Matching Items (53)
Filtering by
- All Subjects: energy
- All Subjects: Heat Transfer
- All Subjects: Renewable Energy
- Creators: Phelan, Patrick
- Creators: Chemical Engineering Program
Description
Fossil fuels are currently the main source of energy in the world’s transportation sector. They are also the primary contributor to carbon emissions in the atmosphere, leading to adverse climate effects. The objective of the following research is to increase the yield and efficiency of algal biofuel in order to establish algal-derived fuel as a competitive alternative to predominantly used fossil fuels. Using biofuel commercially will reduce the cost of production and ultimately decrease additional carbon emissions. Experiments were performed using hydrothermal liquefaction (HTL) to determine which catalyst would enhance the algal biocrude oil and result in the highest quality biofuel product, as well as to find the optimal combination of processing temperature and manure co-liquefaction of biomass ratio. For the catalytic upgrading experiments, Micractenium Immerum algae was used in conjunction with pure H2, Pt/C, MO2C, and HZSM-5 catalysts at 350℃ and 400℃, 430 psi, and a 30-minute residence time to investigate the effects of catalyst choice and temperature on the crude oil yield. While all catalysts increased the carbon content of the crude oil, it was found that using HZSM-5 at 350℃ resulted in the greatest overall yield of about 75%. However, the Pt/C catalyst increased the HHV from 34.26 MJ/kg to 43.26 MJ/kg. Cyanidioschyzon merolae (CM) algae and swine manure were utilized in the co-liquefaction experiments, in ratios (algae to swine) of 80:20, 50:50, and 20:80 at temperatures of 300℃ and 330℃. It was found that a ratio of 80:20 at 330℃ produced the highest biocrude oil yield of 29.3%. Although the 80:20 experiments had the greatest biomass conversion and best supported the deacidification of the oil product, the biocrude oil had a HHV of 33.58 MJ/kg, the lowest between the three different ratios. However, all calorific values were relatively close to each other, suggesting that both catalytic upgrading and co-liquefaction can increase the efficiency and economic viability of algal biofuel.
ContributorsMurdock, Tessa A (Author) / Deng, Shuguang (Thesis director) / Varman, Arul (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Ionic liquids are salts with low melting temperatures that maintain their liquid form below 100 °C, or even at ambient temperature. Ionic liquids are conductive, electrochemically stable, non-volatile, and have a low vapor pressure, making them a class of excellent candidate materials for electrolytes in energy storage, electrodeposition, batteries, fuel cells, and supercapacitors. Due to their multiple advantages, the use of ionic liquids on Earth has been widely studied; however, further research must be done before their implementation in space. The extreme temperatures encountered during space travel and extra-terrestrial deployment have the potential to greatly affect the liquid electrolyte system. Examples of low temperature planetary bodies are the permanently shadowed sections of the moon or icy surfaces of Jupiter’s moons. Recent studies have explored the limits of glass transition temperatures for ionic liquid systems. The project is centered around the development of an ionic liquid system for a molecular electronic transducer seismometer that would be deployed on the low temperature system of Europa. For this project, molecular dynamics simulations used input intermolecular and intramolecular parameters that then simulated molecular interactions. Molecular dynamics simulations are based around the statistical mechanics of chemistry and help calculate equilibrium properties that are not easily calculated by hand. These simulations will give insight into what interactions are significant inside a ionic liquid solution. The simulations aim to create an understanding how ionic liquid electrolyte systems function at a molecular level. With this knowledge one can tune their system and its contents to adapt the systems properties to fit all environments the seismometers will experience.
