Littérature scientifique sur le sujet « Mass flow analysis (MFA) »

In this paper, material flows and resource potentials for plastics at a national level in Denmark are mapped using an Environmentally Extended Multiregional Input-Output (EE-MRIO) database. EE-MRIO offers an operative improvement to current and prevalent methods for assessing the industrial and societal metabolism of resources, including plastics. The Exiobase is applied to map (1) the major sources, (2) calculate the total supply, (3) uses of plastics and waste generation, and (4) end of life pathways in order to indicate the potentials of plastics in the circular economy in Denmark with a focus on recycling. Furthermore, it elaborates how and why this method for performing Mass Flow Analysis (MFA) differs from mainstream assessments of material flows and from default uses of national statistical data. Overall, the results are that Denmark has a total supply of ≈551 kilotonnes (Kt) of plastics, out of which ≈522 Kt are used domestically and ≈168 Kt of plastic waste are generated annually. Out of the yearly amount of plastic waste, ≈50% is incinerated and 26% is recycled. These results indicate significant potentials for applying circular economy strategies and identify relevant sectors for closing the plastic loops. However, other initiatives are necessary, such as improvements in product design strategies, in the collection and sorting systems as well as in cross-sectoral collaboration.

Quantification of mass flows in production lines and waste treatment lines, as well as quantification of energy consumption at a factory is always challenges in cleaner production and pollution control decision making. The case study has conducted at a representative steel making complex in Vietnam, simulating the material flows of water and waste streams, and energy balance (EB) for water production and wastewater treatment processes, by using STAN (subSTance flow ANalysis) and SANKEY software, respectively. Input data were taken from secondary data sources, and additional monitoring of wastewater flows at the complex. COD was a selected parameter for material flow analysis (MFA) for evaluation of performance of wastewater treatment plants. Further, two scenarios were given for comparison of water and energy consumptions at existing and upgraded wastewater treatment plants. The results have shown that scenario 2, using disc filter (DF) and ultrafiltration (UF) membrane in combination with ultraviolet (UV) for improving quality of treated wastewater, could allow factory to reuse wastewater for production purposes. At the saved amount of fresh water 10,000 m3/day by reuse of treated wastewater, the saved energy was 1,489.5 kWh/day. The quantitative flows of MFA and EB were clearly presented in STAN and SANKEY diagrams.

This paper investigated mercury (Hg) flows and stock through mercury thermometers and sphygmomanometers in Thailand for 2010 using Material Flow Analysis (MFA) based on mass balance principles. All calculations in this study are based on data from hospital surveys and reliable secondary data sources. This study indicates that all thermometers and sphygmomanometers used in Thailand were only imported. Mercury contained in thermometers and sphygmomanometers was about 1,675 kg and 5,375 kg respectively. During the use phase, thermometers can release roughly 70% of Hg into the environment (air and water) while no emissions were emitted from sphygmomanometers. This study also shows that about 20-30% of mercury thermometer and sphygmomanometer waste were disposed of in landfills and incinerators. Hg can be released into air, land, and water at approximately 53%, 35%, and 12% respectively. According to our scenario analysis, it shows that phasing out Hg medical-based devices combined with preventing the breakage and spillage of Hg-thermometers can give higher potential reduction of Hg in Thailand.

The non-symmetric flow over a stretching/shrinking surface in an other-wise quiescent fluid is considered under the assumption that the surface can stretch orshrink in one direction and stretch in a direction perpendicular to this. The problem is reduced to similarity form, being described by two dimensionless parameters, γ the relative stretching/shrinking rate and S characterizing the fluid transfer throughthe boundary. Numerical solutions are obtained for representative values of γ and S, a feature of which are the existence of critical values γc of γ dependent on S, these being determined numerically. Asymptotic forms for large γ and S, for both fluid withdrawal, S > 0 and injection S < 0 are obtained and compared with the corresponding numerical results.

The paper presents an experimental study of the influence of heat transfer fluid (HTF) mass flow rate on phase change materials (PCM) behaviour. The experimental study was performed on a specially designed test bench. Research object – PCM based thermal energy storage unit which consists of a stainless steel tank with dual circuit tube-fin copper heat exchanger. The tank (storage volume) was filled with phase change material RT82. The experiment was carried out using three different mass flow rates of HTF: high – 0.25 kg/s, medium – 0.125 kg/s, low – 0.05 kg/s. The analysis showed that in the case of high and medium mass flow rates the melting/solidification process highly depends on the temperature of inlet HTF. Influence of mass flow rate is higher in the case of low mass flow rate.

The aim of this study is modeling a solar-air heater humidification-dehumidification unit with applying particle swarm optimization to find out the maximum gained output ratio with respect to the mass flow rate of water and air entering humidifier, mass flow rate of cooling water entering dehumidifier, width and length of solar air heater and terminal temperature difference (TTD) of dehumidifier representing temperature difference of inlet cooling water and saturated air to dehumidifier as its decision variable. A sensitivity analysis, furthermore, is performed to distinguish the effect of operating parameters including mass flow rate and streams’ temperature. The results showed that the optimum productivity decreases by decreasing the ratio of mass flow rate of water entering humidifier to air ones.Article History: Received: July 12th 2017; Revised: December 15th 2017; Accepted: 2nd February 2018; Available onlineHow to Cite This Article: Afshar, M.A., Naseri, A., Bidi, M., Ahmadi, M.H. and Hadiyanto, H. (2018) Modeling and PSO Optimization of Humidifier-Dehumidifier Desalination. International Journal of Renewable Energy Development, 7(1),59-64.https://doi.org/10.14710/ijred.7.1.59-64

In this subject, a new spatial structure of the membrane contactor is explored and designed from analysis of mass transfer process, resistance theory and flow type. Under laboratory conditions, the experiment uses several methods including fluid mechanics, mass transfer process and the analysis of the fluid flow to achieve CO2 absorption function with the new hollow fiber membrane contactor. This new design of device is tested in conditions of two absorption liquids: MEA, DEA; three absorption concentrations: 6L/h, 8L/h, 10L/h; liquid velocity: 1mol/L, 0.5mol/L and air speed: 1L/min, 0.5L/min, to absorb CO2 from the gas mixture to make sure that if it has good properties. Through these experiments, we could see that the new hollow fiber membrane contactor has an increase in absorption efficiency by 10% on average.

