Boiling heat transfer experiments were carried out at reduced pressure conditions for a single horizontal heated tube with a narrow annular gap around it. Liquids used for the experiments were distilled water and lithium bromide/water solutions. The effects of pressure, concentration, annulus length on the boiling heat transfer were investigated. The experimental study proved that the boiling performance was sensitive to annulus geometrical size in the case of distilled water but was relatively insensitive with the lithium bromide/water solutions.

KEYWORDS: heat flow, lithium bromide, water, vacuum, boiling, absorption refrigeration, refrigeration, heat exchangers, horizontal, experiment, tubes.