Gas–liquid two-phase flow in microchannels: Part II: void fraction and pressure drop

Providing a comprehensive introduction to the fundamentals and applications of flow and heat transfer in conventional and miniature systems, this fully enhanced and updated edition covers all the topics essential for graduate courses on two-phase flow, boiling, and condensation. Beginning with a concise review of single-phase flow fundamentals and interfacial phenomena, detailed and clear discussion is provided on a range of topics, including two-phase hydrodynamics and flow regimes, mathematical modeling of gas-liquid two-phase flows, pool and flow boiling, flow and boiling in mini and microchannels, external and internal-flow condensation with and without noncondensables, condensation in small flow passages, and two-phase choked flow. Numerous solved examples and end-of-chapter problems that include many common design problems likely to be encountered by students, make this an essential text for graduate students. With up-to-date detail on the most recent research trends and practical applications, it is also an ideal reference for professionals and researchers in mechanical, nuclear, and chemical engineering.

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Two-phase flow, boiling and condensation in conventional and miniature systems

https://espace.library.uq.edu.au/view/UQ:637718/UQ637718_OA.pdf

A critical review of flow maps for gas-liquid flows in vertical pipes and annuli

Review on condensation on the containment structures

A diffusion layer model for steam condensation within the AP600 containment

Condensing two-phase channel flow occurs in many industrial applications, including heating and refrigeration systems. It can also occur in certain nuclear reactor accidents. For example, during a small-break loss-of-coolant accident in a pressurized water reactor, following the partial depletion of the primary coolant, condensation of steam on the primary side of the steam generator tubes can provide a heat sink for disposal of the decay heat generated in the reactor core. Condensing two-phase flow can also play an important role in the operation of the passive emergency cooling system in the advanced simplified boiling water reactor. Here, steady-state condensation in the presence of a noncondensable in a concurrent two-phase channel flow is analyzed using a two-fluid model. The effect of noncondensables on the combined heat transfer at the liquid-gas mixture interphase is accounted for by using the stagnant film model, and closure relations relevant to the annular-dispersed two-phase flow regime are applied. The conservation equations are cast into a system of coupled ordinary differential equations, which are numerically integrated. Model predictions are compared with published experimental data, with satisfactory results. It is shown that the two-fluid model can correctly predict all major data trends and is preferable to empirical methods.

Two-Fluid Modeling of Condensation in the Presence of Noncondensables in Two-Phase Channel Flows

Hydrodynamic characteristics of countercurrent two-phase flow in vertical and inclined channels are investigated. Experiments are performed using air and water at room temperature (25 to 27° C) and...

Countercurrent Two-Phase Flow Regimes and Void Fraction in Vertical and Inclined Channels

A phenomenological model is developed for the transient thermal-hydraulic processes on the secondary side of a once-through steam generator during auxiliary feedwater (AFW) injection. Detailed modeling of the thermal-hydraulic processes above the top tube support plate (TSP) is particularly emphasized. The nonuniform distribution of the AFW on the secondary-side tubes is represented by dividing the secondary side into a number of tube groups. For each tube group, the quasi-steady-state conservation equations representing the flow of a falling liquid film and steam on the secondary side and the primary coolant on the primary side are numerically solved for each time step, thereby providing the axial variation of flow rates and temperatures in the primary and secondary sides. Modeled processes include cooling due to the impingement of the AFW jet on the tubes, the forced convection/boiling heat transfer at the liquid film-tube interface, evaporation and condensation at the film-gas interphase, countercurrent flow limitation in the TSP passages, and the formation of a swollen two-phase pool above the top TSP. The aforementioned model for the thermal-hydraulic phenomena above the top TSP is incorporated into a transient model for the entire steam generator where the secondary side is divided into four regions. Global conservationmore » equations representing the transient behavior of each region are numerically solved. Model predictions are compared with a typical test from the Multiloop Integral System Test experiments. Parametric and sensitivity calculations are also reported.« less

Modeling of Transient Thermal-Hydraulic Phenomena in a Once-Through Steam Generator During Auxiliary Feedwater Injection

A phenomenological model is developed for the thermal-hydraulic processes on the secondary side of a once-through steam generator during auxiliary feedwater injection. Based on experimental observa...

Two-phase flow and heat transfer in a once-through steam generator during auxiliary feedwater injection

Gravity-driven countercurrent two-phase flow, in channels connected to a sealed tank at one end and open to the atmosphere at the other end, was analytically studied. This type of gravity-driven co...

B. K. Kamboj

Papers

Two-Fluid Modeling of Condensation in the Presence of Noncondensables in Two-Phase Channel Flows

Countercurrent Two-Phase Flow Regimes and Void Fraction in Vertical and Inclined Channels

Modeling of Transient Thermal-Hydraulic Phenomena in a Once-Through Steam Generator During Auxiliary Feedwater Injection

Two-phase flow and heat transfer in a once-through steam generator during auxiliary feedwater injection

Modeling of Gravity-Driven Oscillatory Countercurrent Two-Phase Channel Flows