3454 -- Mathematical Modeling of a Steam-Injected Bubble Pump PDF

The absence of an inexpensive and reliable solution pump for small absorption heat pumps, using the water/ammonia combination, has been a serious hindrance to their development and commercialisation. One successful design incorporates a self-powered reciprocating mechanism, which delivers an intermittent flow of absorbent, and a circulating bubble absorber to achieve continuous absorption. The exact manner in which this circulating bubble absorber functions is not fully understood, and the work described is concerned with improving this understanding. A mathematical model has been developed to describe the two-phase flow along the lift tube of a bubble pump, containing the vapour and liquid of a single fluid from which heat is removed. This model has been validated by tests involving the introduction of steam into water at low pressure. The model provides the starting point for the development of an extended model that can be used to analyse the behaviour of an ammonia/water bubble pump as used in the circulating bubble absorber, taking the heat of solution and solution concentration effects into account.

KEYWORDS: calculating, heat pumps, absorption heat pumps, steam engine heat pumps, water, ammonia, reciprocating engine heat pumps