| Popis: |
NASA’s future missions involve sending astronauts back to the moon, and further. Challenges associated with this goal are not limited to the science involved with propelling these astronauts to their destination. Life support systems must also advance to improve astronaut health during their long flights in space. Currently, food consumed in space is processed to be shelf stable, and recent experiments have shown that nutrients of these shelf stable foods decay over time. Refrigeration storage for more nutritional food has remained undeveloped due to fluid flow and heat transfer management difficulties in microgravity. As part of a NASA SBIR Phase I project, Purdue University and Air Squared Inc., have designed a modular refrigerator that is able to preserve food in a frozen state. The proposed vapor compression refrigeration system reduces the instability of flow in microgravity through both reduction on liquid reliance via a coupled oil-free scroll compressor and expander, and through specific methods of design that manage two phase refrigerant flow through the heat exchangers. R134a is the working fluid, as it is non-toxic, non-flammable, has favorable volumetric characteristics, and will be available in the future. Air is pulled across the evaporator of the vapor compression loop to be cooled, and then fed into four identical food storage compartments. Absorbed heat from the air is rejected out of the condenser into a central cooling water loop in the spacecraft. Developments of more effective vapor compression systems in space may also yield improved systems for use on earth. |
