Manabendra Chowdhury

I am trying to design a methanation plant. For that I am using a heat exchanger and gibbs reactor. The problem i am having whenever i am trying to run the model, I am getting either heat transfer coefficient or heat exchange area infinity. I cannot fix both the values together because i need a certain temperature to come out of the heat exchanger which will then go to the gibbs reactor. If anybody has any solution for this, please help me. If you have any suggestion please let me know.