Analysis on Hollow Fiber Membrane Heat Exchanger Applying to the Lithium Bromide Absorption Refrigeration System

The aim of this work is to bring forward a new style heat exchanger about hollow fiber membrane module, and to analyze the performance which can expectantly be applied in the lithium bromide absorption refrigeration system. Polyvinylidene fluoride hollow fiber membrane module was adopted as the new style solution heat exchanger, hot feed solution from the generator flowed into the lumen side of membranes while cold feed solution from the absorber flowed away the shell side. Heat transfer and water vapor mass transfer occurred simultaneously in the membrane module, only water vapor can diffuse across the membrane pore from one side to the other side according to the water vapor pressure difference between the both sides of the membrane. Mathematical equations of distributed parameter for heat transfer and mass transfer process in membrane heat exchanger was built, parameters of solution heat exchanger for traditional 10kw cooling capacity absorption refrigeration system was adopted as the simulation parameters, and the parallel-flow process and the counter-flow process was compared by numerical simulation. The simulation result shows that the counter-flow process was the better flow mode because the mean temperature difference was larger and the mass transfer process were more steadily from the lumen side to the shell side. The heat caused by mass transfer may be one third of the total heat transfer.