Evelyn Wang

Evelyn Wang
Massachusetts Institute of Technology | MIT · Department of Mechanical Engineering

About

364
Publications
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14,811
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Publications

Publications (364)
Article
Sorption and desorption with hygroscopic hydrogels hold significant promise for thermal management, passive cooling, thermal energy storage, and atmospheric water harvesting. However, a comprehensive understanding of the energy and mass transport mechanisms in hygroscopic hydrogels remains missing, impeding accurate modeling and optimization. In th...
Article
The efficiency of a heat engine can be significantly improved by operating in a high-temperature and high-pressure environment, which is crucial for a wide range of applications such as hybrid and electric aviation as well as power generation. However, such extreme operating conditions pose severe challenges to the heat exchanger design. Although r...
Article
Full-text available
Boiling is an effective energy transfer process with substantial utility in energy applications. Boiling performance is described mainly by the heat transfer coefficient (HTC) and critical heat flux (CHF). Recent efforts for the simultaneous enhancement of HTC and CHF have been limited by an intrinsic trade‐off between them — HTC enhancement requir...
Article
Full-text available
Thermophotovoltaics (TPVs) convert predominantly infrared wavelength light to electricity via the photovoltaic effect, and can enable approaches to energy storage1,2 and conversion3–9 that use higher temperature heat sources than the turbines that are ubiquitous in electricity production today. Since the first demonstration of 29% efficient TPVs (F...
Article
Full-text available
Recent advances in thermally localized solar evaporation hold significant promise for vapor generation, seawater desalination, wastewater treatment, and medical sterilization. However, salt accumulation is one of the key bottlenecks for reliable adoption. Here, we demonstrate highly efficient (>80% solar-to-vapor conversion efficiency) and salt rej...
Article
Surface engineering has been leveraged by researchers to enhance boiling heat transfer performance, with benefits ranging from improved thermal management to more efficient power generation. While engineered surfaces fabricated using cleanroom processes have shown promising boiling results, scalable methods for surface engineering are still limited...
Article
Full-text available
An optically transparent and thermally insulating (OTTI) silica aerogel demonstrates promising results for various solar thermal applications, particularly concentrated solar power systems. Higher system efficiency can be achieved by integrating OTTI materials by reducing heat loss at higher receiver temperature. However, the thermal stability of O...
Article
Full-text available
We present a surface-engineering approach that turns all liquids highly wetting, including ultra-high surface tension fluids such as mercury. Previously, highly wetting behavior was only possible for intrinsically wetting liquid/material combinations through surface roughening to enable the so-called Wenzel and hemiwicking states, in which liquid f...
Article
Ultra-high vacuum (UHV) is essential to many surface characterization techniques and is often applied with the intention of reducing exposure to airborne contaminants. Surface contamination under UHV is not well-understood, however, and introduces uncertainty in surface elemental characterization or hinders surface-sensitive manufacturing approache...
Article
The boiling crisis determines the maximum heat flux for the safe operation of boiling equipment, which is widely used in various applications including power generation, thermal management of electronics and water desalination. Here we present a mechanistic and predictive theory for the boiling crisis, combining the thermo-fluidic interaction betwe...
Article
Full-text available
Sorption and desorption with hygroscopic hydrogels hold significant promise for thermal management, passive cooling, thermal energy storage, and atmospheric water harvesting. However, a comprehensive understanding of the energy and mass transport mechanisms in hygroscopic hydrogels remains missing, impeding accurate modeling and optimization. In th...
Article
The dusty-gas model is an empirical formulation commonly used to describe gas flows in porous media. While experiments have validated the model for pores with high aspect ratios, a validation for near-unity aspect ratios is lacking. We used direct simulation Monte Carlo to evaluate the accuracy of the dusty-gas model for binary diffusion in low asp...
Article
The critical heat flux during pool boiling has been investigated for a range of applications including electrical power generation and thermal management. Reported experimental CHF values during pool boiling of water on flat metallic surfaces, however, show a large discrepancy across studies. Here, we address this discrepancy in CHF values by accou...
Article
s Micro-structured surfaces have a significant impact on the flow boiling process in microchannels, but few numerical studies have been carried out due to their complex nature. In this study, the numerical investigation of flow boiling on micro-fin, micro-cavity, and smooth surfaces in a microchannel was conducted, with water serving as the working...
