Hi friends I have a generated a model depicting a small portion of heat exchanger .my purpose of this model is to dehumidify the air ie the warm air which is a mixture of air and water vapour is allowed to pass into the heat exchanger and gets cooled by the counter flow chilled water. My outlet will be cooled dry air ie it consits of only air ,no water vapour (Dehumification process) well in fluent I tried to used species model to simulate this condition ,however the mixture(air+ water vapour )is constant through out the flow whereas at the outlet boundary condition I require only the dry cooled air.. can any one try to help me to know how to approach this problem .and moreover in fluent for species model ,phase change is not allowed.. ..Help me out its very urjent......Thank you

you should write a user-defined function (UDF) to represent the condensation process including both the heat and mass transfer effects that it would have.