Hydrodynamic modeling of mineral wool fiber suspensions in a two-dimensional flow

A consequence of a loss of coolant accident is that the local insulation material is damaged and maybe transported to the containment sump where it can penetrate and/or block the sump strainers. An experimental and theoretical study, which examines the transport of mineral wool fibers via single and multi-effect experiments is being performed. This paper focuses on the experiments and simulations performed for validation of numerical models of sedimentation and resuspension of mineral wool fiber agglomerates in a racetrack type channel. Three velocity conditions are used to test the response of two dispersed phase fiber agglomerates to two drag correlations and to two turbulent dispersion coefficients. The Eulerian multiphase flow model is applied with either one or two dispersed phases.

CFD-Analyses on the behaviour of mineral wool in the reactor sump

The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behaviour of emergency core cooling systems during all types of loss of coolant accidents. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Görlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/Görlitz, the theoretical modelling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. In the current presentation the basic concepts for CFD modelling are described and feasibility studies are presented. On the example of a complex flow situation at plunging jet conditions the model capabilities are demonstrated.

Transglutaminase mediated grafting of silk proteins onto wool fabrics leading to improved physical and mechanical properties

Transglutaminases have the ability to incorporate primary amines and to graft peptides (containing glutamine or lysine residues) into proteins. These properties enable transglutaminases to be used in the grafting of a range of compounds including peptides and/or proteins onto wool fibres, altering their functionality. In this paper we investigated the transglutaminase mediated grafting of silk proteins into wool and its effect on wool properties. A commercial hydrolysed silk preparation was compared with silk sericin. The silk sericin protein was labelled with a fluorescent probe which was used to demonstrate the efficiency of the TGase grafting of such proteins into wool fibres. The TGase mediated grafting of these proteins led to a significant effect on the properties of wool yarn and fabric, resulting in increased bursting strength, as well as reduced levels of felting shrinkage and improved fabric softness. Also observed was an accumulation of deposits on the surface of the treated wool fibres when monitored by SEM and alterations in the thermal behaviour of the modified fibres, in particular for mTGase/sericin treated fibres which, with the confocal studies, corroborate the physical changes observed on the treated wool fabric. © 2006 Elsevier Inc. All rights reserved.

Transglutaminase treatment of wool fabrics leads to resistance to detergent damage

Biological detergents are now routinely used in domestic laundry because the enzymes they contain provide the added benefit of low temperature washes with improved cleaning performance. One of the key enzymes found in these detergents are proteases, which if exposed to natural protein fibres such as wool or silk can cause irreversible damage, leading to loss of fabric strength, shape and poor colour fastness. Transglutaminases (TGases) are protein cross-linking enzymes capable of adding tensile strength to wool proteins, and as a consequence are capable of remediating the damage caused by previous chemical treatments, and more importantly, by proteases. In this paper we treated dyed wool fabric with TGase and then washed the fabric with biological and non-biological detergents to investigate whether TGases would protect wool garments from damage by the undue use of biological detergents in domestic laundry. We demonstrate using different cycles of detergent washes containing biological and non-biological detergents and different TGase treatments, that wool fabric treated previously with TGase release less dye into the washing liquor and in addition maintain fabric strength at levels greater than the washed controls. As a consequence, wool garments previously treated with TGase are likely to have increased resistance to domestic washing and thus provide increased longevity. © 2005 Elsevier B.V. All rights reserved.

Generic experiments at the sump model "Zittauer Strömungswanne" (ZSW) for the behaviour of mineral wool in the sump and the reactor core

The investigation of insulation debris transport, sedimentation, penetration into the reactor core and head loss build up becomes important to reactor safety research for PWR and BWR, when considering the long-term behaviour of emergency core cooling systems during loss of coolant accidents. Research projects are being performed in cooperation between the University of Applied Sciences Zittau/Görlitz and the Helmholtz-Zentrum Dresden-Rossendorf. The projects include experimental investigations of different processes and phenomena of insulation debris in coolant flow and the development of CFD models. Generic complex experiments serve for building up a data base for the validation of models for single effects and their coupling in CFD codes. This paper includes the description of the experimental facility for complex generic experiments (ZSW), an overview about experimental boundary conditions and results for upstream and down-stream phenomena as well as for the long-time behaviour due to corrosive processes. © Carl Hanser Verlag, München.

Experimental investigation and CFD simulation of the behaviour of mineral wool in the reactor sump

The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behavior of emergency core cooling systems during all types of loss of coolant accidents (LOCA). The insulation debris released near the break during a LOCA incident consists of a mixture of disparate particle population that varies with size, shape, consistency and other properties. Some fractions of the released insulation debris can be transported into the reactor sump, where it may perturb/impinge on the emergency core cooling systems. Open questions of generic interest are the sedimentation of the insulation debris in a water pool, its possible re-suspension and transport in the sump water flow and the particle load on strainers and corresponding pressure drop. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Gorlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/Gorlitz, the theoretical modeling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. In the current paper the basic concepts for CFD modeling are described and feasibility studies including the conceptual design of the experiments are presented. Copyright © 2008 by ASME.

