I am performing a simulation in Ansys fluent using multiphase flow settings for two phase flow problem and with out multiphase flow settings for single phase flow. The results differs heavily and huge enhancements in multiphase flow.
Yes, you can do it. Enhancement in multiphase flow arises because of a high heat transfer coefficient compared to a single-phase flow. Another thing is that the pressure drop in the multiphase flow should be higher because of higher friction due to vapor.