Abstract This study aims to find the cumulative energy demand (CED) and the cumulative cost demand (CCD) in the synthesis of antistatic bionanocomposites (AS BNC) compared with the synthesis of polypropylene (PP). The CED was identified using SimaPro 9.1.1 software, and the CCD was identified using the material and energy flow analysis (MEFA) method. The analysis results show that the CED required per kg mass of AS BNC pellets was 87.80 MJ, which is lower than the CED required per kg mass of PP pellets (91.19 MJ). This shows that the use of 94.38% of PP, 2% of M-DAG, 2.5% of CNC, 1% of MAPP, 0.02% of MO, 0.03% of AO 1010, and 0.07% of AO 168 in the synthesis of AS BNC can reduction the CED required, with a percentage of CED reduced was 3.71%. The CCD required per kg mass of AS BNC pellets was 68,314.54 IDR, which is higher than the CCD required per kg mass of PP pellets (25,577.27 IDR). The efficiency of energy and natural resources use are necessary to decrease the CED and CCD per kg mass of AS BNC pellets.

One fluid formulation is an approach used for modeling and analysis of mass transfer between two immiscible phases. In this study we implement and analyze the advantages and limitations of this approach for CO2 physical mass transfer into MEA. The domain is a flat plate and gas liquid flow is counter current. The analysis was carried for operating parameters like liquid phase Reynolds number, MEA mass fraction and the angle of inclination of flat plate. The results clearly show that the model effectively captures the deviation in liquid side mass transfer coefficient due to the surface instabilities and liquid properties which are generally neglected by standard correlations. Also the model shows that the standard Higbie correlation is preferable at low Reynolds number at any angle of inclination. The grid independent studies show that a size of 6.25 µm is required in the interface region for effectively using this approach. The computational resource time at this resolution was found as the only limitation for using this approach and we suggest a procedure to overcome this limitation. The present simulation results can help CFD researchers investigating immiscible gas-liquid mass transfer using OpenFOAM.

The stochastic continuum approach, as an alternative to the discrete fracture-network approach, is applied to hydraulic conductivity data from fractured crystalline rock at Fanay-Augeres, France. Small-scale measurements are transformed into binary indicator values. Viewing the transformed data as defined over a continuum, the statistical correlation structure of the stochastic process is determined. Estimates of hydraulic conductivity and its probability field are obtained using ordinary and median indicator kriging. Indicator kriging results are input into sequential conditional indicator simulation, generating equally likely sets of hydraulic conductivities. An adjoint-state, finite element inverse model is used to derive the effective hydraulic conductivity of an equivalent homogeneous porous medium. Stochastic realizations of hydraulic conductivities are input into a flow model to study their effect on the variability of resulting hydraulic heads and flow rates. Results show that flow in the fractured medium can be analyzed without any reference to geometric fracture data.

