- An experimental investigation was undertaken to study the performance of the bubble pump for diffusion absorption refrigeration units. The bubble pump is the motive force of the diffusion absorption cycle and is a critical component of the absorption diffusion refrigeration unit. The purpose of the bubble pump (besides the circulation of the working fluid) is to desorb the solute refrigerant from the solution. Therefore the efficiency of the bubble pump will be set by the amount of the refrigerant desorbed from the solution. The performance of the diffusion absorption cycle depends primarily on the efficiency of the bubble pump. A continuous experimental system was designed, built and successfully operated. The experiments were performed in which some of the parameters affecting the bubble pump performance were changed. During the experimental investigation, photographs were taken showing that the bubble pump operates at slug flow regime with a churn flow regime at the entrance of the bubble pump tube. It was obtained that the performance of the bubble pump depends mainly on the motive head and on the heat input to the bubble pump.