Mechanistic modeling of pollutant removal, temperature, and evaporation in chemical air scrubbers

Chemical air scrubbers reduce the concentration of water-soluble components such as ammonia from the outgoing ventilation air through absorption in water, followed by chemical conversions and removal of the end products. A mechanistic model for a countercurrent air scrubber was set up. Mass balances for ammonia, hydrogen sulfide, nitrous oxide, and methane were implemented, as well as the water mass balance and heat balances. The model was validated against experimental data from a conventional fattening pig housing facility. The effect of influent characteristics, design parameters, and control handles on the removal efficiency, the temperature profile, and the water evaporation rate were investigated through simulation. The model was able to describe the behavior of a countercurrent chemical air scrubber

Throughput and Power Consumption Comparisons of Zigbee-based and ISM-based Implementations of WSAN

Wireless sensor and actuator networks have expanding applications which requires better throughput, power efficiency and cost effectiveness. This study intends to contribute to the growing pool of knowledge on WSAN especially in the design for novel applications such as image or video over WSANs, and solar energy and RF energy harvesting for the WSAN nodes. Two basic scalable wireless sensor and actuator networks were implemented and characterized in terms of throughput and power consumption. The two WSANs are the Zigbee-based WSAN which is based on the IEEE 802.15.4 protocol, and the ISM-based Zigbee which makes use of the industrial, scientific and medical (ISM) radio bands. The star topology was used for both WSAN implementations. The throughput is quantified with varied factors including distance from node to node, obstructions in between nodes and cochannel interference. As distance and obstructions between nodes are increased, the throughput for both networks decreases with varying degrees. Co-channel interference is also considered. The ISM-based WSAN network is weak in dealing with co-channel interference and error rate as compared to the Zigbee-based WSAN, thus requiring it to have a better data encryption. Power consumption is generally larger for the ISM-based WSAN as compared to its Zigbee-based counterpart. However, the ISM-based nodes consume the same power even up to a few hundreds of meters distance and are thus practical for covering large distances. Therefore, the Zigbee-based WSAN system is more appropriate for closed environment, such as in room automation and home automation applications where distance from node to node is relatively shorter. The ISMbased WSAN prototype, on the other hand, can be developed further for applications in larger areas such as deployment in fields and cities, since transmission is not generally limited by distance and obstructions

Recent developments in the production of liquid fuels via catalytic conversion of microalgae: experiments and simulations

Due to continuing high demand, depletion of non-renewable resources and increasing concerns about climate change, the use of fossil fuel-derived transportation fuels faces relentless challenges both from a world markets and an environmental perspective. The production of renewable transportation fuel from microalgae continues to attract much attention because of its potential for fast growth rates, high oil content, ability to grow in unconventional scenarios, and inherent carbon neutrality. Moreover, the use of microalgae would minimize ‘‘food versus fuel’’ concerns associated with several biomass strategies, as microalgae do not compete with food crops in the food chain. This paper reviews the progress of recent research on the production of transportation fuels via homogeneous and heterogeneous catalytic conversions of microalgae. This review also describes the development of tools that may allow for a more fundamental understanding of catalyst selection and conversion processes using computational modelling. The catalytic conversion reaction pathways that have been investigated are fully discussed based on both experimental and theoretical approaches. Finally, this work makes several projections for the potential of various thermocatalytic pathways to produce alternative transportation fuels from algae, and identifies key areas where the authors feel that computational modelling should be directed to elucidate key information to optimize the process

Daldinia concentrica

Fung

Hydrothermal Process of Swine Manure to Oil Using a Continuous Reactor System

182 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.Hydrothermal processing of swine manure is a novel technology that has shown very promising results in treating waste and producing oil. Oil yields of up to 70% were achieved in batch experiments. Since a continuous-mode process is more applicable for scale-up operations, a continuous hydrothermal process (CHTP) reactor system was developed. The effects of temperature, pressure, hydraulic residence time, and use of process gas, were evaluated to determine the optimal process condition. Products' (i.e., oil, aqueous and gas) composition were determined to better understand the mechanics of the reaction process and to provide information for further developments. The CHTP, composed of a high-pressure slurry feeder, a process gas feeder, a continuous-stirred tank reactor, a products separation vessel, and process controllers, had a capacity of processing up to 48 kg of manure slurry per day. Results showed an interaction between operating temperature and pressure. The highest oil yield of 70% of volatile solids was achieved at 305°C, 10.1 MPa, and 80 min hydraulic residence time without process gas. The addition of carbon monoxide in the process did not improve the oil yield but produced a more fluid oil product. The heating value of the oil product ranged from 25,176 kJ/kg to 33,065 kJ/kg. An energy balance showed that the process was a net energy producer. The carbon and hydrogen content of the oil were 62.7+/-6.4% and 9.6+/-0.4%, respectively. The nitrogen and sulfur content of the oil were 3.9+/-0.3% and 0.3+/-0.1%, respectively. The oil was primarily resins (∼45%) and asphaltenes (∼44%) with small amounts of saturates (∼3%) and aromatics (∼2%). Majority of the hydrocarbon compounds in the oil has boiling points within 316°C to 482°C. The aqueous product was found to contain volatile organic compounds primarily ketones and benzenyl compounds. Most of the N, P, and K content of the manure went to the aqueous product. The main gas product was CO2 accounting for ∼98% of the total. Carbon monoxide accounted for most of the rest. Methane, ethane, and ethene were also produced in negligible amounts. Trace amounts of aromatic compounds including benzene, ethylbenzene, toluene, and styrene were also detected in the gas product stream.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD