MASS TRANSFER IN CHANNELS HAVING REGULARLY REPEATING OBSTACLES

摘要

Steady laminar obstacle flows have been investigated for various obstacle arrangements:channel centered, surface mounted and alternating surface mounted. Each channel was made up of 10 repeating obstacles, and mass transfer was considered by simulating the effects of a reverse osmosis desalination process.Simulations were run at Re_D=100 and R_(e6)92,with obstacles covering 25%of the channel height.It was found that while fully developed hydrodynamic solutions develop within a few obstacles,the mass transfer results are far from fully developed,even after 10 obstacles. This situations is considerably worse as Re_D increases. rnIt was found that obstacles improve the desalination process in all cases.Alternating surface mounted ob- stacles are most performant,while channel centred obstacles are least performant and should be avoided.Finally,the presence of obstacles results in maximum concentrations in excess of the case with no obstacles, and this could present problems in certain processes which are susceptible to gel layer formation.