Transport phenomena and heat transfer with direct contact condensation

During a postulated small break loss of coolant accident cooling water is injected into the primary system to refill the reactor pressure vessel. To estimate the thermal stress at the reactor pressure vessel structure caused by subcooled water it is important to know the condensation heat transfer to the water layer in the cold leg of the primary loop. The LAOKOON test facility at the Technical University of Munich was designed to investigate direct contact condensation at stratified flow in a rectangular duct at pressure levels up to 6 MPa. To estimate the local overall heat transfer coefficient at a certain position of a water layer it is necessary to investigate the transport phenomena in the liquid phase and the vapor phase separately. Turbulence at the water layer determines the liquid phase heat transfer resistance. The presence of non-condensable gases cause an additional heat transfer resistance at the vaporous phase. The major phenomena determining the overall heat transfer resistance are discussed and summarized.