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This thesis is missing pages 98-107, all of which are not in the other copies of the thesis. -Digitization Centre / In total knee arthroplasty with bone defect of the tibia, it was believed that with older designs of tibial tray, both block and stem augments must be used with the tibial tray to improve the knee stability. Obviously, the extended stem causes more difficulties to the surgery as well as more suffering to the patients. Getting rid of the extended stem and still maintaining enough stability is therefore very desirable. The newest tray design, Deltafit Keel tray, which provides much more contact with the human bone structure, may provide enough stability without the extra long stem. The objective in this project is to answer the questions - Is the stem augmentation definitely required alongside the block implant for the cases of bone defect in TKA (Total Knee Arthroplasty) when using the Deltafit Keel tibial tray design? In other words, does the configuration of Deltafit Keel tray with a block provide enough stability in the cases of bone defect? In order to give a reliable answer, three configurations have been studied by conducting both experiments and FEA simulation. The three cases are Deltafit Keel tibial tray only (case 1-no bone defect defect), tray with block augment (case 2-with bone defect assumed) and tray with block and extended stem (case 3-with bone defect assumed). In this study, three commercially available composite bones with isotropic material properties are utilized. For each configuration, the bones are clamped in a testing apparatus and 3000 N static compressive load is imposed on the top surface of the tibia tray at central, medial and lateral locations. In experiment, the strains and displacements at strategically selected locations were measured by strain rosettes (strain gages) and DVRT (Differential Variable Reluctance Transducer) displacement transducers, respectively. In order to simulate the three cases, FE model is established by employing several advanced software including CATIA, True Grid Mesh generator and Abaqus. In order to compare with the experimental results, nine cases (three implant configurations with three different loading positions for each) have been simulated using Abaqus/Standard 6.4. In addition to the nine-case studies, the influence of load offsetting is also investigated by shifting the nodal load along medial-lateral and anterior-posterior directions. It is found that load shifting one node in either direction does not cause significant change in either strain or displacement. Furthermore, FE results of adjacent elements are checked as well and no sudden changes are observed. Since the discrepancy of the output from adjacent elements is negligible, an average value of the elements can be used to represent the output in a small region to compare the experimental strain measured by strain rosettes. Both the experimental data and FEA simulation results lead to the conclusion that comparable stability can be achieved with the configuration of Deltafit Keel tibial tray and a block as compared to the case of Deltafit Keel tray only without bone defect. Moderate improvement of stability, but with significant stress shielding, is found when the extended stem is implanted. For the amount of bone defect and the bone material properties used in this study, the Deltafit Keel tray with a block is the best choice because it is able to provide adequate stability and avoid excessive stress shielding. The loss of a substantial amount of bone to implant an extended stem to trade for the excessive stability may not be worthwhile. Besides, stress shielding is a potential problem which may exist if the extended stem is used. / Thesis / Master of Applied Science (MASc)

Doctor of Philosophy / Department of Hospitality Management and Dietetics / Carol W. Shanklin / This study used two operational research components to explore strategies to decrease waste in university dining facilities. Component one assessed students’ beliefs and behaviors toward food waste in a selected dining center. The relationships between students’ food waste behavior, sustainability beliefs, and demographics were evaluated with the use of a self-administered survey and continual food waste monitoring. This study also assessed whether simple prompt-type message interventions had an impact or if the addition of more personally relevant feedback-based data elicited a greater change in consumer beliefs and behaviors On average, more than 57 grams of edible food was left on each tray. Food waste behaviors were not influenced by demographic factors. Individuals with higher levels of food waste beliefs also disposed of less edible food items. The simple prompt-type messages stimulated a 15% reduction in food waste. The addition of more personalized feedback-based messages did not stimulate a change above that of the prompt message. These findings indicate that simply making university students aware of the topic of food waste may be useful in improving their behaviors. Component two evaluated the operational feasibility of implementing tray free dining at Kansas State University Dining Services. Telephone interviews with managers of university dining facilities involved in tray free dining were conducted to identify best practices. Focus groups of students were used with a written survey to gain insight into their perceptions of tray free dining. Benefits included: decreased waste, reduced chemical, resource, and food costs, and improved student satisfaction. Managers identified complaints and dining room cleanliness as negative outcomes. Student involvement, education, and communication were strongly recommended by both managers and students. This research supports the recommendation to consider the implementation of tray free dining at Van Zile. Decreased costs, improved satisfaction, and positive public perception are likely positive outcomes.

