Four years of operational data for five hydrogen refueling stations

Worldwide about 550 hydrogen refueling stations (HRS) were in operation in 2021, of which 38%. were in Europe. With their number expected to grow even further, the collection and investigation of real-world station operative data are fundamental to tracking their activity in terms of safety issues, performances, costs, maintenance, reliability, and energy use. This paper shows and analyses the parameters that characterize the refueling of 350 bar fuel cell buses in four HRS within the 3Emotion project. The HRS are characterized by different refueling capacities, hydrogen supply schemes, storage volumes and pressures, and operational strategies. From data logs provided by the operators, a dataset of three years of operation has been created. In particular total hydrogen quantity, the fill amount dispensed to each bus, the refueling duration, the average mass flow rate, the number of refueling events and the daily number of refills, the daily profile, the utilization factor, and the availability are investigated. The results show similar hydrogen amount per fill distribution, but quite different refueling times among the stations. The average daily mass per bus is around 12.95 kg, the most frequent value 15 kg, the standard deviation 7.46. About 50% of the total amount of hydrogen is dispensed overnight and the refueling events per bus are typically every 24 hours. Finally, the station utilization is below 30% for all sites.

Methodological approach to the resource base efficiency monitoring in oil fields development

The article discusses the issue of resource base management in a complex structure of residual reserves. To increase the efficiency of the reserves development, constant monitoring of their distribution is necessary - how much they are involved, is there any potential for additional involvement, how efficient are the areas already involved in development. The paper proposes a methodological approach to the residual reserves control process organization, which allows planning and adjusting the program of reserves development. This is of particular relevance for companies that develop assets in the late stages of development, which do not have the ability to indiscriminate drilling. On the example of one of the enterprises developing assets in the Volga-Ural oil and gas province, the structuring of residual reserves was carried out, on the basis of which a strategy for increasing the reserves involvement in development was formed. To analyze the efficiency of reserves recovery in the involved areas, a reserve utilization factor based on the displacement forecast is proposed. Its implementation made it possible to identify problem areas, on the example of one of which a highly effective program for drilling horizontal wells was subsequently implemented. Keywords: oil fields development; oil reserves; resource management; reserves development; horizontal wells.

FORMATION OF QUALITATIVE INDICATORS OF PRODUCTS BY ROLLING STAMPING PROCESSES

The influence of rolling stamping on the service characteristics of products is investigated in the work. Based on the analysis of deformation kinematics, stress-strain state, microstructure and evaluation of deformability of workpiece material, ways to increase geometric accuracy, vacuum tightness, electrolytic stability and mechanical characteristics of product material, as well as ways to improve the material of workpieces for their subsequent processing. The influence of active friction forces on the nature of the material flow during SHO was established, which contributed to the development of new processes that allow to bring the shape and dimensions of the workpiece as close as possible to the finished part. Thus accuracy of the sizes of details corresponds to 7-11th qualities of accuracy, and roughness of the processed surfaces makes Ra = 2,5… 0,63 microns. The process of reshaping the square billets into round ones by the method of SHO is effective, which increases the utilization factor of the metal and reduces the anisotropy of its mechanical properties. The characteristic of flat anisotropy λr, adopted in sheet metal stamping as a characteristic of the ability of the material to form scallops, decreases as a result of reshaping by 70-80%. The relative difference in yield strength in the plane of the sheet decreases from 0.10-0.15 to 0.03-0.05. The ultimate tensile strain increases by 8-10%, and the uniform uniform strain - by 5-8%. This improvement in the characteristics of the material reshaped by rolling blanks leads to the fact that when drawing cylindrical products, the value of scallops decreases by 2-2.5 times, and the value of the maximum degree of drawing increases by 10-15%. This reduces the relative difference in wall thickness along the perimeter of the elongated workpiece, and the change in wall thickness along its height becomes linear. Thus, the use of SHO processes significantly improves the quality characteristics of products.

Performance Investigation Based on Vital Factors of Agricultural Feeder Supported by Solar Photovoltaic Power Plant

Solar photovoltaic (SPV) installations are growing in the distribution network due to the continuously decreasing prices of solar photovoltaic panels. Installing the SPV Plant on the distribution feeder supplying to the agricultural pumps is a challenging task due to the varying agricultural load pattern of the Agricultural Feeder (AG Feeder). Supply of power and demand creates potential challenges in the low voltage (LV) distribution system. This paper presents a case study of a 2 MW SPV connected to an agricultural feeder in India. Performance analysis has been carried out using field measurement data. The key parameters such as PV Penetration and Capacity Utilization Factor (CUF) are calculated for analysis. Parameters such as Grid Dependency of the load and PV Contribution have been introduced in this paper, which relates to the SPV system behavior more aptly. It is recommended that the Time of Day (ToD) metering with the lowest cost during the solar generation hours will make agricultural consumers shift their demand matching with solar generation hours. Extensive analysis of agricultural feeder connected SPV power plant indicates that the power supply has improved for the feeder during winter and summer months.

