Experiments on Supercritical Pressure Convective Heat Transfer Having Relevance to SPWR
- School of Engineering, University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom)
Some experiments on supercritical pressure convective heat transfer in long vertical heated tubes are reported. The working fluid was carbon dioxide at a pressure just above thermodynamic critical value (p/p{sub c} {approx} 1.03). Due to the very strong dependence of fluid properties on temperature, the effectiveness of heat transfer was affected by buoyancy under conditions of relatively low flow rate. This was as a result of the mean flow and turbulence fields being modified. Such effects have recently become of interest in connection with proposals to use fluids at supercritical pressure in a number of new engineering applications, including innovative nuclear reactors cooled by water at pressures above the critical value (the SPWR). Clearly, in such a sensitive application it is of considerable importance that reliable assessments of the effectiveness of heat transfer can be made in order to ensure that the temperatures achieved in the core do not exceed acceptable limits. Ultimately, this will be done on the basis of a combination of experimental work and advanced computational modelling designed to closely simulate the conditions which will be encountered in the reactor. However, at this early stage in the evaluation of the Supercritical Pressure Water Reactor it is necessary to make use of relevant currently available experimental data of the kind reported here to identify the problems which might be encountered. The experiments reported highlight features of heat transfer to fluids at supercritical pressure which could prove to be of considerable importance in determining the extent to which a nuclear reactor operating at such pressures can be cooled effectively, especially under conditions of reduced flow rate where the effects of buoyancy on heat transfer can become very strong. In this paper experimental results are presented which exhibit striking features due to such influences and clearly illustrate the potential for severe localised impairment of heat transfer. They provide an indication of when such effects might be encountered and, therefore, a means whereby decisions could be made to restrict the operating conditions so that the problem is avoided. They can also be used for validating computer codes for modelling variable property, buoyancy-influenced turbulent flow in heated vertical passages and for developing improved models. (authors)
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 21160793
- Country of Publication:
- United States
- Language:
- English
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