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- Genre: Academic theses
- Genre: Masters Thesis
- Creators: Kusel, Scott Daniel
- Creators: Michael, Katina
- Member of: Theses and Dissertations
Description
In the past, the photovoltaic (PV) modules were typically constructed with glass superstrate containing cerium oxide and EVA (ethylene vinyl acetate) encapsulant containing UV absorbing additives. However, in the current industry, the PV modules are generally constructed without cerium oxide in the glass and UV absorbing additives in EVA to increase quantum efficiency of crystalline silicon solar cells in the UV regions. This new approach is expected to boost the initial power output of the modules and reduce the long-term encapsulant browning issues. However, this new approach could lead to other durability and reliability issues such as delamination of encapsulant by damaging interfacial bonds, destruction of antireflection coating on solar cells and even breakage of polymeric backbone of EVA. This work compares the durability and reliability issues of PV modules having glass without cerium oxide and EVA with (aka, UVcut or UVC) and without (aka, UVpass or UVP) UV absorbing additives. In addition, modules with UVP front and UVC back EVA have also been investigated (aka, UVhybrid or UVH). The mini-modules with nine split cells used in this work were fabricated at ASU’s Photovoltaic Reliability Laboratory. The durability and reliability caused by three stress variables have been investigated and the three variables are temperature, humidity/oxygen and UV dosage. The influence of up to 800 kWh/m2 UV dosage has been investigated at various dosage levels. Many material and device characterizations have been performed to ascertain the degradation modes and effects. The UVC modules showed encapsulant discoloration at the cell centers as expected but the UVH modules showed a ring-shaped encapsulant discoloration close to the cell edges as evidenced in the UV fluorescence (UVF) imaging study. The PV modules containing UVP on both sides of cells with limited access to humidity or oxygen through backsheet (covered backsheet with adhesive aluminum tape) seem to experience encapsulant delamination as evidenced in the UVF images. Plausible explanations for these observations have been presented.
ContributorsArularasu, Pooja (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Mu, Bin (Thesis advisor) / Varman, Arul M (Committee member) / Arizona State University (Publisher)
Created2019
Description
With the growing popularity of 3d printing in recreational, research, and commercial enterprises new techniques and processes are being developed to improve the quality of parts created. Even so, the anisotropic properties is still a major hindrance of parts manufactured in this method. The goal is to produce parts that mimic the strength characteristics of a comparable part of the same design and materials created using injection molding. In achieving this goal the production cost can be reduced by eliminating the initial investment needed for the creation of expensive tooling. This initial investment reduction will allow for a wider variant of products in smaller batch runs to be made available. This thesis implements the use of ultraviolet (UV) illumination for an in-process laser local pre-deposition heating (LLPH). By comparing samples with and without the LLPH process it is determined that applied energy that is absorbed by the polymer is converted to an increase in the interlayer temperature, and resulting in an observed increase in tensile strength over the baseline test samples. The increase in interlayer bonding thus can be considered the dominating factor over polymer degradation.
ContributorsKusel, Scott Daniel (Author) / Hsu, Keng (Thesis advisor) / Sodemann, Angela (Committee member) / Kannan, Arunachala M (Committee member) / Arizona State University (Publisher)
Created2017
Description
Ultraviolet (UV) radiation is the most well-known cause of skin cancer, and skin cancer is the most common type of cancer in the United States. People are exposed to UV rays when they engage in outdoor activities, particularly exercise, which is an important health behavior. Thus, researchers and the general public have shown increasing interest in measuring UV exposures during outdoor physical activity using wearable sensors. However, minimal research exists at the intersection of UV sensors, personal exposure, adaptive behavior due to exposures, and risk of skin damage. Three studies are presented in this dissertation: (1) a state-of-the-art review that synthesizes the current academic and grey literature surrounding personal UV sensing technologies; (2) the first study to investigate the effects of specific physical activity types, skin type, and solar angle on personal exposure in different outdoor environmental contexts; and (3) a study that develops recommendations for future UV-sensing wearables based on follow-up interviews with participants from the second study, who used a wrist-worn UV sensor while exercising outdoors. The first study provides recommendations for 13 commercially available sensors that are most suitable for various types of research or personal use. The review findings will help guide researchers in future studies assessing UV exposure with wearables during physical activity. The second study outlines the development of predictive models for individual-level UV exposure, which are also provided. These models recommend the inclusion of sky view factor, solar angle, activity type, urban environment type, and the directions traveled during physical activity. Finally, based on user feedback, the third study recommends that future UV-sensing wearables should be multi-functional watches where users can toggle between showing their UV exposure results in cumulative and countdown formats, which is intuitive and aesthetically pleasing to users.
ContributorsHenning, Alyssa Leigh (Author) / Vanos, Jennifer (Thesis advisor) / Johnston, Erik (Thesis advisor) / Frow, Emma (Committee member) / Michael, Katina (Committee member) / Downs, Nathan (Committee member) / Arizona State University (Publisher)
Created2021