Thermal insulation performance of lightweight substrate for solar array on stratospheric airships

Experimental and theoretical studies are reported on the thermal insulation performance of three types of lightweight substrate for application in solar array on stratospheric airships. A concept, specific temperature difference, is proposed which expresses temperature difference of unit area density and can estimate the overall thermal insulation performance of lightweight substrate. The experimental apparatus and instrumentation have been designed and built to measure temperature difference between the upper and lower surface of the test samples under different solar radiation flux conditions. The experimental data are studied to assess thermal insulation performance of the lightweight substrates. The theoretical models of three types of insulation structures are investigated to predict the temperatures. Then, the models are verified by comparison with the experimental data. On the basis of analyzing theoretical models, the effects of two critical parameters of the heat sink substrate on thermal insulation performance are analyzed which give the most important evidences for optimizing the design of heat sink substrate. The obtained result is a valuable reference for the selection of insulation substrate of solar array on stratospheric airships.