The high-temperature removal of SO, by sorbents consisting of sodium and lithium salts supported on a-Al,O, has been investigated with emphasis on the chemistry of regeneration. The sulfated sorbents were regenerated by reduction with CO at 700-800°C in a thermogravimetric analyzer and a packed-bed microreactor. Sulfur removal from the sorbent and distribution of gaseous products were measured at different alkali loadings, temperatures, and CO concentrations. The results are interpreted in terms of a network of reactions wherein alumina is important as a catalyst and as a reactant. During regeneration sulfate is converted to aluminate and sulfide, the fraction of aluminate defining the extent of regeneration. The rate and extent of sulfur removal increase with the ratio of alumina to alkali and are higher in the presence of lithium. The product gas consists of SO,, COS, and elemental sulfur, the latter compound constituting up to 35% of the sulfur removed.
It has long been noted that interior vapor barriers in wood frame walls in hot-humid climates can lead to interstitial condensation within walls. The bases for this recognition are predictive simulations, anecdotal observations, and a limited number of experimental studies. This paper describes an experimental study conducted in a hot-humid climate that investigated the influence of an interior vapor retarder and compares observed performance with simulation predictions. The wall performance data reviewed here was gathered as part of a larger test program evaluating the performance of a range of typical wood frame, residential wall constructions in a hot-humid climate. The approach chosen was to use real-time field exposure using a “test hut” located in Tampa, Florida. The test hut had two long sides, which provided the ability to test 16 wall specimens each. Wall specimens were instrumented with a variety of temperature, humidity, and moisture sensors. In addition to natural weather exposure, the wall specimens could be manually wetted by a water injection system to simulate rain leakage. More specifically, this paper focuses on using the data collected before and after the installation of an interior vapor barrier (vinyl wallpaper) to show the change in moisture loading and the potential condensation within the walls resulting from the installation. The field data is compared with predictions of the wall behavior using a commonly available hygrothermal model. There is increasing reliance on the use of predictive models to assess the moisture performance of building assembly designs. These predictive models need to be validated against real data to test their variance from real systems.
As building, energy, and green codes become more stringent, new building technologies and innovations are being incorporated into the building envelope. When incorporating new technologies into building assemblies, traditional construction practices need to be adapted. However, as these adaptations of construction practices take place, they still need to maintain adherence to basic principles of water management to prevent moisture accumulation in building assemblies. A critical component of water management is water-resistive barriers. Water-resistive barriers are used in light-frame wall assemblies behind the cladding to control the ingress of water, which penetrates the cladding, and keep it from penetrating further into the wall. Traditional water-resistive barriers were asphalt-impregnated papers and felts, which were applied in shingle fashion over the wall studs or sheathing. Plastic building wraps have to a large extent replaced the traditional building papers, comprising 75 % of the U.S. housing market. Recently, new materials being used as water-resistive barriers include panel materials and fluid-applied coatings. Assessing the durability of water-resistive barriers has been complicated by this range of material types. Because of the shingle-fashion installation, durability assessment of traditional materials and building wraps has focused on the material durability. The new materials require additional durability assessments relating to compatibility and durability of adhesion, most importantly at panel and substrate joints. This article describes the framework for evaluating water-resistive barrier durability.
Architects typically design details for conditions around the perimeter of window openings prior to the final selection of the actual windows used in the building. This requires the architect to make reasonable, general details regarding the attachment of the window frames, the position of the windows in the wall cross-section, and the weathertight details around the perimeters of the windows. Often, once the final selection of the windows has been made, these general details no longer apply or are not sufficiently detailed to clearly reflect the design intent. In some instances, the details for the windows are intentionally shown in a general, approximate fashion, with the assumption that the actual details will be “designed” during the shop drawing phase. However, the shop drawings typically do not accurately reflect all of the conditions surrounding the windows, and the window installation subcontractor understandably does not want the liability of showing or designing all of these details which they will not build and for which they have no responsibility. Further, while the window shop drawings are reviewed by the architect, the purpose of the architect’s “approval” of the shop drawings is limited. Additionally, shop drawings are not part of the contract documents and, therefore, not part of the design. This results in a common situation where there is no clear basis of design for the weathertightness detailing around the windows. Unfortunately, at present, the authors believe this situation represents the state of the design practice in the building industry. This paper explores common, current practices for designing perimeter weathertightness details for non-flanged windows in commercial applications and how these practices influence the potential for performance problems and water leakage. Suggestions are provided for improvements and alternative methods in design practices. While the paper generally discusses window openings, similar conditions occur at doors.
In the mid to late 1990s, the exterior insulation and finishing systems (EIFS) industry introduced drainage into its wall systems, aimed at increasing the water management of those systems. Along with this introduction came the development of test methods for drainage efficiency and the inclusion of drainage criteria in code requirements. More specifically, ASTM E2273, Standard Test Method for Determining the Drainage Efficiency of Exterior Insulation and Finish Systems (EIFS) Clad Wall Assemblies, was developed and published initially in 2003. This test method was adopted into code for EIFS with drainage with a drainage efficiency requirement of 90 %. The EIFS industry became leaders in this area, and the drainage methods originally developed for EIFS were adapted to evaluate non-EIFS wall systems as well, which in some cases (such as in the Oregon Residential Specialty Code) had decreased required drainage efficiencies. In parallel to the development of ASTM E2273, researchers have proposed other drainage efficiency test methods, although none has been standardized at this point. This paper provides a review of ASTM E2273 and other drainage test methods that has been reported. The applicability to water management in EIFS wall systems and to wall systems with other claddings is discussed. This paper also reviews code requirements and code evaluation acceptance criteria that require drainage validation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.