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Distillation is one of the most widely used processes for the separation of fluids with different volatilities. Due to the popularity of this process it is often assumed that the hydrodynamic behaviour inside distillation columns is well-defined. However, this is not always the case and this study therefore endeavoured to provide additional insight into the topic through a systematic investigation into the hydrodynamics and the capacity limitations of a sieve tray distillation column. The objective of the study was to measure and evaluate the effects of the following variables on entrainment and weeping: - Fluid flow rate (gas and liquid). - Plate geometry (i.e. hole diameter and fractional hole area). - Liquid properties (i.e. surface tension, viscosity and density). - Gas properties (i.e. viscosity and density). The hydrodynamic effects were evaluated at zero mass transfer in a pilot-scale tray column, by passing pure liquids and gases in counter current configuration. The pilot column was rectangular in shape with internal dimensions of 175 mm by 635 mm. A chimney tray was used to capture the weeping liquid, while a de-entrainment tray was used in combination with a mist eliminator pad to capture the entrained liquid. The fractional hole areas for the sieve trays under investigation were 7%, 11% and 15% and the hole diameters were 3.2 mm (⅛ in.), 6.4 mm (¼ in.) and 12.7 mm (½ in.). The experimental liquids were ethylene glycol, butanol, water and silicone oil, while the gases were air and carbon dioxide (CO2). These experimental measurements produced over 10 000 data points for entrainment and over 7 000 data points of weeping. The results were repeatable and the entrainment values compared reasonably well with previous data produced by Nutter (1971) and Uys (2012). The differences between entrainment for the different liquids were more significant in the spray regime than in the froth regime, and butanol was entrained more readily than silicone oil, ethylene glycol and water. Fluids that caused a larger spray layer in the dispersion zone produced more entrainment. Entrainment increased with decreasing liquid density, decreasing liquid surface tension and decreasing liquid viscosity. The more unstable the dispersion layer, the higher the entrainment. The liquid density strongly influenced weeping, i.e. weeping increased with increasing liquid density. On the other hand, gases with higher densities – and thus with a higher mass flow rates at similar volumetric flow rates through the sieve tray – displayed less weeping and more entrainment than less dense gases, because of an increased upward drag force on the fluids. When considering tray geometry and when operating in the spray regime, the magnitude of entrainment increased with decreasing fractional hole area, while the dependency of entrainment on fractional hole area was more prominent at lower fractional hole areas. When operating in the froth regime – typically above 23 m3/(h.m) – the fractional hole area had a relatively small influence on the magnitude of entrainment, while the cross-flowing liquid rate dominated related effects. In the spray regime, i.e. typically below 23 m3/(h.m), the entrainment increased with increasing sieve tray hole diameter, while hole diameter had a relatively small influence on entrainment at higher liquid flow rates between 23 and 60 m3/(h.m). However, at even higher liquid flow rates in the froth regime, i.e. above 60 m3/(h.m), the effect of hole diameter on the entrainment became more prominent again, with increased entrainment for smaller hole diameters. The effect of hole diameter on weeping differed with changing fluid combinations and the 12.7 mm hole size caused notably less weeping than the 3.2 mm and 6.4 mm trays at higher liquid flow rates. It is believed that weeping occurred preferentially at so-called localised high pressure zones on the sieve tray. At high gas and liquid flow rates, the resultant extended dispersion layer allows minimal intimate contact between the plate and the liquid (minimising such localized high-pressure zones). In effect, the liquid ‘jumps’ over the entire flow path length in the test rig, thus resulting in low weeping rates at high gas and liquid rates. The effects of fractional hole area and hole diameter on entrainment and weeping can be correlated with combinations of well-known hydrodynamic dimensionless numbers, such as the Weber number (We), Froude number (Fr) and Reynolds number (Re). Within the limitations of this study, the flow-Froude