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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Phase equilibria of the magnesium sulfate-water system to 4 kbars

Magnesium sulfate is the most abundant salt in carbonaceous chondrites, and it may be important in the low-temperature igneous evolution and aqueous differentiation of icy satellites and large chondritic asteroids. Accordingly, we are investigating high-pressure phase equilibria in MgSO4-H2O solutions under pressures up to four kbars. An initial report was presented two years ago. This abstract summarizes our results to date including studies of solutions containing 15.3 percent, 17 percent, and 22 percent MgSO4. Briefly, these results demonstrate that increasing pressure causes the eutectic and peritectic compositions to shift to much lower concentrations of magnesium sulfate, and the existence of a new low-density phase of magnesium sulfate hydrate.

Hogenboom, D. L.↗
NASA NTRS2019

Planetary Water Recycling Systems Trade Study

Long-term planetary space missions present new and unique challenges in life-support systems. Water constitutes the majority of the mass required to sustain human life in space and it follows that efficient water recycling has the potential to lower mission costs. The effect of partial gravity in planetary missions mean that terrestrial systems could be applicable. This trade study evaluates terrestrial and NASA developed water recycling technologies on the basis of applicability as a planetary base water recycling systems. Various bioreactors, membrane reactors, filtration, and district water reclamation systems are investigated and rated based on several standardized parameters. A customer-oriented Quality Function Deployment (QFD) is utilized to analyze the ratings of the technologies for the tasks required. The trade study aims to rank the various systems based on their Equivalent System Mass (ESM), Technology Readiness Level (TRL), scalability, crew time, and overall logistics requirements, among others. The results of the study can serve as a basis for future inquiries and studies by NASA and other interested parties. The results of this study provide a down selection from 24 systems to 5 systems that trade very close to each other. The results provide a context and justification for a future comparative hardware test program to determine which of these systems offer the best solution.

Flynn, Michael↗
DOE OSTI2023

Large-scale molecular dynamics simulations of bubble collapse in water: Effects of system size, water model, and nitrogen

Molecular dynamics simulations in the microcanonical ensemble are performed to study the collapse of a bubble in liquid water using the single-site mW and the four-site TIP4P/2005 water models. To study system size effects, simulations for pure water systems are performed using periodically replicated simulation boxes with linear dimensions, L, ranging from 32 to 512 nm with the largest systems containing 8.7 × 10 6 and 4.5 × 10 9 molecules for the TIP4P/2005 and mW water models, respectively. The computationally more efficient mW water model allows us to reach converging behavior when the bubble dynamics results are plotted in reduced units, and the limiting behavior can be obtained through linear extrapolation in L –1 . Qualitative differences are observed between simulations with the mW and TIP4P/2005 water models, but they can be explained by the models’ differences in predicted viscosity and surface tension. Although bubble collapse occurs on time scales of only hundreds of picoseconds, the system sizes used here are sufficiently large to obtain bubble dynamics consistent with the Rayleigh–Plesset equation when using the models’ thermophysical properties as input. For the conditions explored here, extreme heating of the interfacial water molecules near the time of collapse is observed for the larger mW water systems (but the model underpredicts the viscosity), whereas heating is less pronounced for the TIP4P/2005 water systems because its larger viscosity contribution slows the collapse dynamics. The presence of nitrogen within the bubble only starts to affect bubble dynamics near the very end of the initial collapse, leading to an incomplete collapse and strong rebound for the mW water model. Although nitrogen is non-condensable at 300 K, it becomes highly compressed and reaches a liquid-like density near the collapse point. We find that the dissolution of nitrogen is much slower than the movement of the collapsing water front, and the re-expansion of the dense nitrogen droplet gives rise to bubble rebound. The incompatibility of the collapse and dissolution time scales should be considered for continuum-scale modeling of bubble dynamics. Finally, we also confirm that the diffusion coefficient for dissolved nitrogen is insensitive to pressure as the liquid transitions from a compressed to a stretched state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

A Systematic Classification for HVAC Systems and Components

Depending on the application, the complexity of an HVAC system can range from a small fan coil unit to a large centralized air conditioning system with primary and secondary distribution loops, and central plant components. Currently, the taxonomy of HVAC systems and the components has various aspects, which can get quite complex because of the various components and system configurations. For example, based on cooling and heating medium delivered to terminal units, systems can be classified as either air systems, water systems or air-water systems. In addition, some of the system names might be commonly used in a confusing manner, such as “unitary system” vs. “packaged system.” Without a systematic classification, these components and system terminology can be confusing to understand or differentiate from each other, and it creates ambiguity in communication, interpretation, and documentation. It is valuable to organize and classify HVAC systems and components so that they can be easily understood and used in a consistent manner. This paper aims to develop a systematic classification of HVAC systems and components. First, we summarize the HVAC component information and definitions based on published literature, such as ASHRAE handbooks, regulations, and rating standards. Then, we identify common HVAC system types and map them to the collected components in a meaningful way. Classification charts are generated and described based on the component information. Six main categories are identified for the HVAC components and equipment, i.e., heating and cooling production, heat extraction and rejection, air handling process, distribution system, terminal use, and stand-alone system. Components for each main category are further analyzed and classified in detail. More than fifty system names are identified and grouped based on their characteristics. The result from this paper will be helpful for education, communication, and systems and component documentation.

Li, Han↗
NASA NTRS1992

A systems approach to water recovery testing for space life support - Initial biomedical results from the ECLSS Water Recovery Test and plans for testbed utilization

Among the challenges of designing and constructing Space Station Freedom is the development of the water system. A review of past efforts in reclaiming waste water in enclosed environments reveals that there are many gaps in the biomedical understanding of this process. Some of the key uncertainties of human interaction with a closed water system include determining potential contaminants and establishing safe levels of multiple compounds in the enclosed system of Space Station. Another uncertainty is the microbial constituency of such a system and what impact it could have on crew health and performance. The use of iodine as the passive biocide may have both an indirect and direct impact on the crew. In this paper the initial results of the Water Recovery Test are reviewed from a biomedical perspective, revealing areas where more information is needed to develop the ECLSS water system. By including the approach of 'man as a subsystem', consideration is given to how man interacts with the total water system. Taking this systems approach to providing the crew with a safe source of water gives useful insight into the most efficient design and utilization of closed system testbeds.

Aten, Laurie A.↗
DOE OSTI2015

Systems Measures of Water Distribution System Resilience

Resilience is a concept that is being used increasingly to refer to the capacity of infrastructure systems to be prepared for and able to respond effectively and rapidly to hazardous events. In Section 2 of this report, drinking water hazards, resilience literature, and available resilience tools are presented. Broader definitions, attributes and methods for measuring resilience are presented in Section 3. In Section 4, quantitative systems performance measures for water distribution systems are presented. Finally, in Section 5, the performance measures and their relevance to measuring the resilience of water systems to hazards is discussed along with needed improvements to water distribution system modeling tools.

42 ENGINEERING↗