Papers by Senhorinha Fátima Capela Fortunas Teixeira
The objective of this paper is to help fulfill the lack of information about the parameters neede... more The objective of this paper is to help fulfill the lack of information about the parameters needed to simulate a pressurized metered-dose inhaler (pMDI) spray (using a commercial computational fluid dynamics tool), providing future researchers the necessary information to study other pMDIs related devices, such as holding chambers. Following a previous bibliographic research about the characteristics of a pMDI spray, a further compilation was needed regarding the information to computationally define the spray in Fluent™. A very common drug asthma treatment (Ventolin®) was used in this study, with particles diameters going from 1.22 µm to 49.5 µm in a Rosin-Rammler distribution. The parameters were tested in Fluent™ (v6.3.26), using a three-dimensional "testbox" created especially for this purpose and meshed using the Gambit™ software (v2.2.30). The results showed that the selected parameters have produced a simulated spray very similar to the real one. It was also observed that the air behavior inside the "testbox" had a predictable response.
DergiPark (Istanbul University), May 28, 2020
Jet impingement is a complex heat transfer technique which involves several process variables, su... more Jet impingement is a complex heat transfer technique which involves several process variables, such as nozzle-toplate distance, jet diameter, Reynolds number, jet temperature, among others. To understand the effect of each variable, it is important to study them separately. In industrial applications that use forced convection by air jet impingement, such as reflow soldering, the correct analysis of the flow structure and accurate definition of the variables values that affect the heat transfer over the target surface leads to an increase of the process performance decreasing the manufacturing costs. To reduce costs and time, the introduction of numerical methods has been fundamental. Using a Computational Fluid Dynamics software, the number of experiments is highly reduced, being possible to focus on the phenomena that are highly relevant for the purpose of the study. In this work, the nozzle-to-plate distance (H/D) variable is analyzed. This is considered one of the most important parameters since it influences the entire structure of the jet flow as well as the heat transfer coefficient over the target surface. The results present a comparison between different H/D under isothermal and non-isothermal conditions for a Reynolds number of 2,000.
A Case Study of Standardization of a Project Management Tool in an Automotive Company
Lecture notes in mechanical engineering, Aug 24, 2023
VHC Performance Evaluation at Connstant Flow: 30 L/Min
The first author would like to express his acknowledgments for the support given by the Portugues... more The first author would like to express his acknowledgments for the support given by the Portuguese Foundation for Science and Technology (FCT) through the PhD grant SFRH/BD/76458/2011. This work was financed by National Funds-Portuguese Foundation for Science and Technology, under Strategic Project UID/SEM/04077/2013 and UID/CEC/00319/2013.
Forced convection by submerged multiple jet impingement for cooling applications is widely implem... more Forced convection by submerged multiple jet impingement for cooling applications is widely implemented in several industrial sectors. However, the complexity of the flow makes this process difficult to control. Therefore, it is important to conduct an in-depth study in order to characterize the flow field and this is possible through Particle Image Velocimetry (PIV) technique. PIV allows the measurement of the velocity field and information regarding flow vorticity and turbulence intensity can be obtained. To conduct the PIV measurements, an experimental setup was specially built to analyze the flow dynamics of multiple air jets impinging on a surface with a step. In PIV, the selection of the most appropriate tracer particles is crucial to ensure accurate measurements. In that sense, this work comprises an analysis of different seeding particles produced by a Concept Smoke Aerotech system. The measurement region consists of an array of multiple air jets spaced 3 D (jet diameters) between them according to a staggered configuration. The jets are confined and a distance between the nozzle plate and the target surface of 2 D is applied. The central, back, and front rows are analyzed in order to determine the effect of the jet's interactions on the velocity fields and heat transfer. The results show that the complexity of the flow is increased by the implementation of a non-flat surface. The step induces a strong flow reversal that affects the jet flow development over the surface. Moreover, the measured data highlights the complex interactions between jets and confirm that PIV is able to capture the large-scale structures induced in the vicinity of the target plate, as well as the strong fountain flows generated between the adjacent jets. Furthermore, the results show that the combination of PIV and heat flux sensors is appropriate to characterize the jet's flow dynamics and the heat transfer of multiple jets impinging on a surface, providing relevant insights for several engineering applications. This study underlines the advantages of the PIV system for a detailed characterization of a multiple jet impingement flow and the importance of a proper definition of the experimental condition to ensure the accuracy of the measurements.
