Multiple lift tube pumps boost refrigeration capacity in absorption plants

Abstract

The technology of the diffusion absorption refriger-ator is receiving renewed attention due to its ability to use exclusively, low-grade heat to produce cool-ing or heating. Its capacity, however, has been large-ly restricted to small domestic-type units because of the flow rate limitations imposed by its single lift-tube pump. To increase its refrigeration capacity, a multiple lift-tube bubble pump can be used, in order to increase the volume flow rates of the fluids, which are directly related to the amount of refriger-ant produced. Testing on a diffusion absorption plant using a multiple lift tube bubble pump, and the effects of additional tubes on the system’s per-formance have been recorded. Although a full range of heat inputs could not be implemented, because of the limitations of the components of the unit itself, it was observed that the refrigeration cooling capacity was increased without a significant drop in Coefficient of Performance (COP). It was concluded that the multiple lift tube bubble pump has no limitation to the fluid flow rate and depends solely on the amount of heat input. This gives the freedom to design the lift tube pump according to the refrigeration demand of the unit, and not the other way round which is the current approach by the manufacturers world wide.