Density-wave oscillations

An equivalent linearization method has been introduced for density-wave oscillation analysis Unlike the frequency domain approach with linearized equations assuming an infinitely small amplitude, the present method can deal with large amplitude oscillations with the nonlinearity effect on limit cycle amplitudes taken into account in the frequency domain Equivalent linear equations have been derived based on a one-dimensional separated flow model A profile fit model was adopted for subcooled boiling The characteristics of the equivalent linear equations and factors to limit the amplitudes were phenomenologically examined Analyses of the experimental data by Saha et al using the present method revealed that, given an appropriate set of two-phase flow correlations, the equivalent linearization method can predict limit cycle amplitudes after instability initiation as well as the stability boundary

Extended Equivalent Linearization Method for Density Wave Instability Analysis

Linear stability analysis of density-wave oscillations

Experimental Study of Effect of Geometry on Density-Head-Driven Instability in Boiling Channels

With fossil fuel running out in the foreseeable future, it is essential to develop substitution strategies. The heat market in industrial countries in the Northern Hemisphere has two peaks. The dominant one occurs at --90/sup 0/C and is due to the energy demand for space heating and warm water production. A smaller peak, mainly for metallurgical processes, occurs at --1300/sup 0/C. From thermodynamics considerations, using the high flame temperature of fossil fuels - or electricity - to supply the lower temperature range is obviously wasteful. On the other hand, contemporary light water reactor (LWR) technology makes it feasible to provide the space heating sector with hot water in a district heating network. Basically, existing reactor systems are adequate for this. Some 40 to 50% of the heat demand arises in the range below 120/sup 0/C, causing a corresponding fraction of air pollution by SO/sub 2/ and to a lesser extent NO/sub x/, if fossil fuels are used. When analyzing an adequate district heating system, units in the 10- 50-MW power range are found to be most suitable for Switzerland, both with respect to network size and the democratic decision-making structure. They would have the best chance of penetrating and covering more » the heat market. In a cooperative effort among some members of Swiss industry and the Swiss Federal Institute for Reactor Research, a small LWR for heating purposes only is being developed. The Swiss Heating Reactor (SHR) is a small, 15-bar boiling water reactor. Its core, together with its primary heat exchanger, is located in a reactor pressure vessel and a shroud within an underground water pool. « less

Hiromasa Kobayashi

Papers

Two-Phase FLow Instability by Density Head Pressure Drop

Two-Phase Flow Instability Caused by Density Head Pressure Drop