Modeling transient heat transfer in stratospheric airships

This paper describes a comprehensive analytical thermal model for transient heat transfer analysis of stratospheric airship in a floating condition, powered by a solar regenerative fuel cell system. The model can be used to study the effect of solar radiation, ambient wind, and altitude and location of deployment of the airship on the temperature of buoyant gas and solar array of the airship. The solar array is modeled as three layers, viz., outer layer, solar cell and substrate, and the heat transfer equations involving radiative, infra-red, convective and conductive heat are solved simultaneously using a standard fourth order Runge-Kutta Method. The model has been coded in MATLAB®, and can be easily integrated to a multidisciplinary design optimization framework. Using this model, the variation of temperature with time for a stratospheric airship was obtained, and a good match was seen with some experimental data and numerical results quoted in literature. The effect of some operational parameters, viz., deployment location, altitude and ambient wind speed are presented to illustrate their effect.