Transient Heat Transfer from a Horizontal Wire in Subcooled He II at Atmospheric Pressure for a Wide Range of Wire Diameter

Abstract

Transient heat transfer caused by large stepwise heat inputs to a horizontal wire in subcooled He II at atmospheric pressure was measured for the wire diameters of 0.08, 0.2, 0.5 and 0.7 mm. Liquid temperatures tested were 1.8, 1.9, 2.0 and 2.1 K. The steady-state critical heat flux which is dependent on liquid temperature and wire diameter was well expressed by the authors’ correlation based on Gorter-Mellink equations. The lifetime of quasi-steady Kapitza conductance state, which corresponds to that of a certain point on the extrapolation of stead-state Kapitza conductance curve, was systematically measured on the wires: the quasi-steady state rapidly changes to film boiling regime at the end of the lifetime. The lifetime at an excess heat flux beyond steady-state critical heat flux, is longer for a larger diameter wire, though the steady-state critical heat flux is lower. Excessive heat flux beyond steady-state critical heat flux, when integrated from the time that the heat flux reaches the steady-state critical heat flux to the end of the quasi-steady state lifetime is almost constant and it is independent of the step heights and of the initial waveform during the rise time to the step height. A correlation for the average integrated value was given as a function of the wire radius and bulk liquid temperature. The lifetimes for the ideal step heat inputs (rise time = 0) are given from the correlation.KeywordsHeat FluxHeat InputDiameter WireStep HeightCritical Heat FluxThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.