Film boiling on vertical surfaces in turbulent regime

Film boiling on vertical surfaces in turbulent regime using cryogenic fluid

Modeling of zero gravity venting

The venting of cylindrical containers partially filled with initially saturated liquids was conducted under zero gravity conditions and compared with an analytical model which determined the effect of interfacial mass transfer on the ullage pressure response during venting. A model is proposed to improve the estimation of the interfacial mass transfer. Duhammel's superposition integral is incorporated in this analysis to approximate the transient temperature response of the interface, treating the liquid as a semiinfinite solid with conduction heat transfer. This approach to estimating interfacial mass transfer gives improved response when compared to previous models. The model still predicts a pressure decrease greater than those in the experiments reported

Modeling of zero gravity venting: Studies of two-phase heat transfer under reduced gravity

The objective is to predict the pressure response of a saturated liquid-vapor system when undergoing a venting or depressurization process in zero gravity at low vent rates. An experimental investigation of the venting of cylindrical containers partially filled with initially saturated liquids was previously conducted under zero-gravity conditions and compared with an analytical model which incorporated the effect of interfacial mass transfer on the ullage pressure response during venting. A new model is presented to improve the estimation of the interfacial mass transfer. Duhammel's superposition integral is incorporated to approximate the transient temperature response of the interface, treating the liquid as a semi-infinite solid with conduction heat transfer. Account is also taken of the condensation taking place within the bulk of a saturated vapor as isentropic expansion takes place. Computational results are presented for the venting of R-11 from a given vessel and initial state for five different venting rates over a period of three seconds, and compared to prior NASA experiments. An improvement in the prediction of the final pressure takes place, but is still considerably below the measurements

Boiling of liquid nitrogen in reduced gravity fields with subcooling

Film and nucleate boiling of liquid nitrogen in reduced gravity fields with subcoolin

Transient boiling heat transfer in saturated liquid nitrogen and F113 at standard and zero gravity

Transient and steady state nucleate boiling in saturated LN2 and F113 at standard and near zero gravity conditions were investigated for the horizontal up, vertical and horizontal down orientations of the heating surface. Two distinct regimes of heat transfer mechanisms were observed during the interval from the step increase of power input to the onset of nucleate boiling: the conduction and convection dominated regimes. The time duration in each regime was considerably shorter with LN2 than with F113, and decreased as heat flux increased, as gravity was reduced, and as the orientation was changed from horizontal up to horizontal down. In transient boiling, boiling initiates at a single point following the step increase in power, and then spreads over the surface. The delay time for the inception of boiling at the first site, and the velocity of spread of boiling varies depending upon the heat flux, orientation, body force, surface roughness and liquid properties, and are a consequence of changes in boundary layer temperature levels associated with changes in natural convection. Following the step increase in power input, surface temperature overshoot and undershoot occur before the steady state boiling temperature level is established

Dynamics of moving bubbles in single and binary component systems

Dynamics of a single bubble moving in a quiescent liquid is analyzed for single and binary component systems. The transport of energy and/or mass at thermodynamic-phase equilibrium governs the dynamics of the bubble at its interface

Further considerations of two-dimensional condensation drop profiles and departure sizes

The problem of the equilibrium shape and departure size of two-dimensional dropwise condensation drops on a vertical surface, presented in an earlier work, is extended to include advancing contact angles to 180°. The equation of the surface of the drop is obtained by minimizing (for a given volume) the total energy of the drop, consisting of surface and gravitational energy, using the techniques of variational calculus. The solution is tractable once the advancing contact angle is known, and is taken as an approximation to the axial meridian profile of a threedimensional drop. The receding contact angle is obtained as part of the solution. The drop size is specified by imposing its vertical length in contact with the wall. A maximum value of this length exists which provides a real solution, and this is taken as the departure size of the drop. It is shown that the general departure shape for an advancing contact angle of 180° includes the cases for all advancing contact angles. Das bereits in einer früheren Arbeit behandelte Problem der Gleichgewichtsform und der Abreißgröße eines Kondensationstropfens an einer senkrechten Fläche wird hiermit auf Vorrückwinkel bis zu 180 ° erweitert. Die Gleichung für die Tropfenoberfläche wird dabei durch Minimierung der Gesamtenergie des Tropfens (bei gegebenem Volumen), die ihrerseits die Oberflächen und die Gravitationsenergie enthält, mit Hilfe der Variationsrechnung bestimmt. Dabei erfordert die Lösung für den zweidimensionalen Tropfen lediglich die Kenntnis des Vorrückwinkels. Sie kann dann als Näherung für den axialen Meridian-Schnitt eines dreidimensionalen Tropfens verwendet werden. Dabei ergibt sich der Rückzugswinkel des Tropfens als ein Teil der Lösung.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46655/1/231_2005_Article_BF01377573.pd

Pressurization of Liquid Oxygen Containers Progress Report No. 7, Nov. 1963 - Nov. 1964

Pressurization of liquid oxygen containers - cryogenic fluid boiling under high and low gravity, liquid hydrogen boiling, injection cooling, and two-dimensional heat transfe

The effects of buoyancy on the critical heat flux in forced convection

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76972/1/AIAA-1993-575-151.pd

Enhancements of nucleate boiling under microgravity conditions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76852/1/AIAA-2000-853-986.pd