Effect of operating conditions on the performance of the bubble pump of absorption-diffusion refrigeration cycles

Abstract

The mathematical model will be able to predict the operated condition (required tube diameters, heat input and submergence ratio?.). That will result in a successful bubble pump design and hence a refrigeration unit. In the present work a one-dimensional two-fluid model of boiling mixing ammonia-water under constant heat flux is developed. The present model is used to predict the outlet liquid and vapor velocities and pumping ratio for different heat flux input to pump. The influence of operated conditions such as: ammonia fraction in inlet solution and tube diameter on the functioning of the bubble pump is presented and discussed. It was found that, the liquid velocity and pumping ratio increase with increasing heat flux, and then it decreases. Optimal heat flux depends namely on tube diameter variations. Vapour velocity increases linearly with increasing heat flux under designed conditions.