Spinning-Scroll Pump for Cryogenic Feed System

One of the key advantages of the proposed technology is its scalability. Not only can the speed be varied across a wide range, but the size of the unit can be changed to meet additional applications. Once the technology is proven through this Phase I, it can be modified to fit a wide range of cryogenic applications. A small, cryogenic scroll pump would have several NASA cryo propellant applications. It would enable efficient, low boil off or zero boil off cryogenic systems by circulating cryogenic helium gas from a cryocooler to broad area thermal shields surrounding the tanks. This would eliminate the need for high-efficiency heat exchangers that are required with ambient temperature circulator pumps. The pump would also enable thermodynamic vent systems in which cryo propellants are dropped in pressure and temperature, and heat exchanged with liquid pumped in a circulation loop within the tank. NASA Marshall has done considerable work with such systems involving spray bar tank heat exchangers and destratifiers. NASA topic Z10.02: Methane In-Space Propulsion expresses an interest in a cryogenic methane pump for high thrust in space chemical propulsion capabilities. These thrusters are critical to enable human and robotic missions to Mars and beyond. For these long duration missions, zero boil off conditions need to be achieved. Therefore, the development of cryogenic circulating pumps with long life, variable speed operation, and very low leakage are required.

A strong demand exists for small cryogenic pumps for use in liquid hydrogen fueled aircraft. The Boeing Company and AeroViroment, Inc. have developed and flown hydrogen powered, unmanned aircraft as reconnaissance platforms. Typically, these aircraft fuel systems require the hydrogen to be delivered at a pressure of 90 PSIG. Currently, this performed by making the operating pressure of the tanks at a minimum of 90 PSIG. This results in tanks that can operate with a safety margin above this pressure. If the tanks could operate at a lower pressure, such as 30 PSIG, the tank walls could be thinner and lighter. The estimated weight savings of a pump system for the Boeing Phantom Eye hydrogen fueled aircraft is over 400 pounds per aircraft. The scroll pump is a significant contributor in increasing aircraft endurance or payload. Another commercial application would be a liquid natural gas pump (LNG), for LNG transport. Currently, there are limited options for positive displacement LNG pumps. Progress Rail (Caterpillar Subsidiary) has already contacted Air Squared about using a positive displacement LNG scroll pump for locomotive transportation and has invested in an Air Squared, orbiting scroll type LNG pump prototype. While the size and weight aren't primary concerns, the proposed pump development could be used as an LNG fuel pump. More »