained for evaluation of stresses and load deflection dependencies. They can be useful for design of diaphragms for positive expulsion propellant spherical tanks of launch vehicles and for other applications.

МЕТОДИКА РАСЧЕТА ВЕЛИЧИНЫ ПРОВАЛА ДАВЛЕНИЯ НА ВХОДЕ В ЭЛЕКТРОНАСОСЫ ПРИ ЗАПРАВКЕ РАКЕТОНОСИТЕЛЯ С АНАЛИЗОМ ПОЛУЧЕННЫХ ЭКСПЕРИМЕНТАЛЬНЫХ ДАННЫХ

Definition of the scheme of binding and operating modes of pumps of filling system with propellants of launch vehicle tanks for providing requirements for their operation was purpose of researches. Definition of influence of parameters of propellants for providing requirements for their operation was a task. The failure of pressure is understood as a difference between stationary pressure (after an exit to the mode) at the minimum pressure on an entrance to the pump. Cavitation and desaturation of working fluid on an entrance to the pump are possible at pressure drop lower than pressure of saturated steam. Cavitation is fast flowing physical and mathematical processes in the liquid arising at reduction of pressure up to the value smaller than pressure of saturated steam at this temperature. Thus in separate place of a stream there is rupture of a continuity with filling of emptiness with small vials of saturated steam and the dissolved air emitted from liquid. Cavitation as a rule leads to decrease in a pressure, feeding and efficiency of the pump, to emergence of noise and vibrations. At centrifugal pumps the zone of emergence of the cavitation effect is near an entrance, to the driving wheel. The method of cavitation of value of failure of pressure on an entrance to the pump in the inclusion mode with filling of launce vehicle experimentally is developed. Turing on of the pump happened at the closed valved on the pressure line which opens after a pump exit to the nominal mode. Depending on time of opening of valve accelaration of liquid stream in the pipeline changes. Experimental data of amplitude and duration of a failure of pressure depending of propellants and hydraulic system are presented. It is shown than for implementation of the requirement about turning on of the pump at the closed valve on the pressure line it is necessary to install the valve with the electric drive for ensuring uniform speed of its opening. Satisfactory convergence of estimated and experimental data is shown

Optimal Parameter Determination on Friction Stir Welding Process of AA6061 using Grey Taguchi Method

The Friction Stir Welding (FSW) process is an innovative technique to join metals in the plasticity field, thus not reaching the melting temperature and consequently the liquid state as it happen in traditional welding processes. This feature of the FSW proved an enhancement of the fatigue behavior and strength of the joints, leading some companies to adopt the process for the manufacturing of airplanes fuselages and cryogenic tanks for Space launch vehicles. The ultimate goal of this paper is to determine the optimal influencing parameter of Friction Stir welding process using Taguchi method of optimization. Here we used L9 Taguchi orthogonal design for designing the experiment. Three major controllable parameters are welding speed or feed, rotational speed and length of the tool pin are used for the present work. To convert the multi objectives like Tensile strength and the Hardness of the welded work pieces, Grey relation analysis is used. The graph plots the Signal to Noise ratio which identifies the optimal process parameters. The work material used for experimental work is aluminium alloy AA 6061

Understanding the effect of methane gas sensitivity using ultrasonic sensors and multi-matching layers inside a natural gas vehicle tank

This research paper is the experimental study to investigate the effect of ultrasound sensitivity in the pure methane gas space as the pressure and sensor distance increases. We offer the solution to overcome the low sensitivity characteristics of ultrasonic sensors in the methane gas space. This proposal shows the physical characteristics analyzed with self-induced vibration, beam pattern, amplitude, attenuation, and Gaussian distribution validation in CH4 gas space. An ultrasonic sensor is designed with PbTio3 material of an MS-50 PTZ. The signal processing analysis system (APAS) is composed of the mechanical and controlling sections including three mass flow controllers, an air cylinder, safety valves, three pressure regulators, a CVC, ultrasound sensors, and two gas tanks (air and CH4). The experiment is performed in a wide range of the initial conditions, i.e., supplying voltage of 25 V, current of 0.2 A, pulse rate of 7 Hz, measuring distance of 0.32 to 1.02 m, resonance frequency of 57.3 Hz, ambient temperature of 296 K, and pressure increases of 1, 2, 3 and 4 bar. The ultrasonic sensitivity of a sensor (T: EVA and R: EVA) significantly enhanced the acoustic impedance in a methane gas space as pressure increases. It is verified that the sensitivity effect of an ultrasonic sensor used with ethylene vinyl acetate (EVA) matching layer is higher in the methane gas space than a chemical wood (CW) matching layer. Consequently, the effect of gas sensitivity computed by a GDA including the width (W), area (A), and height (H) is enhanced by an EVA sensor in comparison to other Models.

