Analysis of in-line tube bundle heat transfer to vertical foam flow

Abstract

Liquid or gas (single phase coolant) is widely used for heat removal in heat exchangers. Nevertheless usage of two-phase system (foam flow - particulary) as a coolant in some cases allows achieving better results: smaller coolant mass flow rate, relatively large heat transfer rate, low energy consumption required for coolant delivery to heat transfer place and etc. An experimental study of the in-line tube bundle heat transfer to the vertically upward and downward after 180 degree turn laminar foam flow was performed. One type of gas-liquid foam - statically stable foam flow was used as a coolant during the experiments. It was determined dependence of heat transfer intensity on flow parameters: flow velocity, direction of flow, volumetric void fraction of foam and influence of liquid drainage from foam. Apart of this, influence of tube position of the bundle to heat transfer was investigated. Results of the investigation showed, that heat transfer intensity of the in-line tube bundle to the foam flow is much higher than to the one-phase airflow under the same flow velocity. Heat transfer intensity of the frontal and further tubes to vertical foam flow is different in comparison with one-phase fluid flow.