Interfacial Transport Phenomena Stability in Liquid-Metal/Water Systems
- Univ. of Wisconsin, Madison, WI (United States). Wisconsin Institute of Nuclear Systems
- Argonne National Lab. (ANL), Argonne, IL (United States). Reactor Engineering Div.
One concept being considered for steam generation in innovative nuclear reactor applications, involves water coming into direct contact with a circulating molten metal. The vigorous agitation of the two fluids, the direct liquid-liquid contact and the consequent large interfacial area can give rise to large heat transfer coefficients and rapid steam generation. For an optimum design of such direct contact heat exchange and vaporization systems, detailed knowledge is necessary of the various flow regimes, interfacial transport phenomena, heat transfer and operational stability.In order to investigate the characteristics of such a molten metal/water direct contact heat exchanger, a series of experiments were performed in both a 1-D and 2-d experimental facility. The facilities primarily consist of a liquid-metal melt chamber, heated test section, water pumping/injection system, and steam suppression tank (condenser). A real-time high energy X-ray imaging system along with several temperature measurements and flow measurements were developed and utilized to measure the multiphase flow and obtain an empirical database of local as well as overall system parameters. Results have found volumetric void fraction between 0.05-0.2, overall volumetric heat transfer coefficient ranging from 4-20 kW/m3K, evaporation zone lengths on the order of 10cm and local heat transfer coefficients varying between 500-5000 W/m2K depending on the inlet water injection conditions and system pressure. Time-dependent void fraction distribution and generated water-vapor bubble characteristics (i.e. bubble formation rate, bubble rise velocity, and bubble surface area) were measured using an X-ray image analysis technique. These measurements aided in the determination of the volumetric thermal performance as well as well as the first detailed information on local interfacial phenomenon. This information in turn resulted in the first experimental measurements of the local heat transfer coefficient at different locations within the liquid metal pool. The effect of the system operating pressure and the water injection rate on the performance and the stability of the liquid metal/water direct contact heat exchange was obtained and are reported in detail within the following report. The effects of water injection from a 2.0 mm nozzle at flow rates from 1.5g/s to 8g/s into a heavy liquid metal (Pb and Pb/Bi alloy) at temperatures of 300-500 oC and system pressures ranging from 1- 10 bar were investigated. These conditions were chosen to span the two major flow regimes (nucleate and film boiling) that may be present in reactor based direct contact systems. Detailed information regarding the thermal performance and the operational stability of a liquid metal/water direct contact heat exchange were obtained for these conditions. The resulting extensive experimental database can be used to aid in the design of reactor scale components dealing with high temperature direct contact heat transfer.
- Research Organization:
- Univ. of Wisconsin, Madison, WI (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy, Science and Technology (NE); NERI
- DOE Contract Number:
- FG03-99SF21928
- OSTI ID:
- 806034
- Report Number(s):
- DOE-UWISC-21928
- Country of Publication:
- United States
- Language:
- English
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