Miscible WAG Efficiency Assessment on a Large Mature Carbonate Field

This paper is based on the analysis of miscible WAG for an onshore Middle-East field, with strongly undersaturated light oil. Water Alternate Gas operations have been ongoing for around 5 years, which is relatively recent compared to more than 40 years of production history. Goal of this work was to assess the efficiency of this miscible hydrocarbon WAG and to optimize it on the different compartments, with respect to miscibility, voidage replacement, and recycling. As this is a large mature field, with WAG operations dispatched on around 50 injectors and 9 fault blocks (compartments), the method of analysis had to be robust with respect to the different injection strategies followed in the past. It was essentially based on injection and production data, but also used pressure data when available. We computed the following dimensionless variables: oil recovery factor, BSW, voidage replacement ratio (VRR), and also WAG ratio and gas recycling ratio (GRR). Their evolution versus time was analyzed and compared between fault blocks. Using dimensionless variables allowed to compare fault blocks with different initial volumes in place, and to illustrate trends versus time. It was also found beneficial to lump some compartments, when communication was substantiated by pressure data. On the production side, we used the conventional BSW and GOR variables to quantify the water and gas recycling ratio. On the injection side, we observed that in some compartments, the historical WAG ratio was too low in the oil zone, which could be quantified by excluding the peripheral water injection volumes. The analysis allowed also to estimate the gas utilization factor and efficiency, which confirmed the overall high efficiency of miscible gas injection in 3-phase mode. It was also found that the injected fluid efficiency correlated with geology: gas injection tends to be more efficient in zones with high permeabilities at the bottom (coarsening downwards), while water injection is better adapted to zones with high permeabilities at the top (coarsening upwards). Estimating these water and gas efficiencies also allowed to optimize the injection strategy on a field level, by comparing the water efficiency with other units of the field only under waterflood.

Insights into Oil Recovery Mechanism by Nothing-Alternating-Polymer NAP Concept

This paper discusses the application of polymer injection in a heavy oil reservoir in the South of the Sultanate of Oman containing oil with a viscosity of 300-800cP underlain by a strong bottom-up aquifer. Due to unfavorable mobility ratio between aquifer water and oil and the development of the sharp cones significant amount of oil remains unswept. To overcome these issues, a polymer injection pilot started in 2013 with three horizontal injectors, located a few meters above the oil/water contact. Initially a polymer solution with a viscosity of 100 cP was continuously injected at high injection rates. However, it was challenging to sustain the injectivity mainly due to surface facilities, water, and polymer quality issues. This resulted in frequent shutdowns of the injectors. Interestingly, the water cut reversal and oil gain continued during the shut-in periods. This observation has led to the development of a new cyclic polymer injection strategy, in which the injection of polymer is alternated with shut-ins. The strategy is referred to as Nothing-Alternating-Polymer (NAP). This paper discusses the oil recovery mechanism from the NAP strategy. A 3D model was constructed to match the actual pilot results and capture the observed behavior. The injected polymer squeezes the cones and partly restores the barrier between the aquifer and the oil column, suppressing the aquifer flux and hence the negative affect of the cones. It was found that during polymer injection, the oil is recovered by conventional mobility and sweep enhancement mechanisms ahead of the polymer front. Additionally, during this stage the injected polymer creates a barrier between the aquifer and the oil column, suppressing the aquifer flux and hence the negative effect of the cones or water channels (blanketing mechanism). Moreover, injection of polymer pushes the oil to the depleted water cones, which is then is produced by the water coming from the aquifer during shut-in period (recharge mechanism). During the shut-in or NAP period, the aquifer water also pushes the existing polymer bank and hence leads to extra oil production. The NAP strategy reduces polymer loss into aquifer and improves the polymer utilization factor expressed in kg-polymer/bbl of oil, resulting in a favorable economic outcome.

Refinement of the rail–wheel contact pair to improve rail–wheel interaction conditions for railway vehicles with an increased axle load

At present, one of the global trends in railway transport development, which becomes clearer and clearer, is increasing the axle load of freight cars, which gives a considerable economic benefit. In this connection, of importance is not only the car design, but also the car capacity utilization factor: the higher this factor, the more economically efficient the car use. Because of this, one of the priority global lines in increasing the volume of fright traffic and the railway operation efficiency is increasing the carrying capacity of freight cars. Preparing the railways for cars with increased axle loads calls for the development of measures to decrease the track deformability, in particular by choosing appropriate wheel and rail profiles. The aim of this work was to develop recommendations on refining the wheel?rail contact pair to improve curve negotiation by railway vehicles with an increased axle loads on the Ukrainian railways. This paper presents the proprietary R-ITM wear-resistant railhead profile. The effect of the new profile on wheel?rail interaction in negotiating a curve of radius 300 m at a constant speed was studied for different cars. In doing so, emphasis was on wheel?rail interaction for a new-generation freight car on 18-9817 trucks with an axle load increased to 36 tf. The studies conducted made it possible to formulate the following recommendations: to improve curve negotiation by railway vehicles with increased axle loads, reduce the adverse effect on the track and improve traffic safety, new proprietary contact pair profiles are recommended: the ITM-73-03 wheel profile for cars, and the R-ITM railhead profile for outer rails together with the standard R65 railhead profile for inner rails.

