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Desorption processes are an important part of all processes which involve utilization of solid adsorbents such as adsorption cooling, sorption thermal energy storage, and drying and dehumidification processes and are inherently energy-intensive. Here, how those energy requirements can be reduced through the application of ultrasound for three widely used adsorbents namely zeolite 13X, activated alumina and silica gel is investigated. To determine and justify the effectiveness of incorporating ultrasound from an energy-savings point of view, an approach of constant overall input power of 20 and 25 W was adopted. To measure the extent of the effectiveness of using ultrasound, the ultrasonic-power-to-total power ratios of 0.2, 0.25, 0.4 and 0.5 were investigated and the results compared with those of no-ultrasound (heat only) at the same total power. Duplicate experiments were performed at three nominal frequencies of 28, 40 and 80 kHz to observe the influence of frequency on regeneration dynamics. Regarding moisture removal, application of ultrasound results in higher desorption rate compared to a non-ultrasound process. A nonlinear inverse proportionality was observed between the effectiveness of ultrasound and the frequency at which it is applied. Based on the variation of desorption dynamics with ultrasonic power and frequency, three mechanisms of reduced adsorbate adsorption potential, increased adsorbate surface energy and enhanced mass diffusion are proposed. Two analytical models that describe the desorption process were developed based on the experimental data from which novel efficiency metrics were proposed, which can be employed to justify incorporating ultrasound in regeneration and drying processes.
ContributorsDaghooghi Mobarakeh, Hooman (Author) / Phelan, Patrick (Thesis advisor) / Wang, Liping (Committee member) / Wang, Robert (Committee member) / Calhoun, Ronald (Committee member) / Deng, Shuguang (Committee member) / Arizona State University (Publisher)
Created2021
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
The paper analyzes the growing desire to use waste-to-energy strategies on municipal solid waste (MSW) to generate power. The two waste-to-energy technologies that will be explored are incineration and gasification. The background of these two technologies will be explained because incineration, which has been the pioneering technology for the past century, has come to be rivaled by gasification with its unique purification feature. Following this section, gasification and incineration power generation are studied to conclude which technology is sounder. This study will be conducted via an analysis to find the thermal and exergetic efficiencies and emissions of each. After analyzing the two technologies, both utilizing a vapor cogeneration power system, their efficiencies were found. For the gasification process, the thermal efficiency was 26% and the exergetic efficiency was 59%. The incineration process had a thermal efficiency of 25% and an exergetic efficiency of 55%. Lastly, the emission from the power generation of each method was explored to see which system had a greater impact on the environment. It was found that the primary emissions of these technologies were carbon dioxide and water.
ContributorsJackson, Cole Alan (Author) / Deng, Shuguang (Thesis director) / Milcarek, Ryan (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05