Experimental and analytical study of intermittency in direct contact condensation of steam in a cross-flow of water

The topology of a condensing steam jet, at low steam mass fluxes, injected in a cross-flow of water has been investigatedexperimentally for various conditions (system pressure around 3 bar). The intermittent character of the steam pocket growthand collapse clearly appeared from the high speed recordings. The typical pocket size grows almost linear until it reaches amaximum penetration depth. Pocket disappearance occurs either via partial detachment and collapse or instantaneous break-upof the entire pocket. The main effect of the liquid cross-flow is an increased heat transfer coefficient for otherwise identicalprocess conditions. This results in a notable reduction of both growth time and maximum penetration depth. A model has beendeveloped and presented to facilitate interpretation of measurement results and to increase our predictive capacity of unstabledirect steam injection. Comparison of model predictions and experimental findings shows that the steam pocket growth timeand its maximum penetration depth are generally well-predicted. The chugging regime occurring at the lowest watertemperature is atypical and has nonzero waiting times. The growth of a steam pocket in unstable condensation regimes is foundto be controlled by fluid inertia and momentum of the injected steam, while drag is negligible.