The paper reviews basic theoretical studies of laminar film condensation since Nusselt (1916). Particular attention is given to those investigations in which the relative importance of the additional complicating factors is revealed and where approximate heat-transfer formulae are provided. For natural convection condensation on vertical plates and horizontal tubes, detailed solutions show that the simple Nusselt results (Eqs. (16) and) are surprisingly accurate over a wide range of conditions. Effects of inertia and convection in the condensate film and vapour shear at the condensate surface are generally of minor importance. Relatively simple, accurate, equations, which take account of these factors, are, however, available (Eqs. (30) and (32)). For forced convection condensation, detailed solutions for horizontal plates indicate that inertia and convection are generally unimportant for the normal practical ranges of the variables. A relatively simple result (Eq. (63)), equivalent to the Nusselt equation for natural convection, gives the heat transfer for this case with good accuracy. An interpolation formula (Eqs. (64) and (67)), which satisfies equations (16) and (63) for the natural and forced convection dominated extremes, gives accurate results for condensation in downflow over a vertical plate. For forced convection condensation on a horizontal tube, vapour boundary layer separation and condensate film instability resulting from opposing effects of vapour shear stress and pressure gradient over the downstream half of the tube, present significant difficulties. Approximate equations which either neglect these effects or make conservative allowances are available.

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It has been shown recently that plasma jets or electric discharges work effectively on the flame stabilization or the promotion of combustion reaction in several combustion experiments. In the first part of this review, the outlines of two investigations on the mechanism of combustion-reaction promotion, one is the case of injection of plasma jet and the other is the case of application of direct electric discharge, there exists active participation of vibrationally excited species produced by electric discharges on the promotion of combustion reaction through the route where vibrationally excited fuel molecules transform into radicals via specific reactions with high rate constant, although in the case of plasma jet, the participation of vibrationally excited species may be less important compared to that of specific radicals involved in plasma jet. The second part of this review refers to three experiments on the effect of plasma jet in supersonic combustions or a high-velocity stream combustion, of which results also suggest the role of vibrationally excited species on combustion promotion.

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The need of accurate data on transport properties of fluids for chemical industry justifies a careful analysis of the available experimental methods for the measurement of those properties, in wide temperature and pressure ranges. This paper presents a critical review of the methods for the measurement of viscosity and thermal conductivity of fluids and fluid mixtures, with specific emphasis on absolute methods.

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Oscillatory convective flows play an important role in fire growth since large-scale turbulence enhances combustion due to surface and bulk mechanisms. The periodic motion of a plume rising from a horizontal line heater was numerically studied using a finite difference method. Calculations showed that a plume above a line heater regularly sways from side to side with frequencies similar to the experimental results by Noto et al. The relationship between the swaying frequency (f__-) and heating rate (Q__-) is expressed as f__-=k__-·Q^1/3__-, which is similar to that in a vertical venting study by the author. Heat loss through the walls had a significant effect upon the frequency. Vortices along the plume and a pressure imbalance at both sides of the plume cause the regular swaying motion. In addition, calculations showed that the behavior or the vortices around a turbulent free jet is very similar to that of a plume above a heat source.

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An experimental investigation has been conducted to clarify heat-transfer characteristics and flow behaviors around four elliptic cylinders having an axis ratio 1 : 2. They were placed in tandem arrangement with a constant angle of attack to the upstream uniform flow. The Reynolds number based on the major axis length, c, ranged from about 15 000 to 70 000. The angle of attack was varied from o^o to 90^o at 30^o intervals and the nondimensional cylinder spacing l/c from 1.25 to 4.0, where l denotes the streamwise distance between the neighboring cylinder centers. It has been found that the heat-transfer features vary drastically with the angle of attack and also with the cylinder spacing, corresponding to a great change in the flow features. Further, the heat-transfer capability of the present elliptic cylinders at narrower cylinder spacings and smaller angles of attack is shown to be comparable to that of the in-line circular cylinders.