number was shown to be the most useful dimensionless number, since it displayed a monotonic relationship with magnitude of entrainment for different combinations of fluid systems and tray configurations. Furthermore, both the construction number and fluid density ratio could be used in a sensible manner to correlate some of the effects of tray geometry on entrainment. / AFRIKAANSE OPSOMMING: Distillasie word wêreldwyd op groot en klein skaal toegepas as ʼn metode om chemiese komponente van mekaar te skei, gebasseer op hul verskil in vlugtigheid. Die hidrodinamiese gedrag van vloeistowwe en hul damp binne ʼn distillasiekolom beïnvloed die effektiwiteit van die skeidingsproses. Hierdie studie beoog dus om bykomende insig te verskaf tot die hidrodinamika en kapasiteitsbeperkings van ʼn plaat-distilleerkolom. Die doelwit van die studie was om die invloed van die volgende veranderlikes op die meesleuring en deurdripping van vloeistowwe te ondersoek: - Gas- en vloeistof vloeitempo. - Plaatgeometrie (i.e. gatdeursnit en fraksionele deurvloei-area). - Vloeistofeienskappe (i.e. oppervlakspanning, viskositeit en digtheid). - Gaseienskappe (i.e. viskositeit en digtheid). Die hidrodinamiese studie is uitgevoer in ʼn reghoekige plaatkolom met interne afmetings van 175 mm x 635 mm. Die vloeistof en gasfases is in kontak gebring op ʼn teenstroom basis, met geen massa-oordrag wat plaasvind nie. ʼn Skoorsteenplaat het die vloeistof opgevang wat deurdrip terwyl ʼn ekstra plaat aan die bokant van die kolom die meegesleurde vloeistof opgevang het. Hierdie ekstra plaat is gebruik tesame met ʼn mis-elimineerder om al die meegesleurde vloeistof op te vang. Plate met verskillende deurvloei-areas (7%, 11% en 15%) en gat deursnitte (3.2 mm, 6.4 mm en 12.7 mm) is gebruik in die ondersoek. Die vloeistowwe wat gebruik is, sluit in etileen glikol, butanol, water en silikon olie. Lug en koolstofdioksied is as gasse gebruik. Die eksperimentele data het goeie herhaalbaarheid getoon en is vergelykbaar met die gepubliseerde data van Nutter (1971) en Uys (2012). Meer as 10 000 data punte is gemeet vir vloeistofmeesleuring en meer as 7 000 vir deurdripping. Die verskil in hoeveelheid meesleuring tussen die vloeistowwe, soos ondersoek in hierdie studie, was mees beduidend in die spoei-regime. Butanol is die meeste meegesleur, gevolg deur silikon olie en dan etileen glikol. Water is die minste meegesleur is. Vloeistowwe wat ʼn groter sproeivolume in die dispersielaag bo die plaat gevorm het, is die meeste meegesleur. Meesleuring het toegeneem met ʼn afname in digtheid, oppervlakspanning en viskositeit van die vloeistof. ʼn Onstabiele dispersielaag bo die plaat het meer meesleuring tot gevolg gehad. Vloeistofdeurdripping is sterk beïnvloed deur vloeistofdigtheid, i.e. deurdripping het sterk toegeneem met digtheid. Gasse met ʼn hoër digtheid veroorsaak weer ʼn afname in deurdripping a.g.v. die hoër opwaartse sleurkragte wat ʼn gas met hoë digtheid op die vloeistof uitoefen. In die sproei-regime (tipies by vloeistofvloeitempos laer as 23 m3/(h.m) is gevind dat meesleuring toeneem met ʼn afname in fraksionele deurvloei-area. Meesleuring se afhanklikheid van fraksionele deurvloei-area was meer beduidend by laer fraksionele deurvloei-areas. In die skuim-regime (tipies by vloeistofvloeitempos hoër as 23 m3/(h.m)) was die afhanklikheid van meesleuring op fraksionele deurvloei-area relatief klein. In die sproei-regime is gevind dat meesleuring toeneem met ʼn toename in gat deursnit, terwyl dieselfde veranderlike ʼn minder beduidende invloed op meesleuring getoon het by hoër vloeistofvloeitempos (tussen 23 en 60 m3/(h.m)). By vloeitempos hoër as 60 m3/(h.m) het meesleuring weer begin toeneem met ʼn afname in gat deursnit. By hoë vloeistofvloeitempos het die plaat met 12.7 mm gat deursnit aansienlik minder deurdripping getoon as plate met 3.2 mm en 6.4 mm deursnitte. Daar word vermoed dat deurdripping hoofsaaklik plaasvind by lokale hoëdruk gebiede op die plaat. By hoër vloeistof- en gasvloeitempos beslaan die dispersielaag ʼn groter volume en is daar dus minder gebiede van digte vloeistofkontak met die plaat, wat ʼn afname in die lokale drukgebiede veroorsaak. Dit lei tot ʼn afname in deurdripping by hoër gas- en vloeistofvloeitempos. Die invloed van fraksionele deurvloei-area en gatdeursnit op meesleuring en deurdripping korreleer goed met kombinasies van welbekende hidrodinamiese dimensielose getalle, i.e. die Webergetal (We), die Froudegetal (Fr) en die Reynoldsgetal (Re). Die vloei-Froudegetal is mees bruikbaar om die invloed van vloeistof-en-gas kombinasies en kolomuitleg op meesleuring te korreleer. Die konstruksiegetal asook die digtheidsverhoudings tussen vloeistof en gas kan op ʼn sinvolle manier aangewend word om van die invloede van plaatgeometrie op meesleuring te beskryf.