Dynamic boil-off characterization for discharge process of LNG vehicle tank

This study aims to find the optimal boil-off gas (BOG) recovery procedure during the regular LNG vehicle tank maintenance. The BOG discharge process links to rapid depressurization and other important physical characteristics. We set up a full-scale field prototype and test on different initial working conditions. A numerical model was developed accounting for fluid mechanics, interphase heat and mass transfer, which had been verified with the experiments. Based on experimental results and model predictions, we characterized the instantaneous thermodynamic properties of BOG and the relationship between discharge mass and discharge time. In practical situations, spending too much time in BOG recovering would affect the regular maintenances of the vehicle tank. Designing a reasonable recovery time for each tank is crucial to achieve the maximum BOG recovery efficiency. Finally, the mappings of recovery time and the equivalent recovery rate under different initial conditions are established to guide the design of practical operating scheme.

Особенности экспериментальной отработки процесса осаждения компонентов топлива в баках космических ступеней ракет

Особенности экспериментальной отработки процесса осаждения компонентов топлива в баках космических ступеней ракет

Performance Enhancement of Capacitance-Type Level Measurement System using CCII-Based Interface

In this paper, a simple design of a short-range non-inductive capacitance-type level sensor which is developed for closed tanks (like fuel tanks of vehicles) is proposed. The level sensor is analytically and experimentally verified for measuring the level of non-conducting liquids. Second-generation current conveyor (CCII) based interface circuit is used to measure the capacitance of the level sensor which gives output in the form of frequency. The developed capacitance-based level measurement system is simple in design, low-cost and it is found that the error in the measurement of a level is very small in the range of 0.04% for a non-conducting liquid level from 10 to 145 mm of the sensor length.

Welding-induced buckling prediction for large thin-walled cylindrical structures with non-uniform stress fields by friction stir welding

The non-uniform welding stress distribution in large thin-walled cylindrical structures easily causes the buckling distortion due to weak structural stiffness and nonlinear geometric deformation. The non-uniform temperature field model induced by friction stir welding is analytically developed and is used to theoretically deduce the non-uniform stress model in the weld region. Both the two models are verified by the experimental data. A prediction model of critical buckling load is established for large thin-walled cylindrical structures considering the non-uniform welding stress distribution. The deflection function for buckling analysis is developed by using polynomials and the Chebyshev polynomials of the first kind that satisfy the boundary conditions along the four edges of the structure. The critical buckling loads are calculated for various cylindrical welded shell structures, which obviously decrease with the increase of the diameter-thickness ratio and the length-diameter ratio. The mitigation of buckling distortion is achieved by the correlation of the buckling load and the welding stress with various welding process parameters. The results are beneficial for the determination of geometric configuration and welding process parameters for large thin-walled cylindrical structures in fabrication of propellant tanks of launch vehicles.

ДОСЛІДЖЕННЯ НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ ПАЛИВНОГО БАКА ВАФЕЛЬНОЇ КОНСТРУКЦІЇ РАКЕТИ-НОСІЯ

Проведені дослідження напружено-деформованого стану паливних баків вафельного типу ракет-носіїв з метою прогнозування їх несучої здатності. Використовувалося програмне забезпечення, розроблене на основі методу скінченних елементів, що дозволяє проводити аналіз термонапруженого стану конструкцій у тривимірній постановці з урахуванням пластичних деформацій. При побудові розрахункової моделі враховувалися конструктивні особливості паливного бака. Розрахункові значення руйнівних навантажень визначаються діаграмами пружно-пластичного деформування матеріалу бака.

