TES. These effects are assumed to be of minor importance, because contamination and corrosion should be minimized for reasons of maximizing the lifetime of the TES. Figure 6 summarizes the relevance of microgravity and shows influences and interactions with regard to TES performance and lifetime. Drop Tower Experiments Background The drop tower BREMEN, which will be finished in Autumn 1989 will provide a microgravity level of 10~5 to 10-6 g for 4.75 seconds. This time can be doubled by shooting the capsule up from the bottom of the drop tower tube. The payload mass is limited to 200 kg. Due to the short duration of weightlessness available the cooling rate has to be very high to solidify a reasonable amount of PCM. But a high cooling rate will probably influence crystallization and the phase change convection might be not effective enough—due to the inertia of the liquid PCM—to influence the PCM distribution. The solution proposed here is to drastically reduce the dimensions of the PCM canisters. Due to the aforementioned fractal character of void order and structure this measure will not change the effects to be observed if the wall thickness of the canisters can be reduced by the same amount.
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