Nguyen C.T.,Sierra Lobo, Inc.
Cryogenics | Year: 2010
Cooling distribution is a vital technology concerning cryogenic thermal management systems for many future space applications, such as in-space, zero boil-off, long-term propellant storage, cooling infrared sensors at multiple locations or at a distance from the cryocooler, and focal-plane arrays in telescopes. These applications require a cooling distribution technology that is able to efficiently and reliably deliver cooling power (generated by a cryocooler) to remote locations and uniformly distribute it over a large-surface area. On-going efforts by others under this technology development area have not shown any promising results. This paper introduces the concept of using a Resonant Self-Pumped Loop (RSPL) integrated with the proven, highly efficient pulse tube cryocooler. The RSPL and pulse tube cryocooler combination generates cooling power and provides a distributive cooling loop that can be extended long distances, has no moving parts, and is driven by a single linear compressor. The RSPL is fully coupled with the oscillating flow of the pulse tube working fluid and utilizes gas diodes to convert the oscillating flow to one-directional (DC) steady flow that circulates through the cooling loop. The proposed RSPL is extremely simple, lightweight, reliable, and flexible for packaging. There are several requirements for the RSPL to operate efficiently. These requirements will be presented in this paper. Compared to other distributive cooling technologies currently under development, the RSPL technology is unique. © 2010 Elsevier Ltd. All rights reserved. Source
Codron D.A.,NASA |
Nawaz A.,Sierra Lobo, Inc.
44th AIAA Plasmadynamics and Lasers Conference | Year: 2013
The present effort aims to strengthen modeling work conducted at the NASA Ames Research Center by measuring the critical plasma electron characteristics within and slightly outside of an arc jet plasma column. These characteristics are intended to give physical insights while assisting in the formulation of boundary conditions to validate full scale simulations. Single and triple Langmuir probes have been used to achieve estimates of the electron temperature (Te), electron number density (ne) and plasma potential (outside of the plasma column) as probing location is varied radially from the flow centerline. Both the electron temperature and electron number density measurements show a large dependence on radial distance from the plasma column centerline with Te ≈ 3 - 12 eV and ne ≈ 1012 - 1014 cm-3. Source
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.95K | Year: 2008
The ability to store large amounts of cryogenic fluids for long durations has a profound effect on the success of many future space programs using these fluids for propellants, reactants, and life support systems. The high cost of delivering payload mass to orbit will require storage systems capable of limiting cryogenic losses due to boil-off to less than two percent per year for mission durations of up to ten years; or in some cases, completely eliminating boil-off losses. Although Multi-Layer Insulation (MLI) Systems have been extensively used to insulate cryogenic vessels in a space environment, it has been for short-duration missions that require from 30 to 50 layers to meet the mission requirements. Conversely, 150 layers or more of MLI will likely be needed to meet the requirements of future long-term missions. Limited data exists on the performance and physical characteristics of these thick MLI systems. A key opportunity relative to the development of advanced MLI insulation systems is identifying and analyzing concepts for minimizing heat-leak through seams and penetrations, which will be the major contributor to cryogenic losses for thick MLI systems. Sierra Lobo proposes to identify the more promising seam and penetration concepts, based upon previous research with the Missile Defense Agency, and to provide an analytical model to evaluate their performance.
Agency: National Aeronautics and Space Administration | Branch: | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2010
The ability to restore large amounts of vented gaseous helium (GHe) at rocket test sites preserves the GHe and reduces operating cost. The used GHe is vented into the atmosphere, is non-recoverable, and costs NASA millions dollars per year. Helium, which is non-renewable and irreplaceable once released into the atmosphere, is continuously consumed by rocket test facilities at NASA centers such as KSC, SSC, and CCAFS at a rate of more than 6.6 Mscf per year. This use is projected to increase to more than 10 Mscf by the year 2018, assuming the same inefficient and costly operating procedures and facilities continue to be used. Given the decrease in the world's supply of helium, NASA is heading toward to an economic, operational, and programmatic disaster. New and highly innovative approaches are required to drive down launch operation life cycle costs. Scaling-up of existing systems to meet an increased demand of helium is not an option. Our team, Sierra Lobo, Inc. and University of Hawaii at Manao, proposes the use of PEM fuel cells to remove most of the impure oxygen and hydrogen in the helium gas stream. The small traces of oxygen and hydrogen impurities in the GHe will be removed by cryo-separation using commercial cryocoolers.
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 79.89K | Year: 2012
The Navy has stated a need for a backup cryogenic cooling method for shipboard superconducting systems. The cooling method must be as compact as practical and should operate without consumables even if power is lost for an extended period. Ideally, the backup cooling method should take advantage of the energy associated with a phase change. One known compound has a solid-to-liquid phase transition within the temperature range of interest (at 77 K) and remains a liquid up to and above room temperature. The compound presents no unusual hazards and is commercially available. Despite its apparent promise, the compound has not been previously explored for use in cryogenic applications. Sierra Lobo proposes to develop a backup Cryogenic Cooling Unit (CCU) using the compound. In the CCU, the energy storage medium is completely enclosed, does not need replenishment, and is storable at atmospheric pressure at room temperature. While power is available, helium gas is cooled to cryogenic temperatures by a dedicated cryocooler and circulated through tubes embedded in the energy storage medium. When power is lost, valves switch the flow through the heat exchanger from the dedicated cryocooler to the superconducting equipment"s cooling loop to deliver cooling power.