Gas-Liquid Heat Transfer in Pressure Vessel

[DeltaWing]

Propellant tanks for rocket engines often use helium gas to provide pressure to the tanks. To minimize the amount of gas used, the gas is heated in an exchanger at the rocket nozzle before passing into the propellant tanks. To calculate the heat transfer between the helium and the liquid propellant during engine operation, I need to know the gas-liquid heat transfer coefficient. I know that the coefficient for helium/N2O4 is 0.002 Btu/sec-ft2-deg R. I'm trying to find the coefficient for helium/H2O2 (hydrogen peroxide). Any ideas?

 

[DeltaWing]

I think I made some progress. If I use the Churchill-Chu correlation for free convection from a vertical surface (because the liquid-gas interface is oriented vertically during horizontal flight), with the appropriate data for helium at 540R and a temperature difference of 180 R, I get a coefficient of 0.0022 Btu/sec-ft2-deg R. This is comparable to the experimental value of 0.002 quoted by Huzel and Huang (The Design of Liquid Propellant Rocket Engines, 1974) for helium/N2O4. Since the coefficient scales as the 1/3 power of the Rayleigh number, operation in low-g conditions doesn't affect the result as much as I would have expected. Operating at 50% of sea-level gravity will only reduce the coefficient by around 20%.

 

[vpl]

I spent some time trying to find a value yesterday but couldn't find anything reasonably available. Glad you were able to come up with something.

Patricia Lougheed

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