Effect of CaO and Fe2O3 on Partitioning of As and S within Ash Fractions from Fluidised-Bed Co-Combustion of Coal and Wastes

Possible interaction of volatilized As and S with CaO and Fe2O3 (creating solid product) could efficiently improve coal combustion flue gas cleaning. For this reason, S-CaO, As-CaO, S- Fe2O3 and As- Fe2O3 relationships were evaluated in bottom ash and fly ash fractions from fluidised-bed co-combustion of coal and wastes (and limestone as desulphurization additive) through calculation of correlation coefficients and composition of magnetic concentrates. It was concluded that S exhibited a dominant association with CaO while As exhibited affinity to both CaO and Fe2O3 - the significance differed a little in bottom ash and fly ash. In the bottom ash, the affinity of As to CaO was more significant, while in the fly ash the association to Fe2O3 slightly prevailed.

Thermal Dissolution of Shenfu Sub-Bituminous Coal Promoted by Lignin

Objective: Thermal Dissolution (TD) and Co-thermal Dissolution (CTD) of Shenfu (SF) coal and lignin were studied. The effect of temperature on the TD and CTD of SF coal and lignin was discussed. Method: The synergistic effect of SF coal and lignin in CTD was probed with the characterization of thermal dissolution soluble fraction by elementary analysis, FTIR and TG determinations. Result: The results suggested that TD activity of lignin was higher than that of SF coal. Both SF coal and lignin gave their maximal thermal dissolution yield (TDY) of 57.6 and 82.5%, respectively at 360oC. In CTD of SF coal and lignin process, the experimental values (expressed by EXP) of TDY and Thermal Dissolution Soluble Yield (TSY) were both higher than the corresponding calculated weighted mean values (expressed by CAL) of TDY and TSY obtained from the individual TD of SF coal and lignin, suggesting that there existed a synergistic effect in the CTD of SF coal and lignin. Both TDY and TSY in CTD were enhanced to maximal values at 360oC with (EXP-CAL) values of 3.4 and 7.5%, respectively. Conclusion: There were interactions between SF coal and lignin in the CTD process. The pyrolysis of lignin at low temperature may form some intermediates such as phenoxy radicals, and these intermediates can further cause depolymerization of coal, thus promoting the TD of coal.

On the Influence of the Slot Orifice in Diesel Common Rail Nozzle

Background:The paper deals with a diesel common rail nozzle in which a novel orifice layout is implemented.Objective:Its influence on the nozzle mechanical-hydraulic behavior and on the spray shape transient development is experimentally investigated.Methods:In the research, a solenoid injector for light duty diesel engines is equipped with the novel nozzle prototype and tested. The prototype layout is described, pointing out the features of the nozzle orifices, in which a Slot cross-section is adopted; the investigation is accomplished extending the hydraulic tests and the spray visualizations to a reference nozzle with standard holes. The influence of the hole layout on the mechanical-hydraulic behavior of the nozzle is assessed by experimental analysis based on the rate of injection measurement, in comparison with the reference nozzle. Once the hydraulic behavior of the novel nozzle has been characterized in terms of mass flow rate, the slot influence on the spray shape is assessed analyzing the macroscopic features such as the penetration distance and the spray angle, in non evaporative conditions. The study is carried out under transient injection conditions, for different injection pressures, up to 1400 bar.Results:The results on spray characteristics also provide reference information to set up spray models suited to take the Slot orifice into account.