An Experimental Setup to Study the Fundamental Phenomena Associated With Biomass Combustion
During the combustion of solid biomass in a grate-fired boiler, each particle experiences a seque... more During the combustion of solid biomass in a grate-fired boiler, each particle experiences a sequence of processes which include heating, drying, devolatilization, and char combustion. Furthermore, in the gas phase, products may react with oxygen. As it is impossible to maintain repeatable and fully controlled environments, and to monitor all the dynamics involved in field-scale experiments, it becomes necessary to perform investigations at a small scale. This should be sufficient to provide a controlled environment, and large enough to define realistic conditions. In this way, to evaluate the thermal behavior of biomass particles under an oxidative atmosphere and determine the composition of the flue gas released into the atmosphere, a small-scale reactor was developed and presented in this paper. The results of the different mass loss profiles at different combustion conditions and with samples with different size are presented. Additionally, the composition of the gases released over the devolatilization period was determined using a gas chromatograph and they are here correlated with the reactor temperature. This work proved to be very useful since it is important for the computational modeling of industrial boilers and is required for the design and operation of biomass combustion equipment. In the future, this study will be very valuable to develop a computational tool to analyze the combustion process inside an industrial grate-fired boiler.
Evaluation of Nozzle for Water Atomization in Agriculture
Different Teaching Methods
Advances in educational technologies and instructional design book series, Jan 27, 2023
A Correlative CFD Study Between Recirculation Area and FPM in VHC Design
The first author would like to express his acknowledgments for the support given by the Portugues... more The first author would like to express his acknowledgments for the support given by the Portuguese Foundation for Science and Technology (FCT) through the PhD grant SFRH/BD/76458/2011. This work was financed by FCT, under the Strategic Project UID/SEM/04077/2013. Additionally, by COMPETE: POCI-01-0145-FEDER-007043 and FCT within the Project Scope: UM/CEC/00319/2013.
The recent surge of electric vehicles has put pressure on the development and manufacture of batt... more The recent surge of electric vehicles has put pressure on the development and manufacture of batteries. However, batteries are still expensive, bulky and heavy, creating the need for inboard electricity generation using an internal combustion engine, usually referred as "range extender". This paper presents the initial development of a DI-SI engine to work as range extender, focusing on the interaction between fuel spray and airflow inside the combustion chamber. To enable efficient combustion of lean and extra lean mixtures, a technique called stratified charge, is used. With direct injection spark ignition (DI-SI) engines it is important, under part load, to direct the fuel spray to the vicinities of the spark plug, enabling a fast and stable combustion of a lean mixture. A rich mixture region is created near the spark plug allowing an easy kernel formation and development. There are three types of systems for "directing" the fuel spray towards the spark plug: wall guided, air guided and spray guided. The developed design is a mixture of wall and air guided systems and the idea is to inject the spray towards the piston crown and to divert it to the spark plug location by the barrel swirl existent within the combustion chamber at this time. The system development was carried out using CFD FLUENT code. The study comprises three parts, the design of the components and its location (combustion chamber, piston crown, intake passage and injector location and aim), the air flow modelling and finally, the two phase modelling. A simple engine geometry and mesh were created in the Ansys CFD software. The air flow was considered to be transient, incompressible, Newtonian and viscous turbulent. The turbulence model used was the standard k-ε model, since it is the most common, simple and well-known model of turbulence. The spray has been simulated using the Discrete Phase Model. The Lagrangian discrete phase model in Fluent™ follows the Euler-Lagrange approach, where the fluid phase is treated as a continuum by solving the time-averaged Navier-Stokes equations, while the dispersed phase is solved by tracking a large number of particles through the calculated flow field. Preliminary results are now being obtained.
International journal of applied thermodynamics, May 28, 2020
Jet impingement is a complex heat transfer technique which involves several process variables, su... more Jet impingement is a complex heat transfer technique which involves several process variables, such as nozzle-toplate distance, jet diameter, Reynolds number, jet temperature, among others. To understand the effect of each variable, it is important to study them separately. In industrial applications that use forced convection by air jet impingement, such as reflow soldering, the correct analysis of the flow structure and accurate definition of the variables values that affect the heat transfer over the target surface leads to an increase of the process performance decreasing the manufacturing costs. To reduce costs and time, the introduction of numerical methods has been fundamental. Using a Computational Fluid Dynamics software, the number of experiments is highly reduced, being possible to focus on the phenomena that are highly relevant for the purpose of the study. In this work, the nozzle-to-plate distance (H/D) variable is analyzed. This is considered one of the most important parameters since it influences the entire structure of the jet flow as well as the heat transfer coefficient over the target surface. The results present a comparison between different H/D under isothermal and non-isothermal conditions for a Reynolds number of 2,000.
