Modeling contaminant exposure in a single-family house

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001.Includes bibliographical references (p. 144-146).New, stricter building codes for energy conservation mandates tighter building construction, which directly reduces the amount of available fresh air from infiltration. This decrease in fresh air is a subject of intensive study as health becomes a progressively sensitive issue. Mechanical ventilation is a system increasingly implemented to respond to and aid these burgeoning trends to reduce the risk of overexposure to indoor pollutants. In this study, occupational exposure to household contaminants in a single-family house with several ventilation, heating, and climactic conditions was simulated using CFD. Typical household exposure to CO2, CO, HCHO (formaldehyde), NO2, and water vapor is evaluated over the day for a generic occupational schedule of four family members, consisting of a mother, father, son, and daughter. The ventilation types included a bimodal, relative humidity controlled, and balanced system, coupled with either room convectors, or a combination of a heated floor and room convectors. Both the winter and summer conditions were considered to the drastic difference in outdoor conditions, as well to isolate the effects of the heating system. Characteristically, high degrees of thermal and contaminant stratification were found during the winter months, where low infiltration rates mimic displacement ventilation. This leads to lower contaminant exposure due to a lower concentration reservoir of air below the breathing zone. Entrainment of this air to the breathing region results in lower exposure. Also, it is found that the stratification effect is more efficient at curbing exposure than increasing the global ventilation rate for the cases evaluated. Door positions play a key role in the mitigation of contaminant migration throughout the house. In addition, the centralized location of the exhaust devices draws contaminated air from the periphery of the house radially inward to the core, where the occupants are less likely to be during the day. The period of sleeping greatly dictates the overall exposure to bioeffluents, as this is the activity in which the family partakes for the greatest percentage of time they are at home.by Jeffrey M. Huang.S.M

Microgravity science and applications program tasks, 1991 revision

Presented here is a compilation of the active research tasks for FY 1991 sponsored by the Microgravity Science and Applications Division of the NASA Office of Space Science and Applications. The purpose is to provide an overview of the program scope for managers and scientists in industry, university, and government communities. Included is an introductory description of the program, the strategy and overall goal, identification of the organizational structures and the people involved, and a description of each. The tasks are grouped into several categories: electronic materials; solidification of metals, alloys, and composites; fluids, interfaces, and transport; biotechnology; combustion science; glasses and ceramics; experimental technology, instrumentation, and facilities; and Physical and Chemistry Experiments (PACE). The tasks cover both the ground based and flight programs

Microgravity Science and Applications. Program Tasks and Bibliography for FY 1993

An annual report published by the Microgravity Science and Applications Division (MSAD) of NASA is presented. It represents a compilation of the Division's currently-funded ground, flight and Advanced Technology Development tasks. An overview and progress report for these tasks, including progress reports by principal investigators selected from the academic, industry and government communities, are provided. The document includes a listing of new bibliographic data provided by the principal investigators to reflect the dissemination of research data during FY 1993 via publications and presentations. The document also includes division research metrics and an index of the funded investigators. The document contains three sections and three appendices: Section 1 includes an introduction and metrics data, Section 2 is a compilation of the task reports in an order representative of its ground, flight or ATD status and the science discipline it represents, and Section 3 is the bibliography. The three appendices, in the order of presentation, are: Appendix A - a microgravity science acronym list, Appendix B - a list of guest investigators associated with a biotechnology task, and Appendix C - an index of the currently funded principal investigators

Process Simulation of Technical Precipitation Processes - The Influence of Mixing

This work develops and shows up methods to tackle multi-scale challenges in particle formation during precipitation crystallization. Firstly, molecular, micro- and meso-scale interactions in confined impinging jet mixers are investigated and simulatively predicted. Secondly, to build up on developed methods, macroscale as present for instance in stirred tank reactors is added to the considerations