Lithium Ion Accelerated Charge Procedure Developed from Half Cell Characterization

With the continued implementation of electric vehicles (EV) into the transportation market, consumer convenience is a major hurdle to overcome, namely, an EV recharge time similar to that of refilling a gasoline vehicle tank. To accomplish this, fast charging lithium-ion cells are needed. The majority of commercial cells are manufactured with varied positive electrode active materials, coupled with a graphite negative electrode. Along with the reversibility, a significant benefit of graphite is the fact that the lithiated graphite has a voltage close to that of Li/Li+, resulting in a large overall cell voltage. The downside of this low voltage is that as attempts are made to fast charge or quickly lithiate the graphite, a small polarization results in a voltage below that of Li/Li+, which is favorable to lithium metal plating on the negative graphite electrodes1. To overcome this issue, material development and modification are being perused to reduce lithium ion diffusion length and resistance with the goal to limit negative electrode polarization during charge 2. Meanwhile, modified charging procedures for commercial lithium-ion cells with conventional graphite negative electrodes such as multistage constant current charging and boost charging, are being implemented, where charging currents are initially high and reduced as cell voltage limits are reached 3,4. These processes largely rely on overall cell voltage to drive the charging current selection and appear independent of negative electrode loading, composition, porosity, and cell matching ratio. The presented work provides an outline for the development of an accelerated charge procedure through half-cell characterization of the limiting graphite negative electrode, which may be applied to any graphite electrode formulation and full cell design. This work provides an example of an accelerated charging procedure based off negative electrode performance and percentage of negative electrode utilization. The outlined procedure reduces charging current when percentages of negative electrode lithiation are reached, where the current and lithiation percentage result in a negative electrode voltage of ~10 mV vs. Li/Li+. Also demonstrated is a measure of charging efficiency, where an ideal fast charging process would involve a negative electrode held at a voltage slightly above Li/Li+ (10 mV), and an overall cell voltage below the cell charging voltage limit, maximizing current and minimizing cell charge time. The described work was performed on cells with a capacity loading of ~2.4 mAh/cm2, representative a commercial cell loading, where recharge times to 80% state of charge occurred in approximately 34 minutes. While demonstrating similar capacity fade to cells cycled using conventional CCCV techniques. References C. Uhlmann, J. Illig, M. Ender, R. Schuster, and E. Ivers-Tiffée, Journal of Power Sources, 279, 428–438 (2015).Q. Cheng, R. Yuge, K. Nakahara, N. Tamura, and S. Miyamoto, Journal of Power Sources, 284, 258–263 (2015).D. Anseán et al., Journal of Power Sources, 321, 201–209 (2016).P. H. L. Notten, J. H. G. O. het Veld, and J. R. G. van Beek, Journal of Power Sources, 145, 89–94 (2005).

An experimental study to investigate typical temperature conditions in fuel tanks of European vehicles

Vehicular evaporative emissions have been recognized as an important source of volatile organic compounds to the environment and are of high environmental concern since these compounds have been associated to the formation of surface ozone and secondary organic aerosols. Evaporative emissions occur during any vehicle operation. In Europe, a revised legislative test procedure has been recently introduced to better control evaporative emissions during parking. However, emissions related to normal driving conditions—the so-called running losses—have received less attention compared with the other categories. The current study aims at giving some insights to the prevailing temperature conditions in fuel tanks of typical European vehicles during normal driving operation. The effects of ambient air temperature, trip duration, vehicle speed, and fuel tank level on the temperature reached by the fuel inside the tank under different real-world operating conditions were studied. Tank temperature can exceed 40 °C depending on ambient and driving conditions. Ambient temperature was found to be the most important parameter affecting the tank temperature. Trip duration and driving pattern may also have an influence on the tank temperature particularly when long trips combined with high vehicle speed are examined. Additionally, the difference between tank and ambient temperature was examined during the individual trips and was found to vary between 1 and 10 °C depending on the testing conditions. The most important parameters affecting the delta temperature were found to be the trip duration and the maximum vehicle speed. Finally, the purging strategy of two of the test vehicles was monitored, and the parameters affecting the purging flow rate were investigated. No strong correlation between the canister flow rate with ambient temperature, vehicle speed, or fuel level was observed in either of the tested vehicles. Substantially different canister flow rate levels between the two vehicles point to different purging strategies.

Friction Stir Welding of Aerospace Alloys

Friction Stir Welding (FSW) is a solid state joining process which possesses a great potential to revolutionise the aerospace industries. Distinctive materials are selected as aerospace alloys to withstand higher temperature and loads. Sometimes these alloys are difficult to join by a conventional welding process but they are easily welded by FSW process. The FSW process in aerospace applications can be used for: aviation for fuel tanks, repair of faulty welds, cryogenic fuel tanks for space vehicles. Eclipse Aviation, for example, has reported dramatic production cost reductions with FSW when compared to other joining technologies. This paper will discuss about the mechanical and microstructure properties of various aerospace alloys which are joined by FSW process.