Negli ultimi tre decenni la domanda globale di cibo, in particolare di proteine animali (carne, latte, uova), è aumentata in base alla crescita della popolazione che dovrebbe arrivare a 9 miliardi di persone entro il 2050. Questi alimenti rappresentano infatti un'importante fonte di energia, proteine di alta qualità, micronutrienti e vitamine. Pertanto, questo miglioramento potrebbe contribuire all'aumento della durata della vita e della domanda di cibo. Ciò ha costretto il settore agricolo ad un'ulteriore intensificazione che ha interessato anche la coltivazione di colture per l'alimentazione animale. Le produzioni agricole e zootecniche hanno un impatto ambientale rilevante, e questo argomento è oggetto di critiche e di indagini scientifiche anche per definire più accuratamente il loro contributo e le relative potenziali strategie di mitigazione, considerando anche che la fase agricola è il principale contributore dell'impatto ambientale della catena di produzione alimentare. Si riconosce infatti che il settore agricolo contribuisce direttamente al 21% delle emissioni totali di gas serra di origine antropica a livello mondiale e consiste per lo più di metano seguito da protossido di azoto e anidride carbonica. Queste emissioni sono per lo più associate alla produzione zootecnica, in particolare all'allevamento di ruminanti che contribuisce con le emissioni dirette di metano dovute alla fermentazione dei ruminanti e alla fermentazione del letame; la restante parte è composta da emissioni indirette dovute alla deforestazione, all'uso di energia e alla produzione di mangimi. Lo scopo di questa tesi è stato la valutazione dell'impronta ambientale nel settore zootecnico a diversi livelli di scala tematica. La filiera italiana della carne, gli allevamenti lattiero-caseari, un caseificio per la produzione di Grana Padano DOP e i singoli animali sono stati studiati per quantificare l'impronta ambientale. Nel primo lavoro è stata valutata la filiera italiana della carne con un approccio di analisi dei flussi di massa e di valutazione del ciclo di vita. In primo luogo, la quantificazione della carne è stata effettuata dalla macellazione al consumo domestico, partendo dal peso della carcassa fino alla carne realmente consumata. A questo livello si è tenuto conto della carne di bovini, suini, ovini e caprini, equidi e conigli. Durante la catena sono state quantificate anche le perdite di carne e i rifiuti. In particolare, i sottoprodotti di origine animale (SOA) sono stati quantificati per singole specie e classificati in base al rischio a livello sanitario secondo il regolamento (CE) 1069/2009. Secondo la categoria (Cat 1, Cat 2 o Cat 3), supponendo che tutti i SOA fossero destinati al processo di rendering, l'uso e lo smaltimento dei prodotti dopo rendering è stato identificato. L'analisi dei flussi di massa ha confermato come l'Italia sia un importatore netto di carne bovina e suina, mentre è autosufficiente per quanto la carne avicola. L'analisi dei flussi di massa rivela che nel 2013 sono stati consumati in Italia 2,86 Mt di carne. Questo valore equivale a 131 g/giorno/pro-capite e a 47,91 kg/anno/pro-capite di carne consumata. In percentuale la quantità totale di carne consumata è rappresentata dal 46% da carne suina, dal 28% di carne avicola, dal 23% di carne bovina e dal 3% di altre carni (coniglio, equini, ovini e caprini). Questo approccio ha permesso di quantificare anche sottoprodotti di origine animale (SOA) prodotti durante la fase di macellazione e gli scarti alimentari a livello di vendita al dettaglio e fase di consumo. La fase di macellazione è risultata essere la principale fonte di rifiuti, producendo il 48% di rifiuti originati nella filiera della carne. I risultati hanno evidenziato come i SOA siano già quasi completamente riutilizzati, compatibilmente con il loro rischio a livello sanitario, dimostrando la circolarità del sistema e permettendo di quantificare anche i prodotti evitati grazie al loro riutilizzo e le relative emissioni di gas serra evitate. Per quanto riguarda gli altri rifiuti alimentari, i risultati della presente valutazione possono essere considerati solo una stima per la mancanza di specifici coefficienti nazionali. Dopo la fase di quantificazione, è stato applicato l'approccio del Life Cycle Assessment (LCA) per valutare l'impronta ambientale, considerando anche il prodotto evitato grazie al riutilizzo dei sottoprodotti del rendering. I risultati dell'LCA rivelano che il consumo giornaliero di carne pro-capite emette 4,0 kg di CO2eq, con un contributo della care bovina pari al 30%, della carne suina pari al 9.6% e della carne avicola pari all’8%. Le emissioni relative ai SOA sono risultate essere pari al 60% di quelle totali e il loro riutilizzo ha permesso una riduzione di queste del 10%. Il secondo ed il terzo lavoro sono stati invece relativi al potenziale di riscaldamento globale (GWP) di latte bovino e Grana Padano DOP. Complessivamente sono stati valutate ventisette aziende zootecniche con bovine da latte, con latte destinato al formaggio Grana Padano DOP, e un caseificio, situato nella provincia di Piacenza. I dati primari sono stati raccolti utilizzando un questionario appositamente redatto. Questo ha incluso per le aziende agricole la richiesta di dati relativi alla composizione della mandria, la gestione dell'alimentazione, la produzione di latte e performance riproduttive, piani colturali e l'utilizzo delle risorse energetiche e dei materiali di lettime, mentre per il caseificio sono stati richiesti dati relativi all'utilizzo delle risorse energetiche e gli input richiesti dal processo di caseificazione. Nel secondo lavoro sono state valutate 10 aziende lattiere per valutare l'impronta di carbonio del latte (CF) e individuare le principali fonti di emissioni. Lo studio ha utilizzato un approccio dalla culla alla tomba considerando come unità funzionale un 1 kg di latte corretto per contenuto di grasso e proteine (FPCM). Il valore medio di CF di 1 kg di FPCM è risultato essere pari a 1,33 kg di CO2eq/kg FPCM con però un ampio range di variazione, da 1,02 a 1,62 kg di CO2eq/kg FPCM. Le emissioni dovute alle fermentazioni enteriche e alle fermentazioni da reflui rappresentano il 52% del totale, mentre le emissioni relative agli alimenti acquistati il 36%. L'autoproduzione e il consumo energetico rappresentano invece rispettivamente il 6% e il 6%. Nel terzo lavoro invece è stata presa in considerazione la produzione di Grana Padano DOP. In questo caso è stato utilizzato un approccio dalla culla al cancello del caseificio considerando come unità funzionali 1 kg di FPCM e 1 kg di Grana Padano DOP stagionato 9 mesi. Il latte destinato alla produzione del formaggio ha mostrato un valore medio di CF pari a 1,38 kg CO2eq/kg FPCM, con un valore minimo di 1,02 e uno massimo di 1,94 kg CO2eq/kg FPCM. Il valore medio di CF di 1 kg di formaggio Grana Padano DOP è stato invece pari a 9,99 kg di CO2eq, con un contributo della fase agricola pari al 94%. I risultati di questi lavori si sono mostrati in accordo con studi simili riportati in bibliografia e hanno inoltre permesso di evidenziare come gli allevamenti da latte mostrassero un maggior livello di sostenibilità ambientale ma con possibilità di miglioramento principalmente attraverso il miglioramento della gestione delle mandrie (prestazioni produttive e riproduttive). Il quarto lavoro ha riguardato invece lo sviluppo di proxy in grado di prevedere le emissioni di metano da singole bovine da latte. Questo focus è un punto caldo di ricerca, soprattutto perché di fondamentale importanza per individuare strategie di mitigazione efficaci per la riduzione delle emissioni di metano dovute a fermentazioni ruminali, gas ad effetto serra riconosciuto avere il maggior contributo sul totale delle emissioni. Le emissioni di metano dipendono principalmente dal quantitativo di concentrato assunto e dalla composizione generale della dieta, ma tuttavia nelle aziende agricole commerciali risulta difficile quantificare con precisione l’ingestione di alimenti. Lo studio ha quindi mirato a verificare la possibilità di utilizzare la tecnologia del vicino infrarosso (NIRS) utilizzando lo spettro di campioni di feci (NIRSf) e/o in combinazione con altri parametri fenotipici disponibili a livello aziendale per prevedere la produzione di metano (MP, g/giorno) dalle singole vacche da latte in lattazione. Il NIRSf da solo ha permesso una stima abbastanza buona della produzione di metano e le stime sono state migliorate in misura simile quando sono stati considerati il peso vivo o la produzione di latte tal quale o la produzione di latte corretta per il contenuto energetico, mentre la combinazione del NIRSf con più di un altro parametro ha migliorato le stime solo in misura molto limitata. Il metano può essere previsto utilizzando modelli che considerano l’ingestione di sostanza sezza, il peso vivo o la produzione di latte ma il limite principale è rappresentato dalla disponibilità dei dati a livello aziendale. La tecnica del vicino infrarosso applicata ai campioni fecali, in particolare se combinata con altri parametri fenotipici, può rappresentare una valida alternativa per misurazioni su larga scala in allevamenti da latte commerciali, quando l’ingestione di sostanza secca di solito non è disponibile, per la selezione genetica di vacche da latte a bassa emissione.
