Simulation Analysis Of Falling Film Absorption At High Temperature And Design Of AHT Prototype

Absorption heat transformers(AHT) for upgrading of heat is very useful for heat recovery of low-level thermal energy,In industrial applications,AHT takes thermal energy from a low-temperature process stream and deliver it to a higher-temperature process.The recycled thermal energy will therefore reduce the prime energy needed in the process.For the purpose of developing more efficient and compact AHT on different conditions,More abroad and elaborate work about AHTs are needed to be done in these area,including the heat and mass transfer enhancement,thermodynamic analysis and absorption mechanism,the development of new working fluids,and the optimization and simulation of absorption process.The coupled heat and mass transfer of falling film absorption of aqueous lithium bromide solution over a vertical tube is analyzed theoretically.The model simulation results are used to elucidate the variation of outlet LiBr temperature and concentration with the liquid spraying density and coolant velocity.The optimal tube length is determined for the combination of liquid spraying density and the expected temperature.Experimental researches of falling film absorption are mainly studied below 130℃so far.Based on the characteristics of falling film flow,this paper designs an experimental setup of falling flim at the high temperature.Experiment system mainly includes falling film absorber,generator,oil tank,data collection system and control system.A prototype of AHT with falling films absorption outside vertical tube is designed.With the optimal COP,the temperature difference between absorption and evaporation can be above 30℃.Additionally,the areas of generator,absorber,evaporator,condensator and heat exchanger have been designed.