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  • 1
    Online Resource
    Online Resource
    Multi-Point-of-View Energy Loss Analysis in a Refuse Truck Hydraulic System
    MDPI AG ; 2021
    In:  Energies Vol. 14, No. 9 ( 2021-05-09), p. 2707-
    Details
    In: Energies, MDPI AG, Vol. 14, No. 9 ( 2021-05-09), p. 2707-
    Abstract: In recent years, much research has focused on reducing the power consumption of mobile hydraulic machines due to rising fuel costs, regulations on combustion engine emissions and the need to reduce the size and weight of the storage devices in hybrid drives. Current approaches to improve the energy efficiency of a hydraulic system can be classified into four basic groups: reduction of the energy demand, recovery of part of the supplied energy (ERS systems), regeneration of part of the supplied energy and reuse of the recovered and regenerated energy (hybrid systems). Today’s mobile hydraulic systems are often complex, perform different tasks and work under different load conditions, which makes it difficult to analyse energy losses. A study of the energy losses of a hydraulic system from different points of view, such as an energy balance for a complete machine cycle, an analysis of the individual cycle phases and a power analysis for the different operation quadrants of the actuators, can give an global picture of the energy losses, being very useful to rate its energy efficiency, identify main power losses and decide which of the different energy-saving techniques to apply. This paper describes the data collection process, its analysis from various points of view and the summary of the results in easy to understand charts as useful tools to identify and quantify the main energy losses. Only system architecture losses are considered. Losses in the ICE engine or the electric motor, hydraulic pump losses and mechanical losses are outside the scope of this study.
    Type of Medium: Online Resource
    ISSN: 1996-1073
    URL: Article
    DOI: 10.3390/en14092707
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2437446-5
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  • 2
    Online Resource
    Online Resource
    Study of the Effect of Vertical Airfoil Endplates on Diffusers in Vehicle Aerodynamics
    MDPI AG ; 2021
    In:  Designs Vol. 5, No. 3 ( 2021-07-21), p. 45-
    Details
    In: Designs, MDPI AG, Vol. 5, No. 3 ( 2021-07-21), p. 45-
    Abstract: Diffusers and the floor ahead of them create the majority of the downforce a vehicle creates. Outside motorsports, the diffuser is relatively unused, although its interaction with the ground is a consistent field of study owing to the aerodynamic benefits. The diffuser flow behavior is governed by three fluid-mechanical mechanisms: ground interaction, underbody upsweep, and diffuser upsweep. In addition, four different flow regimes appear when varying ride height, the vortices of which have great importance on downforce generation. The present study focuses on the diffuser’s fluid-dynamic characteristics undertaken within an academic framework with the objective of finding and understanding a high level of performance in these elements. Once the functioning of diffusers has been analyzed and understood, a new configuration is proposed: rear vertical airfoil endplates. The aim of the paper is to study the effect in performance of vertical airfoil endplates on diffusers in vehicle aerodynamics in a simplified geometry. The candidate to this geometry is the inversed Ahmed body, a geometry that is used as a model that simulates the flow behavior of car diffusers. Three different diffuser configurations are performed, namely 0° diffuser, 25° diffuser, and in the third case vertically installed rear vertical airfoil endplates are added to the 25° diffuser Ahmed body to change the flow field. These analyses are carried out by using open-source CFD simulation software OpenFOAM. An inlet velocity of 20 m/s is considered, as this is a typical velocity when cornering in motorsport. It is concluded that the 25° diffuser configuration generated more downforce than the 0° diffuser, which makes sense as the aim of adding a diffuser is to increase the amount of downforce produced. In addition, and as a result of the newly proposed configuration, the 25° diffuser Ahmed body with the vertical airfoil endplates emerges in a substantial increase of downforce thanks to the low-pressure zone generated at the back of the body.