Project-Based Learning in a Mechanical Engineering Course: A new proposal based on student's views
The International journal of mechanical engineering education, Feb 14, 2022
The evolution of learning in higher education is nowadays evident. Several discussions and studie... more The evolution of learning in higher education is nowadays evident. Several discussions and studies have been performed about new methodologies that can disrupt the way the classes are taught in universities. In this context, Project-Based Learning (PBL) is the most emphasized. In the Mechanical Engineering course at the University of Minho (UM), the Integration Project (IP) courses apply a PBL methodology, being these classes the differentiating element of the Integrated Master in Mechanical Engineering (IMME) compared with other Portuguese universities. However, even if the innovative aspect of this approach is recognized nationally, the opinions between students and Professors, about the structure and organization of this class, are still divided. In that sense, this work presents a new proposal for the IP courses in which the opinion of students and successful models implemented in international universities are considered. This study analyses the best PBL methodologies implemented in Engineering courses and presents a PBL model actually implemented at the IMME. This information is combined with the student's views obtained from a survey conducted at the Department of Mechanical Engineering (DEM), regarding the actual PBL model. Through this study, a new proposal for the IP courses is presented. This proposal intends to provide an effective answer to the necessity of the students, using successful tools and methodologies to improve the teaching and learning process in the IMME course. Through this proposal, it is expected to increase the learning process and motivation of the students making them better prepared for a productive profession.
Interest in hydrogen as a transportation fuel is growing. Fuel cell electric vehicles fed by hydr... more Interest in hydrogen as a transportation fuel is growing. Fuel cell electric vehicles fed by hydrogen are expected to play a key role in the decarbonization of the transportation sector. Its impact will depend upon the existence of reliable and cost-effective fuelling stations. Numerical simulation allows sizing hydrogen refuelling on-site stations in order to identify the most cost-effective solution for a specific utilization pattern. This study aims to define a numerical optimization model for a hydrogen refuelling station to supply both light and heavy vehicles. The objective function is to minimize the total storage volume, taking into account the number of vehicles to be refuelled. The pressure at each storage skid is considered a decision variable, as well as the hydrogen mass that is provided at each vehicle filling. The model considers the hydrogen properties and the physical constraints to size the station prior to its construction. Additionally, a cost analysis based on the capital expenditure concept was developed. The hydrogen refuelling station must be able to supply 300 kg/day of hydrogen. The station includes four main systems: the hydrogen production equipment, an electrolyzer, and a system that can store hydrogen to feed the compression cascade. The station should be able to fill 10 heavy vehicles at 350 bar (H35), considering 2 skid pressure levels and a supplied mass of 30 kg and 30 light vehicles at 700 bar (H70), considering 3 skid pressure levels, dispensing 4.2 kg of hydrogen each. At all vehicle fillings, a pressure differential of 50 bar between the high-pressure skid and the vehicle tank is mandatory so the refuelling can be validated. The results show that it is possible to refuel 10 heavy vehicles considering a total storage volume of 36.9 m 3 , whereas, for light vehicles, it is possible to refuel 30 vehicles with a total volume of 22.9 m 3. Based on capital expenditure, the most representative capital costs are the production equipment (30%), high-pressure storage unit (20%) and the hydrogen compression system (18%).
International Journal of Mechanical Sciences, Sep 1, 2019
Carotid artery blood flow is studied to compare models with rigid and elastic walls. Considering ... more Carotid artery blood flow is studied to compare models with rigid and elastic walls. Considering a patient-specific geometry and transient boundary conditions. In the case of rigid walls, only the fluid (blood) behavior is considered, in a typical Computational Fluid Dynamics study. With the elastic walls, the reciprocal influence of both fluid and solid (blood and artery) are taken into account, constituting a Fluid-Structure Interaction study. Furthermore, the study of the influence of mechanical properties of the artery, which become stiffer with the progression of atherosclerosis, on blood flow is also presented, an innovative approach relative to the work done in this field. Results show that the carotid sinus is the preferential zone to develop atherosclerosis, given its low values of Time-Averaged Wall Shear Stress. Additionally, it is fundamental to consider the arterial wall as elastic bodies, given that the rigid model overestimates the flow velocity and Wall Shear Stress. On the different mechanical properties of the vessel, its influence is minimal in the Time-Averaged Wall Shear Stress profiles. However, given the results of the displacement and velocity profiles, their inclusion in blood flow simulations in stenosed arteries should be considered.
