My academic work

(If you can read in Portuguese, you can see my CV Lattes here.)

Overview of my academic work

My whole career has been developed inside the academia. I’m passionate about science, I believe that technology exists primarily to make human life more confortable (without causing disconfort to the environment), and now I see that research and education are the best way I can contribute to Engineering.

With the help of my supervisors, colleagues and professors, my work is based upon two basic principles.

First, my research efforts are focused on the use of thermodynamics in innovative cold production systems. The need for refrigeration cannot be questioned, but at the same time the market and regulations create pressure for systems that are efficient and have low environmental impact. My work currently attempts to unify these two points, emphasizing first principles in search of alternative systems.

Second, I strongly believe that interdisciplinarity is key to technological innovation. I’m a Mechanical Engineering by trade, but during my Master’s studies I used concepts of Chemical Engineering to create mixture models applied to refrigeration systems. Now, in my PhD studies, I dedicate myself to Electromagnetic Theory and Permament Magnet Design, with some interesting results. To emphasize: having an open mind and being willing to learn new subjects is one of my strongest qualities and a necessary requirement for a successful scientific career.

Education

  • 2006-2011:Graduation in Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Brazil
  • 2012-2014: Master’s Degree in Mechanical Engineering,
    Federal University of Santa Catarina, Florianópolis, Brazil

    • Dissertation (in Portuguese): Análise experimental e teórica da formação de espuma em misturas óleo-refrigerantePDF (Title in English: Experimental and theoretical analysis of foam formation in oil-refrigerant mixtures)
    • Supervisor: Prof. Jader R. Barbosa Jr.
    • Abstract: In most vapor compression refrigeration systems, specially those in which the cooling capacity is controlled by the cycling of the hermetic
      compressor, lubricating oil is necessary in the compressor. While the compressor is off, refrigerant coming from high-pressure parts is absorbed by the oil present in the sump. As the electric motor starts up, the crankcase pressure rapidly decreases, and the oil-refrigerant mixture in the sump becomes supersaturated, which causes refrigerant desorption, bubble cavitation and foam formation. The inflow of liquid from the foam into the compression chamber must be avoided to preserve the integrity of valve system and minimize the undesirable transport of oil from the sump to other parts of the system. In this study, an experimental evaluation of refrigerant desorption and foam formation in mixtures of polyol ester oil and refrigerants 134a and 1234yf under controlled conditions is carried out. An experimental facility was designed and built to allow measurement of depressurization rate, foam height and mass flux due to gas expansion and refrigerant desorption from the supersaturated mixture. Quantitative data, together with high-speed video analysis, allowed identification of the main physical mechanisms associated to this problem. Experimental results as a function of time were explored relative to test conditions (temperature and initial mass fraction), showing that there are two characteristic regimes for this phenomenon: a growth stage followed by a drainage stage, and that foam height is inversely proportional to temperature. An integral mathematical model was proposed and validated with experimental data, showing good agreement (deviations smaller than 20%) when the empirical parameters were adjusted specifically for each experimental condition.
  • 2014- : PhD in Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Brazil
    • Preliminary title: Integrated design of the magnet-regenerator assembly for a magnetic refrigerator
    • Advisor: Prof. Jader R. Barbosa Jr.
    • Co-advisor: Dr. Jaime A. Lozano
    • Abstract (as published in my Qualifying Exam):Most domestic refrigeration systems use vapor mechanical compression cycles due to their
      high performance. However, the use of refrigerant fluids that may be toxic or inflammable (in the case of natural fluids), or damaging to the ozone layer or to the greenhouse effect (as it happens with synthetic fluids) is a major disadvantage of this type of system, making it object of increasing regulation in international markets. One of the proposed alternatives is magnetic refrigeration, which uses the property of magnetocaloric materials of increasing their temperature when magnetized, a fact that can be employed on the construction of a regenerative cycle for refrigeration purposes. Such cycles have a lower degree of thermodynamic irreversibilities than vapor compression systems and use only a solid refrigerant based on rare earths alloys and/or transition metals and a water-based working heat transfer fluid, all environmentally-neutral substances. Since the 1970s, several configurations and prototypes of magnetic refrigeration have been proposed, but the literature review shows that no published work can reach the operating point of 60 W for the cooling capacity and 20 K for the temperature span between the reservoirs, typical values for a low-capacity system, e.g. a wine cooler. This proposed PhD Thesis seeks to fill this gap through the integration and optimization of the best available designs of magnetic circuits made of permanent magnets (which generate the magnetic field necessary for the magnetocaloric effect) and of active magnetic regenerators (where the thermal-hydraulic interactions happen). As a first result, an analytical model for the magnetic field generated between two concentric and infinite magnet cylinders (based on previous works from the literature) is presented, and the obtained expressions can be applied into optimization methods and combined with models for active magnetic regenerators. It is believed that this geometry can generate magnetic fields high enough to yield the desired magnetocaloric effect, and that the careful study of regenerators can decrease the residual heat exchange rates which tend to consume the cooling capacity. The results obtained in this proposed Thesis will be of great utility in a global project of a magnetic refrigerator, which is being executed by researchers and students in the present author’s research group.

Research Interests

  • Magnetic refrigeration
  • Thermodynamics of magnetic systems
  • Mixtures thermodynamics
  • Thermal regenerators

Skills

  • Unix: use of terminals and shells (including in Windows systems)
  • Python programming:
    • Numerical computation with NumPy/pandas
    • Plotting with matplotlib
    • Symbolic mathematical computation with SymPy
    • Interactive scientific computation with Jupyter
  • Scientific documents with LaTeX
  • Other computing skills:
    • MATLAB
    • Mathematica
  • Experiences with design and assembly of experimental devices in thermal sciences

Check my GitHub profile for examples of my computing skills.

Languages

  • Native speaker of Portuguese
  • English (reading, writing, listening, speaking)
  • German (reading, listening, speaking)

International experiences

  • 2009-2011: Erasmus Mundus exchange student at Porto University, Porto, Portugal
  • 2011-2012: Mandatory internship (for my Mechanical Engineering degree) at the Karlsruher Institut für Technologie (KIT), Karlsruhe (Germany)
    • Activities: creation of routines to simulate refrigeration systems using Visual Basic for Applications

Publications

See my main publications here

Advertisements