    Type of Medium: Online Resource
    ISSN: 2411-9660
    URL: Article
    DOI: 10.3390/designs5030045
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2912711-7
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  • 3
    Online Resource
    Online Resource
    Parameterization, Modeling, and Validation in Real Conditions of an External Gear Pump
    MDPI AG ; 2021
    In:  Sustainability Vol. 13, No. 6 ( 2021-03-11), p. 3089-
    Details
    In: Sustainability, MDPI AG, Vol. 13, No. 6 ( 2021-03-11), p. 3089-
    Abstract: This article presents a methodology for predicting the fluid dynamic behavior of a gear pump over its operating range. Complete pump parameterization was carried out through standard tests, and these parameters were used to create a bond graph model to simulate the behavior of the unit. This model was experimentally validated under working conditions in field tests. To carry this out, the pump was used to drive the auxiliary movements of a drilling machine, and the experimental data were compared with a simulation of the volumetric behavior under the same conditions. This paper aims to describe a method for characterizing any hydrostatic pump as a “black box” model predicting its behavior in any operating condition. The novelty of this method is based on the correspondence between the variation of the parameters and the internal changes of the unit when working in real conditions, that is, outside a test bench.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    URL: Article
    DOI: 10.3390/su13063089
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2518383-7
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  • 4
    Online Resource
    Online Resource
    A Review of Gerotor Technology in Hydraulic Machines
    MDPI AG ; 2019
    In:  Energies Vol. 12, No. 12 ( 2019-06-24), p. 2423-
    Details
    In: Energies, MDPI AG, Vol. 12, No. 12 ( 2019-06-24), p. 2423-
    Abstract: Over the years, numerous investigations have established the gerotor fundamentals. This work aims to provide a complete review of the literature from the last decade, focusing on the articles published in the past five years on gerotor technology in hydraulic machines. The report gives a catalogue of guidelines based on the trochoidal-envelope definition, a background analysis, the worldwide distribution of articles in each continent and country and the most frequently used keywords in the field. The paper identifies state-of-the-art research, and reports on current mainstream ideas. From the historical background, this literature review reports the current approaches in gerotor pumps (geometry and performance approaches, modeling and numerical simulations), orbital motors and new concepts. The report will serve as a guide and a directory for novel engineers working with gerotor technology in hydraulic machines. Another intention of this paper is to disseminate the works of the researchers who use this technology around the world, and to provide a scenario for future international collaboration. The paper gives an account of the disparity between academia and engineering applications. There is currently very little published literature on design and production methodologies for gerotor pumps and orbital motors. Hence, the future goal is to collect recommendations that combine academia and industry expertise to make better use of these extensive studies in the field.
    Type of Medium: Online Resource
    ISSN: 1996-1073
    URL: Article
    DOI: 10.3390/en12122423
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2437446-5
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  • 5
    Online Resource
    Online Resource
    Model of the Floating Bearing Bushing Movement in an External Gear Pump and the Relation to Its Parameterization
    MDPI AG ; 2021
    In:  Energies Vol. 14, No. 24 ( 2021-12-18), p. 8553-
    Details
    In: Energies, MDPI AG, Vol. 14, No. 24 ( 2021-12-18), p. 8553-
    Abstract: This article presents the modeling, simulation and experimental validation of the movement of the floating bearing bushing in an external gear pump. As a starting point, a complete pump parameterization was carried out through standard tests, and these parameters were used in a first bond graph model in order to simulate the gear pump behavior. This model was experimentally validated under working conditions in field tests. Then, a sophisticated bond graph model of the movement of the floating bushing was developed from the equations that define its lubrication. Finally, as a result, both models were merged by integrating the dynamics of the floating bushing bearing with the variation of the characteristic parameters (loss coefficients). Finally, the final model was experimentally validated both in laboratory and field tests by assembling the pump in a drilling machine to drive the auxiliary movements. The novelty of this article is the conception and construction of a simple and experimentally validated tool for the study of a gear pump, which relates its macroscopic behavior as a black box (defined by the loss coefficients) to the internal changes of the unit (defined by its internal lubrication).
