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- Creators: Prokofiev, Sergey, 1891-1953
Description
The concept of this thesis came up as a part of the efforts being devoted around the world to reduce energy consumption, CO2 emissions, global warming and ozone layer depletion. In the United States, HVAC units in residential buildings consumed about 350 billion kWh in 2017 [1],[2]. Although HVAC manufacturers are investing in new technologies and more efficient products to reduce energy consumption, there is still room for further improvement.
One way of reducing cooling and heating energy in residential buildings is by allowing the centralized HVAC unit to supply conditioned air to only occupied portions of the house by applying smart HVAC zoning. According to the United States Energy Information Administration [3], the percentage of houses equipped with centralized HVAC units is over 70%, which makes this thesis applicable to the majority of houses in the United States. This thesis proposes to implement HVAC zoning in a smart way to eliminate all human errors, such as leaving the AC unit on all day, which turns out to be causing a serious amount of energy to be wasted.
The total amount of energy that could be saved by implementing the concepts presented in this thesis in all single-family houses in the U.S. is estimated to be about 156 billion kWh annually. This amount of energy reduction is proportional to the electricity bills and the amount of dollars paid annually on energy that is technically being wasted.
One way of reducing cooling and heating energy in residential buildings is by allowing the centralized HVAC unit to supply conditioned air to only occupied portions of the house by applying smart HVAC zoning. According to the United States Energy Information Administration [3], the percentage of houses equipped with centralized HVAC units is over 70%, which makes this thesis applicable to the majority of houses in the United States. This thesis proposes to implement HVAC zoning in a smart way to eliminate all human errors, such as leaving the AC unit on all day, which turns out to be causing a serious amount of energy to be wasted.
The total amount of energy that could be saved by implementing the concepts presented in this thesis in all single-family houses in the U.S. is estimated to be about 156 billion kWh annually. This amount of energy reduction is proportional to the electricity bills and the amount of dollars paid annually on energy that is technically being wasted.
ContributorsFairag, Amr (Author) / Phelan, Patrick (Thesis advisor) / Bocanegra, Luis (Committee member) / Shuaib, Abdelrahman (Committee member) / Arizona State University (Publisher)
Created2018
Description
In this research, a new cutting edge wear estimator for micro-endmilling is developed and the reliabillity of the estimator is evaluated. The main concept of this estimator is the minimum chip thickness effect. This estimator predicts the cutting edge radius by detecting the drop in the chip production rate as the cutting edge of a micro- endmill slips over the workpiece when the minimum chip thickness becomes larger than the uncut chip thickness, thus transitioning from the shearing to the ploughing dominant regime. The chip production rate is investigated through simulation and experiment. The simulation and the experiment show that the chip production rate decreases when the minimum chip thickness becomes larger than the uncut chip thickness. Also, the reliability of this estimator is evaluated. The probability of correct estimation of the cutting edge radius is more than 80%. This cutting edge wear estimator could be applied to an online tool wear estimation system. Then, a large number of cutting edge wear data could be obtained. From the data, a cutting edge wear model could be developed in terms of the machine control parameters so that the optimum control parameters could be applied to increase the tool life and the machining quality as well by minimizing the cutting edge wear rate.
In addition, in order to find the stable condition of the machining, the stabillity lobe of the system is created by measuring the dynamic parameters. This process is needed prior to the cutting edge wear estimation since the chatter would affect the cutting edge wear and the chip production rate. In this research, a new experimental set-up for measuring the dynamic parameters is developed by using a high speed camera with microscope lens and a loadcell. The loadcell is used to measure the stiffness of the tool-holder assembly of the machine and the high speed camera is used to measure the natural frequency and the damping ratio. From the measured data, a stability lobe is created. Even though this new method needs further research, it could be more cost-effective than the conventional methods in the future.
In addition, in order to find the stable condition of the machining, the stabillity lobe of the system is created by measuring the dynamic parameters. This process is needed prior to the cutting edge wear estimation since the chatter would affect the cutting edge wear and the chip production rate. In this research, a new experimental set-up for measuring the dynamic parameters is developed by using a high speed camera with microscope lens and a loadcell. The loadcell is used to measure the stiffness of the tool-holder assembly of the machine and the high speed camera is used to measure the natural frequency and the damping ratio. From the measured data, a stability lobe is created. Even though this new method needs further research, it could be more cost-effective than the conventional methods in the future.
ContributorsLee, Jue-Hyun (Author) / SODEMANN, ANGELA A (Thesis advisor) / Shuaib, Abdelrahman (Committee member) / Hsu, Keng (Committee member) / Artemiadis, Panagiotis (Committee member) / Liu, Yongming (Committee member) / Arizona State University (Publisher)
Created2019
Description
This work aimed to characterize and optimize the variables that influence the Gas Diffusion Layer (GDL) preparation using design of experiment (DOE) approach. In the process of GDL preparation, the quantity of carbon support and Teflon were found to have significant influence on the Proton Exchange Membrane Fuel Cell (PEMFC). Characterization methods like surface roughness, wetting characteristics, microstructure surface morphology, pore size distribution, thermal conductivity of GDLs were examined using laser interferometer, Goniometer, SEM, porosimetry and thermal conductivity analyzer respectively. The GDLs were evaluated in single cell PEMFC under various operating conditions of temperature and relative humidity (RH) using air as oxidant. Electrodes were prepared with different PUREBLACK® and poly-tetrafluoroethylene (PTFE) content in the diffusion layer and maintaining catalytic layer with a Pt-loading (0.4 mg cm-2). In the study, a 73.16 wt.% level of PB and 34 wt.% level of PTFE was the optimal compositions for GDL at 70 °C for 70% RH under air atmosphere.