Article
Boiling heat transfer is dictated by interfacial phenomena at the three-phase contact line where vapor bubbles form on the surface. Structured surfaces have shown significant enhancement in critical heat flux (CHF) during pool boiling by tailoring interfacial phenomena. This CHF enhancement has been primarily explained by two structural effects: ro...
Data
Supporting Information for "Toward optimal heat transfer of 2D-3D heterostructures via van der Waals binding effects"
Preprint
We report the fabrication and measurement of thermophotovoltaic (TPV) cells with efficiencies of >40%. The TPV cells are 2-junction devices with high-quality 1.0-1.4 eV materials that target high emitter temperatures of 1900-2400{\deg}C. These cells can be integrated into a TPV system for thermal energy grid storage (TEGS) to enable dispatchable re...
Article
Full-text available
Stimuli‐responsive materials have been lately employed in soft robotics enabling new classes of robots that can emulate biological systems. The untethered operation of soft materials with high power light, magnetic field, and electric field has been previously demonstrated. While electric and magnetic fields can be stimulants for untethered actuati...
Article
Bubble growth and departure are ubiquitous phenomena in gas-evolving reactions, which govern the overall energy and mass transport. However, an in-depth understanding of the relationship between bubble dynamics and the electrochemical processes, in particular, the wettability effect on a gas-evolving porous electrode remains elusive. Here, we repor...
Article
Full-text available
Solar desalination holds significant promise for the water-energy nexus. Recent advances in passive solar desalination using thermal localization show great potential for high-efficiency freshwater production, which is particularly beneficial for areas without well-established water and energy infrastructure. However, there is a significant knowled...
Article
Boiling is an essential process in numerous applications including power plants, thermal management, water purification, and steam generation. Previous studies have shown that surfaces with microcavities or biphilic wettability can enhance the efficiency of boiling heat transfer, that is, the heat transfer coefficient (HTC). Surfaces with permeable...
Article
Full-text available
Non-thermalized electrons in metals, featured by deviation from the Fermi-Dirac distribution, have recently shown potential to facilitate realization of ultrafast photonic devices such as all-optical modulators. Dissection of non-thermalized electron dynamics and its influence on optical response of metals is therefore essential for optimization of...
Article
Full-text available
Antibubbles are fluid entities with the inverse phase of regular bubbles. While the structure and stability of antibubbles have been studied, a fundamental understanding of antibubble formation remains limited. We report a theoretical and experimental study of antibubble formation. In the experiment, pairs of surfactant-laden water drops impinged s...
Article
Full-text available
Nucleation site distribution is ubiquitous in many natural and industrial processes, such as liquid-to-vapor phase change, gas-evolving reactions, and solid-state material growth. However, a comprehensive understanding of nucleation site distribution remains elusive. These limitations are due to the challenge of probing micro/nanoscopic nucleation...
Article
Full-text available
Bubble nucleation is ubiquitous in gas evolving reactions that are instrumental for a variety of electrochemical systems. Fundamental understanding of the nucleation process, which is critical to system optimization, remains limited as prior works generally focused on the thermodynamics and have not considered the coupling between surface geometrie...
Article
Condensation is an important process in the Rankine cycle that significantly affects overall efficiency. Condensate typically forms a liquid film due to the high surface energy of industrial condenser materials; by engineering the condenser surface with a superhydrophobic layer, however, we can increase condensation heat transfer by an order of mag...
Article
Hydrophobic coatings with low thermal resistance promise a significant enhancement in condensation heat transfer performance by promoting dropwise condensation in applications including power generation, water treatment, and thermal management of high-performance electronics. However, after nearly a century of research, coatings with adequate robus...
Article
Saturated steam (>121 oC and >205 kPa) is widely used in the medical sterilization process known as autoclaving. However, solar-driven steam generation at such high temperature and pressure requires expensive optical concentrators. We demonstrate a passive solar thermal device mostly built from low-cost off-the-shelf components capable of deliverin...
Article
The relationship between bubble departure frequency and diameter is fundamental to the boiling process and needs to be fully understood for prediction of overall boiling heat transfer performance. Hydrody-namic models for bubble departure were developed in previous studies. However, these models could not explain the dependence of bubble frequency...