    Type of Medium: Online Resource
    ISSN: 1996-1073
    URL: Article
    DOI: 10.3390/en14248553
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2437446-5
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  • 6
    Online Resource
    Online Resource
    Numerical simulations of the flow and aerosol dispersion in a violent expiratory event: Outcomes of the “2022 International Computational Fluid Dynamics Challenge on violent expiratory events”
    AIP Publishing ; 2023
    In:  Physics of Fluids Vol. 35, No. 4 ( 2023-04-01)
    Details
    In: Physics of Fluids, AIP Publishing, Vol. 35, No. 4 ( 2023-04-01)
    Abstract: This paper presents and discusses the results of the “2022 International Computational Fluid Dynamics Challenge on violent expiratory events” aimed at assessing the ability of different computational codes and turbulence models to reproduce the flow generated by a rapid prototypical exhalation and the dispersion of the aerosol cloud it produces. Given a common flow configuration, a total of 7 research teams from different countries have performed a total of 11 numerical simulations of the flow dispersion by solving the Unsteady Reynolds Averaged Navier–Stokes (URANS) or using the Large-Eddy Simulations (LES) or hybrid (URANS-LES) techniques. The results of each team have been compared with each other and assessed against a Direct Numerical Simulation (DNS) of the exact same flow. The DNS results are used as reference solution to determine the deviation of each modeling approach. The dispersion of both evaporative and non-evaporative particle clouds has been considered in 12 simulations using URANS and LES. Most of the models predict reasonably well the shape and the horizontal and vertical ranges of the buoyant thermal cloud generated by the warm exhalation into an initially quiescent colder ambient. However, the vertical turbulent mixing is generally underpredicted, especially by the URANS-based simulations, independently of the specific turbulence model used (and only to a lesser extent by LES). In comparison to DNS, both approaches are found to overpredict the horizontal range covered by the small particle cloud that tends to remain afloat within the thermal cloud well after the flow injection has ceased.
    Type of Medium: Online Resource
    ISSN: 1070-6631 , 1089-7666
    URL: Article
    DOI: 10.1063/5.0143795
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1472743-2
    detail.hit.zdb_id: 241528-8
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  • 7
    Online Resource
    Online Resource
    Microwave Oven Application for the Preparation and Sterilization of Microbiological Culture Media: A Feasible Method with An Adapted Water Bath and Perforable Cap
    MDPI AG ; 2024
    In:  Applied Sciences Vol. 14, No. 6 ( 2024-03-11), p. 2340-
    Details
    In: Applied Sciences, MDPI AG, Vol. 14, No. 6 ( 2024-03-11), p. 2340-
    Abstract: There is currently increased interest in the use of alternatives to autoclaved culture media, in order to maintain the properties of the media, while saving energy and time. In this study, we assess a new system for culture media preparation, using a conventional microwave with a water bath and a glass bottle with a rubber cap that allows depressurization. Sterilization, using the proposed system (1000 W, 3 to 20 min), was compared with autoclaving for the preparation of tryptone soy agar (TSA), tryptone soy broth (TSB), Sabouraud 4% dextrose agar (SDA), and violet red bile glucose agar (VRBG). Microwave exposure for 7 min yielded sterile TSA plates. The productivity of both sterilization methods was assessed using the pour plate method, and significant increases in the growth of certain micro-organisms after using a microwave were observed for every culture medium, especially those that were sterilized by boiling (VRBG). The kinetics of microbial destruction showed that Escherichia coli and Bacillus subtilis spores were destroyed after 3 and 7 min in a microwave, respectively, while three decimal reductions were obtained for Geobacillus stearothermophilus spores after 15 min in an autoclave. This new sterilization method could be a feasible, rapid, and economical method to prepare microbiological media, with a quality similar to that obtained through autoclaving.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app14062340
    Language: English
    Publisher: MDPI AG
    Publication Date: 2024
    detail.hit.zdb_id: 2704225-X
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  • 8
    Online Resource
    Online Resource
    Helical Static Mixer Simulations for Its Integration in the Pour Plate Method: Mixing Agar and a Nutrient Solution