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Fluid flow and heat transfer in a plate-fin and tube heat exchanger were studied, using a fundamental model consisting of a pair of parallel plates and a square cylinder passing perpendicularly through the plates, which simulated plate-fins and a tube, respectively. The analytical results are reported about the unsteady flow and heat transfer at the Reynolds number Re=1 000 and the Prandtl number Pr=0.71. The unsteady flow around a cylinder is shown in terms of time histories, velocity flucutuation intensity conoturs and the Strouhal numbers. Complicated aspects of the fluid flow are shown in terms of velocity vectors, streamlines, streak lines, pressure contours and wall shear stress contours. Furthermore, heat transfer characteristics under a constant wall heat flux condition are shown in terms of distributions of temperatures and local Nusselt numbers, and the mechanisms of fluid flow and heat transfer are systemtically examined in detail.

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Flow characteristics, and the heat and mass transfer in a countercurrent annular two-phase flow in a vertical circular tube, where hot water flows downward as a film and air at room temperature flows upward, have been investigated. It is shown by the experiment that the pressure loss, and the heat and mass transfer rate in the gas phase increase due to the roughness effect of the interfacial wave. It is further shown that when the temperature of water is high, condensation of vapor occurs in the gas phase, and the heat transfer rate is enhanced by the release of latent heat accompanied by mist formation. A theoretical model based on the low Reynolds number k-ε turbulence model is proposed, where an additional production term is considered to incorporate the wave effect. The calculated results of the friction factor and the Nu and Sh numbers are compared with the experimental ones.

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A transient laminar jet was simulated by numerical computations based on the time-dependent conservation equations of mass, momentum and species with variable density and viscosity in a two-component gas mixture. The flow and mixing process in cooperation with vortex formation predicted by computations were compared with the experiments. The results indicate that (1) the flow field is characterized by the superposition of convection in the axial direction and the rotation by vortices formed in the jet, (2) the vortices entrain the surrounding gas which is laminated in the vortices to enhance mixing, and (3) the computed results simulate well the characteristics of the flow and mixing processes observed in the experiments.

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This paper presents a feasibility study of glass tempering using mist cooling. First, transient tests of mist cooling were conducted to investigate the effects of the thermal properties of a cooling surface. To do this, test plates made of silver, nickel, stainless steel (SUS 304), and fused quartz were used. The experimental conditions of mist flow were as follows : the air velocity was V_a=20 m/s, the temperature of the water droplets was T_l=21°C, and the volumetric droplet flow rate was D=0.000 3∼0.01 m³/(m²·s). The experimental data show that both the plate temperature corresponding to the minimum heat flux (T_M) and the heat transfer coefficients at wall temperature above T_M increase as the thermal conductance of the surface material decreases. Second, tempering tests of soda-lime glass plates of 2.95 and 3.90 mm thickness were conducted using mist cooling. The initial temperature of the glass plates was about 690°C. The plates were cooling. The initial temperature of the glass plates was about 690°C°C. The plates were cooled only from one side. The test results indicate that thin and low-cost tempered glass plates can be made by mist cooling without fracture.

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This paper describes an experimental study on heat transfer and flow characteristics of dilute gaseous solid suspension medium within circular riser tubes. Main attention is focused on the examination of universality and validity of correlation procedures and/or dimensionless parameters which so far have been proposed by several authors. Pressure drop and heat transfer were measured by use of the suspension of air and glass particles of three different sizes. Experimental results show that four examined procedures failed in correlating the pressure drop data of the different conditions, while they provided fairly adequate correlation for the heat transfer. Therefore, the main contribution of the suspended phase to the frictional pressure drop is seemingly through solid to solid friction between the particles and tube wall, while the change in heat transfer performance is due to the change in turbulent structure, the latter being minor for the dilute case.