Flexibility of Organic Thermoelectric Material for Photovoltaic Solar Energy Management and Conversion

Objective:The flexibility on a design maneuvering of building automation systems with the integration of organic solar cells is investigated.Methods:The energy demand load of the Engineering Lecture Theatre (ELT) at the University of Lagos is analyzed and parametric studies of the heat and charge transport within aMimosa pudicabased solar wafer are conducted, along with the modelling of a network of microchannels. A walk-through energy audit of all the devices that are installed or operated within the ELT and the thermophysical properties of the building envelope are considered, with the aim of satisfying the ASHRAE standard for thermal comfort and indoor air quality. A two-dimensional finite volume formulation of the heat and charge transfers within the boundaries of the flexible laminate and the organic extract is utilized.Result:Parametric analysis of the flow phenomenon and temperature distribution, especially across the wafer, at various operating conditions helps to determine significant design criteria, and assists in confirming the feasible power performance of the organic solar cell for building energy management.Conclusion:The results are anticipated for the design of reliable building automation systems for effective demand side monitoring, and for estimation of the economic viability of a proposed development of hybrid organic-inorganic based solar energy system for independent power generation within the Faculty of Engineering.

Exergy Assessment of a Solar-Assisted District Energy System

Background:District Energy (DE) is a technology capable of using renewable energy (e.g., solar thermal systems) and waste heat as energy sources efficiently. DE technology nonetheless has potential for improvement. Thermal Energy Storage (TES) can enhance DE performance significantly.Objective:An exergy analysis of a DE system which includes a solar thermal energy system and TES is performed, so as to improve understanding of its performance.Method:A case study based on the Friedrichshafen DE system in Germany is used to assess thermodynamically the role of solar energy and TES in a DE system. The system performance is separated into three modes: (1) fossil fuel is the only source of energy, (2) a discharging TES and fossil fuel provide heat for the DE system, and (3) solar energy and fossil fuels are the energy supplies. Exergy analyses are conducted for each performance mode and the overall DE system.Results:The results quantify the benefits of incorporating solar energy and TES on the performance of the Friedrichshafen DE system, and demonstrate that the overall exergy efficiency of the DE system increases from 23% to 27% with assistance of solar thermal collectors and TES, while the total energy efficiency increases from 83% to 87%.Conclusion:An increase of exergy efficiency is observed when TES is added to a DE system, due to a reduction in solar thermal energy loss by the TES, which allows more solar energy to be converted to useful energy to satisfy the DE system thermal energy demand.

Design and Construction of A Domestic Solar Power Bank in a Convective Environment

Objective:This research seeks to solve the problem of storing solar energy in small scale modules for domestic use.Method:The Solar Power Bank (SPB) was constructed with local materials based on their individual properties. The functionality of the SPB was tested in a convective environment. Davis automatic Weather Station (DWS) was used to get the weather parameters (like solar irradiance, solar energy and temperature) for each day the SPB was tested. The maximum solar irradiance for four days (during the experiment) were 220 W/m2, 208 W/m2, 450 W/m2and 900 W/m2. The maximum solar energy was 0.33 J, 03 J, 0.64 J and 1.33 J.Result:The maximum voltage and power obtained from the Solar Power Bank (SPB) was 0.18V and 0.065W respectively. The design showed tremendous heat energy entrapment during solar irradiance peak as the temperature in the SPB was about three times the DWS.Conclusion:It was specifically noted that the convection of the heat transfer that is triggered by the glass shield determines the functionality of the thermo-electric module. This is a clear indication that though the power output may be low to charge the batteries, the prospects of the SPB to operate in convective-rural communities (in tropic region) is very high.

The Effect of CaBr2 on Mercury Speciation in Flue Gas: An Experimental and DFT Study

Background: Additives affect the formation of different mercury speciation in coal-fired derived flue gas. Objective: In order to study the effect of the additive CaBr2 content, the Ontario Hydro Method (OHM) method has been applied to analyze the mercury speciation at the entrance and export of denitration (SCR). Method: Density Functional Theory (DFT) has been used to study the adsorption of mercury halide on unburned carbon surface. Result: The results show that along with the increasing amount of additive CaBr2, there is an increasing trend of the ratio of Hg2+ in flue gas. Conclusion: CaBr2 addition contributes to oxidize Hg 0 to Hg2+ and increase the mercury concentration through SCR. DFT results indicate that the adsorption of HgBr and HgBr2 on unburned carbon surface is chemisorption, and Br-C bond is stronger than Hg-C bond, both these bonds are covalent interaction.