ContributorsDavis, Vincent Champneys (Author) / Dai, Lenore (Thesis director) / Gliege, Marisa (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Nuclear power has recently experienced a resurgence in interest due to its ability to generate significant amounts of relatively clean energy. However, the overall size of nuclear power plants still poses a problem to future advancements. The bulkiness of components in the plant contribute to longer construction times, higher building and maintenance costs, and the isolation of nuclear plants from populated areas. The goal of this project was to analyze the thermal performance of nanocrystalline copper tantalum (NC Cu-Ta) inside the steam generator of a pressurized water reactor to see how much the size of these units could be reduced without affecting the amount of heat transferred through it. The analysis revealed that using this material, with its higher thermal conductivity than the traditional Inconel Alloy 600 that is typically used in steam generators, it is possible to reduce the height of a steam generator from 21 meters to about 18.6 meters, signifying a 11.6% reduction in height. This analysis also revealed a diminishing return that occurs with increasing the thermal conductivity on both reducing the required heat transfer area and increasing the overall heat transfer coefficient.
ContributorsRiese, Alexander (Author) / Phelan, Patrick (Thesis director) / Bocanegra, Luis (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Ensuring that people across the globe have enough water and electricity are two large issues that continue to grow. This study performs a test on whether using solar photovoltaic modules to shade water can potentially help diminish the issues of water and power. Using the setup of a PV module shading water, a stand-alone PV module, and unshaded water, it was found that shading water can reduce evaporation and lower PV module operating temperature at the same time. Using averaged data from two days of testing, the volume per unit surface area of water that evaporated per hour was 0.319 cm3/cm2 less for the shaded water compared to the unshaded water. The evaporation rates found in the experiment are compared to those of Lake Mead to see the amount of water lost on a large scale. For the operating temperature of the PV module, the module used for shading had a consistently lower temperature than the stand-alone module. On the first day, the shading module had an average temperature 5.1 C lower than the stand-alone module average temperature. On day two, the shading module had an average temperature 3.4 C lower than the stand-alone module average temperature. Using average temperatures between the two days from 10:30am and 4:45pm, the average daily temperature of the panel used for shading was 4.5C less than the temperature of the stand-alone panel. These results prove water shading by solar PV modules to be effective in reducing evaporation and lowering module operating temperature. Last, suggestions for future studies are discussed, such as performance analysis of the PV modules in this setting, economic analysis of using PV modules as shading, and the isolation of the different factors of evaporation (temperature, wind speed, and humidity).
ContributorsLee, John C (Author) / Phelan, Patrick (Thesis director) / Roedel, Ronald (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
There is an increasing need to understand and develop clean cooking technologies in low- and middle-income countries (LMICs). The provision of clean energy where modern energy is not available is important in advancing the 17 sustainable development goals as set by the United Nations. Green charcoal is a cooking fuel technology made from ground and compressed biochar, an organic material made from heating a feedstock (biomass, forest residues, agriculture waste, invasive species, etc.) in an oxygen deprived environment to high temperatures. Green charcoal behaves similarly to wood charcoal or coal but is different from these energy products in that it is produced from biomass, not from wood or fossil fuels. Green charcoal has gained prominence as a cooking fuel technology in South-East Asia recently. Within the context of Nepal, green charcoal is currently being produced using lantana camara, an invasive species in Nepal, as a feedstock in order to commoditize the otherwise destructive plant. The purpose of this study was to understand the innovation ecosystem of green charcoal within the context of Nepal’s renewable energy sector. An innovation ecosystem is all of the actors, users and conditions that contribute to the success of a particular method of value creation. Through a series of field interviews, it was determined that the main actors of the green charcoal innovation ecosystem are forest resources governance agencies, biochar producers, boundary organizations, briquette producers, distributors/vendors, the political economy of energy, and the food culture of individuals. The end user (user segment) of this innovation ecosystem is restaurants. Each actor was further analyzed based on the Ecosystem Pie Model methodology as created by Talmar, et al. using the actor’s individual resources, activities, value addition, value capture, dependence on green charcoal and the associated risk as the building blocks for analysis. Based on ecosystem analysis, suggestions were made on how to strengthen the green charcoal innovation ecosystem in Nepal’s renewable energy sector based on actor-actor and actor-green charcoal interactions, associated risks and dependence, and existing knowledge and technology gaps. It was determined that simply deploying a clean cooking technology does not guarantee success of the technology. Rather, there are a multitude of factors that contribute to the success of the clean cooking technology that deserve equal amounts of attention in order to successfully implement the technology.