Considerando as dificuldades envolvidas no processo de moldagem com a moldeira aberta convencional, objetivou-se neste estudo avaliar a precisão da moldagem de transferência de implantes dentais utilizando uma nova moldeira, desenvolvida com o objetivo de facilitar a técnica de moldagem. Foi confeccionado um modelo de referência de uma mandíbula edentada e instalados quatro implantes nas regiões dos elementos 44, 42, 32 e 34, denominados implantes 1, 2, 3 e 4, respectivamente. Sobre este modelo confeccionou-se uma barra de Cr-Co, para análise do desajuste. Foram realizadas 10 moldagens com silicona de adição para cada grupo (controle, moldeira aberta convencional) e teste (nova moldeira, Miratray Implant!) do modelo de referência, e após obtenção do modelo em gesso, a barra metálica foi parafusada somente no implante 1, e medida a fenda gerada na face vestibular dos implantes 3 e 4 por meio de microscópio óptico com aumento de 16x. As imagens foram analisadas por um único operador no tempo inicial e após uma semana por meio do software ImageLab. Os grupos foram comparados pelo teste de Mann-Whitney e Wilcoxon, com nível de significância estabelecido em 5%, pelo software estatístico SPSS. Os resultados mostraram diferença estatística (p = 0,04) ao comparar a média da primeira repetição do implante 3 (teste x controle); ao comparar a primeira repetição com a segunda para o implante 4 apenas no grupo controle; e na comparação dos valores máximos entre os implantes 3 e 4 do grupo controle. Em relação aos valores máximos do implante 3, obteve-se a média de 116 ± 45 m para o grupo controle, e 158 ±17 m para o grupo teste. Já para o implante 4, obteve-se a média de 106 ± 46 m para o grupo controle e 156 ± 22 m para o grupo teste. Considerando que o máximo desajuste permitido seria de 150 m, apenas o grupo controle teria um desajuste considerado aceitável clinicamente para o implante 3, entretanto sem diferença estatística para o implante 4. Como os valores dos grupos teste e controle foram muito próximos, dentro das limitações deste estudo pode-se concluir que a nova moldeira promove uma precisão do sistema barra/implante muito próxima à moldeira aberta convencional. / Considering the difficulties involved in the impression taking process when using the conventional open impression tray, the aim of this study was to evaluate the accuracy of transfer impression of dental implants using a new impression tray developed with the object of facilitating the impression-taking technique. A reference model of an edentulous mandible was fabricated, and four implants were placed in the regions of teeth 44, 42, 32 and 34, denominated implants 1, 2, 3 and 4, respectively. To analyze misfit, a Cr-Co bar was fabricated on this model. Ten impressions were taken with polyvinyl siloxane for each group (control, conventional open impression tray) and test (new impression tray, Miratray Implant!) from the reference model. After obtaining the plaster model, a metal bar was screw-retained on implant 1 only, and the gap generated at the vestibular face of implants 3 and 4 was measured by optical microcopy at 16x magnification. A single operator analyzed the images at the initial time and after one week, using ImageLab software. Groups were compared by the Mann-Whitney and Wilcoxon tests, with level of significance established at 5%, using statistical SPSS software. The results showed statistical difference (p = 0.04) when the mean of the first repetition of implant 3 (test x control) was compared; when the first repetition was compared with the second, for implant 4 only in control group; and in comparison of the maximum values between implants 3 and 4 of control group. As regards maximum values of implant 3, a mean of 116 ± 45 m was obtained for control group, and 158 ±17 m for test group. Whereas, for implant 4, a mean of 106 ± 46 m was obtained for control group and 156 ± 22 m for test group. Considering that the maximum misfit permitted would be 150 m, only control group would have a misfit considered clinically acceptable for implant 3, however, without statistical difference for implant 4. As the test and control group values were very close, within the limitations of this study, it could be concluded that the new impression tray promotes bar/implant system accuracy very close to that of the conventional open impression tray.