Microgravity Science and Applications Program tasks, 1990 revision

The active research tasks as of the end of the fiscal year 1990 sponsored by the Microgravity Science and Applications Division of the NASA Office of Space Science and Applications are compiled. The purpose is to provide an overview of the program scope for managers and scientists in industry, university, and government communities. The report includes an introductory description of the program, the strategy and overall goal; an index of principle investigators; and a description of each task. A list of recent publications is also provided. The tasks are grouped into six major categories: electronic materials; solidification of metals, alloys, and composites; fluid dynamics and transport phenomena; biotechnology; glasses and ceramics; combustion; experimental technology; facilities; and Physics And Chemistry Experiments (PACE). The tasks are divided into ground-based and flight experiments

NAS (Numerical Aerodynamic Simulation Program) technical summaries, March 1989 - February 1990

Given here are selected scientific results from the Numerical Aerodynamic Simulation (NAS) Program's third year of operation. During this year, the scientific community was given access to a Cray-2 and a Cray Y-MP supercomputer. Topics covered include flow field analysis of fighter wing configurations, large-scale ocean modeling, the Space Shuttle flow field, advanced computational fluid dynamics (CFD) codes for rotary-wing airloads and performance prediction, turbulence modeling of separated flows, airloads and acoustics of rotorcraft, vortex-induced nonlinearities on submarines, and standing oblique detonation waves

Investigation into the mechanisms of size-resolved particle dry deposition across three environments

2022 Summer.Includes bibliographical references.Airborne particulate matter, or aerosols, have significant impacts on radiative forcing through both their direct - scattering and absorbing light - and indirect effects- acting as cloud condensation nuclei and altering the lifetime of clouds. The magnitude of these effects is largely determined by particle lifetime, which is defined by their rate of removal through wet and dry deposition. Dry deposition, specifically of accumulation mode aerosols (0.1 – 1 µ), is one of the largest sources of uncertainty in global models. The processes that influence deposition are poorly constrained and few comprehensive measurements are available to improve our understanding. Characterizing these mechanisms is vital for predicting spatial and temporal trends in particle dry deposition and lifetime. While there have been improvements in quantifying and understanding dry deposition, large gaps in our knowledge still exist that make predicting the impacts of aerosols on Earth's climate difficult. To improve understanding of the underlying mechanisms that determine the rate of particle deposition in an environment this dissertation reports size-resolved dry deposition measurements from three distinct environment types. First, we report measurements from a test house which identify dilution and deposition as the most important factors influencing particle concentrations indoors. This analysis also shows that deposition indoor is governed by the same fundamental process that we consider for outdoor environments. Second, we present particle flux and deposition measurements from a Ponderosa pine forest over four seasons where significant enhancement in deposition during the wintertime was observed. This is attributable to changes in interception, caused by changes in plant physiology and surface structure during the winter that leads to an increase in their ability to uptake particles. Finally, we show particle and black carbon deposition from a low Arctic tundra during snow-cover that are elevated compared to predictions of dry deposition in that region. Incorporating interception into the model parameterizations improved model measurement agreement and provides evidence to suggest that surface structure and microroughness impact deposition even when there is snow-cover

Aeronautics and space report of the President, 1980 activities

The year's achievements in the areas of communication, Earth resources, environment, space sciences, transportation, and space energy are summarized and current and planned activities in these areas at the various departments and agencies of the Federal Government are summarized. Tables show U.S. and world spacecraft records, spacecraft launchings for 1980, and scientific payload anf probes launched 1975-1980. Budget data are included

Microgravity Science and Applications

The report presents fifteen papers from a workshop on microgravity science and applications held at the Jet Propulsion Laboratory in Pasadena, California, on December 3 to 4, 1984. The workshop and panel were formed by the Solid State Sciences Committee of the Board on Physics and Astronomy of the National Research Council in response to a request from the Office of Science and Technology Policy. The goal was to review the microgravity science and applications (MSA) program of NASA and to evaluate the quality of the program. The topics for the papers are metals and alloys, electronic materials, ceramics and glasses, biotechnology, combustion science, and fluid dynamics