Engineering topics

Mills, G. L.

Publications and source records attributed to Mills, G. L..

5 records

DOE OSTI2014

Load responsive multilayer insulation performance testing

Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that provide high thermal performance both in atmosphere and vacuum. LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI.

42 ENGINEERING↗

NASA NTRS1991

Design and development of a leak tight helium II valve with low thermal impact

The Lambda Point Experiment is a precision measurement of the specific heat of liquid helium near the lambda point phase transition, in the low gravity of the space shuttle. It requires a valve for the helium sample chamber that operates at helium II temperature, has minimal thermal disturbance to the rest of the instrument, and is leak tight to helium II. A valve meeting these and all of the other science and engineering requirements of the mission has been developed by Ball. Initially, both torque and pressure actuated valve concepts were considered; the final flight design is pressure actuated. The rational for this decision as well as the rest of the valve design are given. The paper also discusses the manufacturing and testing of the prototype and flight valves. Test data is presented and discussed.

Mills, G. L.↗

NASA NTRS1990

BASG thermomechanical pump helium 2 transfer tests

The purpose of the effort described was to perform experiments and calculations related to using a thermomechanical pump in the space-based resupply of the Space Infrared Telescope Facility (SIRTF) with Helium 2. Thermomechanical (fountain effect) pumps have long been suggested as a means for pumping large quantities of Helium 2. The unique properties of Helium 2 have made it useful for cooling space instruments. Several space science missions, including SIRTF, are now being planned which would benefit greatly from on-orbit resupply of Helium 2. A series of experiments were performed to demonstrate that large volumes of Helium 2 can be transferred with a thermomechanical pump at high flow rates and at high efficiency from one dewar to another through valves and lines that are similar to the plumbing arrangement that would be necessary to accomplish such a transfer on-orbit. In addition, temperature, pressure, and flow rate data taken during the tests were used to verify and refine a computer model which was developed.

Mills, G. L.↗

NASA NTRS1990

Performance of a thermomechanical pump

This paper presents the results of a series of thermomechanical pump tests to determine the performance of a simulated transfer system. The tests compared heater power versus transfer rates with accurate temperature, pressure, flow rate and heater power data. Test data were also compared to a computer model. The thermomechanical pump performance was found to be primarily a function of supply liquid temperature and heat input near the plug.

Mills, G. L.↗

NASA NTRS1988

Experiments on transferring helium II with a thermomechanical pump

Porous plugs were tested as thermomechanical pumps for the transfer of helium II from one dewar to another through a transfer line and two valves. SEM images for two different size porous plugs are presented. The present pump design was shown to transfer 80 liters at a maximum flow rate of 90 liters/hr. Temperature, pressure, flow rate, and heater power data are compared with theoretical results.

Mills, G. L.↗