Development of CFD Model to Study the Spread of Wildfires
Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering, Oct 30, 2022
Wildfires are a worldwide phenomenon that as an impact on all surrounding forms of life. Studying... more Wildfires are a worldwide phenomenon that as an impact on all surrounding forms of life. Studying these events is essential to develop and optimize the tools used for combat and prevention, and its behavior is associated with the state of the vegetation, atmospheric conditions, ground properties, and many others, constituting an expensive and challenging task. This work presents itself as a complementary work to study the flow over a forest through a CFD model, which causes a modification in the velocity profile due to the drag produced by the forest presence, and the values obtained can be used in a mathematical model to study the fire rate of spread and fireline intensity considering the new velocity field. The CFD model was applied in the commercial software Ansys Fluent. The results confirmed that the wind is a dominant force during a forest fire, i.e., at high velocities the fire has an aggressive behavior and at low velocities tends to calm down. However, due to the unpredictability of certain weather conditions, it is dangerous to say that a forest fire is fully controlled since its behavior can change in a matter of minutes.
Energy and Exergy Analysis of a Biomass Power Plant
The fulfilment of energy targets regarding the use of renewable energy has been a strong incentiv... more The fulfilment of energy targets regarding the use of renewable energy has been a strong incentive to the development of dedicated power plants using biomass. Because these facilities operate with low value residues, this orientation has also received a strong incentive by the quest to reduce the amount of fuel in the woods and lowering the risk of fire. This issue is a major problem in dry climates. Although the number of plants planned for Portugal was very large, the actual number of units in operation is small. The first plant to enter production in Portugal was the thermal power plant of Mortágua. In this paper the energy and exergy analysis in this plant is presented. The objective of this work is to develop an analysis for the energy conversion in the plant. This is based on parameters that were retrieved during its normal operation and include: biomass and air flow rate, temperature measurements of the flue gases throughout the facility including the economizer, the two superheaters and flue gas composition. The elemental analysis of the biomass resulting from a blend of various sources was measured in addition to its moisture (ranging between 20 and 45% depending on the sources). The analysis was carried out for a fuel batch with a moisture of 35%. The plant was operated at three loads (full load, 80% and 65% load) and from the energy/mass balances the overall efficiency was calculated to be approximately 26%. The data were also used to perform a second law analysis of the plant which enables the calculation of the exergy destruction in the various components of the facility, including the external irreversibility. It was observed that the combustion chamber is the prime contributor to the overall loss of efficiency. The exergy efficiency was found approximately 22%.
Numerical simulation of an industrial worker route using thermal human body software
Thermal comfort studies tend to establish the better thermal environment to human occupancy and t... more Thermal comfort studies tend to establish the better thermal environment to human occupancy and these studies can be motivated by objective and subjective reasons. The evaluation of the thermal conditions to which the individuals are exposed, provides crucial information about how they feel and how satisfied they are within the environment. Such information could help managers and engineers to take actions in order to ensure the thermal comfort of people, protecting their health, and to design thermally efficient buildings reducing the energy waste. The human body is an active system that responds to a certain environmental input in different setting conditions. Thermal human body software is based on differential equations modeling the heat and moisture exchange of a human body with and it can predict the body and clothes temperatures and humidity felt by the body, which will influence the human comfort. The main purpose of this paper is to understand how human body thermal software can analyze the human response along an industrial task where different environment conditions are felt. Experimental data, obtained from a field investigation made in an industrial plant, has been used to define ambient temperature and humidity. Results indicate that the software can differentiate body parts concerning its thermal behavior and the temperature at different parts of the body tend to the same behavior with respect to different environmental conditions. The model seems reliable and comparative studies could be made in order to define the best track to achieve an industrial task.
Numerical Analysis of the Influence of the Jet-To-Jet Spacing Between Two Adjacent Air Jets Impinging a Flat Plate
Proceeding of 4th Thermal and Fluids Engineering Conference, 2019
Biomass & Bioenergy, Aug 1, 2023
INTRODUCTION Vegetable fats and oils are extensively used as raw material and inputs for industri... more INTRODUCTION Vegetable fats and oils are extensively used as raw material and inputs for industrial food, medicine, and cosmetic production 1. The possibility of an acute shortage in edible and industrial vegetable fats and oils together with a clear tendency favoring the use of natural vegetable fats for the replacement of those from hydrogenated vegetable oil has encouraged the investigation of edible plants as possible sources of usable fats and oils 1, 2. Krabok Irvingia Malayana is a large-grown and woody wild almond tree widely distributed in tropical and subtropical areas. It is from the Irvingia family, which consists of two species. The other species is Ivingia gabonensis or African wild mango, which has been studied extensively. It is a commercial and indigenous fruit tree of West and Central Africa, which has been identified as the most important tree for domestication 3. The fruits are used as condiment and are highly valued for their food thickening properties. In Thailand, the krabok tree is commonly used for wood and charcoal production, whereas the seeds, after peeling, are consumed by people 4. In Cambodia, the tree is known as the pauh
Convection from multiple air jet impingement - A review
Applied Thermal Engineering, 2023
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Papers by Senhorinha Fátima Capela Fortunas Teixeira