| 41. |
- Soltani Dehkharqani, Arash
(författare)
-
An Experimental Investigation of a Prototype Kaplan Turbine and Numerical Analysis of Fluid Added Parameters on the Corresponding Model Turbine Runner
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Among the renewable energy sources, hydropower plays an important role by providing approximately 60% of the renewable electricity. Globally, there is a growing installed capacity of renewable energy sources. This, along with the energy policies to reduce greenhouse gas emissions promotes the development of alternative renewable energy sources such as solar and wind power. The penetration of intermittent energy sources seriously impacts the energy balance as well as the stability of the electrical grid. Therefore, it is required to guarantee a smooth integration of this share into the existing power grids. Hydraulic power plants are one of the key components to stabilize the electric grid. As a result, the extended operations and flexibility of hydraulic turbines increase, and hydraulic turbines are subject to unstable flow conditions and unfavorable load fluctuations at off-design operations. A better understanding of off-design and transient effects, particularly in full-scale hydraulic turbines, has the potential to provide new methodologies to predict the sources of load fluctuations on the runner and to mitigate issues associated with them. Such knowledge can increase turbine refurbishment time intervals and avoid structural failures in extreme cases.This thesis aims to develop methodologies (i.e., experimental and numerical) to assess Kaplan turbines flow conditions and flow effects on the structure under different operational conditions. The work is divided into two parts; an experimental measurement campaign performed on a full-scale Kaplan turbine, Porjus U9, and a numerical investigation of fluid-structure interaction in the corresponding model turbine. In the measurement campaign, several operational conditions ranging from start-up, speed-no-load, steady-state, load variations, emergency shutdown, runaway, and stop were examined. Steady-state and load variation measurements were carried out under on-cam and off-cam conditions. The main objective was to investigate the effect of the operation conditions on the pressure and stain fluctuations on the runner as well as the strain variations on the shaft. This would lead to propose a measurement methodology in which the blade loading can be predicted by strain measurements on the shaft. The pressure and strain measurements on the runner showed that different sources of fluctuations corresponding to a specific operating condition, e.g. part load and start-up, resulted in load fluctuations on the runner blade. The region in the proximity of the runner blade hub was observed as the most critical in terms of high strain value. During a start-up sequence, the strain measurement on the shaft revealed that both guide vane opening, and runner blade’s angle have a great effect on the strain value on the shaft. A correlation between the blade and shaft measurements seems to exist.The numerical simulations performed on the Porjus U9 model demonstrated that the added inertia and damping were important, whereas the stiffness was negligible. The dimensionless added polar inertia was 23%–27% of the reference value. Added damping significantly contributed to the moment at low excitation frequencies, whereas the inertia became dominant at higher frequencies. Considering the presence of multiple perturbations in the simulations, the added polar inertia could be assumed independent. Whereas, the interaction of the harmonics modified the added damping value, particularly at high perturbation frequencies.
