Investigation of transient regimes with steam absorption by water solution of lithium bromide
N.S. Bufetov, R.A. Dekhtyar, V.V. Ovchinnikov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: absorption, lithium bromide solution, surfactant, Marangoni effect, thermocapillary convection, temperature inhomogeneity
Abstract
Transient processes are experimentally investigated at the initial stage of heat and mass transfer with steam absorption on the surface of 57.8% water solution of lithium bromide in a bath with a diameter of 70 mm. The experiments were carried out both with a pure solution and with a solution where n -octanol surfactant was added. It is shown that with a sharp steam pressure increase in the volume above the surface of an absorbing solution, local temperature inhomogeneities are generated on the solution surface. The growth rate of these inhomogeneities is proportional to the growth rate of the steam pressure. It was found that, in contrast to the solution without surfactant, where convective flow is observed only during a short time interval after steam supply to the absorber, in a fixed layer of water LiBr solution with surfactant addition, there is stable thermocapillary convection in the near-surface layer of solution during absorption. It is shown that for variable bottom topography, there can be space-localized zones, where the temperature on the solution surface is determined by the shape of bottom topography.
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