Article
Adsorption-based atmospheric water harvesting (AWH) technologies can enable decentralized and distributed water supplies in arid and water scarce regions with limited infrastructure. Recent advances in novel adsorbents, such as metal-organic frameworks (MOFs) and advanced zeolites, with high sorption capacity at low humidity and facile regeneration...
Article
Recent work has demonstrated adsorption-based solar-thermal-driven atmospheric water harvesting (AWH) in arid regions, but the daily water productivity (L/m 2 /day) of devices remains low. We developed and tested a dual-stage AWH device with optimized transport. By recovering the latent heat of condensation of the top stage and maintaining the requ...
Article
Boiling is a ubiquitous process in many applications including power generation, desalination, and high-heat flux electronic cooling. At the same time, boiling is a complicated physical process involving hydrodynamics and interfacial heat and mass transfer on multiple scales. One of the key limiting factors of boiling is the critical heat flux (CHF...
Article
Full-text available
Environmental scanning electron microscopy (ESEM) is a powerful technique that enables imaging of diverse specimens (e.g., biomaterials, chemical materials, nanomaterials) in a hydrated or native state while simultaneously maintaining micro-to-nanoscale resolution. However, it is difficult to achieve high signal-to-noise and artifact-free secondary...
Article
Full-text available
Evaporation plays a critical role in a range of technologies that power and sustain our society. Wicks are widely used as passive, capillary-fed evaporators, attracting much interest since these devices are highly efficient, compact, and thermally stable. While wick-based evaporators can be further improved with advanced materials and fabrication t...
Article
Full-text available
The time-domain thermoreflectance (TDTR) technique has been widely used to measure thermal properties. The design and interpretation of the TDTR experiment rely on an in-depth understanding of the thermoreflectance signature for a given metal thermal transducer. Although the TDTR signals of several metal thermal transducers have been experimentally...
Article
Full-text available
During pool boiling, a significantly high heat flux leads to the transition from nucleate boiling to film boiling, where a vapor film forms over the boiling surface, drastically increasing thermal resistance. This transition at the critical heat flux (CHF) results in an abrupt increase in surface temperature and can lead to catastrophic failure of...
Article
Manipulating the degree of droplet contact with a surface significantly impacts applications involving drag reduction, corrosion inhibition, droplet transportation, and thermal management. Extensive studies have been conducted to study droplet wetting behavior on plain and micro/nanostructured surfaces, with a particular focus in the recent literat...
Article
Full-text available
The simultaneous imaging of magnetic fields and temperature (MT) is important in a range of applications, including studies of carrier transport, and semiconductor device characterization. Techniques exist for separately measuring temperature (e.g., infrared (IR) microscopy, micro-Raman spectroscopy, and thermo-reflectance microscopy) and magnetic...
Article
Full-text available
Water is often considered as the highest performance working fluid for liquid-vapor phase change due to its high thermal conductivity and large enthalpy of vaporization. However, a wide range of industrial systems requires using low surface tension liquids where heat transfer enhancement has proved challenging for boiling and evaporation. Here, we...
Article
Full-text available
Passive vapor generation systems with interfacial solar heat localization enable high-efficiency low-cost desalination. In particular, recent progress combining interfacial solar heating and vaporization enthalpy recycling through a capillary-fed multistage architecture, known as the thermally-localized multistage solar still (TMSS), significantly...
Chapter
Water is a key component in numerous processes impacting our daily lives including thermal management, energy production, and desalination. While significant efforts have been made to improve these processes, recent advancement of nanotechnology has allowed for precise control of surface structuring and chemistry which plays a central role in manip...
Article
The bubble nucleation, growth, and departure cycle is a fundamental aspect of nucleate pool boiling. While much research on this subject has been performed in the previous century, new correlations and models have not been developed in light of important results in simulations and experiments in recent decades. In this work, we provide an updated u...
Article
Solar thermal energy systems combined with low-cost thermal storage provide a sustainable, dispatchable source of renewable energy. One approach to increase the attractiveness of these systems is to use high-performing solar transparent, thermally insulating silica aerogel to significantly increase efficiency. Several past works have proposed using...