ContributorsDieu, Megan (Author) / Chhetri, Netra (Thesis director) / Henderson, Mark (Committee member) / Chemical Engineering Program (Contributor, Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This honors thesis is focused on two separate catalysis projects conducted under the mentorship of Dr. Javier Pérez-Ramírez at ETH Zürich. The first project explored ethylene oxychlorination over supported europium oxychloride catalysts. The second project investigated alkyne semihydrogenation over nickel phosphide catalysts. This work is the subject of a publication of which I am a co-author, as cited below.
Project 1 Abstract: Ethylene Oxychlorination
The current two-step process for the industrial process of vinyl chloride production involves CuCl2 catalyzed ethylene oxychlorination to ethylene dichloride followed by thermal cracking of the latter to vinyl chloride. To date, no industrial application of a one-step process is available. To close this gap, this work evaluates a wide range of self-prepared supported CeO2 and EuOCl catalysts for one-step production of vinyl chloride from ethylene in a fixed-bed reactor at 623 773 K and 1 bar using feed ratios of C2H4:HCl:O2:Ar:He = 3:3 6:1.5 6:3:82 89.5. Among all studied systems, CeO2/ZrO2 and CeO2/Zeolite MS show the highest activity but suffer from severe combustion of ethylene, forming COx, while 20 wt.% EuOCl/γ-Al2O3 leads to the best vinyl chloride selectivity of 87% at 15.6% C2H4 conversion with complete suppression of CO2 formation and only 4% selectivity to CO conversion for over 100 h on stream. Characterization by XRD and EDX mapping reveals that much of the Eu is present in non-active phases such as Al2Eu or EuAl4, indicating that alternative synthesis methods could be employed to better utilize the metal. A linear relationship between conversion and metal loading is found for this catalyst, indicating that always part of the used Eu is available as EuOCl, while the rest forms inactive europium aluminate species. Zeolite-supported EuOCl slightly outperforms EuOCl/γ Al2O3 in terms of total yield, but is prone to significant coking and is unstable. Even though a lot of Eu seems locked in inactive species on EuOCl/γ Al2O3, these results indicate possible savings of nearly 16,000 USD per kg of catalyst compared to a bulk EuOCl catalyst. These very promising findings constitute a crucial step for process intensification of polyvinyl chloride production and exploring the potential of supported EuOCl catalysts in industrially-relevant reactions.
Project 2 Abstract: Alkyne Semihydrogenation
Despite strongly suffering from poor noble metal utilization and a highly toxic selectivity modifier (Pb), the archetypal catalyst applied for the three-phase alkyne semihydrogenation, the Pb-doped Pd/CaCO3 (Lindlar catalyst), is still being utilized at industrial level. Inspired by the very recent strategies involving the modification of Pd with p-block elements (i.e., S), this work extrapolates the concept by preparing crystalline metal phosphides with controlled stoichiometry. To develop an affordable and environmentally-friendly alternative to traditional hydrogenation catalysts, nickel, a metal belonging to the same group as Pd and capable of splitting molecular hydrogen has been selected. Herein, a simple two-step synthesis procedure involving nontoxic precursors was used to synthesize bulk nickel phosphides with different stoichiometries (Ni2P, Ni5P4, and Ni12P5) by controlling the P:Ni ratios. To uncover structural and surface features, this catalyst family is characterized with an array of methods including X-ray diffraction (XRD), 31P magic-angle nuclear magnetic resonance (MAS-NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Bulk-sensitive techniques prove the successful preparation of pure phases while XPS analysis unravels the facile passivation occurring at the NixPy surface that persists even after reductive treatment. To assess the characteristic surface fingerprints of these materials, Ar sputtering was carried out at different penetration depths, reveling the presence of Ni+ and P-species. Continuous-flow three-phase hydrogenations of short-chain acetylenic compounds display that the oxidized layer covering the surface is reduced under reaction conditions, as evidenced by the induction period before reaching the steady state performance. To assess the impact of the phosphidation treatment on catalytic performance, the catalysts were benchmarked against a commercial Ni/SiO2-Al2O3 sample. While Ni/SiO2-Al2O3 presents very low selectivity to the alkene (the selectivity is about 10% at full conversion) attributed to the well-known tendency of naked nickel nanoparticles to form hydrides, the performance of nickel phosphides is highly selective and independent of P:Ni ratio. In line with previous findings on PdxS, kinetic tests indicate the occurrence of a dual-site mechanism where the alkyne and hydrogen do not compete for the same site.