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A Linear solution of oscillation frequencies at condensation oscillation, which occurs when steam is fed into subcooled pool water at a steam mass flux between 30∼120 kg/(m²·s), was compared with published empirical correlations as well as approximate solutions. At atmospheric conditions, these solutions and correlations are almost consistent with each other and correspond well to data obtained in small-scale experiments. At the condition of loss of coolant accident of a real BWR suppressiontype containment (higher pressure and larger vent tube diameter), the linear solution can explain the tendency of the data obtained by large-scale test rigs. However, the correlations are not always adequate for such higher-pressure applications, because they are based on data at atmospheric pressure. It was also clarified that the condensation heat-transfer coefficient, adequate data of which is not available for higher pressures, considerably influences the solutions.

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Visual observation of flow patterns in the condenser and heat transfer measurements were conducted for heat transfer rate ranges of 18-800W using a vertical annular device with various quantities of R113 as a working fluid. As a result of visual observations, it was shown that ripples (interfacial waves) were generated on the condensate film surface when the condensation heat transfer was promtted. A simple theoretical analysis was presented in which the effects of interfacial waves and vapor drag were both considered. This analysis agreed very well with experimental results when the working fluid quantity was small enough so that the two-phase mixture generated by boiling the working fluid didn't reach the condenser. The effects of interfacial waves and vapor drag on condensation heat transfer were also investigated theoretically.

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An experimental investigation was made into hold-up, frictional pressure drop and circumferential distribution of film thickness of an air-water two-phase annular flow in horizontal and near horizontal tubes of 26.0 mm ID. Superficial velocities of both phases ranged from 10 m/s to 50 m/s for air and from 0.002 m/s to 0.40 m/s fir water. The measured values of those physical quantities and the highest circumferential location from which liquid film starts to form toward the tube bottom are presented, and the effects of the inclination angle on them are examined. As a result, it was made clear that the effect of the inclination on these parameters, even if it is within a small angle, could not be neglected and that the mean film thickness averaged over the circumference of the tube was approximately equal to the local film thickness at θ=120^o independent of the inclination.

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Flow and heat transfer characteristics of refrigerant R 113 injected dispersively into hot water are investigated based on the flow pattern observation and local flow and heat transfer measurements. Heat transfer characteristics are strongly influenced by the boiling regime just downstream of the nozzle outlet. An increase of inlet temperature of both liquids or an increase of the nozzle Reynolds number promotes evaporation and bubble coalescence. As a result, the boiling regime changes from an unstable one to a stable and further to a column-like one, and heat transfer is improved in accordance with this order of the boiling regime. In the column-like boiling regime in which the highest performance is attained, the heat transfer coefficient is mainly influenced by both the mass velocity of liquid R 113 and the temperature driving force of water. the local and also the average value over a test section of volumetric heat transfer coefficient are correlated in terms of these two influencing parameters.

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This paper presents an evaluation of the leak flow rate from a circumferential through-wall fatigue crack in a pipe under the fluid conditions of high-pressure saturated water of a boiling water reactor (BWR), related to the leak-before-break (LBB) concept which is considered to be applicable to nuclear power plants. The following three items are discussed and clarified ; (1) examination of the leak flow path and surface roughness of a circumferential through-wall fatigue crack which was obtained in a fatigue growth test using a STS 42 carbon steel pipe, (2) analytical estimation methods of the leak rate as two-phase critical flow, which are greatly influenced by the crack opening displacement, the ratio of flow path length to hydraulic diameter L/D, surface roughness and the exit tot the stagnation area ratio of the leak flow path, (3) experimental evaluation of the leak flow rate using artificial slits simulating the through-wall crack.

