The vapor surfactant theory holds that 2-ethyl-hexanol is a surfactant that causes absorption enhancement by driving Marangoni convection in the liquid. The alcohol arrives at the liquid surface via the vapor by bulk flow of the absorbate (water vapor). This implies that the alcohol circulates through the machine with the refrigerant. This circulation has not received much attention but it is a complex and interesting problem. The alcohol is sometimes observed to collect in the evaporator where it is isolated from the absorption process. Also, the alcohol is known to coat the interior walls of the vessels in all components. The present study is an attempt to understand and quantify the alcohol circulation rates. In particular, it is desirable to know the alcohol vapor concentration of the refrigerant flowing from the evaporator to the absorber. The model described here predicts this value based on physical models of each of the system components. The model is compared against data obtained from transient tests on an absorption chiller.

Units: SI