University Applications for PhD

As someone who has been engaged in academic research for several years, I see my goal of seeking a Ph.D. in mechanical engineering, and more specifically in the thermal and energy sciences, as the natural outcome of the evolution of my increasing involvement with the field, and as a requirement to continue contributing to it as a professor. My goal is to continue pushing the limits of thermal technology, and to engineer novel ways of fluid and heat transport to keep up with the operational requirements of electronic, biological and power generation systems.

My motivation is aligned with the growing challenges that the thermal sciences have been facing for the past few decades. The amount and severity of requirements and constraints to which a thermal energy system must abide have been increasing due to a number of factors, namely device miniaturization, global warming and extreme operating conditions. As a result, thermal management has had to find routes that go beyond the generally well-known diffusion-based and single/multiphase convective systems. Some of these new technologies, which involve surface and material engineering at the nano- and microscales, often require the exploitation of unintuitive and non-linear behaviors that certain fluids or materials exhibit under very specific conditions. As a Ph.D. student, I want to explore how these physical phenomena enable the construction of efficient heat transfer devices, and learn how they can integrate and improve macroscale thermal systems, such as power generation and thermal energy storage plants, thermal management circuits and high heat flux systems in general.

I have found in supercritical fluids an excellent sandbox to explore how unusual properties can trigger interesting and potentially useful phenomena. In the vicinity of their liquid-vapor critical point, most substances exhibit highly non-linear thermophysical property variations, such as diverging heat capacity. Under the guidance of Prof. X, my undergraduate and Master’s advisor, I have investigated how these unintuitive thermal behaviors can be used in favor of constructing efficient heat transfer equipment, such as heat exchangers. Our collaboration has already resulted in several publications and in my Bachelor’s thesis, to which was granted the ABCM-Embraer Award, in recognition of the nation-wide best final year project in mechanical engineering in Brazil. As a result, I was invited by the Brazilian Association of Mechanical Sciences (ABCM) to speak about our research at the country’s largest mechanical engineering conference. In continuation of my undergraduate research, I have been exploring how these unusual properties—particularly the enhanced heat transfer and heat capacity—can aid the development of high energy density and high power density thermal energy storage systems. Some of our most recent and exciting results have recently been published in Applied Energy, and we expect to present a theoretical analysis of supercritical natural convection heat transfer at the 2018 IHTC in Beijing.

I have had the opportunity to collaborate in an international setting during the one year I spent as an undergraduate exchange student at Washington University in St. Louis, where I joined Prof. X’s Computational Fluid Dynamics group. One of our most promising endeavors included advancing solar aviation by developing a methodology that allows the calculation of solar radiation incidence over aircraft wings, and by performing energetic-aerodynamic optimizations of airfoils, effectively combining his expertise on aeronautical engineering with my previous experience working with solar energy. Our successful collaboration made me confident that I could thrive in a foreign research-intensive environment. During my Master’s, I also spent a short period at UT Austin with Prof. X, as we, along with Prof. X, investigated how porous media should be distributed to improve convective heat transfer performance. Contrary to recent trends that suggest employing uniform, highly conductive matrixes to increase conductance, we discovered that even insulative matrixes (such as 3D-printed plastic) can be used to increase thermal performance by driving the flow towards heated surfaces and increasing boundary layer mass flow rate, while not affecting pressure drop.

More recently, I have become increasingly involved in thermal management at high heat fluxes, an interest that has motivated me to investigate phase-change heat transfer, and which has driven my attention towards the research being conducted by several groups at MIT. Partly motivated by Prof. X’s and Prof. X’s research on surface structuring for critical heat flux (CHF) enhancement, some of the questions I and Prof. X have been attempting to answer include whether enhanced surface capillarity can offset the low CHF that is commonly found in reduced gravity environments. To answer that, we have been building a remote nanofluid boiling experimental platform that will board a sounding rocket for microgravity experimentation. While using capillary-driven flows can be an effective strategy to passively manage boiling heat transfer and to avoid boiling crisis at a low CHF, I am, similarly to Prof. X, also interested in the active control of high heat flux systems. More specifically, I proposed an investigation about whether machine learning and statistical techniques such as deep learning and principal component analysis can be used to identify boiling heat transfer regimes using inexpensive low-speed and low-resolution visualization set-ups, a project about which we have a paper submitted for publication and an abstract that we will present at the 2018 ICBCHT in Nagasaki.

Prepared by my previous experience, my goal as a Ph.D. student is to further explore unusual small scale phenomena for heat transfer management, in particular at high heat fluxes. While conventional phase-change heat exchangers can transfer over 1MW/m² at reasonable temperature gradients, it is uncertain whether much higher fluxes can be attained without resorting to engineering at the nano- and microscales. Therefore, I am particularly interested in Prof. X’s research, who has been pushing the limits of heat transfer with the assistance of small scale phenomena. In addition to her work on nanostructured surfaces for boiling heat transfer—which has resulted in multiple breakthroughs, including reaching heat fluxes just short of 10 MW/m² in microchannels while simultaneously suppressing longstanding issues of temperature oscillations—, Prof. X’s research is also heavily focused on understanding the underlying physics of nano- and microscale fluid-solid interaction, which is then exploited for heat transfer enhancement in, for instance, thin-film evaporation and condensation heat transfer, both in which I am deeply interested. Given MIT’s strong involvement with small scale phenomena for various applications, there are many other faculty members with whom I would be thrilled to collaborate. Prof. X’s work on engineered surfaces for controlled wetting, which he has shown to be promising for phase-change heat transfer, is directly related to my interests. At even smaller scales, I believe that Prof. X’s research on nanoscale transport, and the exploitation of quantum mechanical phenomena for energy applications, such as ballistic phonon transport, will continue enabling fundamental breakthroughs in how we understand and design macroscale heat transfer systems. Moreover, MIT’s excellence in the nano- and microsciences is unmatched in the world, and the inauguration of the MIT.nano center will guarantee that MIT remains atop the field. Therefore, I am confident that MIT—in particular the Department of Mechanical Engineering—provides the perfect atmosphere to mature as a scientist, and is the university to which I look forward to contributing.

My long-term career goal is to continue providing for the development of the thermal and energy sciences. Consequently, I wish to secure a stable academic position that enables me to fully develop my research interests and advise—and hopefully inspire—students to advance the areas about which they feel passionate, which I believe is the cornerstone of a successful career in science. To do so, I have learned from experience that being immersed in an environment that fosters excellence in all human endeavors is fundamental to nurturing collaboration, creativity and drive, which I am sure MIT excels in providing.