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Experimental data of the circumferentially local heat transfer coefficient as well as the circumferentially averaged coefficient were obtained for R-22 and R-12 flowing at mass velocities of 50 to 500 kg/(m²·s), in three types of spirally grooved evaporator tubes oriented horizontally. The heat transfer in the grooved tubes was found to be effectively enhanced over a smooth tube at mass velocities lower than 100kg/(m²·s), but, as the mass velocity increased, the enhancements were rapidly reduced, and then the heat transfer coefficients gradually approached the value in a smooth tube, a simplified model, which took account of the heat transfer through the meniscus liquid film in the grooves, was developed, and thereby the heat transfer characteristics in the grooved tube were explained.

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Pool boiling heat transfer within a confined space was studied for the vertical narrow space between parallel heated and unheated planes. Experiments were performed for water under atmospheric pressure at a heat flux range up to the critical heat flux. The gap size was decreased from 5 mm to 0.15 mm in four steps and two heating surfaces of different heights were tested under the open or closed periphery condition of the narrow space. Based on observed boiling behavior, heat transfer mechanisms were deduced and the heat fluxes calculated by proposed models were compared with experimental data.

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Both analytical and experimental investigations are performed for vapor bubble growth in a uniformly superheated water under rapid decompression. Numerical and analytical solutions are obtained by solving a complete set of governing equations for bubble growth, and compared with experimental data obtained in the present experiment and previously by Toda and Kitamura. Bubble growth rates calculated numerically are lower than the experimental data, however, they approach more favorably our experimental data than the analytical solutions without the added correction factor given by Toda and Kitamura. Their solutions with the correction factor of π/2 are the best-fit solutions reported thus far. Available solutions by other researchers are found to underpredict bubble growth rates. Transient temperature distributions across the thermal boundary layer on the bubble interface are also estimsted. It is found that for initial periods the thermal boundary layer fully develops and the bubble interface temperature approaches that of saturation corresponding to decompressed liquid pressure.

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An experimental investigation has been conducted to determine boiling heat-transfer performance at the critical water level in a porous bed. The porous bed contained in a vertical circular cylinder was made up of packed spherical beads whose diameters ranged from 2.0 to 16.2 mm. Four kinds of the particles of glass, alumina, steel, and copper beads were adopted as the testing beds. Measurements were carried out as the temperature difference ΔT_s between the heating surface and saturated water varied from 0.2 to 8.3 K. It was observed that there might be a critical water level at which a maximum boiling heat-transfer coefficient took place for a given ΔT_s. The critical water-level condition was carefully obtained by injecting the saturated water. The boiling heat flux was found to be relatively independent of ΔT_s for smaller ΔT_s values, while it tends to level off as ΔT_s increases for small bead diameters.

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Combined conductive and radiative heat transfer through a layer of glass beads was studied experimentally and theoretically. The temperature profiles and the mean effective thermal conductivities of two soda-lime-silica glass bead layers with different layer thickness were measured for various hot boundary temperatures between 410 to 680 K. The energy equation and the equation of transfer governing the coupled conduction and radiation heat transfer through the layer were solved numerically under the conditions corresponding to the experiment. The effective thermal conductivity by conduction alone and radiative properties of the glass bead layer were evaluated based on Bruggeman's theory and Mie's theory, respectively. Furthermore, porosity distribution within the layer was assumed to be constant. As a result, excellent agreement between theory and experiment was found, and it was concluded that the present analytical method could be used effectively for predicting the temperature profiles and the heat-transfer characteristics of a glass bead layer with comparatively larger bead diameter and layer thickness.

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This paper reports the experimental results on heat transfer performance of a newly suggested temperature equalizer with the radiative converter for a slab in the continuous casting direct rolling process. The present temperature equalization is based on the effective energy conversion method between gas enthalpy and thermal radiation using a porous media. The model temperature equalizer used is about one fifth of the actual one its dimensions. To simulate the continuous casting direct rolling process in the experiment, the uniformly preheated model slab was first cooled by thermal radiation, and subsequently fed into the temperature equalizer. By measurements of transient slab temperatures, it is proved that the radiative converter equalizes the slab temperature quickly owing to local heating of the slab edge. Furthermore, estimation of the overall energy balance in the temperature equalizer demonstrated that efficient temperature equalization is feasible if the available energy flowing out of it is recovered.

