Frequency Response of Pool Boiling Plants

Dynamic analysis of a pool boiling plant is accomplished by using small perturbation technique. Mass and energy balance equations are established by basing on the dynamic model constructed and considering additional factors such as steam voids in the liquid phase, water droplets in the steam phase, and the heat transfer behavior at heating surface. Analytical methods for the steam void and dryness fraction dynamics are developed so that their approximate numerical solutions may be readily obtained. Two small boiler plants were constructed and experimental work was carried out by varying the heat input and the valve position in a sinusoidal manner. The experimental results of pressure, steam flow, and water level frequency responses were found to be in closer agreement with the analytical results obtained from the present model than those obtained from the simple mass and energy equations.