BUBBLE PUMP MODELING FOR SOLAR HOT WATER HEATER SYSTEM DESIGN OPTIMIZATION
Solar thermal water heating systems reduce household energy bills by using the free solar radiation provided by the sun to heat water for residential needs. In order to eliminate the need for electricity to run a pump to drive the fluid circulation in these systems, fluid buoyancy effects can be employed to move the fluid from lower elevations to higher elevations. There are several operational challenges with conventional “thermosyphon” systems, such as reversing flow and overheating, which can all be addressed by using a bubble pump mechanism. Although the solar thermal bubble pump water heating system has been on market, little research has been done on the optimization of the system to improve its efficiency. Engineering Equation Solver software is used to implement a mathematical model for the bubble pump system operation. The model allows for parametric studies of the design attributes to investigate optimum efficiency conditions for the thermally driven pump.
A general design equation for air lift pumps operating in slug flow
Air lift pumps are finding increasing use where pump reliability and low maintenance are required, and where corrosive, abrasive, or radioactive fluids must be handled. Although air lifts are used in nuclear fuel reprocessing plants, no general, theoretically sound equation has been proposed in the literature for tall air lift design. Such an equation is developed from two-phase flow theory to predict the height to which an air lift pump operating in the slug flow regime can lift a given volumetric flow rate of liquid, given the air flow rate and pressure at the point of gas introduction. The widely used drift-flux model for the prediction of holdup is combined with an approximate relationship to predict pressure loss, and is substituted into the total pressure differential. Integration of the resulting equation provides an explicit formula for the calculation of lift. Experimental work using a variety of liquids in a 38 mm dia. air lift test installation supports the new design equation and demonstrates its flexibility.
Annual Reports
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