Experimental investigation of pool boiling of lithium bromide solution on a vertical tube under subatmospheric pressures

This study investigates the saturation pool boiling of 55%w lithium bromide solution on an electrically heated vertical tube under subatmospheric pressures. Boiling curves for pressure of 30, 70, 150 and 300 torr, are presented. A delayed transition from natural convection to nucleate boiling is observed due to too few active nucleation sites. Observations show that the size range of bubble departure diameter is wider at lower pressure. Boiling curves shift leftwards when the pressure increases. Comparison of boiling curves with those on a horizontal tube shows that the case of vertical tube has better heat transfer performance.