Boiling, flow transition,

It is concluded that thermodynamic equilibrium cannot exist in film boiling and transitional regimes during cool-down. Although this is generally expected, the extent of the departure from vapor-liquid equilibrium was previously unknown. This departure from equilibrium and the occurrence of mist and slug flows during cool-down have provided a means for the determination of vapor fractions under transient, nonisothermal conditions. 

A separator is fed with a condensate/gas mixture. The condensate leaves the bottom of the separator, passes a flowmeter and is followed by a choke valve, after which the condensate is boiling. The flow can not be measured using the transit time method, due to the combination of short piping, the absence of a suitable injection point and the flow properties of the condensate, which is non-newtonian due to a high contents of wax particles The condensate can not be representatively sampled, as it boils upon depressuratioh... 

Steam-liquid flow. Two-phase flow maps and heat transfer prediction methods which exist for vaporization in macro-channels and are inapplicable in micro-channels. Due to the predominance of surface tension over the gravity forces, the orientation of micro-channel has a negligible influence on the flow pattern. The models of convection boiling should correlate the frequencies, length and velocities of the bubbles and the coalescence processes, which control the flow pattern transitions, with the heat flux and the mass flux. The vapor bubble size distribution must be taken into account. 

Kandlikar SG, Balasubramanian P (2004) An extension of the flow boiling correlation to transition, laminar and deep laminar flows in mini-channels and micro-channels. Heat Transfer Eng 25 86-93... 

Prodanovic V, Fraser D, Salcudean M (2002) On transition from partial to fuUy developed subcooled flow boiling. Int J Heat Mass Transfer 45 4727-4738 Qu W, Mudawar I (2003a) Measurement and prediction of pressure drop in two-phase micro-channel heat sinks. Int J Heat Mass Transfer 46 2737-2753 Qu W, Mudawar I (2003b) Flow boiling heat transfer in two-phase micro-channel heat sink. 1 Experimental investigation and assessment of correlation methods. Int J Heat Mass Transfer 46 2755-2771... 

Two-phase flows are classified by the void (bubble) distributions. Basic modes of void distribution are bubbles suspended in the liquid stream liquid droplets suspended in the vapor stream and liquid and vapor existing intermittently. The typical combinations of these modes as they develop in flow channels are called flow patterns. The various flow patterns exert different effects on the hydrodynamic conditions near the heated wall thus they produce different frictional pressure drops and different modes of heat transfer and boiling crises. Significant progress has been made in determining flow-pattern transition and modeling. 

Check the static instabilities by steady-state correlations, to avoid or alleviate the primary phenomenon of a potential static instability, namely, boiling crisis, vapor burst, flow pattern transition, and the physical conditions that extend the static instability into repetitive oscillations. 

Dhir, V. K., 1990, Nucleate and Transition Boiling Heat Transfer under Pool and External Flow Conditions, Proc. 9th Int. Heat Transfer Conf, vol. 1, pp. 129 155 see also Int. J. Heat Fluid Flow 12(4) 290. (2)... 

Gandiosi, G., 1965, Experimental Results on the Dependence of Transition Boiling Heat Transfer on Loop Flow Disturbances, GEAP-4725, General Electric, San Jose, CA. (6)... 

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