Vertical upflow boiling experiments were performed in pursuit of identifying the trigger mechanism for subcooled flow boiling critical heat flux (CHF). While virtually all prior studies on flow boiling CHF concern the prediction or measurement of conditions that lead to CHF, this study is focused on events that take place during the CHF transient. High-speed video imaging and photomicrographic ...

The concept of disjoining pressure, developed from thermodynamic and hydrodynamic analysis, has been widely used as a means of modeling the liquid-solid molecular force interactions in an ultra-thin liquid film on a solid surface. In particular, this approach has been extensively used in models of thin film transport in passages in micro evaporators and micro heat pipes. In this investigation, ...

Boiling heat transfer rates impact the performance of various processes like quenching, steam generation, desalination, and boiling water reactors. The film boiling regime of the boiling curve has very low heat transfer rates around the Leidenfrost point which corresponds to the formation of a stable and continuous vapor layer at the solid-liquid interface (Leidenfrost effect). This insulating ...

The physical mechanisms of entropy generation in a condenser with high fractions of noncondensable gases are examined using scaling and boundary layer techniques, with the aim of defining a criterion for minimum entropy generation rate that is useful in engineering analyses. This process is particularly relevant in humidification-dehumidification desalination systems, where minimizing entropy g...

We demonstrate humidity sensing using a change of the electrical resistance of single-layer chemical vapor deposited (CVD) graphene that is placed on top of a SiO2 layer on a Si wafer. To investigate the selectivity of the sensor towards the most common constituents in air, its signal response was characterized individually for water vapor (H2O), nitrogen (N2), oxygen (O2), and argon (Ar). In o...

An improved method for calculating tropospheric temperature and moisture from satellite radiometer measurements is developed. The troposphere is modeled by two temperature lapse rates and a single moisture lapse rate. These lapse rates as well as an optimum pressure level for dividing the two layers of constant lapse rate and surface temperature are calculated from three observations in the 1 5...

Using continuum dynamic van der Waals theory in a radial 1D geometry with a Lennard-Jones fluid model, we investigate the nature of vapor bubble nucleation near a heated, nanoscale-curved convex interface. Vapor bubble nucleation and growth are observed for interfaces with sufficiently large radius of curvature while phase stabilization of a superheated fluid layer occurs at interfaces with sma...

Photonic nanoarchitectures occurring in the scales of Blue butterflies are responsible for their vivid blue wing coloration. These nanoarchitectures are quasi-ordered nanocomposites which are constituted from a chitin matrix with embedded air holes. Therefore, they can act as chemically selective sensors due to their color changes when mixing volatile vapors in the surrounding atmosphere which ...

Water transport through the gas diffusion layer (GDL) of a proton exchange membrane (PEM) fuel cell is of critical importance in the operation of the fuel cell. In this study, the transport of water vapor through the GDL is investigated. A one-dimensional, single-phase heat and mass transfer model is developed to investigate the diffusivity of water vapor through the GDL of a PEMFC. An experime...

5 [1] A two-dimensional cloud resolving model with explicit bin microphysics is used to 6 study the maintenance of tropical tropopause layer (TTL) cirrus. Numerical simulations 7 using this model show that a TTL cirrus with a maximum radiative heating rate of 3 K/day 8 is able to self-maintain for as long as 2 days if it contains ice crystals whose initial 9 mean radius is smaller than about 5 ...