In the last three decades global demand of food, in particular animal proteins (meat, milk, and eggs), has increased according to the population growth, that is expected to go up to 9 billion by the 2050. These, in fact, represent an important source of energy, high-quality protein, micronutrients and vitamins. Therefore, this improvement could contribute to the lifespan increase and food demand. The latter forced the agricultural sector to a further intensification that affected also the cultivation of crops for animal feeding. Agricultural and livestock productions have a relevant environmental impact, and this topic is object of criticism and scientific investigation also to more accurately define its contribution and potential mitigation strategies, considering also that agricultural stage is the main contributor to the environmental impact of the food production chain. It is recognized, in fact, that agricultural sector directly contribute to the 21% of total global anthropogenic greenhouse gas emissions, mostly consisting of methane followed by nitrous oxide and carbon dioxide. These emissions are mainly associated with the livestock production, in particular with ruminants breeding that contributes directly to methane emissions due to ruminal and manure fermentation; the remaining part is composed by indirect emissions from deforestation, energy use and animal feed production. The scope of this thesis was the evaluation of environmental footprint in the livestock sector at different subject scale level. Italian meat supply chain, dairy farms, Grana Padano PDO cheese factory and single animals was investigated in order to quantify environmental footprint. In the first work, the Italian meat supply chain has been evaluated whit a mass flow analysis (MFA) approach and life cycle assessment (LCA) approach. Firstly, the quantification of meat had been made from slaughter to household consumption, starting form carcass weight to real meat consumed. At these levels, meat form cattle, pig, sheep and goat, equidae, and rabbit was taken in account. During the chain also meat losses and waste were quantified. In particular animal by-products (ABPs) were quantified for single species and categorized into heath level risk according to the Regulation (EC) 1069/2009. According to the category (Cat 1, Cat 2 or Cat3), assuming that all ABPs were destinated to rendering process, use and disposal of rendered products was identified. The MFA confirmed how Italy is a net importer of cattle and pork meat while it is self-sustaining for poultry meat. Mass flow analysis revealed that in 2013, 2.86 Mt of meat were consumed in Italy. It is equivalent to 131 g/day/pro-capita and to 47.91 kg/year/pro-capita of meat consumed. In percentage the total amount of consumed meat is represented by 46% of pig, 28% of poultry and 23% of cattle and 3% of other meat (rabbit, equidae, and sheep and goat). This approach quantified the ABPs produced at slaughtering level and food wastes at retail and consumer levels. Slaughter phase was the main source of waste, producing 0.80 Mt of ABPs, 48% of the total amount of waste originated in the meat supply chain. Results highlighted how the ABPs are already almost completely reused, compatibly with their health level risk, demonstrating the circularity of the system through the quantification of the avoided products and relative GHGs emissions. Concerning other food wastes, the results of the present evaluation could be considered only an estimate due to the lack of specific national coefficients. After quantification LCA was applied in order to evaluate environmental footprint, considering also avoided product due to the re-use of rendered ABPs. LCA results reveal that daily meat consumption pro-capita emits 4.0 kg CO2eq represented by 30% of cattle meat, 9.6% of pig meat and 8% of poultry meat. Emissions allocated to ABPs are the 60% and their re-use decrease the emissions about 10%. Second and third works focused the milk and PDO Grana Padano global warming potential (GWP). Overall, twenty-seven dairy farms, producing milk destinated to Grana Padano PDO cheese and one cheese factory, situated in the Piacenza province were evaluated. Primary data were collected by using a specific survey. This included for the farms the request of data regarding herd composition, feeding management, milk production, herd management and performace, crops cultivation and resource use, whereas for the cheese factory, the survey included energy resource use and input requested by cheese making process. In the second work, 10 dairy farms were evaluated in order to assess the milk Carbon Footprint (CF) and the main source of emissions. The system boundary was a cradle-to-farm-gate and functional unit is 1 kg of FPCM (Fat and Protein corrected milk). The CF of 1 kg of FPCM resulted equal to 1.33 kg CO2eq/kg FPCM with a wide range of variation from 1.02 to 1.62 kg CO2eq/kg FPCM. Emissions due to enteric fermentation and manure fermentation represented the 52% of the total, while acquired feed the 36%. Self-production and energetic consumption represented 6% and 6% respectively. In the third, Grana Padano PDO production was considered. The milk destinated to cheese processing showed an average value of CF equal to 1.38 kg CO2eq/kg FPCM, with a minimum value of 1.02 and a maximum one of 1.94 kg CO2eq/kg FPCM. Instead, the CF average value of 1 kg of PDO Grana Padano cheese was equal to 9.99 kg CO2eq, showing an agricultural stage contribution of 94%. Results of these works were in accord with similar studies reported in literature and had pointed out how dairy farms showed a greater level of environmental sustainability but with possibilities for improvement, mainly through herd management enhancement (productive and reproductive performances). Fourth work was about the development of proxies able to predict the methane emissions from individual cows. This focus is a hot research point in order to improve the mitigation strategies to reduce methane emissions because of the main GHG contributor. Methane emission is mainly driven by feed intake and diet composition, but it is difficult to measure intake in commercial farms. The study aimed to verify the possibility of using NIRS of faeces (NIRSf) alone and in combination with other phenotypic parameters available at a farm level to predict methane production (MP, g/d) from individual lactating dairy cows. NIRSf alone allowed a fairly good estimation of methane yield and the estimations were improved to a similar degree when BW, MY or ECM were considered, whereas combining NIRSf with more than one other parameters improved the estimations with a very little extent only. Methane can be predicted using models that consider the DMI, BW or MY but the main limitation is represented by the data availability. Near Infrared technique applied to faecal samples, in particular when combined with other phenotypic parameters, can represent a valid alternative for large-scale measurements in commercial dairy farms for genetic selection of low emitters dairy cows, when DMI measurement is usually not available.