For most electrochemical processes the oxygen reduction is very vita reaction. Pt loading in the electrocatalyst contributes towards the total cost of electrochemical devices. Reducing the Pt loading in electrocatalysts with high efficiency is important for the development of fuel cell technologies. To this end, this thesis work reports the approach to lower down the Pt loading in electrocatalyst based on N-doped carbon nanotubes derived from Zeolitic Imidazolate Frameworks (ZIF-67) for oxygen reduction. This electrocatalyst perform with higher electrocatalytic activity and stability for oxygen reduction in fuel cell testing. The electrochemical properties are mainly due to the synergistic effect from N-doped carbon nanotubes derived from ZIF and Pt loading. The strategy with low Pt loading forecasts in emerging highly active and less expensive electrocatalysts in electrochemical energy devices.
This thesis focuses on: (i) methods to obtain greater power density by optimizing content of wet-proofing agent (PTFE) and fine-grained, hydrophobic, microporous layer (MPL); (ii) modeling full factorial analysis of PEMFC for evaluation with experimental results and predicting further improvements in performance; (iii) methods to obtain high levels of performance with low Pt loading electrodes based on N-doped carbon nanotubes derived from ZIF-67 and Pt.
For most electrochemical processes the oxygen reduction is very vita reaction. Pt loading in the electrocatalyst contributes towards the total cost of electrochemical devices. Reducing the Pt loading in electrocatalysts with high efficiency is important for the development of fuel cell technologies. To this end, this thesis work reports the approach to lower down the Pt loading in electrocatalyst based on N-doped carbon nanotubes derived from Zeolitic Imidazolate Frameworks (ZIF-67) for oxygen reduction. This electrocatalyst perform with higher electrocatalytic activity and stability for oxygen reduction in fuel cell testing. The electrochemical properties are mainly due to the synergistic effect from N-doped carbon nanotubes derived from ZIF and Pt loading. The strategy with low Pt loading forecasts in emerging highly active and less expensive electrocatalysts in electrochemical energy devices.
This thesis focuses on: (i) methods to obtain greater power density by optimizing content of wet-proofing agent (PTFE) and fine-grained, hydrophobic, microporous layer (MPL); (ii) modeling full factorial analysis of PEMFC for evaluation with experimental results and predicting further improvements in performance; (iii) methods to obtain high levels of performance with low Pt loading electrodes based on N-doped carbon nanotubes derived from ZIF-67 and Pt.
ContributorsKasat, Harshal Anil (Author) / Kannan, Arunachalana (Thesis advisor) / Phelan, Patrick (Thesis advisor) / Shuaib, Abdelrahman (Committee member) / Arizona State University (Publisher)
Created2016
Description
Semiconductor manufacturing is one of the most complex manufacturing systems in today’s times. Since semiconductor industry is extremely consumer driven, market demands within this industry change rapidly. It is therefore very crucial for these industries to be able to predict cycle time very accurately in order to quote accurate delivery dates. Discrete Event Simulation (DES) models are often used to model these complex manufacturing systems in order to generate estimates of the cycle time distribution. However, building models and executing them consumes sufficient time and resources. The objective of this research is to determine the influence of input parameters on the cycle time distribution of a semiconductor or high volume electronics manufacturing system. This will help the decision makers to implement system changes to improve the predictability of their cycle time distribution without having to run simulation models. In order to understand how input parameters impact the cycle time, Design of Experiments (DOE) is performed. The response variables considered are the attributes of cycle time distribution which include the four moments and percentiles. The input to this DOE is the output from the simulation runs. Main effects, two-way and three-way interactions for these input variables are analyzed. The implications of these results to real world scenarios are explained which would help manufactures understand the effects of the interactions between the input factors on the estimates of cycle time distribution. The shape of the cycle time distributions is different for different types of systems. Also, DES requires substantial resources and time to run. In an effort to generalize the results obtained in semiconductor manufacturing analysis, a non- complex system is considered.
ContributorsSalvi, Tanushree Ashutosh (Author) / Bekki, Jennifer M (Thesis advisor) / Sodemann, Angela (Thesis advisor) / Shuaib, Abdelrahman (Committee member) / Ren, Yi (Committee member) / Arizona State University (Publisher)
Created2017
ContributorsProkofiev, Sergey, 1891-1953 (Composer)
ContributorsProkofiev, Sergey, 1891-1953 (Composer)
ContributorsProkofiev, Sergey, 1891-1953 (Composer)
ContributorsProkofiev, Sergey, 1891-1953 (Composer)
ContributorsProkofiev, Sergey, 1891-1953 (Composer)
ContributorsProkofiev, Sergey, 1891-1953 (Composer)