    MDPI AG ; 2023
    In:  Energies Vol. 16, No. 15 ( 2023-08-05), p. 5816-
    Details
    In: Energies, MDPI AG, Vol. 16, No. 15 ( 2023-08-05), p. 5816-
    Abstract: In microbiology laboratories, it is essential to obtain high-quality samples where the culture media are completely homogeneous. The pour plate method includes having to melt the culture media—a mixture of agar and a nutrient solution—before seeding. A static mixer is designed for this purpose, employing CFD (Computational Fluid Dynamics) with the software OpenFOAM to simulate the fluid’s behaviour in a helical static mixer with both internal and external configurations. The objective is to validate the CFD model by comparing it with the literature and provide a first approach to the mixer design. After satisfactory validation of the model, the results of the initial designs for Reynolds number 14 reveal the notably different behaviour of the fluids during mixing due to their differing properties, since agar and the nutrient solution present a high viscosity ratio. While the mixing efficiency is similar for the internal and external mixers, improved performance is demonstrated in the internal mixer, even for a shorter version. The external version of the mixer reaches a value for a mixing efficiency of 0.89 whereas the internal version performs more homogeneous mixing for the same number of mixing elements. This evaluation is based on a simplified internal design for computational simulations, whereas the external mixer is easier to manufacture but more complex to implement computationally. Finally, homogeneous mixing is achieved for the internal mixer configuration when adjusting its dimensions to those available on the market.
    Type of Medium: Online Resource
    ISSN: 1996-1073
    URL: Article
    DOI: 10.3390/en16155816
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2437446-5
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  • 9
    Online Resource
    Online Resource
    Taguchi Techniques as an Effective Simulation-Based Strategy in the Design of Numerical Simulations to Assess Contact Stress in Gerotor Pumps
    MDPI AG ; 2022
    In:  Energies Vol. 15, No. 19 ( 2022-09-28), p. 7138-
    Details
    In: Energies, MDPI AG, Vol. 15, No. 19 ( 2022-09-28), p. 7138-
    Abstract: The contact problem of a trochoidal gear is a drawback and a well-known performance indicator of a gerotor pump. Although numerical simulations aid in the evaluation of contact stress, the difficult task of determining geometrical parameters, operating conditions, and the number of simulations to run falls to the designer. This paper presents the Taguchi techniques as an effective simulation-based strategy to narrow down the geometrical parameter combinations, reducing the solution space and optimizing the number of simulations. The work is first focused on the validation of the proposed numerical model by means of published contact stress results of recognized researchers in the field, as well as the unification of nomenclature and notation. Then, the Taguchi approach is based on a sequence of four experiments, ranging from the screening case with two levels and seven parameters to multiple levels and four parameters with three software input operating conditions (temperature, torque, and friction coefficient) emulating noise effects. The contact stresses of 128 gear sets, having common volumetric capacity and dimensional constraints to detach mechanical performance from flow rate and casing, were analyzed. Results prove the feasibility of the proposed methodology by identifying the most suitable gear set configuration and predicting the quantifiable performances of a real-working gerotor pump.
    Type of Medium: Online Resource
    ISSN: 1996-1073
    URL: Article
    DOI: 10.3390/en15197138
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2437446-5
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  • 10
    Online Resource
    Online Resource
    Methodology for developing teaching activities and materials for use in fluid mechanics courses in undergraduate engineering programs
    Omnia Publisher SL ; 2015
    In:  Journal of Technology and Science Education Vol. 5, No. 1 ( 2015-03-11)
    Details
    In: Journal of Technology and Science Education, Omnia Publisher SL, Vol. 5, No. 1 ( 2015-03-11)
    Type of Medium: Online Resource
    ISSN: 2013-6374
    URL: Article
    DOI: 10.3926/jotse.135
    Language: Unknown
    Publisher: Omnia Publisher SL
    Publication Date: 2015
    detail.hit.zdb_id: 2649603-3
    SSG: 5,3
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