An analytical investigation and conceptual design of a disk-shaped asymmetric heat pipe is presented in this work. Using the conservative formulations for the steady incompressible vapor and liquid flow for a disk-shaped heat pipe, an in-depth integral analysis is applied. Analytical results for the asymmetric vapor velocity profile, the vapor and liquid pressure distributions, and the vapor te...

Efficient and robust methods for phase determination in multiphase-multicomponent equilibrium are key tools for chemical processes simulation. The most widely used methods for equilibrium calculations are generally based on Gibbs free energy minimization or on simultaneous solving of the material balance and equilibrium equations. Both techniques exhibit numerical challenges due to the involvem...

Experiments were performed to enable the development of a new theoretical model for the enhancement in CHF commonly observed with flow boiling on concave heaters as compared to straight heaters. High-speed video imaging and photomicrography were employed to capture the trigger mechanism for CHF for each type of heater. A wavy vapor layer was observed to engulf the heater surface in each case, p...

the pressure drop of refrigerant r-134a flow boiling inside a horizontal tube has been investigated experimentally. the test set-up which was used in this investigation is a well instrumented vapor compression refrigeration system. these instruments are thermocouples, flow meter, pressure gauges and the pressure drop measuring apparatus. this system consisted of three electrically heated evapor...

We have developed a tunable temperature profiler based on a highly stable synthesizer that can observe at multiple frequencies on the shoulder of the 60 GHz atmospheric oxygen feature. We are developing a similar radiometer to obtain the vertical distribution of water vapor by making observations on the pressure broadened water vapor line from 22 to 29 GHz. Information on cloud liquid water pro...

A small-angle neutron scattering (SANS) porosimetry technique is presented for characterization of pore structure in nanoporous thin films. The technique is applied to characterize a spin-on organosilicate low dielectric constant (low-k) material with a random pore structure. Porosimetry experiments are conducted using a "contrast match" solvent (a mixture of toluene-d8 and toluene-h8) having t...

The global phase behavior (i.e., vapor-liquid and fluid-solid equilibria) of rigid linear Lennard-Jones (LJ) chain molecules is studied. The phase diagrams for three-center and five-center rigid model molecules are obtained by computer simulation. The segment-segment bond lengths are L = sigma, so that models of tangent monomers are considered in this study. The vapor-liquid equilibrium conditi...

Boiling crisis experiments are carried out in the vicinity of the liquid-gas critical point of H2. A magnetic gravity compensation setup is used to enable nucleate boiling at near critical pressure. The measurements of the critical heat flux that defines the threshold for the boiling crisis are carried out as a function of the distance from the critical point. The obtained power law behavior an...

Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 +/- 0.05 for the evaporation coefficient, identical to that previously...