Experimental research on steam condensation in presence of non-condensable gas under high pressure

•An experimental study on steam condensation heat transfer in presence of non-condensable gas under high pressure up to 4.12 MPa were conducted.•The increase in pressure or decrease in the mass fraction of non-condensable gas would enhance the steam condensation heat transfer.•A significant increase of 98.2% in condensation heat transfer coefficient of steam with 10% Ar was obtained as the system pressure increased from 1.76 MPa to 3.12 MPa.