The impact of diurnal solar patterns on indoor air mixing
Abstract/Contents
- Abstract
- Outdoor weather changes characterized by solar and windspeed patterns can affect indoor air mixing and ultimately pollutant distribution in indoor spaces. This research focuses on the spatial distribution and turbulence characterization of a continuous point source inside a residential home under both quiescent and human-perturbed conditions. Laser particle monitors were arranged in two different 3D arrays between both quiescent and human-perturbed conditions in order to capture spatial and temporal distributions of PM 2.5. Cigarette effluent was released at the center of the room after source and ambient temperature readings matched, revealing a neutrally-buoyant source. This resulted in roughly 2-hour experiments with 20 minute emission times and a 1 hour 40 minute decay period. Vertical temperature stratification was captured via real-time temperature monitors with resolutions of 0.1m/sensor and 0.5m/sensor in quiescent and human-perturbed experiment arrays, respectively. The air change rate, measured by a particle-size differentiating particle counter, read an average of 0.7 hr-1 ¬for quiescent settings, and 2.0 hr-1 for perturbed conditions. By using the volume of the space and source strength of the cigarette, a well-mixed concentration prediction was created for the room. A ratio of the measured concentrations to the well-mixed maximum readings (normalized concentration spikes) near the source height reached an average of 15× and 3.5× for quiescent and perturbed settings, respectively. In order to quantify the extent of mixing in each direction, an iterative solver for the turbulent diffusion coefficient (K) was written which accounted for particle removal, wall reflection, and assumed isotropic mixing based on Fick's 2nd law. Vertical and horizontal axes were isolated by only iterating through concentration readings along an x or y axis. A negative linear correlation was found between vertical K and vertical temperature slope (R2 = 0.72) in quiescent cases. In the cases of the perturbed experiments, horizontal K-- increased by outdoor windspeed from the opening of a door, was found to dominate over temperature stratification effects, and was found to create an exponential drop in normalized concentration spikes.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2017 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Zheng, Yan |
|---|---|
| Associated with | Stanford University, Civil & Environmental Engineering Department. |
| Primary advisor | Hildemann, Lynn M. (Lynn Mary) |
| Thesis advisor | Hildemann, Lynn M. (Lynn Mary) |
| Thesis advisor | Cheng, Kai-Chung, (Research Associate) |
| Thesis advisor | Monismith, Stephen Gene |
| Advisor | Cheng, Kai-Chung, (Research Associate) |
| Advisor | Monismith, Stephen Gene |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Yan (Daisy) Zheng. |
|---|---|
| Note | Submitted to the Department of Civil and Environmental Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2017. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2017 by Yan Zheng
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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