The aim of this thesis is to discuss and analyse the influenceof data uncertainties with regard to the reliability of materialflow analysis (MFA) studies. MFA, as a part of environmentalsystems analysis, is a method belonging to the research field ofindustrial ecology and more specifically industrial metabolism.As such, the method strives at giving a holistic view of thecomplex world we live in, in order to reduce negativeenvironmental impact. Among other things, MFA studies have beenproposed to be useful for priority setting and following up inmunicipalities.

Serving as a starting point is a local case study of flows ofnitrogen in a Swedish municipality, Västerås. The casestudy has been performed using the ComBoxmodel. The years studiedare 1995 and 1998. The main sectors in society emitting nitrogento water were identified as the agricultural and householdsectors. The dominating sectors emitting nitrogen to air wereidentified as the agricultural, transport and infrastructuresectors.

As a basis for discussing data uncertainties qualitatively andquantitatively a literature survey was performed. 50 articles andbooks were identified as in some way or another dealing with datauncertainties in MFA. The literature survey showed that theuncertainties for results from a MFA study might vary between±30 % and a factor 10 depending on what kind of parameter isinvestigated. Only one method was found that dealt with datauncertainties in MFA in a complete way; a model developed byHedbrant and Sörme (HS model).

When applying the HS model to the case study of nitrogen flowsin Västerås, it was found that when uncertaintyintervals were calculated the possible conclusions changed. Ofthe two pair of flows compared in relation to priority setting,none of the earlier conclusions remained. Of the three flowsanalysed in relation to following up, only the flow from onepoint source supported the same conclusion when uncertainty wasconsidered.

In all, it is concluded that data uncertainties in MFAanalysis are an important aspect and that further research isneeded in order to improve input data quality estimations andframeworks for determining, calculating and presenting data, datauncertainties and results from MFA studies. However, theunderlying reality remains, e.g. that management of materialflows are important for understanding and reducing the negativeenvironmental impact. Thus, MFA is one useful tool in thiswork.

Keywords:data uncertainties, sensitivity analysis,Material flow analysis, MFA, method to determine datauncertainties, case study, ComBox model, nitrogenflows.

A great deal of work has been conducted on in-tube condensation in horizontal and vertical smooth tubes. The available literature points to mechanisms governing two-phase condensation heat transfer coefficients and pressure drops, which are directly linked to the local flow pattern for both horizontal and inclined configurations. However, the work has been limited to flow pattern observations, heat transfer, pressure drops and void fractions for both horizontal and inclined tubes at high mass fluxes. No work has been conducted on the analysis of the observed flow patterns and the effect of temperature difference between the average wall temperature and average saturation temperature for different inclination angles at mass fluxes of 100 kg/m2.s and below. The purpose of this study is to carry out a qualitative analysis of flow patterns, and show the effect of temperature difference on the heat transfer coefficient for inclination angles from +90° (upward flow) to -90° (downward flow) at mass fluxes below 100 kg/m2.s. An experimental set-up provided the measurements for the two-phase condensation of R-143a in a smooth tube with an inside diameter of 8.38 mm and a length of 1.5 m. The mass fluxes were 25 kg/m2.s to 100 kg/m2.s, the saturation temperature was 40 °C and the mean qualities were 0.1 to 0.9. A high-speed camera was used to visually analyse and determine the flow patterns for both the inlet and the outlet of the test section. Through the results, eight flow patterns were observed: stratified-wavy, stratified, wavy, wavy-churn, intermittent, churn, annular and wavy-annular. The maximum heat transfer was observed for downward flow between inclination angles of -15° and -30°. The Thome-Hajal flow pattern map correctly predicted horizontal flow patterns, but failed to predict most of the inclined flow patterns. Various flow pattern transitions were identified and proposed for all the investigated inclination angles in this study. Finally, the heat transfer coefficient was found to be dependent on quality, mass flux, temperature difference and inclination angle.
Dissertation (MSc)--University of Pretoria, 2016.
Mechanical and Aeronautical Engineering
MSc
Unrestricted

