Engineering topics

Elchert, J. P.

Publications and source records attributed to Elchert, J. P..

6 records

NASA NTRS2018

Cryogenic Multilayer Insulation Theory and An Analysis of Seams Under a Variety of Assumptions

The theory of thermal radiation as applied to cryogenic surfaces is explored, andvalidation cases are solved in Thermal Desktop. Some results are compared topreviously published research, and new results are published regarding cracks inboth spherical and cylindrical cryogenic insulations with a cold boundary of 90Kto 220K for ten layer blankets under a variety of assumptions and scenarios.It was found that enabling directional emission{as well as specular, mirrorlikereflections have little impact on the results.

Elchert, J. P.↗

NASA NTRS2012

Efficient Thermally Conductive Strap Design for Cryogenic Propellant Tank Supports and Plumbing

After evalu1ating NASA space architecture goals, the Office of Chief Technologist identified the need for developing enabling technology for long term loiters in space with cryogenic fluids. One such technology is structural heat interception. In this prototype, heat interception at the tank support strut was accomplished using a thermally conductive link to the broad area cooled shield. The design methodology for both locating the heat intercept and predicting the reduction in boil-off heat leak is discussed in detail. Results from the chosen design are presented. It was found that contact resistance resulting from different mechanical attachment techniques played a significant role in the form and functionality of a successful design.

Elchert, J. P.↗

NASA NTRS2012

Efficient Thermally Conductive Strap Design for Cryogenic Propellant Tank Supports and Plumbing

After evaluating NASA space architecture goals, the Office of Chief Technologist identified the need for developing enabling technology for long term loiters in space with cryogenic fluids. One such technology is structural heat interception. In this prototype, heat interception at the tank support strut was accomplished using a thermally conductive link to the broad area cooled shield. The design methodology for both locating the heat intercept and predicting the reduction in boil-off heat leak is discussed in detail. Results from the chosen design are presented. It was found that contact resistance resulting from different mechanical attachment techniques played a significant role in the form and functionality of a successful design.

Elchert, J. P.↗

NASA NTRS2012

The Transport of Mass, Energy, and Entropy in Cryogenic Support Struts for Engineering Design

Engineers working to understand and reduce cryogenic boil-off must solve a. variety of transport problems. An important class of nonlinear problems involves the thermal and mechanical design of cryogenic struts. These classic problems are scattered about the literature and typically require too many resources to obtain. So, to save time for practicing engineers, the author presents this essay. Herein, a variety of new, old, and revisited analytical and finite difference solutions of the thermal problem are covered in this essay, along with commentary on approach and assumptions, This includes a few thermal radiation and conduction combined mode solution with a discussion on insulation, optimum emissivity, and geometrical phenomenon. Solutions to cooling and heat interception problems are also presented, including a discussion of the entropy generation. And the literature on the combined mechanical and thermal design of cryogenic support struts is reviewed with an introduction to the associated numerical methods.

Elchert, J. P.↗

NASA NTRS2012

The Transport of Mass, Energy, and Entropy in Cryogenic Support Struts for Engineering Design

Engineers working to understand and reduce cryogenic boil-off must solve a variety of transport problems. An important class of nonlinear problems involves the thermal and mechanical design of cryogenic struts. These classic problems are scattered about the literature and typically require too many resources to obtain. So, to save time for practicing engineers, the author presents this essay. Herein, a variety of new, old, and revisited analytical and finite difference solutions of the thermal problem are covered in this essay, along with commentary on approach and assumptions. This includes a few thermal radiation and conduction combined mode solutions with a discussion on insulation, optimum emissivity, and geometrical phenomenon. Solutions to cooling and heat interception problems are also presented, including a discussion of the entropy generation. The literature on the combined mechanical and thermal design of cryogenic support struts is reviewed with an introduction to the associated numerical methods.

Elchert, J. P.↗

NASA NTRS2011

Broad Area Cooler Concepts for Cryogenic Propellant Tanks

Numerous studies and ground tests have shown that broad area cooling (also known as distributed cooling) can reduce or eliminate cryogenic propellant boil-off and enable long duration storage in space. Various combinations of cryocoolers, circulators, heat exchangers and other hardware could be used to build the system. In this study, several configurations of broad area cooling systems were compared by weighing hardware combinations, input power requirements, component availability, and Technical Readiness Level (TRL). The preferred system has a high TRL and can be scaled up to provide cooling capacities on the order of 150W at 90K

Christie, R. J.↗