Measuring and modelling dynamic moisture loss of pulpwood during rail transport in South Africa

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dc.contributor.advisorAckermann, Pierre Alexanderen_ZA
dc.contributor.authorMorkel, Russel Georgeen_ZA
dc.contributor.otherStellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science.en_ZA
dc.date.accessioned2022-11-02T07:49:22Zen_ZA
dc.date.accessioned2023-01-16T12:41:41Zen_ZA
dc.date.available2022-11-02T07:49:22Zen_ZA
dc.date.available2023-01-16T12:41:41Zen_ZA
dc.date.issued2022-11en_ZA
dc.descriptionThesis (PhD) -- Stellenbosch University, 2022.en_ZA
dc.description.abstractENGLISH ABSTRACT: The unit of planning in the South African forest industry is volume (m3). The unit of trade and financial reporting for pulpwood, however, is weight (tonnes). As living trees invariably contain more water than wood, this disparity has necessitated a detailed understanding of moisture loss with age-after-felling, to better predict m3/tonne conversion factors (for yield estimation, forest valuation and stock control purposes). All moisture loss research to date, has been conducted in a static setting, where low-speed ambient winds come to the processed wood in a forested environment. No research has assessed the possibility of incremental weight loss induced by the slipstream of a fast-moving freight train. This is not necessarily an academic oversight, more a lack of context. Few countries rail large quantities of debarked, small diameter, wet pulpwood traded by weight. Furthermore, although natural airflow is a primary driver of moisture loss, its quantity and quality are uncontrollable, and its effect in a forest setting often inconsequential. The objective of this research was to measure and model the dynamic weight loss of wet pulpwood, during a 317 km rail journey, on one of the world's largest dedicated timber trains. The research included scaled wind-tunnel experiments and operational trials using a wagon-mounted continuous-weighing platform and mobile automatic weather station. The simplified and more controlled wind-tunnel simulations recorded a statistically significant 6.6% step-down (p<0.001) in the treatment payload weight caused by the slipstream of the train. The treatments lost 114% more moisture than the comparable static controls. Time, temperature, relative humidity, wind speed and wind temperature accounted for 87% of the weight loss of the hardwood treatments over the entire period. The complex and less controllable operational methods recorded smaller slipstream induced weight losses. The modernized operational method treatments lost on average 2.84% more than the static controls (a relative difference of 346%). The treatment regression models showed that time, temperature, relative humidity and wind accounted for between 86% to 96% of the variation in weight loss. The preponderance of nighttime travel (characterized by low temperatures and high relative humidity levels) limited the effect of the slipstream on incremental moisture loss.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die beplanningseenheid wat gebruik word in die Suid-Afrikaanse bosbedryf is volume (m3). Die eenheid van handel en finansiële verslagdoening vir pulphout is egter gewig (ton). Aangesien lewende bome sonder uitsondering meer water as hout bevat, het hierdie verskil 'n gedetailleerde begrip van vogverlies met ouderdom-na-oes genoodsaak, om m3/ton-omskakelingsfaktore beter te voorspel (vir opbrengsskatting, boswaardasie en voorraadbeheerdoeleindes). Alle navorsing oor vogverlies as gevolg van wind is tot hede in 'n statiese omgewing uitgevoer, waar laespoed winde waai oor verwerkte stompe in 'n beboste omgewing. Geen navorsing het die moontlikheid van inkrementele gewigsverlies beoordeel wat veroorsaak word deur die glipstroom van 'n snelbewegende goederetrein nie. Dit is nie noodwendig 'n akademiese oorsig nie, meer eerder 'n gebrek aan konteks. Min lande gebruik treinvervoer om groot hoeveelhede ontbaste, klein deursnee, nat pulphout wat volgens gewig verhandel word, te verskeep. Alhoewel natuurlike lugvloei 'n primêre drywer van vogverlies is, is die hoeveelheid en aard daarvan onbeheerbaar, en die effek daarvan in 'n bos-omgewing dikwels onbelangrik. Die doel van hierdie navorsing was om die dinamiese gewigsverlies van nat pulphout, tydens 'n 317 km treinrit, op een van die wêreld se grootste houtvervoertreine, te meet en te modelleer. Die navorsing het afgeskaalde windtonneleksperimente en operasionele proewe ingesluit met behulp van 'n wa-gemonteerde weegplatform en ‘n mobiele outomatiese weerstasie. Die vereenvoudigde en meer beheerde windtonnelsimulasies het 'n statisties betekenisvolle 6.6% afname (p<0.001) in die vraggewig van toetsvragte aangeteken wat deur die glipstroom van die trein veroorsaak is. Die toetsvragte het 114% meer vog verloor as die vergelykbare statiese kontroles. Tyd, temperatuur, relatiewe humiditeit, windspoed en windtemperatuur was verantwoordelik vir 87% van die gewigsverlies van die loofhoutbehandelings oor die hele tydperk. Die komplekse en minder beheerbare operasionele metodes het kleiner glipstroom-geïnduseerde gewigsverliese aangeteken. Die gemoderniseerde operasionele metode het gemiddeld 2,84% meer gewig verloor as die statiese kontroles ('n relatiewe verskil van 346%). Die regressiemodelle het getoon dat tyd, temperatuur, relatiewe humiditeit en wind tussen 86% tot 96% van die variasie in gewigsverlies veroorsaak. Die gereelde voorkoms van nagreise (gekenmerk deur lae temperature en hoë relatiewe humiditeitsvlakke) het die effek van die glipstroom op inkrementele vogverlies beperk.af_ZA
dc.description.versionDoctoralen_ZA
dc.format.extent166 pages : illustrationsen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/125928en_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectLog transportation -- South Africaen_ZA
dc.subjectWood -- Moisture -- South Africaen_ZA
dc.subjectForest products industry -- South Africaen_ZA
dc.subjectLog driving -- South Africaen_ZA
dc.subjectPulpwood -- South Africaen_ZA
dc.subjectUCTDen_ZA
dc.titleMeasuring and modelling dynamic moisture loss of pulpwood during rail transport in South Africaen_ZA
dc.typeThesisen_ZA
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Doctoral Degrees (Forest and Wood Science)