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| 42. |
- Soria-Salinas, Álvaro
(författare)
-
Development of the Wind and Air Temperature Sensor of the ExoMars 2022 HABIT Instrument
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work presents the development, validation and calibration of the air temperature sensors (ATS) and the air and wind retrieval method of the HABIT (HabitAbility: Brines, Irradiation and Temperature) instrument. HABIT is one of the two European payloads of the ESA/Roscosmos ExoMars 2022 mission that will land at Oxia Planum (18.20° N, 335.45° E), on Mars.One of the main novelties of this Ph.D. thesis is to use the thin fins that work as ATS on HABIT as a wind sensor for the planetary boundary layer of Mars. The thesis is based on the study and modelling of heat transfer along three rods when exposed to forced convection in a gaseous fluid, and that is tested: (1) through computational fluid dynamic simulations, which provided inputs to the early design of the HABIT structure; (2) under laboratory conditions, with the use of a specifically designed prototype and a cooling fan; and (3) within a subsonic wind tunnel facility under terrestrial conditions.A preliminary validation of the wind speed retrieval approach is first performed using temperature measurements from Mars provided by the Rover Environmental Monitoring Station (REMS) instrument, on board the NASA Curiosity rover of the Mars Science Laboratory (MSL) mission. The method is based on modelling forced convection of the ATS of REMS when assumed as thin rods immersed in the extreme low-pressure and high-radiating atmospheric conditions of the Martian thermal boundary layer, at a height of ∼ 1.5 m from the surface. Assuming the previously reported REMS wind sensor (WS) retrieval errors of 20% for the wind speed, ±30° for the horizontal “front” wind directions, and ±45° for the horizontal “rear” wind directions, agreement with the WS values of up to 77% of the acquisition time, on average, for wind speeds and coincidence between 60% and 80% of the time for wind directions is reported for some sols. These promising results are limited to only evening extended acquisitions from 18:00 to 21:00 local mean solar time (LMST) and orientations within the validity region of the retrieval. That is, the method was only considered valid over a narrow angle range of 13° to 107° in azimuth angle. In addition to this, the results of this first study suggested a new optimal orientation when using the ATS for wind speed and direction retrievals of +60° clockwise with respect to the forward direction of the Curiosity rover.The wind retrieval model is also validated and calibrated with the HABIT engineering and qualification model (EQM) in the Aarhus Wind Tunnel Simulator (AWTS) of the Aarhus University, Denmark. The AWTS is designed to reproduce typical winds on the surface of Mars. The data acquired during the wind tunnel campaign were used to validate the forced convective and radiative heat transfer model for each of the three ATS. The campaign investigated winds in steady CO2 flows at a pressure of 9.9 mbar, an ambient temperature of 25°C, and for horizontal free-stream velocities between 0.8 and 12 m/s. Several relationships between the Nusselt number and the Reynolds and Prandtl numbers reported in the literature were evaluated in the tunnel to model forced convection through the ATS rods. Where needed, corrections to account for radiative heat transfer within the AWTS were implemented to correct for experimental artefacts. The tests demonstrated that this retrieval method can be used to derive wind speed for frontal winds on Mars in the range of 0 to 10 m/s, with an error of ±0.3 m/s, using the cooling profile of the ATS rod 3, and for lateral winds in the range of 0 to 6 m/s, with an error of ±0.3 m/s, using the ATS rod 2 cooling profile.The thesis also includes the calibration of the HABIT ATS flight model (FM) in the clean room of Omnisys Instruments AB, and the retrieval model that will be used in operations during the ExoMars 2022 mission and for archiving in the Planetary Science Archive (PSA) of the European Space Agency (ESA).Finally, the wind retrieval method developed in this thesis can be applied not only to the future analysis of HABIT data at Oxia Planum, but also to re-analyse the ATS data of REMS at Gale crater, and for future comparative analysis with the HABIT/ExoMars 2022, the Temperature and Wind Sensors for InSight (TWINS)/InSight, and the Mars Environmental Dynamics Analyzer (MEDA)/Mars 2020 rover instruments.
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| 43. |
- Strandkvist, Ida
(författare)
-
Minimisation of Chromium Leaching from Low-Alloy Electric Arc Furnace Slag by Mineral Modifications
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Iron and steel are produced continuously as a vital part of modern life. The largest by-product of metal production is slag. Slag is an essential part of the production of steel since, in the furnace, the molten slag removes impurities from the metal. When the slag which consists of oxides, solidifies minerals form. Slag can then be used in different applications: fertiliser, water purification, cement, concreate and as building material. By using slag, natural resources can be saved. In the electric arc furnace, EAF, scrap is melted to produce steel. The scrap contains chromium which partly distributes to the slag. Unfortunately, excessive leaching of chromium restricts slag usage. Chromium leaching occurs when chromium-containing minerals in slag dissolve. In low-alloy electric arc furnace slag there are three chromium containing minerals: spinel (Mg,Fe)Cr2O4, magnesiowüstite (Mg,Mn,Fe)O and brownmillerite Ca2(Al,Fe)2O5. Of these minerals the spinel has already been determined to be stable. The aim of this thesis is to minimise the chromium leaching of low-alloy EAF slag by modifying the minerals and/or mineralogy in the slag so that the chromium-containing minerals do not dissolve. In addition, it was discovered that ageing of low-alloy electric arc furnace slag may increase the chromium leaching. Autoclave treatment of remelted slag resulted in chromium leaching at the same magnitude as before remelting. Autoclave treatment was performed before the leaching test to determine the chromium leaching of aged slag.Instead of indirectly examining the chromium leaching from magnesiowüstite and brownmillerite by comparing chromium leaching from slag samples, the dissolution properties of the minerals were investigated individually. Dissolution of different compositions of magnesiowüstite and brownmillerite were studied at pH 7 and pH 10 for 40 hours. The conclusion was that increased iron content decreased the dissolution rate of both magnesiowüstite and brownmillerite. Magnesiowüstite (Mg,Fe)O did not dissolve at pH 10 when it contained 60 wt% FeO and did neither dissolve at pH 7 or pH 10 at higher FeO content. According to thermodynamic calculations, the FeO content in the magnesiowüstite can be affected and this was investigated. Laboratory and full-scale experiments showed that the composition of magnesiowüstite in slag could not be correlated to chromium leaching. The conclusion was that magnesiowüstite was not the main mineral leaching chromium.Brownmillerite composition is difficult to control in slag and had a significant impact on the dissolution rate; therefore, brownmillerite in slag should be avoided to minimise leaching of chromium. From thermodynamic calculations two options to avoid brownmillerite formation were identified: decreasing the basicity (CaO/SiO2 ratio) or increasing the cooling rate. Both methods were tested in laboratory scale using low-alloy electric arc furnace slag. When the basicity was decreased by SiO2 addition, the chromium leaching of the slag decreased. The chromium leaching was correlated to the brownmillerite content, the chromium leaching decreased with the decreasing basicity until brownmillerite was no longer be detected by XRD analysis. After that the chromium leaching did not decrease significantly. This indicates a correlation between basicity, brownmillerite and chromium leaching. When cooling of slag was investigated the slower cooling rates increased the chromium leaching and fast cooling rates decreased the chromium leaching. The results were verified by full-scale experiments. Si-sand addition was used to decrease the basicity to 2.2; according to thermodynamic calculations this would prevent brownmillerite formation. The targeted basicity of 2.2 was difficult to achieve, as the basicity varied between batches since the scrap composition and other parameters changed. Batches from other experiments were included for more data. It was seen that the chromium leaching of batches below basicity 2.2 did not reach the same magnitude as the batches above basicity 2.2. The full-scale trials with different cooling methods confirmed that the faster-cooled water-sprayed slag had lower chromium leaching than slag that had cooled by its own.Basicity between 2.0 and 2.2 minimises chromium leaching but decreasing the basicity to specific values in full-scale is challenging. A decrease in basicity is the most efficient method of decreasing chromium leaching, but faster cooling also decreases the chromium leaching.
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| 44. |
- Strömbergsson, Daniel
(författare)
-
Improving detection and diagnosis of bearing failures in wind turbine drivetrains
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wind power has in the last 20 years grown into one of the main sources of renewable energy in the world, with both the amount and size of the turbines increasing substantially. One of the major challenges for the wind power industry is the premature failures of especially the drivetrain components. These failures cause a lot of turbine downtime, which increases the operation and maintenance costs of the turbines. Failures in the gearbox have been shown to lead to the highest downtime and the multitude of bearings within that subsystem is overrepresented in the total amount of component failures. Vibrationbased condition monitoring is considered the best method to find these types of defects early and avoid prolonged turbine downtime. Previous research has therefore been focused on the different aspects of condition monitoring; i.e. measurement technologies, signal analysis of vibration measurements to improve detection and diagnosis as well as the implementation of machine learning solutions. However, the majority of research work has yet to evaluate the performance of new developments using wind turbine field data, and still no fundamentally new developments have seen a large-scale implementation in the industry. Further, it is known that the positioning of the accelerometer, used to measure the vibrations, affects the ability to detect and diagnose defects. However, it is not known how to optimally position the accelerometers to monitor the individual drivetrain sub-systems. Also, previous research does not show how the influence of the measurement properties of the field data affect the ability to detect and diagnose component failures.Therefore, this thesis provides a comprehensive evaluation of how to improve the detection and diagnosis of bearing failures specifically in wind turbine drivetrains. In this thesis, a simulation model was developed to study how the accelerometer positioning affects the measurement quality. Vibration simulations of a similar sized bearing to ones found in the wind turbine drivetrain show an optimal accelerometer position as close to the primary loaded zone of the bearings as possible. The current placement of the accelerometers in the wind turbine drivetrain are often diametrically opposed to the loaded zone, and the performance of the vibration monitoring with respect to the commonly used signal analysis tools could thereby be increased. Further, wavelet-based signal analysis has been evaluated using historical wind turbine drivetrain field data. A new implementation of the wavelet packet transform to analyse enveloped vibration measurements in the frequency domain was developed, where the measurements were decomposed into packets matching the frequency resolution of the fast Fourier transform, and analysing the packet energy spectra. Finally, an anomaly detection solution utilizing an artificial neural network has been implemented to separate the condition indicator values, used for detection and diagnosis, from their inherent variance due to the dynamic turbine operation seen in the drivetrain rotational speed. The results in this thesis show the inadequacy of the commonly stored vibration measurements to the condition monitoring databases when used in post failure investigations and application of research developments on available field data. Measurements both taken over a long period of time and covering wide frequency range should be stored, instead of the either/or of today. Otherwise, the real-time monitoring of wind turbine drivetrain bearing failures cannot be replicated and monitoring improvements not fully evaluated. By implementing the wavelet packet transform, the detection and diagnosis performance was increased 250% compared to the fast Fourier transform, in an example of gearbox output shaft bearing failure. By implementing the anomaly detection by the artificial neural network, the performance increased further and was able to provide indications in a planet bearing failure case, which was not possible before. For turbine owners, these results provide both practical actions to take and provide an example of an easily implementable signal analysis tool to improve the detection and diagnosis of drivetrain bearing failures. The anomaly detection, which utilizes available historic data from healthy turbines and does not require any amount of labelled data for all considered types of bearing failures, also shows promise to detect failures in the drivetrain components which has been historically problematic. For the research community, the results mainly provides guidance into using historic field data when evaluating new developments. Also, they highlight potential pitfalls one can face using field data and what data properties to look for to successfully show the potential of your work.
