Order-disorder transitions in a sheared many body system

Motivated by experiments on sheared suspensions that show a transition between ordered and disordered phases, we here study the long-time behavior of a sheared and overdamped 2-d system of particles interacting by repulsive forces. As a function of interaction strength and shear rate we find transitions between phases with vanishing and large single-particle diffusion. In the phases with vanishing single-particle diffusion, the system evolves towards regular lattices, usually on very slow time scales. Different lattices can be approached, depending on interaction strength and forcing amplitude. The disordered state appears in parameter regions where the regular lattices are unstable. Correlation functions between the particles reveal the formation of shear bands. In contrast to single particle densities, the spatially resolved two-particle correlation functions vary with time and allow to determine the phase within a period. As in the case of the suspensions, motion in the state with low diffusivity is essentially reversible, whereas in the state with strong diffusion it is not.Comment: 12 pages, 13 figures; Supplemental Movies: https://youtu.be/oFcrWo9Vs6E, https://youtu.be/tcowb7o05JQ, https://youtu.be/GkEUwycn7V4, https://youtu.be/k-XCo8CWFU

Bioenergy Recovery from Cotton Stalk

Cotton stalk (CS) plant residue left in the field following harvest must be buried or burned to prevent it from serving as an overwintering site for insects such as the pink bollworm (PBW). This pest incurs economic costs and detrimental environmental effects. However, CS contains lignin and carbohydrates, like cellulose and hemicelluloses, which can be converted into a variety of usable forms of energy. Thermochemical or biochemical processes are considered technologically advantageous solutions. This chapter reviews potential energy generation from cotton stalks through combustion, hydrothermal carbonization, pyrolysis, fermentation, and anaerobic digestion technologies, focusing on the most relevant technologies and on the properties of the different products. The chapter is concluded with some comments on the future potential of these processes

Experimental Study on Reforming Activity and Oxygen Transfer of Fe- Olivine in a Dual Circulating Fluidized Bed System

Fe-olivine was investigated in a dual circulating fluidised bed reactor system with focus on hydrocarbon reforming activity and effects of oxygen transfer. H2, CO2, CH4 and 1-methylnaphthalene were fed as a surrogate gas mixture to the reforming part. Oxygen transport was developed by solids circulation. Tar decomposition was marginally affected by partial oxidation. The overall degree of tar decomposition was found to be in the range of 70 to 80%

H2-Rich Syngas from Renewable Sources by Dual Fluidized Bed Steam Gasification of Solid Biomass

Steam gasification of solid biomass yields high quality producer gases that can be used for efficient combined heat and power production (CHP) and as a renewable resource for chemical syntheses. The dual fluidized bed steam gasification technology provides the necessary heat for steam gasification by circulating hot bed material that is heated in a second fluidized bed reactor by combustion of residual biomass char. The hydrogen content in producer gas of such gasifiers is about 40 vol% (dry basis). Addition of carbonates to the bed material and adequate adjustment of operation temperatures in the reactors allow selective transport of CO2 from gasification to combustion zone (Adsorption Enhanced Reforming – AER concept). An 8 MW (fuel power) CHP plant successfully demonstrates gasification in Guessing, Austria since 2002. A pilot plant (100 kW fuel power) has been recently operated to investigate the potential of the selective CO2 transport achieving a H2 content of 75 vol% (dry basis) in the producer gas. No significant increase in tar formation occurs despite the low gasification temperatures (600-700 °C). It can be shown, that the selective transport of CO2 yields high hydrogen contents in the producer gas and the possibility of operating at lower temperatures increases the efficiency of energy conversion

INVESTIGATION OF REFORMING ACTIVITY AND OXYGEN TRANSFER OF OLIVINE IN A DUAL CIRCULATING FLUIDISED BED SYSTEM WITH REGARD TO BIOMASS GASIFICATION

Natural olivine (Mg,Fe)2SiO4 is examined in a dual circulating fluidised bed (DCFB) reactor system of 120 kWth with regard to its reforming activity. Further, the oxygen transport capacity due to redox-cycling of the iron containing part of the olivine is considered. Based on a syngas composition derived from biomass gasification, the olivine is exposed to a surrogate gas mixture of H2, CO, CO2, CH4 and a tar compound (1-methylnaphthalene) at 850 °C. The results show the tar conversion at different tar loads. The investigations reveal that a low content of oxygen is transported by the olivine due to the redox-cycling in the reactor system

Pyrolysis of cotton stalks and utilization of pyrolysis char for sustainable soil enhancement and carbon storage

Worldwide, a large amount of biomass accumulates in the form of ligno-cellulosic agricultural by-products that can neither be efficiently used as animal feed nor as feedstock for anaerobic digestion. A clean and energy-efficient utilization in combustion plants is counter-indicated by high contents of elements like Cl, K and Na that decrease the ash-melting-point and lead to fouling and corrosion. Although this biomass is, therefore, not suitable for conventional combustion plants, a pyrolysis process can be applied that works at lower temperatures of 500-600°C. Please click on the file below for full content of the abstract

Synergy Analysis Methodology For Decreasing Fuel Cell Production Costs

For meeting CO2 emission targets in the mobility sector, decarbonization efforts of referring applications are necessary. Fuel cell electric vehicles powered by hydrogen demonstrate a viable option to achieve those targets, especially taking the targets of heavy-duty applications into consideration. Higher ranges, short fueling durations and locally emission-free transport represent advantages offered by fuel cells in comparison to internal combustion engines or battery-electric powertrains. However, production costs of fuel cells are still a drawback. Latest analyses show that the utilization of scale effects even in early technology adaption phases can heavily decrease production costs. As the cell structure of fuel cells and electrolyzers show many similarities, the assumption of production synergies is made. Taking advantage of referring synergies, increased production volumes and thus decreased production cost are assumed for fuel cells. This paper introduces a methodology to identify synergies between fuel cell and electrolyzer production. The methodology is used to evaluate a company's production process portfolio on the example of the three alternative coating processes, based on an initial evaluation of the processes and the use of the Analytic Network Process. The application of the methodology results in synergy coefficients for production processes, using the examples of slot die, gravure and spray coating. The coefficients are transferred into an overall benefit of a production process portfolio. Finally, the effect of the considered synergies between fuel cell and electrolyzer production on the overall benefit of a company's production process portfolio is visualized. This paper is concluded with a critical review of the methodology and a summary of further research