M. Naghash Zadegan, Y. Rezvanifar and K. Javaherdeh

Study the Behavior of a Pump-less Absorption System Using Bubble Pump

Referring to the global warming issue, conventional air conditioning machines contribute both to the release of CFC refrigerants and the emission of carbon dioxide for their energy requirements, to the destruction of the ozone layer. The objective of current study was to simulate LiBr-water pump-less vapor absorption system, using bubble pump to circulate the solution thermally and to eliminate the shaft power. Doing this the heat addition to the fluid at the base of a vertical tube creates vapor, thereby increasing the buoyancy of the fluid causing it to rise through the vertical tube under two-phase flow conditions. In this way, where the power is expensive or unavailable, or where there is waste, gas, geothermal or solar heat available, pump-less absorption machines could provide reliable and quiet cooling. Two-phase flow models will be used to analyze the bubble pump. The relationship between the submergence ratio and the velocities has been obtained. The drift flux model has been used to find the gas void fraction. The results show that a 25 mm bubble pump tube diameter is suitable for residential size absorption chiller. A computer program has been written based on the bubble pump analysis. Heat and mass transfer and the appropriate equations describing the properties of working fluids have been used to analyze the absorption behavior. The results shows, with a single lift tube, it is possible to reach a COP of 0.48.