ISSN Online: 2377-424X
ISBN CD: 1-56700-226-9
ISBN Online: 1-56700-225-0
International Heat Transfer Conference 13
FLOW BOILING OF A HIGHLY VISCOUS POLYMER SOLUTION
Sinopsis
Flow boiling experiments with mixtures of poly dimethyl siloxanes and n-pentane are carried out in a vertical annular channel. The mixtures are fed to the test section with a subcooling of 30 − 65 K. The flow condition at the inlet can be characterized as creeping flow with Re-numbers as small as 0.01. Strong radial temperature gradients prevail throughout the entire evaporation process, indicating a laminar flow character even under boiling conditions.
Analysing the experiments, heat transfer to a homogeneous liquid phase, subcooled boiling, fully developed nucleate boiling, convective heat transfer to a two-phase flow and flash effects due to pressure loss can be distinguished.
Yet heat transfer can be described as a first approximation by a simple model which is based on laminar single phase heat transfer and incorporates an additional convective term reflecting the augmentation of convection through the gas phase.
Analysing the experiments, heat transfer to a homogeneous liquid phase, subcooled boiling, fully developed nucleate boiling, convective heat transfer to a two-phase flow and flash effects due to pressure loss can be distinguished.
Yet heat transfer can be described as a first approximation by a simple model which is based on laminar single phase heat transfer and incorporates an additional convective term reflecting the augmentation of convection through the gas phase.