Article
Full-text available
In the above paper [1] , (19) has been incorrectly published. The correct version should be
Article
Light propagation in random scattering media is a common phenomenon in many scientific and engineering fields. Because of light-matter interaction, part of the light transmitted through a random scattering medium is diffuse and causes haze. Previous approaches to manipulate haze in random media mainly focused on regulating scattering and paid littl...
Preprint
Full-text available
Inspired by non-Hermitian physics, Li et al. (Science 364, 170-173) theoretically predicted and experimentally demonstrated a stationary temperature profile in a diffusive heat transfer system-seemingly indicating that heat "stops" diffusing. By analogy to the wave physics framework, the motionless and moving temperature profiles are manifestations...
Article
Heat at intermediate temperatures (120-220 °C) is in significant demand in both industrial and domestic sectors for applications such as water and space heating, steam generation, sterilization, and other industrial processes. Harnessing heat from solar energy at these temperatures, however, requires costly optical and mechanical components to conc...
Article
Full-text available
Atomically thin two-dimensional (2D) materials have shown great potential for applications in nanoscale electronic and optical devices. A fundamental property of these 2D flakes that needs to be well characterized is the thermal expansion coefficient (TEC), which is instrumental to the dry transfer process and thermal management of 2D material-base...
Article
Porous wicks are of great interest in thermal management because they are capable of passively supplying liquid for thin film evaporation, a promising method to reliably dissipate heat in high performance electronics. While dryout heat flux has been well-characterized for many wick configurations, key design information is missing as many previous...
Article
High-flux evaporators are important for various fundamental research and industrial applications. Understanding the heat loss mechanisms, especially the contribution of natural convection during evaporation is thus a ubiquitous process to predict and optimize the performance of evaporators. However, a comprehensive analysis on natural convection he...
Method
Full-text available
In this study, we used the transport of intensity equation to reconstruct the phase of an electron wave. In this section, we provide the method to adapt the transport of intensity equation to electron-beam imaging. The propagation of the electron wave in a uniform medium can be described by the homogenous Helmholtz equation, ∇ 2 í µí±ˆ(í µí²“) + í...
Article
Full-text available
We experimentally realized and elucidated kinetically limited evaporation where the molecular gas dynamics close to the liquid-vapour interface dominates the overall transport. This process fundamentally dictates the performance of various evaporative systems and has received significant theoretical interest. However, experimental studies have been...
Article
Atmospheric water harvesting (AWH) is the capture and collection of water that is present in the air either as vapor or small water droplets. AWH has been recognized as a method for decentralized water production, especially in areas where liquid water is physically scarce, or the infrastructure required to bring water from other locations is unrel...
Article
Full-text available
Jumping-droplet condensation is promising for various applications where the droplet size distribution plays a key role in the overall system performance. Despite being extensively studied in recent works, inconsistencies existed in previous size distribution models as the droplet growth and removal mechanisms were often not properly described. Her...
Preprint
Full-text available
The simultaneous imaging of magnetic fields and temperature (MT) is important in a range of applications, including studies of carrier transport, solid-state material dynamics, and semiconductor device characterization. Techniques exist for separately measuring temperature (e.g., infrared (IR) microscopy, micro-Raman spectroscopy, and thermo-reflec...
Article
Full-text available
Haze in optically transparent aerogels severely degrades the visual experience, which has prevented their adoption in windows despite their outstanding thermal insulation property. Previous studies have primarily relied on experiments to characterize haze in aerogels, however, a theoretical framework to systematically investigate haze in porous med...
Article
Full-text available
Environmental scanning electron microscopy (ESEM) is a broadly-utilized nanoscale inspection technique capable of imaging wet or insulating samples. It extends the application of conventional scanning electron microscopy (SEM) and has been extensively used to study the behavior of liquid, polymer and biomaterials by allowing for a gaseous environme...
Conference Paper
Passive daytime radiative cooling approaches primarily rely on spectrally selective surfaces whose performance is limited by heat gain due to solar absorption and parasitic conduction and convection. We propose and experimentally demonstrate a directional approach to perfectly reject direct solar radiation and an optically-selective thermally-insul...
Article
2020 American Chemical Society. The simultaneous imaging of magnetic fields and temperature (MT) is important in a range of applications, including studies of carrier transport and semiconductor device characterization. Techniques exist for separately measuring temperature (e.g., infrared (IR) microscopy, micro-Raman spectroscopy, and thermo-reflec...