Influence of the tube diameter on instability in the bubble pump

Operation conditions have a most importance to define the efficiency of several machines. In this area mathematical model can be able to predict the optimal operating condition in several studies. In diffusion absorption machines, where the bubble pump is its motive party, tube diameter, heat flux supplied, submersion ratio and working fluid was the mainly operating conditions influencing its efficiency. In the order to study the influence of tube diameter on the flow stability in the bubble pumps, drift flow model have been used to simulate ammonia water two-phase flow in the transitional conditions. It was found that, the liquid and vapour velocities oscillate for a time about 5s and then increase, mass flow rate has the same behaviour too. Pressure drop is more influenced by the tube diameter changing. However void fraction is no influenced by tube diameter choice.