This work is the subject of a publication of which I am a co-author, as cited below.
D. Albani; K. Karajovic; B. Tata; Q. Li; S. Mitchell; N. López; J. Pérez-Ramírez. Ensemble Design in Nickel Phosphide Catalysts for Alkyne Semi-Hydrogenation. ChemCatChem 2019. doi.org/10.1002/cctc.201801430
Project 1 Abstract: Ethylene Oxychlorination
The current two-step process for the industrial process of vinyl chloride production involves CuCl2 catalyzed ethylene oxychlorination to ethylene dichloride followed by thermal cracking of the latter to vinyl chloride. To date, no industrial application of a one-step process is available. To close this gap, this work evaluates a wide range of self-prepared supported CeO2 and EuOCl catalysts for one-step production of vinyl chloride from ethylene in a fixed-bed reactor at 623 773 K and 1 bar using feed ratios of C2H4:HCl:O2:Ar:He = 3:3 6:1.5 6:3:82 89.5. Among all studied systems, CeO2/ZrO2 and CeO2/Zeolite MS show the highest activity but suffer from severe combustion of ethylene, forming COx, while 20 wt.% EuOCl/γ-Al2O3 leads to the best vinyl chloride selectivity of 87% at 15.6% C2H4 conversion with complete suppression of CO2 formation and only 4% selectivity to CO conversion for over 100 h on stream. Characterization by XRD and EDX mapping reveals that much of the Eu is present in non-active phases such as Al2Eu or EuAl4, indicating that alternative synthesis methods could be employed to better utilize the metal. A linear relationship between conversion and metal loading is found for this catalyst, indicating that always part of the used Eu is available as EuOCl, while the rest forms inactive europium aluminate species. Zeolite-supported EuOCl slightly outperforms EuOCl/γ Al2O3 in terms of total yield, but is prone to significant coking and is unstable. Even though a lot of Eu seems locked in inactive species on EuOCl/γ Al2O3, these results indicate possible savings of nearly 16,000 USD per kg of catalyst compared to a bulk EuOCl catalyst. These very promising findings constitute a crucial step for process intensification of polyvinyl chloride production and exploring the potential of supported EuOCl catalysts in industrially-relevant reactions.
Project 2 Abstract: Alkyne Semihydrogenation
Despite strongly suffering from poor noble metal utilization and a highly toxic selectivity modifier (Pb), the archetypal catalyst applied for the three-phase alkyne semihydrogenation, the Pb-doped Pd/CaCO3 (Lindlar catalyst), is still being utilized at industrial level. Inspired by the very recent strategies involving the modification of Pd with p-block elements (i.e., S), this work extrapolates the concept by preparing crystalline metal phosphides with controlled stoichiometry. To develop an affordable and environmentally-friendly alternative to traditional hydrogenation catalysts, nickel, a metal belonging to the same group as Pd and capable of splitting molecular hydrogen has been selected. Herein, a simple two-step synthesis procedure involving nontoxic precursors was used to synthesize bulk nickel phosphides with different stoichiometries (Ni2P, Ni5P4, and Ni12P5) by controlling the P:Ni ratios. To uncover structural and surface features, this catalyst family is characterized with an array of methods including X-ray diffraction (XRD), 31P magic-angle nuclear magnetic resonance (MAS-NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Bulk-sensitive techniques prove the successful preparation of pure phases while XPS analysis unravels the facile passivation occurring at the NixPy surface that persists even after reductive treatment. To assess the characteristic surface fingerprints of these materials, Ar sputtering was carried out at different penetration depths, reveling the presence of Ni+ and P-species. Continuous-flow three-phase hydrogenations of short-chain acetylenic compounds display that the oxidized layer covering the surface is reduced under reaction conditions, as evidenced by the induction period before reaching the steady state performance. To assess the impact of the phosphidation treatment on catalytic performance, the catalysts were benchmarked against a commercial Ni/SiO2-Al2O3 sample. While Ni/SiO2-Al2O3 presents very low selectivity to the alkene (the selectivity is about 10% at full conversion) attributed to the well-known tendency of naked nickel nanoparticles to form hydrides, the performance of nickel phosphides is highly selective and independent of P:Ni ratio. In line with previous findings on PdxS, kinetic tests indicate the occurrence of a dual-site mechanism where the alkyne and hydrogen do not compete for the same site.
