Experimental evaluation of the limiting critical quality values in circular and non-circular flow geometries

An experimental evaluation of the limiting critical quality (or limiting qu ality in short) values in different flow geometries (circular, rectangular, triangular, and dumb-bell shaped) was performed using R-134a as a coolant. The limiting quality characterized by a sharp drop of critical heat flux ( CHF) is affected by the following geometric parameters: hydraulic-equivalen t diameter, channel shape, and gap size. The effect of flow geometry on lim iting quality is influenced by flow parameters (pressure and mass Bur). The effects of these parameters on limiting quality and CHF were examined, and recommendations for predicting the limiting quality in circular and non-ci rcular geometries have been made. (C) 1999 Elsevier Science S.A. All rights reserved.