The Economic Assessment of The Solution to the Multi-Criteria Problem for Determining Heavy Vehicles Usage Efficiency

The article discusses approaches to assessing the effectiveness of the use of heavy vehicles on the example of equipment for the transportation of bulk cargo. The modernization of the existing methods for assessing the effectiveness of its application and the choice of specific operating conditions in the presence of uncertainties and existing restrictions in the environment is pro-posed, a methodological approach to solving this problem based on the classical theory of linear programming is proposed. As a result, within the framework of the indicated practical problem, the range of optimal solutions for the value of the load-carrying capacity utilization factor has been determined. The modernization of the existing methods for assessing vehicles based on determining the efficiency of their operation, thus, can be recommended for use by the engineer-ing and technical personnel of motor transport enterprises.

Study of Wear and Redistribution Dynamic Forces of Wheel Pairs Restored by a Wear-Resistant Coating 15Cr17Ni12V3F

The relevance of this study lies in the need to research the wear process of the elements of dynamic systems and to establish the dependence of the geometric and structural characteristics of wheels restored by plasma surfacing with a coating of 15Cr17Ni12V3F on dynamic, cyclically varying loads. The study was aimed to establish the dependencies between the deviation of the wear area, the formation of contact and fatigue stresses, and the change in the phase structure of the wheel defect. It is important to justify the permissible limits of wear of the transverse profile in the contact zone of a wheel and ridge. The object of the study was the dynamic interaction of the “wheel–ridge–rail contact surface” system. To achieve the goal, the following methodology was adopted: kinematic analysis, strength calculation, the use of mathematical analysis in dynamic system modelling, virtual modelling in the SOLIDWORKS software environment of the GearTrax application, experiment planning, and model correction through the results of metallographic studies. The results of the study are presented as reasonable prediction criteria that consider contact cycles during the formation of fatigue stresses at the stage of defect origin. The process of the dynamic interaction of the contact worn profile of a wheel with a railway rail is explored. Polynomial equations are proposed to substantiate the optimal design and technological parameters of designing a railway carriage wheel. The permissible limits of wear of the transverse profile in the contact zone of the wheel and the ridge are justified while taking the coefficient of the reduction of contact stresses in the metal into account. The dependences of the change in static load on the utilization factor of the railway carriage load capacity are established. The dependences of changes in fatigue stresses on the design deviation of the contact area of wheel wear are established. It is confirmed that the stress concentration under cyclic loads is formed in the ferritic layers of the material structure before the appearance of wear.

Hybridization of CSP Plants: Characterization of a Molten Salt Heater for Binary and Ternary Nitrate Salt Mixtures Fueled with Gas/Biogas Heaters

Hybridization of CSP plants with alternative energy sources (fuels) represents a means to improve flexibility of operation, power dispatchability and utilization factor of the plant. New generation CSP plants make use of molten salts as Heat Transfer Fluid (HTF) besides Thermal Energy Storage (TES) medium. Therefore, proper interfaces should be developed to effectively transfer the heat from the back-up source to the molten salt. This paper presents the results obtained in the experimental validation of an innovative gas-fueled Molten Salt Heater (MSH) prototype. The objective of this research is to validate the MSH design, where the specific properties of molten salts (compared to other HTFs, e.g., thermal oils) have to be taken into account. The developed reduced-scale MSH (90 kW thermal) consists of a heat exchanger with the molten salt flowing inside finned tubes cross-flowed with the hot flue gas generated in an upstream combustion chamber. LPG or a biogas-like mixture has been used as gas fuel. Experimental results have been obtained with two different molten salt mixtures: the “solar salt” binary mixture (NaNO3/KNO3, 60/40%w) typically used in CSP applications (up to 565 °C) and the ternary mixture known as Hitec XL® containing sodium/potassium/calcium nitrates (NaNO3/KNO3/Ca(NO3)2, 15/43/42%w) characterized by lower freezing temperatures. Experimental tests have been carried out changing some operative parameters like the flow rate of the molten salt (0.45–0.94 kg/s), the inlet temperatures of the molten salt (303–445 °C) and of the hot gas (596–632 °C). For both molten salt mixtures, it was demonstrated that heat transfer correlations based on the Dittus-Boelter equation allow to predict experimental results with <10% deviation between experimental and theoretical values of the heat transfer coefficient.