Environmental and Economically Conscious Magnesium Production: Solar Thermal Electrolytic Production of Mg from MgO

One method to improve the fuel efficiency of American made vehicles is to reduce vehicle weight by substituting steel components with lighter magnesium (Mg) components. Unfortunately, U.S. produced Mg currently costs approximately $3.31 per kg, over seven times the price of steel. Furthermore, Mg production has a staggering energy and environmental impact, consuming up to 102 kW-hr/kg-Mg of energy and producing 36 kg of CO2/kg-Mg. To reduce the overwhelming economic and environmental impact of Mg, a new solar thermal electrolytic process has been developed for the production of Mg from MgO. Through this process, liquid Mg is produced in a solar reactor utilizing both thermal and electrical energy. At elevated temperatures, the thermal energy from concentrated sunlight reduces the required electrical work below that of current processes. The reactor absorbs the concentrated solar energy, heating a molten salt-MgO mixture in an electrolytic cell. Electricity is then supplied to the cell, producing liquid Mg and CO. It is estimated that this new process will produce Mg at$2.50 per kg, with costs decreasing as the technology is further developed. This process requires approximately 8.3 kW-hr/kg-Mg of energy and produces only 3.44 kg of CO2/kg-Mg, large reductions compared to current processes

Position Control of a Floating Ball in a Vertical Air Stream

Quantitative Feedback Theory (QFT) control theory was used to design a control loop in order to provide stability and tracking ability for a ball floating in a jet stream of air. Due to nonlinearity of the system governing equations, a set of linear transfer functions was derived to capture the dynamics of the system. Using this set, a controller and a prefilter were designed that met the stability and tracking performances. The feedback loop was also implemented in an experimental setup consisting of a DC motor, an axial fan, an expansion tank, and a nozzle. The experimental data showed some differences with the simulation results, but the closed-loop system response was satisfactory and the design criteria were met

Speed Control of Shunt-Wound DC Motors Using Switching Technique

In this paper, a switching feedback control system for speed control of a shunt-wound DC motor is described. In the control system a fast-acting switch periodically opens and closes between the motor terminal and the motor driver in order to estimate the motor’s speed. Theoretical results predicted the stability of the control system and it was shown that the tracking error in the motor’s speed is linearly dependent on the switching rate. To prove the applicability of this approach, an experimental setup was built and the switching control system was implemented using the real-time hardware within MATLAB/SIMULINK™ software

Modeling and Experimental Investigation of a Helmholtz Resonator With a Flexible Plate

A Helmholtz resonator with a uniform, flexible end plate is studied in this work. This work shows that the flexible plate modifies the frequency response characteristics of the resonator, providing multiple distinct resonant frequencies instead of a single resonant frequency. Therefore, acoustical transmission loss will increase at each of the multiple resonant frequencies of the resonator and plate assembly versus at a single frequency for the unmodified Helmholtz resonator. By using receptance coupling as the modeling approach, the receptance of the Helmholtz resonator and flexible plate assembly is predicted by coupling receptance models of an unmodified Helmholtz resonator and a clamped plate. Finally, the predicted receptance of the Helmholtz resonator and flexible plate assembly is compared against experimental results

Heliostat Attitude Control Strategy in the Solar Energy Research Facility of Valparaiso University

In this paper, a continuous tracking strategy for the heliostat in the James S. Markiewicz Concentrated Solar Energy Research Facility at Valparaiso University is developed. A model of the nonlinear dynamics of the heliostat motion is developed and the open-loop control strategy is presented. Asymptotic stability of the heliostat control using the Lyapunov and LaSalle\u27s theorems were proven. Simulations using the nonlinear dynamic model are presented and interpreted to identify the feedback gain that maximizes the time response of the heliostat without introducing oscillations in its motion. Finally, the control strategy is put to the test during summer-time operation. Data are presented that show that the tracking strategy has an RMS tracking error of 0.058 mrad, where the error is defined as the difference between the desired and actual heliostat positions. Images of the the aperture of a high-temperature solar receiver over 8 hours of testing are also presented to qualitatively demonstrate the success of the tracking strategy

Speed Control of Shunt-Wound DC Motors Using Switching Technique

In this paper, a switching feedback control system for speed control of a shunt-wound DC motor is described. In the control system a fast-acting switch periodically opens and closes between the motor terminal and the motor driver in order to estimate the motor’s speed. Theoretical results predicted the stability of the control system and it was shown that the tracking error in the motor’s speed is linearly dependent on the switching rate. To prove the applicability of this approach, an experimental setup was built and the switching control system was implemented using the real-time hardware within MATLAB/SIMULINK™ software