The effect of noncondensable gas on laminar film condensation of a liquid metal on an isothermal vertical surface with forced vapor flow is analyzed. Where necessary the interfacial resistance due to thermodynamic nonequilibrium is included for a condensation coefficient σ = 1. A computer program has been developed to solve a finite-difference analog of the governing partial differential equations and is applied here to the mercury–air and sodium–argon systems. Heat-transfer results are presented for vapor velocities in the range 1 to 100 fps with mass fraction of gas varying from 10−5 to 3 × 10−2. The overall temperature difference ranged from 0.1 to 30 deg F while the temperature levels were 1200 and 900 deg R for mercury–air and 2000 and 1500 deg R for sodium–argon. The effect of noncondensable gas is most marked for low vapor velocities and high gas concentrations. At the lower pressure levels the inter facial resistance plays a dominant role, causing maxima in the curves of q/qNu versus x. For the mercury–air system the adverse buoyancy force causes vapor boundary-layer separation when the free-stream vapor velocity is low.

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