Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

NATURAL CONVECTION DRIVEN IN THE GRAVITATIONAL DIRECTION NEAR THE CRITICAL POINT OF CO2

Get access (open in a dialog) DOI: 10.1615/IHTC11.3500
pages 477-481

Abstrakt

Temperature propagation near the critical point of C02 was investigated under lg conditions experimentally. One spot in the test C02 fluid was heated by a thermistor and the temperature propagation was visualised using the shadowgraph technique. As was expected, buoyancy convection was induced in the anti-gravitational direction. However, convection was driven even in the gravitational direction when the system was close to the critical point. The temperature propagation speed in the anti-gravitational direction was higher than that in the gravitational direction. The temperature propagation speed in the gravitational direction became maximum at the critical temperature. The onset of convection in the gravitational direction was delayed after the heat input. The delay time became minimum at the critical temperature and longer as the system temperature deviated from the critical temperature. Temperature propagation near the critical point of C02 is also investigated theoretically. The governing equations of thermal energy transfer near the critical point are introduced and linear analysis is carried out. The amplitudes of temperature propagation in the anti-gravitational and gravitational directions are analysed. It was found that the amplitude of temperature grows in the anti-gravitational direction and decays in the gravitational direction but that the decay time is long when the wavelength of temperature perturbation is long.