Considerando as dificuldades envolvidas no processo de moldagem com a moldeira aberta convencional, objetivou-se neste estudo avaliar a precisão da moldagem de transferência de implantes dentais utilizando uma nova moldeira, desenvolvida com o objetivo de facilitar a técnica de moldagem. Foi confeccionado um modelo de referência de uma mandíbula edentada e instalados quatro implantes nas regiões dos elementos 44, 42, 32 e 34, denominados implantes 1, 2, 3 e 4, respectivamente. Sobre este modelo confeccionou-se uma barra de Cr-Co, para análise do desajuste. Foram realizadas 10 moldagens com silicona de adição para cada grupo (controle, moldeira aberta convencional) e teste (nova moldeira, Miratray Implant!) do modelo de referência, e após obtenção do modelo em gesso, a barra metálica foi parafusada somente no implante 1, e medida a fenda gerada na face vestibular dos implantes 3 e 4 por meio de microscópio óptico com aumento de 16x. As imagens foram analisadas por um único operador no tempo inicial e após uma semana por meio do software ImageLab. Os grupos foram comparados pelo teste de Mann-Whitney e Wilcoxon, com nível de significância estabelecido em 5%, pelo software estatístico SPSS. Os resultados mostraram diferença estatística (p = 0,04) ao comparar a média da primeira repetição do implante 3 (teste x controle); ao comparar a primeira repetição com a segunda para o implante 4 apenas no grupo controle; e na comparação dos valores máximos entre os implantes 3 e 4 do grupo controle. Em relação aos valores máximos do implante 3, obteve-se a média de 116 ± 45 m para o grupo controle, e 158 ±17 m para o grupo teste. Já para o implante 4, obteve-se a média de 106 ± 46 m para o grupo controle e 156 ± 22 m para o grupo teste. Considerando que o máximo desajuste permitido seria de 150 m, apenas o grupo controle teria um desajuste considerado aceitável clinicamente para o implante 3, entretanto sem diferença estatística para o implante 4. Como os valores dos grupos teste e controle foram muito próximos, dentro das limitações deste estudo pode-se concluir que a nova moldeira promove uma precisão do sistema barra/implante muito próxima à moldeira aberta convencional. / Considering the difficulties involved in the impression taking process when using the conventional open impression tray, the aim of this study was to evaluate the accuracy of transfer impression of dental implants using a new impression tray developed with the object of facilitating the impression-taking technique. A reference model of an edentulous mandible was fabricated, and four implants were placed in the regions of teeth 44, 42, 32 and 34, denominated implants 1, 2, 3 and 4, respectively. To analyze misfit, a Cr-Co bar was fabricated on this model. Ten impressions were taken with polyvinyl siloxane for each group (control, conventional open impression tray) and test (new impression tray, Miratray Implant!) from the reference model. After obtaining the plaster model, a metal bar was screw-retained on implant 1 only, and the gap generated at the vestibular face of implants 3 and 4 was measured by optical microcopy at 16x magnification. A single operator analyzed the images at the initial time and after one week, using ImageLab software. Groups were compared by the Mann-Whitney and Wilcoxon tests, with level of significance established at 5%, using statistical SPSS software. The results showed statistical difference (p = 0.04) when the mean of the first repetition of implant 3 (test x control) was compared; when the first repetition was compared with the second, for implant 4 only in control group; and in comparison of the maximum values between implants 3 and 4 of control group. As regards maximum values of implant 3, a mean of 116 ± 45 m was obtained for control group, and 158 ±17 m for test group. Whereas, for implant 4, a mean of 106 ± 46 m was obtained for control group and 156 ± 22 m for test group. Considering that the maximum misfit permitted would be 150 m, only control group would have a misfit considered clinically acceptable for implant 3, however, without statistical difference for implant 4. As the test and control group values were very close, within the limitations of this study, it could be concluded that the new impression tray promotes bar/implant system accuracy very close to that of the conventional open impression tray.