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| 45. |
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| 46. |
- Uusitalo, Petri, 1978-
(författare)
-
Using and Managing Resources in Industrialized House-Building : Characterization of a Swedish Industrialized House-Building Company from a Resource-Based View
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Global reports stress the importance of developing the construction industry to address productivity related issues and challenges with urbanization. McKinsey conclude that the construction industry could be more efficient by how they manage and employ resources to address the low productivity. With an expected intensified urbanization and rapidly changing global economic landscape, pressure is put on the current housing production pace. Therefore, industrialization has been promoted to make industries sustainable, with increased resource-use efficiency and greater adoption of innovation focusing on industrial processes. Technology companies has started to take an interest in the construction market as they see a potential in industrialization and scalability of the house-building and have made heavy investments in construction companies using prefabricated or modular manufacturing technics to build houses.Although industrialized house-building companies have been the subjects of wide-range of research, research into how to utilize industrialized house-building can be important and interesting not only to confront the low productivity but also increased resource-use efficiency and give an explanation how to benefit from the global interest into investing in industrialized house-building. Therefore, an increased understanding of industrialized house-building from a resource-based perspective, exemplified from a Swedish perspective, is considered to be of importance for further development the building industry.The contribution of this thesis is a synthesis of four different constructs (entrepreneurial orientation, dynamic capability, path dependency and technology transfer) discussed in three academic papers to characterize and build a further understanding of how an IHB company employ and manage their resources.Findings shows that on a corporate level, the industrialized house-building company managed resources in many different ways and they did so to secure their business and they showed different approaches towards how they employed resources. From a theoretical perspective, entrepreneurial orientation has a more proactive, long-term, and strategical focus on employing resources (both tangible and intangible) looking more at the bigger picture. Dynamic capability has a more reactive (addresses different aspects of change as it happens) and tactical focus on employing resources looking more at the small steps of sensing and seizing and reconfiguring of resources. Technology transfer can be expressed as an active process (two-way communication) on an operational level on how to employ resources between parties.Entrepreneurial orientation enabled the case company to continuously exploit and renew resources and competences but also to sense, seize, and reconfigure cumulative assets over time, which displayed as exponential build-up of dynamic capabilities. How the company worked with developing corporate assets showed that continuous development of dynamic capabilities also influenced the industry path dependency, by working with decreasing process variation caused by external factors. Later by exponentially develop dynamic capabilities, exploring Lean to renew the corporate culture; the increased standardized work operationalized their accumulated resources. Through small steps of exploitation and exploration and reconfiguration of working methods, the company continuously improved operations; routinized learning and use of built-up assets. The way they worked by constantly sense, seize and reconfigure their operations, address the assumption that companies grow in a path dependent way. This, in turn, has led to the possibility to employ resources through technology transfer of the industrialized house-building platform, into a business.
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| 47. |
- van Eldert, Jeroen, 1987-
(författare)
-
Drill Monitoring for Rock Mass Assessment in Tunnelling
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Site investigations for tunnel projects are often unable to determine rock mass conditions accurately for the entire tunnel, as these investigations obtain qualitative data for only limited parts of the tunnel. This is the case at the Stockholm Bypass project in Sweden. At two ramp tunnels, the rock mass was characterised as significantly poorer during the excavation than had been determined previously in the site investigation. In this study, Measurement While Drilling (MWD) technology was employed to characterise the rock mass for grouting purposes using extraction drill monitoring data from the grout holes. In addition, MWD data were extracted from blast holes at the entrance of one access and two ramp tunnels. The MWD data included the penetration rate and feed, percussive, rotation, and water pressure measurements at less than 3cm intervals in the drill holes. The drill rig supplier’s software was able to characterise the rock mass accurately for fracture zones, as shown in a comparison of the fracturing index of grout holes, blast holes, and the mappedrock mass structures. Since the suppliers’ software packages ignored some essential features of drilling, the study developed an improved MWD data normalisation and filtering process. This new process took the effects of different rock drills and drill rod extensions on the MWD data into account. The new normalisation and filtering process showed the capability to describe the rock mass conditions more accuratelythan the current method. A holistic approach was also developed to optimise the rock support process even further. Here, the rock mass was objectively qualified using measured drilling data instead of observations. This process correlated the fracturing index to rock mass quality and rock support requirements. Lastly, a correlation was made between the rock mass quality and the grout requirements per grout umbrella;these requirements were linked to the rock mass conditions determined by the MWD parameters. Based on these relations, a conceptual grout decision-making model was developed. The study found all-in-all tunnel practices could be improved with the implementation of MWD for rock mass characterisation and as part of a rock mass quality control plan. The MWD technology provides additional information on the rock mass and could be incorporated into the observational method for rock mass excavation.