The applicability of the technique of inductively coupled plasma mass spectrometry to the analysis of geological samples was investigated using a variety of sample introduction techniques including: solution nebulisation; slurry nebulisation; flow injection; electrothermal vaporisation; and laser ablation, Solution sample introduction is limited by the amount of time required to prepare the sample, and the relative intolerance of the technique to high concentrations of sample matrix. The maximum level of dissolved solids for a refractory matrix such as a digested igneous rock was found to be 0.2% w/v. Good accuracy and precision are achievable. Acceptable results can be obtained using slurry nebulisation. However, standardisation is a problem due to the difference in response for aqueous and slurried analytes. Calibration against aqueous standards and the use of an internal standard is therefore precluded. In addition, the preparation of stable slurries is a highly skilled and time consuming task. Flow injection analysis offers the most benefit to the geochemical analyst. Flow injection was found to increase sample throughput and, more important, to improve matrix tolerance by a factor of l0x, thus allowing the direct determination of the platinum group elements and gold in geological samples without pretreatment. Small samples, such as fluid inclusion leachates can also be analysed without dilution and the matrix effects experienced when analysing samples containing high salt concentrations can be reduced by careful control of dispersion. The potential for increased detection limits by electrothermal vaporisation was not proved for geological materials due to the same matrix tolerance problems which limit detection limits in solution work. Laser ablation sampling allows direct analysis of the solid but quantitation requires matrix matched standards or independent variable internal standardisation, limiting the applicability of the technique for bulk screening. The use of laser ablation to analyse trace element concentrations in individual mineral grains has been investigated and partition coefficients for trace elements, including the rare earths in a large zoned pyroxene crystal, were determined.

AbstractBased on a systematic and organized literature review, the academic production for Latin America and the Caribbean (LAC) on Material Flow Analysis (MFA) was evaluated. This allowed us to know the research developments and to identify the influence of the “Barcelona School” (EB) and Professor Joan Martínez-Alier in this field of work in the region. The general balance of the literature reviewed (47 texts), shows the important influence of the EB for LAC: more than half of the publications have its origin, more than a third correspond to doctoral theses linked to the ICTA-UAB and 30% are published in journals originating in the ICTA-UAB. Thematically, the articles evaluated incorporate the main topics promoted by the EB. They are oriented towards studying the relationships between the metabolic dynamics of economies, environmental pressures and liabilities, and ecological distributive conflicts. These orientations correspond precisely to Professor Martínez-Alier’s central field of work: the link between ecological economics and political ecology. Methodologically, the potential and weaknesses of MFA were identified. Long-term material flow series have the potential to study large material-economic transitions, but little depth. Short and more detailed series, combining MFA with other methodologies, allow to better delve into the black box of energy-material flows and the environmental impacts of economic dynamics.

AbstractPlastic in our marine environment is now ubiquitous. Abandoned lost or otherwise discarded fishing gear (ALDFG) is of particular concern due to its ability to continue to function as a trap for marine organisms. In order for decision makers to act on this grave issue, we require data on the flow of ALDFG into the marine environment. One key tool for revealing the flow of material within a specific system is Material Flow Analysis (MFA). MFA takes a life cycle approach (cradle to grave) to assess energy or material flows in a system within space and time boundaries. It can be applied at multiple levels from the industrial process level to the national level. This chapter presents a case study of an MFA conducted on fishing gear in Norway. The MFA methodology was used in this case study to assess the flow of plastic fishing gear from production through to recycling, final disposal or loss to the marine environment. Data was collected for the MFA through stakeholder interviews, literature reviews and analysis of government data sets. The MFA revealed that around 4000 tons of plastic fishing gear enters the system in Norway and around 400 tons enter the marine environment each year. An analysis of the implications of the MFA for the key actors within the life cycle chain of fishing gear is presented and a short description of the links between MFA and the circular economy and sustainable development is provided. Furthermore, the relevance and implications of using MFA tool for policy making at national and regional level is discussed and elaborated while associated challenges are presented here.

AbstractThis chapter explores the principles supporting industrial ecology (IE), circular economy (CE) and material flow analysis (MFA). IE concerns constructing industrial and societal processes according to ecological principles. One of the main features within IE is the principle of closing material loops by avoiding pollution. Insights from IE further aid in building the understanding essential for establishing the principles of circularity in the resource economy. MFA is viewed as an analytical method rooted in the field of IE and Systems Engineering (SE).

The results of an experimental calibration of the NASA Glenn Research Center 16″ Mass-Flow Plug (MFP) are presented and compared to a previously obtained calibration of a 15″ Mass-Flow Plug. An ASME low-beta, long-radius nozzle was used as the calibration reference. The discharge coefficient for the ASME nozzle was obtained by numerically simulating the flow through the nozzle from the WIND-US code. The results showed agreement between the 15″ and 16″ MFPs for area ratios (MFP to pipe area ratio) greater than 0.6 but deviate at area ratios below this value for reasons that are not fully understood. A general uncertainty analysis was also performed and indicates that large uncertainties in the calibration are present for low MFP area ratios.

