Numerical Simulation of Mass Transfer Mechanism of Stratospheric Solar Powered Telecommunication Balloons

Abstract

Stratospheric balloon systems, which have the ability to fly for longer periods of time such as months or even a year in 20 km or higher layers of the atmosphere, have been an elusive goal to achieve in recent years. It is critical issue to resolve the energy matter of stratospheric balloon to supply unmanned vehicles working at target altitudes for extended durations. As an ideal alternative, solar power units are supplied to the balloons by mounting them on the balloon's envelope and classified as solar powered balloons. This method can cause the buoyant gas inside the balloon to overheat and pressurize, leading to further gas leakage from the balloon's polymeric material. In this investigation, modeling of the mass transfer mechanism of a solar-powered zero-pressure balloon has been set up and simulated using iterative techniques in Fortran program for the first time in literature. The simulation has been run for solar powered balloon flight under one of the cities of Turkey’s real atmospheric conditions including solar radiation flux and wind velocities. The temperature variation of interior helium and mass transfer coefficient and diffusion coefficient with thermal effect have been analyzed and compared with the unpowered stratospheric balloon in summer season conditions. The maximum temperature, mass transfer coefficient and diffusivity of the interior helium for solar powered and unpowered balloon is obtained as 350.51 K, 1.74 x 10^-2 m/s, 0.83x10^-8 m/s² and 310.49 K, 1.48x10^-2 m/s, 0.78x10^-8 m/s² respectively. These results will be helpful to design the solar powered balloon systems to stay at higher altitudes for longer durations