Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for +publisher:"Portland State University" +contributor:("Graig Spolek"). Showing records 1 – 3 of 3 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


Portland State University

1. Castillo Garcia, Giorgina Beatriz. Effects of Evaporative Cooling in the Thermal Performance of Green Roofs.

Degree: MS(M.S.) in Mechanical Engineering, Mechanical and Materials Engineering, 2011, Portland State University

Green roofs have become an important urban mitigation technology due to their ability to address multiple environmental issues. One of the most common benefits attributed to green roofs is the reduction in heating and cooling loads in buildings by dissipating heat through evaporation. This study focuses on evaluating the effect that evaporative cooling has on the thermal performance of green roofs. Sponge and floral foam were used as porous media for their ability to retain water inside its body, transport it to the surface, evaporate it at a constant rate and for their different pore sizes. Test trays containing sponge or floral foam saturated with water were tested in a low speed wind tunnel equipped to measure weight, temperature and heat flux. Two types of experiments were conducted: one with evaporation at the surface, and the other with evaporation blocked by an impervious layer. The testing conditions for all tests were kept constant except for the ability of evaporation to happen. Evaporation rate for floral foam was 0.14 kg/m2hr and 0.29 kg/m2hr for sponge. Results of tests with evaporation show a decrease of 45-49% in heat conducted through the roof when compared to the tests without evaporation. For optimal thermal performance of green roofs, a material that enhances water transport and thus evaporation at the surface is necessary with large pores and low field capacity. Surface temperatures on test with evaporation were found to be between 3-7°C lower than those without evaporation. Applying a 2 sample t-test to the data, the relationship between heat flux and evaporation was found to be statistically significant. Advisors/Committee Members: Graig Spolek.

Subjects/Keywords: Green roofs (Gardening); Heat  – Transmission; Evaporative cooling

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Castillo Garcia, G. B. (2011). Effects of Evaporative Cooling in the Thermal Performance of Green Roofs. (Masters Thesis). Portland State University. Retrieved from https://pdxscholar.library.pdx.edu/open_access_etds/181

Chicago Manual of Style (16th Edition):

Castillo Garcia, Giorgina Beatriz. “Effects of Evaporative Cooling in the Thermal Performance of Green Roofs.” 2011. Masters Thesis, Portland State University. Accessed October 22, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/181.

MLA Handbook (7th Edition):

Castillo Garcia, Giorgina Beatriz. “Effects of Evaporative Cooling in the Thermal Performance of Green Roofs.” 2011. Web. 22 Oct 2019.

Vancouver:

Castillo Garcia GB. Effects of Evaporative Cooling in the Thermal Performance of Green Roofs. [Internet] [Masters thesis]. Portland State University; 2011. [cited 2019 Oct 22]. Available from: https://pdxscholar.library.pdx.edu/open_access_etds/181.

Council of Science Editors:

Castillo Garcia GB. Effects of Evaporative Cooling in the Thermal Performance of Green Roofs. [Masters Thesis]. Portland State University; 2011. Available from: https://pdxscholar.library.pdx.edu/open_access_etds/181


Portland State University

2. Liu, Ziyang. Prediction of Soil Layer R-Value Dependence on Moisture Content.

Degree: MS(M.S.) in Mechanical Engineering, Mechanical and Materials Engineering, 2011, Portland State University

This study focuses on how green roof thermal performance is affected by the soil moisture in summer condition. It aims to determine whether moist soil is a better insulator during the summer months than dry soil. A soil model is developed to predict simultaneous conduction, convection, and surface evaporation for a layer of moist soil representing a green roof. It used to analyze evaporation process and its affect on the soil resistance. The model considers only bare soil without vegetation on the roof. The model predicts the soil surface temperature as it is affected by soil moisture content, which can then be used to calculate heat transfer through the soil layer. An experimental dry out test was conducted to measure the soil moisture and soil temperature histories. Comparison of the predicted and measured sol surface temperature shows that the model reasonably captures the actual behavior. The evaporative cooling effectively reduces the soil surface temperature and heat flux in moist soil and can be used as an effective way to insulate the roof. Advisors/Committee Members: Graig Spolek.