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| 48. |
- Vrček, Aleks, 1991-
(författare)
-
Tribology of Rolling-Sliding Contacts under Mixed Lubrication : With focus on a Crankshaft Roller Bearing Application
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A continuous increase in environmental legislation to reduce CO2 emissions is forcing engineers and scientists to develop more efficient and durable mechanical components, i.e. bearings, crankshafts, gears, etc. Such components are forced to operate under more severe operating conditions, reduced lubrication conditions, and under increased power density. The main failure mode has switched from traditionally subsurface to surface-initiated fatigue, typically caused by surface distress or micro-pitting. In this work, the tribology of rolling/sliding contacts, mimicking rolling bearing contact kinematics, operating under mixed lubrication conditions was studied. A special focus was directed to investigate the feasibility of employing such contacts in a crankshaft rolling bearing application by studying the tribological interface between a crankshaft and a roller. Three bearing steels were identified, selected, and then test specimens were manufactured from these steels for this work to represent a possible crankshaft rolling bearing steel for a four-cylinder light-duty internal combustion engine (ICE), as the current crankshaft steel does not meet the requirements to represent the rolling bearing component. Three tribological screening techniques were selected for this work to understand and investigate the surface performance, i.e. micro-pitting and wear damage of the rolling/sliding contact. The effect of the surface roughness and hardness, steel, and lubricant on the surface performance was investigated. This work was purely experimental, utilizing two tribological test devices: a twin-disc machine and a ball-on-disc machine. The results from this work will allow us to select and optimize the tribology of crankshaft rolling bearing contacts and bearing contacts in general to maximize the surface performance and in turn, contribute to increased efficiency and reliability of mechanical components. Based on the results from this Ph.D. work, micro-pitting and wear damage presents the main damage mode that can be associated with the engine tribology for a crankshaft rolling bearing. Micro-pitting and wear damage were found to be strongly dependent on the surface roughness and hardness combination of both contacting surfaces. A critical hardness difference was found between both surfaces, which is dependent on steel and heat treatments, where wear mode changes from severe fatigue wear to mild wear. A fully formulated state-of-the-art engine oil showed an increased wear component and, in some cases, eliminated micro-pitting damage compared to using only the base oil. Furthermore, it was shown that the ZDDP additive, present in the engine oil, can function as an anti-wear (AW) additive, as intended, or an extreme pressure (EP) additive depending on the contact iv severity. The latter increases the wear component through mild corrosion and delamination of the surface tribolayer, which leads to surface-initiated fatigue.
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| 49. |
- Wernicke, Brian
(författare)
-
Diversity of Flow in Production Improvements in House Building
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Flow is a complex construct and has developed differently in different research fields. Some of the interpretations are included within this thesis and categorized in two main perspectives: (1) the individual flow perspective as defined in positive psychology and (2) the system flow perspective based on notations from supply chain management, lean production, construction management, and operations management. Both flow perspectives have at least one commonality which bases this thesis: to improve something towards a desirable condition. In positive psychology, that something is human well‐being and the system perspective focuses on entities that need to be combined to facilitate production. Both flow perspectives have been developed independently without clear consideration of each other, even though several theoretical sources indicate relevant relations between them. This thesis addresses that theoretical gap and aims to describe how system flows and individuals’ flow are related in initiatives intended to improve production in house building.The thesis is operationalized by a flow framework based on system flows and individuals’ flow. Within three different cases of improvement initiatives, qualitative data is analysed to exemplify how flow relations occur in the researched settings. Findings of quantitative patterns of traced flow relations exemplify flow relations and can inspire practitioners in assessing how the different flows are addressed in ongoing improvement initiatives and what other potential flows that could be addressed in future improvements. This thesis concludes that relations between flow on system level and flow on individual level can occur in improvement initiatives in house building production settings, thus exemplifying the ‘Diversity of Flow in Production Improvements in House Building’. Theoretically, this thesis contributes to the understanding of the flow concept in construction management, visualizes the diverse understanding of flow, and advocates that flow should not be treated as homogenous at any level.