This work is the subject of a publication of which I am a co-author, as cited below.
D. Albani; K. Karajovic; B. Tata; Q. Li; S. Mitchell; N. López; J. Pérez-Ramírez. Ensemble Design in Nickel Phosphide Catalysts for Alkyne Semi-Hydrogenation. ChemCatChem 2019. doi.org/10.1002/cctc.201801430
ContributorsTata, Bharath (Author) / Deng, Shuguang (Thesis director) / Muhich, Christopher (Committee member) / Chemical Engineering Program (Contributor, Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Rotary drums are commonly used for their high heat and mass transfer rates in the manufacture of pharmaceuticals, cement, food, and other particulate products. These processes are difficult to model because the particulate behavior is governed by the process conditions such as particle size, particle size distribution, shape, composition, and operating parameters, such as fill level and rotation rate. More research on heat transfer in rotary drums will increase operating efficiency, leading to tremendous energy savings on a global scale. This study investigates the effects of drum fill level and rotation rate on the steady-state average particle bed temperature. 3 mm silica beads and a stainless steel rotary drum were used at fill levels ranging from 10 \u2014 25 % and rotation rates from 2 \u2014 10 rpm. Four heat guns were used to heat the system via conduction and convection, and an infrared camera was used to record temperature data. A three-level, two-factor, full-factorial design of experiments was employed to determine the effects of each factor on the steady-state average bed temperature. Low fill level and high rotation rate resulted in higher steady-state average bed temperatures. A quantitative model showed that rotation rate had a larger impact on the steady-state bed temperature than fill level.
ContributorsBoepple, Brandon Richard (Author) / Emady, Heather (Thesis director) / Adepu, Manogna (Committee member) / W.P. Carey School of Business (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
This paper presents an experimental investigation into the effects of altering electrode surface area roughness on thermogalvanic cell performance. A temperature difference between two electrodes was induced and brought to steady state to achieve a difference of around 50 °C, which was maintained with a DC power generated hot wire and a pumped ice bath. The open-circuit voltage values at steady-state were measured by a programed multimeter and the temperatures were measured by a series of type K thermocouples. Electrode surface area roughness was altered using different grit values of sandpaper and measuring the values using a Zescope Optical Profilometer. Once three different surface area average values were achieved, 6 trials were performed with 2 trials per roughness value. The results were tabulated in Section 4 of this report.
It was predicted that increasing the surface area roughness would increase the number of electrons present in the reduction oxidation reaction and decrease the activation resistance of the thermogalvanic system. Decreasing the activation resistance, a component of total internal resistance, would therefore increase the power output of the cell by a small magnitude. The results showed that changing the surface area roughness of the Copper electrodes evidently had no effect on the outputs of the cell system. Additionally, the Seebeck coefficient was also unaffected by the presence of increased surface area roughness.
The work presented in the following paper is part of a continuing effort to better understand the performance of thermogalvanic cells and their heat to electrical energy transfer properties.