Subjects/Keywords: Green roofs (Gardening); Evaporative cooling; Soil moisture

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Liu, Z. (2011). Prediction of Soil Layer R-Value Dependence on Moisture Content. (Masters Thesis). Portland State University. Retrieved from https://pdxscholar.library.pdx.edu/open_access_etds/125

Chicago Manual of Style (16th Edition):

Liu, Ziyang. “Prediction of Soil Layer R-Value Dependence on Moisture Content.” 2011. Masters Thesis, Portland State University. Accessed October 22, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/125.

MLA Handbook (7th Edition):

Liu, Ziyang. “Prediction of Soil Layer R-Value Dependence on Moisture Content.” 2011. Web. 22 Oct 2019.

Vancouver:

Liu Z. Prediction of Soil Layer R-Value Dependence on Moisture Content. [Internet] [Masters thesis]. Portland State University; 2011. [cited 2019 Oct 22]. Available from: https://pdxscholar.library.pdx.edu/open_access_etds/125.

Council of Science Editors:

Liu Z. Prediction of Soil Layer R-Value Dependence on Moisture Content. [Masters Thesis]. Portland State University; 2011. Available from: https://pdxscholar.library.pdx.edu/open_access_etds/125


Portland State University

3. Cox, Bryce Kevin. The Influence of Ambient Temperature on Green Roof R-values.

Degree: MS(M.S.) in Mechanical Engineering, Mechanical and Materials Engineering, 2010, Portland State University

Green roofs can be an effective and appealing way to increase the energy efficiency of buildings by providing active insulation. As plants in the green roof transpire, there is a reduction in heat flux that is conducted through the green roof. The R-value, or thermal resistance, of a green roof is an effective measurement of thermal performance because it can be easily included in building energy calculations applicable to many different buildings and situations. The purpose of this study was to determine if an increase in ambient temperature would cause an increase in the R-value of green roofs. Test trays containing green roof materials were tested in a low speed wind tunnel equipped to determine the R-value of the trays. Three different plant species were tested in this study, ryegrass (Lolium perenne), sedum (Sedum hispanicum), and vinca (Vinca minor). For each test in this study the relative humidity was maintained at 45% and the soil was saturated with water. The trays were tested at four different ambient temperatures, ranging from room temperature to 120ºF. The resulting R-values for sedum ranged from 1.37 to 3.28 ft²h°F/BTU, for ryegrass the R-values ranged from 2.15 to 3.62 ft²h°F/BTU, and for vinca the R-values ranged from 3.15 to 5.19 ft²h°F/BTU. The average R-value for all the tests in this study was 3.20 ft²h°F/BTU. The results showed an increase in R-value with increasing temperature. Applying an ANOVA analysis to the data, the relationship between temperature and R-value for all three plant species was found to be statistically significant. Advisors/Committee Members: Graig Spolek.

Subjects/Keywords: Temperature measurements; Green roofs (Gardening); Heat  – Transmission  – Effect of temperature on; Buildings  – Thermal properties  – Measurement

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Cox, B. K. (2010). The Influence of Ambient Temperature on Green Roof R-values. (Masters Thesis). Portland State University. Retrieved from http://pdxscholar.library.pdx.edu/open_access_etds/142

Chicago Manual of Style (16th Edition):

Cox, Bryce Kevin. “The Influence of Ambient Temperature on Green Roof R-values.” 2010. Masters Thesis, Portland State University. Accessed October 22, 2019. http://pdxscholar.library.pdx.edu/open_access_etds/142.

MLA Handbook (7th Edition):

Cox, Bryce Kevin. “The Influence of Ambient Temperature on Green Roof R-values.” 2010. Web. 22 Oct 2019.

Vancouver:

Cox BK. The Influence of Ambient Temperature on Green Roof R-values. [Internet] [Masters thesis]. Portland State University; 2010. [cited 2019 Oct 22]. Available from: http://pdxscholar.library.pdx.edu/open_access_etds/142.

Council of Science Editors:

Cox BK. The Influence of Ambient Temperature on Green Roof R-values. [Masters Thesis]. Portland State University; 2010. Available from: http://pdxscholar.library.pdx.edu/open_access_etds/142

.