Mission-based optimization of insulation layer for the solar array on the stratospheric airship

Solar array is essential for converting sunlight energy to electricity and ensure normal operation of propellers, payloads and avionics of stratospheric airship. Apart from electrical energy, excess solar irradiation is transformed to heat load on the airship, seriously affecting the pressure balance and structural integrity. However, the investigation of insulation layers between solar cells and airship film are rare. This paper aims to maximize the output energy of solar array through optimizing the configuration of insulation layers. The energy model and heat transfer model are established. Based on the theoretical model, the influence of insulation parameters on the output energy of solar array and differential pressure are studied. The energy acquirement and differential pressure have negligible change when increasing the thermal conductivity and thickness of insulation substrate in the same proportion. The thermal impedance as the ratio of thickness to thermal conductivity is firstly adopted to describe the configuration of insulation structure. The optimal thermal impedance can be obtained based on flight missions considering airspeeds, latitudes and dates. The output energy can be maximized while keeping the differential pressure within limited range with the optimal thermal impedance. The result provides a conducive reference for the preparation of solar powered airship.