Mechanisms of choking and entrainment

Abstract The related phenomena of choking in pneumatic transport systems and of entrainment from fluid beds have been the subject of considerable empirical correlation and theoretical speculation. For dilute suspensions, such as occur in transport and entrainment, literature data indicate that slip velocity increases as voidage decreases. This paper demonstrates that such a slip—voidage relation leads to a limiting envelope of lines of constant voidage on coordinates of volumetric particle flux versus fluid velocity. The limiting envelope defines the boundary between dilute phase and dense phase flow and determines the solids flux—gas velocity—voidage relationships at choking or entrainment conditions.