Reflooding With Steady and Oscillatory Coolant Injection: Part 2—Quench Front and Liquid Carryover Behavior

Abstract

The reflooding of a tubular test section under oscillatory inlet flow conditions has been investigated experimentally for initial wall temperatures from 316° C to 760°C, oscillation periods from 2 to 6 s, and test section liquid level amplitudes up to 0.76 m. Compared to constant-injection reflooding, the oscillations always increase the liquid carryover rate in the early stages of reflooding. As reflooding progresses, the enhancement diminishes and becomes negative. The crossover point roughly coincides with saturation of the liquid at the quench front. The higher initial liquid carryover increases downstream heat transfer and speeds up quench front propagation, but it also reduces the test section mass accumulation rate, and for this reason delays quench front propagation at later stages. These effects are accentuated at higher oscillation amplitude and frequency. Large oscillations change the reflooding behavior substantially. Quantitative comparisons of quench front velocities and heat transfer immediately downstream of the quench front, obtained through the use of empirical local-condition correlations representing the steady-reflooding rate data, are presented.