Hydrodynamic modeling of mineral wool fiber suspensions in a two-dimensional channel flow

A consequence of a loss of coolant accident is the damage of adjacent insulation materials (IM). IM may then be transported to the containment sump strainers where water is drawn into the ECCS (emergency core cooling system). Blockage of the strainers by IM lead to an increased pressure drop acting on the operating ECCS pumps. IM can also penetrate the strainers, enter the reactor coolant system and then accumulate in the reactor pressure vessel. An experimental and theoretical study that concentrates on mineral wool fiber transport in the containment sump and the ECCS is being performed. The study entails fiber generation and the assessment of fiber transport in single and multi-effect experiments. The experiments include measurement of the terminal settling velocity, the strainer pressure drop, fiber sedimentation and resuspension in a channel flow and jet flow in a rectangular tank. An integrated test facility is also operated to assess the compounded effects. Each experimental facility is used to provide data for the validation of equivalent computational fluid dynamic models. The channel flow facility allows the determination of the steady state distribution of the fibers at different flow velocities. The fibers are modeled in the Eulerian-Eulerian reference frame as spherical wetted agglomerates. The fiber agglomerate size, density, the relative viscosity of the fluid-fiber mixture and the turbulent dispersion of the fibers all affect the steady state accumulation of fibers at the channel base. In the current simulations, two fiber phases are separately considered. The particle size is kept constant while the density is modified, which affects both the terminal velocity and volume fraction. The relative viscosity is only significant at higher concentrations. The numerical model finds that the fibers accumulate at the channel base even at high velocities; therefore, modifications to the drag and turbulent dispersion forces can be made to reduce fiber accumulation.

Agreed-upon procedures report on the Iowa Sheep and Wool Promotion Board for the period July 1, 2013 through June 30, 2015

Agreed-upon procedures report on the Iowa Sheep and Wool Promotion Board for the period July 1, 2013 through June 30, 2015

The art of wool

A curatorial project that brings together garments from the International Woolmark Prize archive with works from the Howard Hinton and Chandler Coventry Collections at New England Regional Art Museum. Themed around qualities of wool that are also present in the artworks, the exhibition considers attributes such as Production, Romance, Pattern, Texture, Drape and Artistry. From the sale yards and shearing sheds of the New England landscape to the international catwalks, merino wool provides a staple thread made durable through works from these extraordinary collections.

Predicting fabric prickle propensity by testing yarns on the Wool ComfortMeter

The Wool ComfortMeter is the first simple and fast objective tool in the world for assessing wool fabric prickle propensity. IWTO-DTM-66 for the measurement of fabrics using the WCM was accepted at the IWTO Cape Town Congress, South Africa in 2014. Since then, interest has been shown in the technology by yarn manufacturers and buyers for testing yarns before fabric is made, in order to obtain the prickle propensity of a fabric while still at yarn stage.Presentation of the yarn sample to the Wool ComfortMeter is critical. An YG381 yarn winder was selected for this project because it is a fast and reliable tool for sample preparation. The investigation into yarn winding density and tension showed that both the winding density and tension did not significantly affect the tested yarn WCM values. Therefore, a sample preparation protocol was established by using a winding density 19 loops/cm and a 20g tension plate on the YG381 winding machine.Further examination by complying with the preparation protocol showed that yarn Wool ComfortMeter value was the only significant predictor of its corresponding fabric Wool ComfortMeter value. Thus, liner and polynomial regression models were developed for predicting the fabric WCM prickle propensity. Based on the prediction performance, a linear model was recommended for the 1-ply yarns and polynomial model for the 2-ply yarns in this report. The prediction errors were approximately 66 for the 1-ply yarns and 14 for the 2-ply yarns.

Report on the second Wool ComfortMeter round trial

The present report analysed the variance between instruments and estimated the measurement precision of the Wool ComfortMeter instrument by conducting an international round trial. The firstinternational round trial was conducted in 2014; however the calculated precision estimates were relatively large. In the present trial, instruments were standardised by harmonising parameters such as wire height and measuring length, and a new calibration method was used to improve the measurement precision. The data from five laboratories, measuring ten fabric-samples and 5 sub-samples per fabric sample, was used to estimate the components of variance and the prickle measurement precision. The results showed good agreement between laboratory measurements. Analysis of the data shows an improvement in the 95% confidence limit for this round trial compared to the first round trial. Particularly, relatively smaller confidence limits were found for low prickle measurements. It is recommended that the new precision estimates be incorporated into the IWTO DTM-66:2014.