Use of Power Balance to Model Converging Flows in Bilateral Junctions forVentilation Systems

摘要

The power balance method and the linear kinetic power model provide one method ofestimating the distribution of flows and the losses in a junction. The power balance model is an application of the law of conservation of energy to determine the energy change per unit time (i.e. power) for conditions typical in converging flow junctions. The linear kinetic power model assumes that the power losses in any junction are related linearly with the kinetic powers of each branch entering the junction. The kinetic power model should theoretically apply to bilateral junction but only single-lateral junctions have been tested with this method. There are many practical applications for bilateral junctions; but, in the absence of data for design, their use is problematic. Bilateral junctions may provide economic benefits; however, the potential costs of using these junctions (i.e. increased pressure requirements, increased settling, etc.) are not currently known. The primary goal of this research was to characterize the flow in a bilateral junction and to determine if the kinetic power model could be successfully applied to predict power losses. If successful, similar research could be completed on many bilateral junctions with various geometric variables to develop a general model applying to a wide range of bilateral junctions as has been done with single-lateral junctions. A secondary goal was to test the hypothesis that the power losses for three flows joined at a bilateral junction are not significantly different than the combined power losses of identical flows joined by two single-lateral junctions. Theses. (JHD)