Heat transfer in a horizontal channel containing two-phase HeII

We report on heat transport in horizontal two-phase He II and vapor in a 2 m long test section with a 3 mm wide by 65 mm tall cross section. Liquid an d vapor temperatures are measured at eight locations, six along the channel and two in the boundary reservoirs. The six measurements along the channel are at three equally spaced axial locations, each with one thermometer in the liquid and one in the vapor. Boundary temperatures selected are 1.4, 1. 8, and 2.0 K and with up to 20 mK temperature difference across the channel . The liquid level at the cold end of the channel is set at 60, 50, or 40 m m, and the warm end level is lower due to increased vapor pressure. The eff ect of bellows pumps forcing up to 0.66 g/s of liquid with or against the t emperature gradient is also investigated. A finite difference numerical model is constructed which solves the main go verning nonlinear ordinary differential equation for energy transport in st ratified two-phase He II. Agreement between the model and experiment is goo d if one assumes a certain reasonable value for parasitic heat load to the experiment. (C) 1999 Elsevier Science Ltd. All rights reserved.