Microscopic and macroscopic analysis on steam heat transfer due to dual-interface resistance from non-condensable gases

This study investigated the condensation heat transfer of steam mixed with non-condensable gas, with a particular focus on the dual-interface thermal resistance caused by the condensate liquid layer and the gas diffusion layer. Theoretical models were established to calculate the thickness of the dual-interface and the condensation heat transfer coefficient. Moreover, this study designed a microscopic visualization steam condensation heat transfer system and a macroscopic visualization steam chamber expansion system. At the microscopic level, the mechanism of steam condensation heat transfer influenced by the dual-interface thermal resistance was revealed. At the macroscopic level, the effects of dual-interface thermal resistance on steam chamber expansion were verified, which subsequently influenced heavy oil thermal recovery. The results showed that the gas diffusion layer was identified as the primary thermal resistance. The non-condensable gas (CO2, N2, and air) fundamentally affected steam heat transfer by increasing the amount of medium and large diameter condensable droplets, extending the condensation cycle by 0.425–1.375 times, decreasing steam heat loss by 2.29 %, and reducing the condensation heat transfer coefficient by 6.48 %–15.10 %. More steam heat was transported deeper into the reservoir model, increasing the average temperature of model from 79.9oC to 93.8oC.