Prediction of Long Term Degradation of Insulating Materials

Stephenson, L. D.; Heffron, Andrew; Mehnert, Brenda B.; Alvey, Jedediah B.; Boddu, Veera M.; Gao, Elizabeth J; Lawrence, Deborah J; Kumar, Ashok

doi:10.21236/ada618149

Cited by 11 publications

(9 citation statements)

References 9 publications

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“…The tent's envelope is drastically thinner, resulting in conduction and convection being the driving heat transfer modes. This relationship can then be applied to heat transfer equations to determine the power needed for the ECU to maintain the desired temperature within a tent, as shown in Equation (1) [34,35]. One load that all of these shelters share is the power required to maintain the shelter at a stable temperature-typically, 21 • C. An environmental control unit (ECU) is attached to every fabric shelter in the base.…”

Section: Methodsmentioning

confidence: 99%

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Cost Analysis of Optimized Islanded Energy Systems in a Dispersed Air Base Conflict

et al. 2020

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The United States Air Force has implemented a dispersed air base strategy to enhance mission effectiveness for near-peer conflicts. Asset dispersal places many smaller bases across a wide geographic area, which increases resupply requirements and logistical complexity. Hybrid energy systems reduce resupply requirements through sustainable, off-grid energy production. This paper presents a novel hybrid energy renewable delivery system (HERDS) model capable of (1) selecting the optimal hybrid energy system design that meets demand at the lowest net present cost and (2) optimizing the delivery of the selected system using existing Air Force cargo aircraft. The novelty of the model’s capabilities is displayed using Clark Air Base, Philippines as a case study. The HERDS model selected an optimal configuration consisting of a 676-kW photovoltaic array, an 1846-kWh battery system, and a 200-kW generator. This hybrid energy system predicts a 54% reduction in cost and an 88% reduction in fuel usage, as compared to the baseline Air Force system. The HERDS model is expected to support planners in their ongoing efforts to construct cost-effective sites that minimize the transport and logistic requirements associated with remote installations. Additionally, the results of this paper may be appropriate for broader civilian applications.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Cost Analysis of Optimized Islanded Energy Systems in a Dispersed Air Base Conflict

et al. 2020

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“…Stephenson et al [137] evaluated the long-term performance of polymeric closed cell PU foam and EPS insulation materials exposed to humid thermal aging in the laboratory. The EPS was tested with two different blowing agents, the PU was not.…”

Section: Combined Aging Factorsmentioning

confidence: 99%

“…The loss of thermal performance was attributed to the gas exchange throughout the foam. The work of Stephenson et al [137] highlights the combined action of heat and moisture on the thermal performance of insulation. PU is clearly more affected than polystyrene, which likely reflects the hydrophilic nature of the polar urethane linkages compared to the hydrophobic and non-polar nature of styrene units.…”

Section: Combined Aging Factorsmentioning

confidence: 99%

Critical Review of Polymeric Building Envelope Materials: Degradation, Durability and Service Life Prediction

2021

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This paper provides a critical review of the degradation, durability and service life prediction (SLP) of polymeric building envelope materials (BEMs), namely, claddings, air/vapour barriers, insulations, sealants, gaskets and fenestration. The rate of material deterioration and properties determine the usefulness of a product; therefore, knowledge of the significant degradation mechanisms in play for BEMs is key to the design of proper SLP methods. SLP seeks to estimate the life expectancy of a material/component exposed to in-service conditions. This topic is especially important with respect to the potential impacts of climate change. The surrounding environment of a building dictates the degradation mechanisms in play, and as climate change progresses, material aging conditions become more unpredictable. This can result in unexpected changes and/or damages to BEMs, and shorter than expected SL. The development of more comprehensive SLP methods is economically and environmentally sound, and it will provide more confidence, comfort and safety to all building users. The goal of this paper is to review the existing literature in order to identify the knowledge gaps and provide suggestions to address these gaps in light of the rapidly evolving climate.

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“…In a continuation of these experiments, XPS, PUR and aerogel blankets have been aged at elevated temperature and humidity conditions, with additional measurements taken to determine moisture levels in the samples. The aging conditions were selected to reflect the previous work and allow for parallel work (outside the scope of the current work) of applying time-temperature superposition techniques, as indicated in [8]).…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the effects of humidity and temperature on aerogel composite and foam insulations

Alvey

Patel

Stephenson

2017

Energy and Buildings

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Building insulation materials have been subjected to various temperature and humidity conditions and their thermal performance during several weeks of controlled environmental exposure. Several commercially available insulation materials (three aerogel composite blankets, two extruded polystyrene foams (XPS) and one blown polyurethane foam (PUR)) were evaluated. The purpose is to compare performance of newer types (aerogel composites) with established types (foams). Thermal conductivity was measured with a heat flow metering apparatus at one week intervals for five weeks. Insulations were exposed to conditions of 65.6°C and 90% RH, 65.6°C and 60% RH, 65.6°C and 30% RH, and 32.2°C and 90% RH. Results indicate that humidity levels play a significant role in PUR performance, but not a significant role in XPS performance. The three aerogel composites have mixed results: one has little relationship between moisture content and thermal performance, one is strongly affected by moisture and the remaining is moderately affected by moisture. Fourier infrared spectrometry was performed on some of the materials to observe chemical stability. Results indicate that factors other than moisture content, such as hygroscopy and volume expansion, significantly contribute to thermal performance.

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Prediction of Long Term Degradation of Insulating Materials

Cited by 11 publications

References 9 publications

Cost Analysis of Optimized Islanded Energy Systems in a Dispersed Air Base Conflict

Cost Analysis of Optimized Islanded Energy Systems in a Dispersed Air Base Conflict

Critical Review of Polymeric Building Envelope Materials: Degradation, Durability and Service Life Prediction

Experimental study on the effects of humidity and temperature on aerogel composite and foam insulations

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