In this paper, the compatibility of various combinations of numerical schemes for the solution of flow and transport equations in porous media is studied and the possible loss of accuracy and global mass conservation are investigated. Here, the flow equations are solved using three popular finite element methods including the Standard Galerkin (SG), Discontinuous Galerkin (DG) and Mixed Finite Element (MFE) methods among which only the DG method possesses the local conservation property. Besides, the transport of a scalar variable which is governed by a convection-diffusion equation is studied in conjunction with the flow equations. The transport equation is solved using both the Streamline Upwind Petrov-Galerkin (SUPG) and the DG methods. Two test cases are numerically solved using various combinations of methods in order to explore the compatibility of flow and transport solution algorithms. In each test case, the error in total mass conservation and the deviation from the exact solution are compared for various solver combinations.

A plate-type constructal flow distributor is implemented as a gas distributor for a proton exchange membrane fuel cell. A 3D complete model is simulated using CFD techniques. The fuel cell model includes the gas flow channels, the gas diffusion layers and the membrane electrode assembly (MEA). The governing equations for the mass and momentum transfer are solved including the pertinent source terms due to the electrochemical reactions in the different zones of the fuel cell. Similar configurations have been already presented in previous studies but using the flow distributor as a heat remover; however, the similarity between heat transfer and mass transfer phenomena has lead to investigate the performance of such distributors in fuel cells. In terms of flow analysis, it was found that the constructal flow distributor presents a low pressure drop for a wide range of Reynolds number conditions at the inlet, as well as an excellent uniformity of flow distribution. Some of the advantages of the constructal model, over traditional flow patterns, are the uniformity of current density distribution, the adequate consumption of species and the possibility to increase the bifurcation levels to cover a larger reaction area.

Abstract Various polyacrylamide polymers have been successfully applied in chemical EOR projects. These polymers are characterised by high molecular weights (MW) to achieve high viscosifying power. The molecular weight distribution (MWD) of the polymers has a major impact on polymer properties and performance. Measuring the molecular weight distribution is challenging using conventional methods. Field-Flow Fractionation (FFF) enables the determination of the distribution to select and quality check various polymers. Polymers with high molar masses (&gt; 1 MDa) are used for EOR to obtain highly viscous aqueous solutions. The MWD of the polymers is crucial for the solution characteristics. Conventional analysis of polymers is performed using either viscometry – which is able to determine the average MW but does not give information on MWD, or size-exclusion chromatography – which is restricted to molecular weights of &lt; 20 MDa. FFF is based on the analytes flowing at different speeds in a channel dependent on their size and mass. This effect leads to separation, which is then used to determine the MWD. FFF allows to determine the MW and MWD of various ultra-high molecular weight polyacrylamides (HPAAMs). The FFF measurements showed, that despite similar MWs are claimed, substantial differences in MWD are observed. This technology offered the quantification the MWD of HPAAMs up to a MW of 5 GDa. Furthermore, gyration radii of the HPAAM molecules were determined. Selecting polymers on viscosifying power only is not addressing issues related to different MW and MWDs such as selective polymer retention and degradation of the high molar mass part of the distribution. The results were used to improve the polymer selection for chemical EOR projects. Overall, this work presents a new technique for analysis of ultra-high molecular weight EOR polymers, which enables the possibility to determine the full range of polymer MWD. This available information enhances the EOR polymer selection process addressing selective polymer retention and mechanical degradation in addition to the viscosifying power of polymers.

Endwalls impose a challenge to cool because of the complex system of secondary flows and separation lines disrupting surface film coolant coverage. The interaction of film cooling flows with secondary flow structures is coupled. The momentum exchange of the film coolant with the mainstream affect the formation the secondary flows, which in turn affect the coolant coverage. Therefore, to develop better endwall cooling schemes, a good understanding of passage aerodynamics as affected by interactions with coolant flows is required. This study presents experimental and computational results for cascade representing the first stage nozzle guide vane of a high-pressure gas turbine. The cascade is subsonic, linear, and stationary with an axisymmetrically-contoured endwall. Two cooling flows are simulated; upstream combustor liner coolant-in the form of an aero-thermal profile simulated in the approach flow and endwall slot film cooling, which is injected immediately upstream of the passage inlet. The experiment is run with engine representative combustor exit flow turbulence intensity and integral length scales, with high turbine passage exit Reynolds number of 1.61 × 106. Measurements are performed with various slot film cooling mass flow rate to mainstream flow rate ratios (MFR). Aerodynamic effects are documented with five-hole probe measurements at the exit plane. Varying the slot film cooling MFR results in minimal effects on total pressure loss for the range tested. Vorticity distributions show a very thin, yet intense, cross-pitch flow on the contoured endwall side. Coolant distribution fields that were previously presented for the same cascade are discussed in context of the aerodynamic measurements. A coolant vorticity parameter presenting the advective mixing of the coolant due to secondary flow vorticity is introduced. This parameter gives developers a new prospective on aerodynamic-thermal performance associated with cooled turbine endwall. The numerical study is conducted for the same test section geometry and is run under the same conditions. The applicability of using RANS turbulence closure models for simulating this type of flow is discussed. The effects of including the combustor coolant in the approach flow is also briefly discussed in context of the numerical results.