The purpose of this in vitro study was to investigate and to compare the precision of two different impression techniques for oral prosthetic construction, namely the analogue modified double tray method, and the digital three-dimensional scanning with Trios 3D shape intraoral scanner. The analog method used was a modified double tray method where the tray had been removed to diminish vertical discrepancies in occlusion. All testing was based on a master model with a prepared acrylic tooth from which a total of 20 milled crowns in polymethylmethacrylate was produced, 10 from each impression method.  The fit of the crowns was evaluated according to a clinical protocol and the cement gap was measured with a measuring microscope. Each crown was fitted on to the master model with Flexitime light body, mimicking a cementing procedure. The resulting “cement layer” was after setting of the silicone impression material removed and divided into 4 equal pieces which subsequently were measured in a measuring microscope. Statistical analysis of the resulting measurements showed no significant differences in precision when comparing the impression methods. Because of a manufacturing error in the milling procedure, all of the milled plastic crowns showed suboptimal fit on the master model. However, it was concluded that no statistical - nor clinical difference between the two methods could be established. Most likely, both methods can be used for fabrication of single unit prosthetic reconstructions with adequate precision for effective treatment.

”Stödbricka för muffinsformar” är ett examensarbete som självständigt utförts av Sara Glanander och Rebecka Westerlund under vårterminen 2011. Det har genomförts vid Karlstads universitet, fakulteten för teknik- och naturvetenskap under innovations- och designingenjörsprogrammet. Siluett of Sweden AB i Kristinehamn är uppdragsgivaren för projektet och kontaktperson samt handledare på företaget är Bernt Rådberg, försäljnings- och marknadschef. Handledare av projektet vid Karlstads universitet är Monica Jakobsson, universitetsadjunkt och programledare för innovations- och designingenjörsprogrammet. Examinator är Fredrik Thuvander, universitetslektor och professor på Karlstads universitet. Siluett, som tillverkar bakformar och andra kartong- och pappersbaserade produkter för bageri- och konditorinäringen, har lagt märke till en ökad efterfrågan av monterade mönstertryckta formar hos sina kunder. Därför startades projektet i syfte att tillgodose detta behov. Då företaget redan lagt märke till kundbehovet genomfördes en mindre förstudie i form av korta intervjuer på ett tiotal bagerier i Karlstad och fyra massproducerande bagerier runt om i landet. Fokus låg på produktspecificeringen där de krav och funktioner som efterfrågades identifierades.  Under konceptgenereringen användes olika idégenereringsmetoder, både självständigt och i grupp. Projektgruppen märkte dock att de fick de enklaste och mest entydiga beskrivningarna genom att göra skissmodeller i papper och enklare kartongmaterial, vilket därför flitigt användes under projektets gång. Här studerades även stödbrickans fysiska ergonomi samt materialets värmebeständighet i form av laborationer. De framtagna koncepten utvärderades och utvecklades. I slutet av projektet återstod fyra koncept vilka presenterades för handledaren på företaget. Det bästa konceptet valdes ut och anpassades för tillverkning av konstruktören, Niklas Karlén, på Petersson Packaging i Norrköping. För närvarande pågår nyhetsgranskning av konceptet, vilket medför att det slutliga resultatet inte kan redovisas. Konceptets mest framstående egenskaper är dock att den är enkel att vika ihop, den är stapelbar och lätthanterlig, vilket var några av projektets mål. / ”Support tray for muffin cups” is a final thesis which was independently executed by Sara Glanander and Rebecka Westerlund during spring 2011. It was carried out through Karlstad University Faculty of Technology and Science in the study program of Innovation and Design Engineering. The employer of the project is Siluett of Sweden AB in Kristinehamn. The contact person and instructor at the company is Bernt Rådberg, sales and marketing manager. The supervisor at Karlstad University is Monica Jakobsson, lecturer and director of studies for the study program in Innovation and Design Engineering. Examiner is Fredrik Thuvander, lecturer and professor at Karlstad University. Siluett manufactures muffin cups and other cardboard- and paperbased products for the bakery- and patisserie industry. They have noticed an increase in demand from their customers for set