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| 50. |
- Wu, Nanhua
(författare)
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Molecular Thermodynamic Models for Nano-Micro Fluid/Solid Interfaces
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introducing materials with large interfaces to enhance process performance has become a feature of advanced chemical engineering, where the research focus has been changed from the traditional ideal isotropic fluid in the bulk phase to the highly non-ideal anisotropic confined fluid on the nano-micro interfaces, owing to the strong and asymmetric interactions between the complex fluids (supported metal nanoparticles, ionic liquids, proteins, etc.) and the sophisticated solid-surface (roughness, electrostatic effects, chemical heterogeneities, etc.). The traditional theories cannot be used to accurately describe the properties of the fluids at the complex solid-surfaces, due to the lack of considering molecular interactions between the fluid and solid-surface, and establishing new models is essential.In this thesis, a generalized interfacial molecular thermodynamic model was proposed with the consideration of molecular interactions between the fluid and solid-surface. Firstly, the original and surface-energy modified Gibbs-Thomson equations were analyzed to calculate the melting points of mono noble metals and compared with the literature data, highlighting the importance of developing new models with the consideration of the interfacial effect. An empirical model was proposed to represent the interfacial effect for calculating the melting points of mono noble metals. Then, the mono noble metal nanoparticle supported at the flat solid-surface was chosen as the “model” system to develop a generalized model, and the developed model was extended to the supported alloy systems. The CO2 absorption capacity (or solubility) of the ionic liquids immobilized on the porous solid materials (substrates) was further investigated with the developed model. The main results were summarized as follows:To develop models for representing the melting points of mono noble metal nanoparticles, the original and surface-energy modified Gibbs-Thomson equations were analyzed and then further modified empirically considering the effect of substrate. The results revealed that the original Gibbs–Thomson equation is invalid for the particles with radii smaller than 10 nm, and the performance of the surface-energy modified equation was improved but further modification by considering the interfacial effect is necessary for the particles smller than 5 nm in radius. The empirical model with the interfacial effect further improved the model performance, and the adjustable parameters can be predicted quantitatively from the thermodynamic properties of the metal and substrate. Additionally, the micro-wetting parameter αw can be used to qualitatively study the overall impact of the substrate on the melting point depression.Combined with the analysis of the corresponding state theory, a generalized molecular thermodynamic model was developed. It was found that, the developed generalized model can provide accurate results of melting points with deviations within ± 15 K. The developed model was used to predict the melting point of Pt nanoparticles on the substrates of TiO2 and carbon (C), and the results showed that Pt on TiO2 was more stable than that on C, being consistent with the newly measured experimental results.The generalized model was further parameterized based on the analysis of the interfacial tensions and molar volumes of Al-Si3N4, Pb-Si, Bi-C, and In-C, and the model showed the deviation was within ± 36 K. The model with fully generalized parameters was extended to the supported alloy nanoparticles to illustrate their stabilities, where the common catalysts, Pd-Au alloy nanoparticles supported on different substrates, developed for H2O2 reaction, were chosen as the examples. The model prediction displayed that the Pd-Au alloy nanoparticles supported on C/TiO2 (molar ratio: 0.01) with the mass proportion Pd5Au1 (i.e., mass ratio of 5:1) is more stable than the mono noble metals. Furthermore, the model prediction indicated that the supported alloy nanoparticles are more stable than the supported Pd.The generalized model was also successfully extended to study the CO2 absorption capacity in the immobilized ionic liquids, where the Gibbs free energy of CO2 in the immobilized ionic liquids was modeled from both macro- and micro-analyses. The theoretical investigations revealed that the substrate has a crucial effect on the gas solubility in the ionic liquid immobilized on the substrates, and the performance of the model with the consideration of surface-energy and interfacial effects was further verified with the newly determined experimental data.
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