Experiments for subcooled water flow and for steam-water two-phase flow were conducted to investigate the effects of pulsation upon transient heat transfer characteristics in a closed-circulation helical-coiled tube steam generator. The non-uniform property of local heat transfer with steady flow was examined. The secondary flow and the effect of interaction between the flow oscillation and secondary flow were analyzed on basis of the experimental data. Some new phenomena were observed and explained. Correlations were proposed for average and local heat transfer coefficients both under steady and oscillatory flow conditions. The results showed that there exist considerable variations in local and peripherally time-averaged Nusselt numbers for pulsating flow. Investigations of pressure drop type oscillations and their thresholds for steam-water two-phase flow in a uniformly heated helical tube were also reported.

Experimental investigations on oil-air-water three-phase flow were carried out in two helically coiled tubes with inner diameter of 39mm and coil diameters of 265 and 522.5mm, respectively. The purpose of this work is to provide a basis for the invention and development of a new kind of separation technology for gas-oil-water mixtures with low oil fraction β≤30%. The flow patterns of oil-water two-phase flow and oil-air-water three-phase flow were directly observed in test sections made of plexiglass tubes. The flows observed in coiled tubes could be classified into more than four flow patterns and some flow regime maps were generated and delineated for these tubes. The present results were compared with some results in horizontal flow. The phase inversion characteristics in helically coiled tubes were also discussed. The frictional pressure drop of oil-air-water three-phase flow were measured. The effects of flow rates and liquid properties on pressure drop were examined. Based on the experimental data and analysis of the flow mechanism the criteria for the flow pattern transition boundaries between two different flow patterns were proposed in terms of dimensionless parameters. Correlations for the predictions of pressure drop were also obtained.

In the present paper, an experimental investigation of the humidifying and desulfuration of flue gas by water spraying is conducted in order to increase the ability of the self-desulfuration efficiency of Ca composition in coal in a power plant boiler. The experimental facility, nozzle structure, measurement method and instruments are introduced. The influence of nozzle structure, the way to enter the liquid and the ratio between phases on the spray characteristics including size distribution of the droplet and spray angle is studied. The results show significant variation and show how to optimize the design and operation of the nozzles.

A linear instability analysis was conducted firstly on the interface of a stratified gas-liquid two-phase flow in a circular piper employing a two-fluid model. The constitutive equations simulation technique was discussed, and the dispersive equation of interfacial waves was derived. The effects of flow rates of gas and liquid, liquid viscosity, surface tension and tube inclination on the stability of interface were investigated. A set of non-linear hyperbolic governing equations was deduced from the complete two-fluid model equation by omitting the effect of the surface tension and assuming a quasi-steady-state for the gas phase. Using characteristic line and finite difference, the propagation and growth of the interfacial disturbances were investigated in terms of gas and liquid superficial velocities. Then the results of the non-linear stability analysis were compared with those obtained by the linear stability analysis and experimental data. The non-linear stability analysis not only confirms the conclusions reached by the linear instability analysis, but also gives an insight into the growth and propagation of the interfacial disturbances on the interface of a gas-liquid two-phase flow.

The present study is to contribute some knowledge of phase separation phenomena of liquid-solid two-phase turbulent flow in curved pipes and provide a basis for the invention and development of a new type of curved pipe separator. Firstly, the solid-liquid two-phase flows in two-dimensional (2D) curved channels were numerically simulated using a two-way coupling Euler-Lagrangian scheme. Phase distribution characteristics of 2D curved channel twophase flow were examined under conditions of different particle size, liquid flowrate and coil curvature. Based on the numerical results, the dynamic effects and contributions to phase separation of particle-subjected forces, including centrifugal force, drag force, pressure gradient force, gravity force, buoyancy force, virtual mass force and lift force, were exposed by kinematic and dynamic analysis alongparticle trajectories. Secondly, measurement of particle size and concentration profiles in helically coiled tube two-phase flow was conducted usinga nonintrusive Malvern 2600 particle sizer based on laser diffraction. Particle size and concentration distribution characteristics of helically coiled tube twophase flow and the effect of secondary flow on phase separation were analyzed based on experimental data.