Mainstream proposes a Modular Membrane Controlled Three-phase Deployable Radiator (MMC-TDR) that has a turndown ratio of 200:1, a mass of only 7.8 kg, and design life of over 15 years. The key enabling components of the MMC-TDR are 1) a passive, reliable membrane phase separator for robust two-phase flow control in the absence of gravity, 2) a passive bypass valve which regulates flowrates in the radiator to control heat rejection, and 3) a modular, deployable tube-on-plate three phase radiator design which is three-phase compatible. The system integrates with a two-phase pumped loop using ammonia as the process fluid. The MMC-TDR uses an integrated membrane phase separator that achieves separation via capillary action, so that operation is insensitive to gravity and inertia effects. Separate vapor and liquid ammonia streams are distributed to the freezable radiator through two distributions headers. The subcooled liquid from both streams is combined at the outlet of the radiator array in the collection header. The MMC-TDR will use increased pressure losses and heat transfer from longer channel lengths with a variable opening PCM bypass valve to selectively reduce flow through outer most channels as heat load is reduced. The reduction in flow will results in high degrees of subcooling until freezing occurs. The percentage of flow through the bypass line vs. the radiator channels is passively controlled by modulating the bypass valve position, increasing or reducing the bypass line pressure drop relative to the channel pressure drops. The PCM bypass valve regulates the flow through the system to achieve the desired subcooled temperature, effectively allowing the radiator channels to gradually lose flow and freeze during periods of low desired heat dissipation. The freezable radiator panel is constructed of a series of parallel “U” channels. The channels are constructed of aluminum encased Inconel tubes.
The proposed research is targeted at improvement in the deployable radiator state of the art. NASA has identified a need for improvements in the turndown ratio and specific weight of deployable radiator designs, for low Lunar orbit, Jupiter orbit, and inner to outer planet exploration mission application.
Mainstream will begin discussions with alternative potential government and commercial customers to further asses the market potential and possible applications. Because the need for increased computing power and decreased size is also relevant to commercial satellites, we will also explore commercial space applications.