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The printing characteristics of thermal printers are studied through an analysis of the developing process of the temperature field formed within a thermal paper. The thermal print head is treated as a moving heat source with a finite width which generates heat according to the control signal. A two-dimensional unsteady energy equation is solved numerically and the time-dependent temperature field within the thermal paper is obtained. The effects of various parameters such as the distribution of heat flux along the head, the width of the thermal head, the head speed, the heating duration, etc. on the temperature distribution in the area for printing one dot are examined and printing performance is discussed.

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An investigation has been made of the relationship between optical parameters such as incident angle, surface roughness, and polarization state, which has led to the development of an improved optical method. Utilizing these enhanced experimental techniques, the deposition rates of rapidly growing films consisting of either Na₂SO₄ or K₂SO₄ on a metal surface exposed to flowing combustion product gases has been measured. The experiments were performed with a film thickness less than the critical thickness for the onset of complications due to run-off. At lower metal surface temperatures, condensation of vapors to aerosols occurs before the vapor reaches the surface. Under these conditions, the mechanism of deposition is no longer determined by vapor diffusion alone but is heavily influenced by the combined action of vapor and aerosol transports. At higher surface temperatures, only the vapor deposition effect is predominant. This study also includes measurements of the dew points and evaporation rates.

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A generalized representation of the vapor-pressure curve for refrigerants was proposed on the basis of the experimental data of vapor pressure for eight refrigerants, i. e., R 12 (CCl₂F₂), R 22 (CHClF₂), R 13 (CCiF₃), R 23 (CHF₃), R 13 Bl (CBrF₃), R 114 (CClF₂CClF₂), R 116 (C₂F₆), and R 152 a (CH₃CHF₂), which were measured by our research group at Keio University. With respect to the functional form of the generalized representation of the vapor-pressure curve, the Pitzer expansion based on the principle of corresponding states with an acentric factor was adopted. The coefficients in the representation were determined by a least squares fitting to the experimental vapor pressure data for the eight refrigerants mentioned above. The proposed generalized representation reproduces most of these data within a pressure deviation of ±1.0% in the reduced temperature range of T_r >0.4.

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Predictive methods of the critical curve are assessed on the basis of a comparison with the experimental results obtained using our own critical parameters for binary refrigerant mixtures. These mixtures included the R 12 (dichlorodifluoromethane ; CCl₂F₂) + R 22 (chlorodifluoromethane ; CHClF₂) system, the R 22 + R 114 (1, 2- dichlorotetrafluoroethane ; CClF₂CClF₂) system, and the R 13 B 1 (bromotrifluoromethane ; CBrF₃) + R 114 system. The following predictive methods for critical parameters of a mixture were assessed: that by Li for critical temperature, that by Cheuh-Prausnitz for critical temperature and critical molar volume, that by Kreglews-ki-Kay for critical pressure. Furthermore, the Soave-Redlich-Kwong (SRK) equation and the Peng-Robinson (PR) equation were also evaluated. From these comparisons, it becomes clear that it is difficult to consistently predict the critical curve for binary refrigerant mixtures using the predictive methods thus far reported. We therefore propose a new correlation so as to represent the composition dependence of the critical parameters for three different systems of binary refrigerant mixtures.

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This paper proposes a method to measure the radiative properties of porous media in which radiative emission, absorption and scattering are occurring. The method is based on measuring radiation intensity out of the porous medium and then estimating properties which agree with the magnitude of emission. The principles of the method and demonstrated with a numerical analysis of the radiative transfer equation. This method is excellent for measurements of albedo, and supplements the conventional methods based on transmission measurements, which give useful information on extinction but not on albedo. Experimental results have offered reasonable values for each property, i. e., extinction coefficient, albedo and back- scattering fraction factor. Among these, albedo is well estimated with this method.

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