A solar-driven absorption energy storage system based on membrane distillation technology

The aim of the article is to propose a novel lithium bromide absorption energy storage system driven by solar energy based on membrane distillation technology. In the system, heat energy is transformed into chemical potential of aqueous lithium bromide solution and the latent energy of refrigerant water. According to the principle of membrane distillation process, the conventional generator was replaced by hollow fiber membrane module, and aqueous lithium bromide solution was separated and concentrated in the module by vacuum membrane distillation process. The driven force of water vapor diffusing across membrane pores was the vapor pressure difference between both sides of membrane, and aqueous lithium bromide solution need not be heated to boiling point. Thus, heating source temperature of solar energy would decrease compared with conventional generator plant. An experimental study on vacuum membrane distillation of aqueous lithium bromide solution was built and a novel lithium bromide absorption energy storage system based on membrane distillation was analyzed. The result shows that hollow fiber membrane module not only offered plenty of contact specific area between aqueous lithium bromide solution and membrane material, but reduced weight and volume of generator plant. Above all, it decreased the temperature of heat source, and low grade energy such as solar energy, geothermal energy and waste heat energy etc. will utilize more adequately.