Abstract Automotive engine downsizing has placed an increased focus on the ability of the turbocharger to provide adequate boost levels across the full engine operating rage. To achieve the desired levels of turbocharger performance the turbine must be capable of operating effectively at the intended design point and also at off-design conditions. Mixed flow turbines (MFTs) provide a potential method to improve performance at off-design conditions and during transient engine operation. A unique feature of a MFT is the spanwise variation of incidence angle at the rotor leading edge. This results in additional flow separation from the blade suction surface near the hub under a wide range of operating conditions. The flow separation generates additional loss and has a detrimental impact on turbine performance. A novel design of turbine volute similar to a conventional twin-entry turbine volute was examined. The novel turbine volutes were designed to produce a spanwise variation in flow conditions at the rotor inlet. The primary objective was to reduce the incidence angle and increase the mass flow rate at the hub side of the passage relative to the shroud side, as it has previously been identified that this can be beneficial for MFT performance. A number of different volute geometries were examined by numerical analysis to determine the impact of key parameters on turbine performance. The results indicated that generating a suitable spanwise flow distribution could produce a moderate improvement in turbine efficiency at off-design operating conditions. The novel volute design also provided a means of achieving a degree of variable geometry operation to further improve off-design performance. Turbine performance was examined under the variable geometry operation and an improvement in turbine power output at low speed, off-design conditions was achieved. This was analogous to operating with a conventional pivoting vane variable geometry system and had the potential to benefit performance during transient engine operation.

The cooling system is required to ensure gas turbine can work at high temperature, which has exceeded the material limitation. An endwall cooling test rig was built up to conduct the endwall cooling research. A detailed work was done for analyzing characteristics of endwall heat transfer and discussing the multi-parameter influence mechanism of overall cooling effectiveness. The main flow side heat transfer coefficient, adiabatic film cooling effectiveness and overall cooling effectiveness were measured in the experiments. The effects of coolant mass flowrate ratio (MFR) were considered through the measurement. In order to analyze how each of the parameters works on overall cooling effectiveness, a one-dimensional correlation was developed. The results showed that obvious enhancement could be found in cooling effectiveness by increasing coolant MFR, and the film jet can be easily attached to the surface after the acceleration of the main flow in the nozzle channel. Comparing with film cooling effectiveness, overall cooling effectiveness distribution is more uniform, which is due to the influence of internal cooling. The verified one-dimensional analysis method showed that the improvement in film cooling would be most efficient to heighten overall cooling effectiveness. The improvement in film cooling would be more efficient when film cooling effectiveness is in high level than in low level. However, the enhancement of internal heat transfer is more efficient when internal heat transfer coefficient is low.

Iron County is a semi-rural area in southwestern Utah that is experiencing an increase in residential development. Although much of the development is on community sewer systems, many subdivisions use septic tank soil-absorption systems for wastewater disposal. Many of these septic-tank systems overlie the basin-fill deposits that compose the principal aquifer for the area. The purpose of our study is to provide tools for waterresource management and land-use planning. In this study we (1) characterize the water quality of four areas in Iron County (Newcastle, Kanarraville, Summit, and Paragonah) with emphasis on nutrients, and (2) provide a mass-balance analysis based on numbers of septic-tank systems, groundwater flow available for mixing, and baseline nitrate concentrations, and thereby recommend appropriate septic-system density requirements to limit water-quality degradation. We collected 57 groundwater samples and three surface water samples across the four study areas to establish baseline nitrate concentrations. The baseline nitrate concentrations for Newcastle, Kanarraville, Summit, and Paragonah are 1.51 mg/L, 1.42 mg/L, 2.2 mg/L, and 1.76 mg/L, respectively. We employed a mass-balance approach to determine septic-tank densities using existing septic systems and baseline nitrate concentrations for each region. Nitrogen in the form of nitrate is one of the principal indicators of pollution from septic tank soil-absorption systems. To provide recommended septic-system densities, we used a mass-balance approach in which the nitrogen mass from projected additional septic tanks is added to the current nitrogen mass and then diluted with groundwater flow available for mixing plus the water added by the septic-tank systems themselves. We used an allowable degradation of 1 mg/L with respect to nitrate. Groundwater flow volume available for mixing was calculated from existing hydrogeologic data. We used data from aquifer tests compiled from drinking water source protection documents to derive hydraulic conductivity from reported transmissivities. Potentiometric surface maps from existing publications and datasets were used to determine groundwater flow directions and hydraulic gradients. Our results using the mass balance approach indicate that the most appropriate recommended maximum septic-tank densities in Newcastle, Kanarraville, Summit, and Paragonah are 23 acres per system, 7 acres per system, 5 acres per system, and 11 acres per system, respectively. These recommendations are based on hydrogeologic parameters used to estimate groundwater flow volume. Public valley-wide sewer systems may be a better alternative to septic-tank systems where feasible.

High pressure EGR provides NOx emission reduction even at low exhaust temperatures. To maintain a safe EGR system operation over a required lifetime, the EGR cooler fouling must not exceed an allowable level, even if the engine is operated under worst-case conditions. A reliable fouling simulation model represents a valuable tool in the engine development process, which validates operating and calibration strategies regarding fouling tendency, helping to avoid fouling issues in a late development phase close to series production. Long-chained hydrocarbons in the exhaust gas essentially impact the fouling layer formation. Therefore, a simulation model requires reliable input data especially regarding mass flow of long-chained hydrocarbons transported into the cooler. There is a huge number of different hydrocarbon species in the exhaust gas, but their individual concentration typically is very low, close to the detection limit of standard in-situ measurement equipment like GC-MS. Therefore, a new measurement and analysis approach has been developed, where the exhaust gas is guided to a metal foam collector, in which HC`s are deposited. The probe is then analyzed in a suited thermogravimetrical system (TGA) in nitrogen atmosphere, temperature range 25°C to 650°C. Analyzing the TGA curve, HC concentration data for 6 different boiling temperature ranges are obtained, provided to an adapted 1-d fouling simulation model. Using these data along with further input parameters like cooler geometry, gas temperature, pressure, flow, particle size distribution and coolant temperature, the simulation model has proven as a suitable tool to predict the fouling and identify engine settings for fouling reduction.