up, patterned, muffin cups. The project was initiated to fulfill this need. Since the company had already noticed the need, only a smaller preliminary study was performed. The study was in the shape of short interviews at ten different bakeries in Karlstad and four mass-producing bakeries around the country. The focus was on the defining of the product where the inquired demands and functions were specified. Different methods were used during the concept generation, both individually and in group. The project team noticed that the easiest way to get understandable descriptions were by making small models in paper and cardboard. This method was diligently used throughout the project. Also the physiological ergonomics was studied and the heat resistance of the material was tested by laboratory experiments. The produced concepts were evaluated and developed. In the end, only four concepts remained and were presented to the instructor at the company. The best concept was chosen and later adjusted for manufacturing by Nicklas Karlén, a constructor at Peterson Packaging AB in Norrköping. For the present a novelty search is going on, which entails that the final result cannot be shown. The most eminent characteristic of the chosen concept is its simplicity. It is easy to fold, easy to stack and easy to handle, which was some of the goals of the project.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Mass transfer efficiency in distillation, absorption and stripping depends on both thermodynamic efficiency and hydrodynamic behaviour. Thermodynamic efficiency is dependent on the system kinetics while hydrodynamics is the study of fluid flow behaviour. The focus of this thesis is the hydrodynamic behaviour in tray columns, which affects entrainment. In order to isolate hydrodynamic behaviour from the thermodynamic behaviour that occurs inside sieve tray columns, investigations are conducted under conditions of zero mass transfer. When the gas velocity is sufficiently high to transport liquid droplets to the tray above, entrainment occurs. The onset of entrainment is one of the operating limits that determines the design of the column and thus impacts on the capital cost. By improving the understanding of the parameters that affect entrainment, the design of the tray and column can be improved which will ultimately increase the operability and capacity while reducing capital costs. Existing correlations predicting entrainment in sieve tray columns are based on data generated mainly from an air/water system. Previous publications recommend that more testing should be performed over larger ranges of gas and liquid physical properties. An experimental setup was therefore designed and constructed to test the influence of the following parameters on entrainment: 1. gas and liquid physical properties 2. gas and liquid flow rates 3. tray spacing The experimental setup can also measure weeping rates for a continuation of this project. The hydrodynamic performance of a sieve tray was tested with air and water over a wide range of gas and liquid flow rates and at different downcomer escape areas. It was found that the downcomer escape area should be sized so that the liquid escaping the downcomer always exceeds a velocity of approximately 0.23 m/s in order to create a sufficient liquid seal in the downcomer. For liquid velocities between 0.23 and 0.6 m/s the area of escape did not have an effect on the percentage of liquid entrained. It was also established that entrainment increases with increasing gas velocity. The rate at which entrainment increases as the gas velocity increase depends on the liquid flow rate. As soon as the liquid flow rate exceeded 74 m3/(h.m) a significant increase in entrainment was noted and the gas velocity had to be reduced to maintain a constant entrainment rate. This is because the increased liquid load requires a longer flow path length for the froth to fully develop. The undeveloped froth, caused by the short (455 mm) flow path, then creates a non-uniform froth that is pushed up against the column wall above the downcomer. Consequently, the froth layer is closer to the tray above resulting in most of the droplets ejected from the froth reaching the tray above and increasing entrainment. By reducing the gas velocity, the froth height and ejecting droplet velocity is reduced, resulting in a decrease in entrainment. The results from the experiments followed similar trends to most of the entrainment prediction correlations found in literature, except for the change noted in liquid flow rates above 74 m3/(h.m). There was, however, a significant difference