1
|
Bilyaz S, Bhati A, Hamalian M, Maynor K, Soori T, Gattozzi A, Penney C, Weeks D, Xu Y, Hu L, Zhu J, Nelson J, Hebner R, Bahadur V. Modeling the impact of high thermal conductivity paper on the performance and life of power transformers. Heliyon 2024; 10:e27783. [PMID: 38524528 PMCID: PMC10958363 DOI: 10.1016/j.heliyon.2024.e27783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 03/01/2024] [Accepted: 03/06/2024] [Indexed: 03/26/2024] Open
Abstract
Degradation of insulation paper is a key contributor to the failure of power transformers. Insulation degradation accelerates at elevated temperatures, which highlights the potential for better thermal management to prolong life. While several studies have analyzed the benefits of high thermal conductivity oil for reducing temperatures inside a transformer, this study is an initial assessment of the benefits of high thermal conductivity paper on transformer life. Blending particulates with cellulosic fibers offers a pathway for high thermal conductivity paper (with good dielectric properties), which can reduce internal temperatures. Presently, life extensions that can be achieved by the use of such thermally conducting papers were estimated, with the thermal conductivity of the paper being the key parameter under study. The analytical-numerical thermal model used in this study was validated against experimental measurements in a distribution transformer, adding confidence to the utility of the model. This model was then used to provide estimates of hot-spot temperature reduction resulting from the use of papers with higher thermal conductivity than baseline. Transformer life was predicted conventionally by tracking the degree of polymerization of paper over time, based on an Arrhenius model. Results indicate that increasing the thermal conductivity of paper from 0.2 W/mK (baseline) to 1 W/mK reduces the hot spot temperature by 10 °C. While degradation significantly depends on the moisture and oxygen content, the model shows that such a temperature reduction can increase life for all conditions, by as much as a factor of three.
Collapse
Affiliation(s)
- S. Bilyaz
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - A. Bhati
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - M. Hamalian
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - K. Maynor
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - T. Soori
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - A. Gattozzi
- Center for Electromechanics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - C. Penney
- Center for Electromechanics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - D. Weeks
- Center for Electromechanics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Y. Xu
- Center for Electromechanics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - L. Hu
- Materials Science and Engineering, University of Maryland, College Park, MD, 20742, USA
| | - J.Y. Zhu
- USDA Forest Products Lab, Madison, WI, 53726, USA
| | - J.K. Nelson
- Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - R. Hebner
- Center for Electromechanics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - V. Bahadur
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| |
Collapse
|
2
|
Reap EA, Roof K, Maynor K, Borrero M, Booker J, Cohen PL. Radiation and stress-induced apoptosis: a role for Fas/Fas ligand interactions. Proc Natl Acad Sci U S A 1997; 94:5750-5. [PMID: 9159145 PMCID: PMC20851 DOI: 10.1073/pnas.94.11.5750] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The lpr gene encodes a defective form of Fas, a cell surface protein that mediates apoptosis. This defect blocks apoptotic deletion of autoreactive T and B cells, leading to lymphoproliferation and lupus-like autoantibody production. The effects of the lpr Fas mutation on other kinds of physiologically relevant apoptosis are largely undocumented. To assess whether some of the apoptosis known to occur after ionizing radiation might be mediated by Fas/Fas ligand (FasL) interactions, we quantitated in vitro apoptosis by flow cytometry measurement of DNA content in splenic T and B cells from irradiated 5- to 8-month-old B6/lpr mice. Total apoptosis of both lpr and control cells was substantial after treatment; however there was a significant difference between B6 (73%) and lpr (25%) lymphocyte apoptosis. Thy1, CD4, CD8, and IgM cells from lpr showed much lower levels of apoptosis than control cells after irradiation. Apoptosis induced by heat shock was also impaired in lpr. The finding that gamma-irradiation increased Fas expression on B6 cells and that irradiation-induced apoptosis could be blocked with a Fas-Fc fusion protein further supported the possible involvement of Fas in this form of apoptosis. Fas/FasL interactions may thus play an important role in identifying and eliminating damaged cells after gamma-irradiation and other forms of injury.
Collapse
Affiliation(s)
- E A Reap
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599-7280, USA
| | | | | | | | | | | |
Collapse
|