It was predicted that increasing the surface area roughness would increase the number of electrons present in the reduction oxidation reaction and decrease the activation resistance of the thermogalvanic system. Decreasing the activation resistance, a component of total internal resistance, would therefore increase the power output of the cell by a small magnitude. The results showed that changing the surface area roughness of the Copper electrodes evidently had no effect on the outputs of the cell system. Additionally, the Seebeck coefficient was also unaffected by the presence of increased surface area roughness.
The work presented in the following paper is part of a continuing effort to better understand the performance of thermogalvanic cells and their heat to electrical energy transfer properties.
ContributorsLopez, Maggie Marie (Author) / Phelan, Patrick (Thesis director) / Miner, Mark (Committee member) / School of Sustainability (Contributor) / School of Music (Contributor) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Solid oxide fuel cells have become a promising candidate in the development of high-density clean energy sources for the rapidly increasing demands in energy and global sustainability. In order to understand more about solid oxide fuel cells, the important step is to understand how to model heterogeneous materials. Heterogeneous materials are abundant in nature and also created in various processes. The diverse properties exhibited by these materials result from their complex microstructures, which also make it hard to model the material. Microstructure modeling and reconstruction on a meso-scale level is needed in order to produce heterogeneous models without having to shave and image every slice of the physical material, which is a destructive and irreversible process. Yeong and Torquato [1] introduced a stochastic optimization technique that enables the generation of a model of the material with the use of correlation functions. Spatial correlation functions of each of the various phases within the heterogeneous structure are collected from a two-dimensional micrograph representing a slice of a solid oxide fuel cell through computational means. The assumption is that two-dimensional images contain key structural information representative of the associated full three-dimensional microstructure. The collected spatial correlation functions, a combination of one-point and two-point correlation functions are then outputted and are representative of the material. In the reconstruction process, the characteristic two-point correlation functions is then inputted through a series of computational modeling codes and software to generate a three-dimensional visual model that is statistically similar to that of the original two-dimensional micrograph. Furthermore, parameters of temperature cooling stages and number of pixel exchanges per temperature stage are utilized and altered accordingly to observe which parameters has a higher impact on the reconstruction results. Stochastic optimization techniques to produce three-dimensional visual models from two-dimensional micrographs are therefore a statistically reliable method to understanding heterogeneous materials.
ContributorsPhan, Richard Dylan (Author) / Jiao, Yang (Thesis director) / Ren, Yi (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
In microbial fuel cells (MFCs) the biocathode is developed as a potential alternative to chemical cathodic catalysts, which are deemed as expensive and unsustainable for applications. These cells utilize different types of microorganisms as catalysts to promote biodegradation of organic matter while simultaneously converting energy released in metabolic reactions into electrical energy. Most current research have focused more on the anodic microbes, including the current generating bacteria species, anodic microbial community composition, and the mechanisms of the extracellular electron transfer. Compared to the anode, research on the microbes of the biocathode of the MFCs are very limited and are heavily focused on the role of the bacteria in the system. Thus, further understand of the mechanism of the microbial community in the biocathode will create new engineering applications for sustainable energy. Previous research conducted by Strycharz-Glaven et al. presented an electrochemical analysis of a Marinobacter-dominated biocathode communitygrown on biocathodes in sediment/seawater-based MFCs. Chronoamperometry results indicated that current densities up to -0.04 A/m2 were produced for the biocathode. Cyclic voltammetry responses indicated a midpoint potential at 0.196 V ± 0.01 V. However, the reactor design for these experiments showed that no oxygen is supplied to the electrochemical system. By incorporating an air diffusion membrane to the cathode of the reactor, chronoamperometry results have produced current density in the system up to -0.15 A/m2. Cyclic voltammetry results have also displayed a midpoint potential of 0.25 V ± 0.01 V under scan rates of 0.2 mV/s. Thus, this electrochemical setup has increased the current output of the system.
ContributorsWang, Zixuan (Author) / Torres, Cesar (Thesis director) / Hart, Steven (Committee member) / Materials Science and Engineering Program (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05