between the experimental results and the correlations developed by Hunt et al. (1955) and Kister and Haas (1988). Although the gas velocities used during the air/water experiments were beyond the suggested range of application developed by Bennett et al. (1995) their air/water correlation followed the results very well. The entrainment prediction correlation developed by Bennett et al. (1995) for non-air/water systems was compared with the experimental air/water results to test for system uniformity. A significant difference was noted between their non-air/water prediction correlation and the air/water results, which motivates the need for a general entrainment prediction correlation over a wider range of gas and liquid physical properties. Based on the shortcomings found in the literature and the observations made during the experiments it is suggested that the influence of liquid flow path length should be investigated so that the effect on entrainment can be quantified. No single correlation was found in the literature, which accurately predicts entrainment for a large range of liquid loads (17 – 112 m3/(h.m)), high superficial gas velocities (3 – 4.6 m/s) and different gas and liquid physical properties. It is therefore recommended that more work be done, as an extension of this project, to investigate the influence of gas and liquid physical properties on entrainment (under zero mass transfer conditions) for a large range of liquid (5 – 74 m3/(h.m)) and gas (2 – 4.6 m/s) flow rates. In order to understand the effect of droplet drag on entrainment, tray spacing should be varied and increased to the extent where droplet ejection velocity is no longer the mechanism for entrainment and droplet drag is responsible for droplet transport to the tray above. Since it is difficult and in most cases impossible to measure exact gas and liquid loads in commercial columns, another method is required to measure or determine entrainment. Since liquid hold-up was found to be directly related to the entrainment rate (Hunt et al. (1955), Payne and Prince (1977) and Van Sinderen et al. (2003) to name but a few), it is suggested that a correlation should be developed between the dynamic pressure drop (liquid hold-up) and entrainment. This will contribute significantly to commercial column operation from a hydrodynamic point of view.

Este trabalho aborda a predição da eficiência de pratos valvulados de dois passes, de escoamento cruzado com downcomers de uma coluna de destilação industrial, através do uso de diferentes modelos com e sem o uso do método Stagnant Regions Model proposto por Lockett em 1986. Contrariando o esperado, poucos artigos foram publicados sobre as principais características de pratos valvulados e bem menos sobre eficiência de pratos valvulados de dois passes. Os resultados encontrados sugerem que a correlação de O'Connell, o modelo de Chan e Fair aplicado aos pratos valvulados de dois passes convertidos para um passe e o modelo de Chan e Fair com uso do método SRM são os que melhor predizem a eficiência de pratos valvulados de dois passes, de escoamento cruzado com downcomers, no caso estudado.Em consonância com os estudos prévios, a correlação de O'Connell subestima o valor da eficiência, mostrando-se levemente conservativa, enquanto as predições pelo uso do modelo de Chan e Fair e do modelo modificado de Chan e Fair com uso do comprimento equivalente proposto por Klemola e Ilme superestimam o valor da eficiência, mostrando-se levemente não-conservativas. / This work approaches the prediction of the efficiency of two passes, crossflow valve trays with downcomers of an industrial distillation column, through the use of different models with and without the use the Stagnant Regions Model, method proposed by Lockett in 1986.Contradicting what it could be expected, few papers were published about the main characteristics of valve trays and fewer about efficiency of two passes valve trays. The results suggest that the O'Connell's correlation, the model of Chan and Fair applied to the two passes valve trays converted for one pass valve tray and the model of Chan and Fair with SRM method are those that best predict the efficiency of two passes, crossflow valve trays with downcomers. In consonance with the previous published studies, the O'Connell'correlation underestimates the value of the efficiency, showing a slightly conservative value, while the predictions using Chan and Fair model and the modified Chan and Fair model with equivalent length proposed by Klemola and Ilme overestimates the value of the efficiency, showing a slightly non-conservative results.