Analysis and modelling of water based bubble pump at atmospheric pressure

Bubble pump (BP), an essential component in coffee percolators, is used to drive solar water heating systems and single pressure absorption refrigerators. However, its mass flow rate cannot be readily predicted. Heat input, tube diameter and submergence ratio affect its mass flow rate. BP has the same working concept as air-lift pump, but its flow is complicated due to the condensation of vapour bubbles. Neither curve fitting models, nor air-lift pump models, can predict the mass flow rate with high fidelity. A new model based on the pumping characteristics of BP is presented and verified by a water based setup at atmospheric pressure. Results show that the average errors for the BP with tube diameter of 6–12 mm, and for the BP with submergence ratio of 0.5–0.8 are 13% and 11%, respectively. The BP performance increases when the tube diameter decreases or the submergence ratio increases.