Advances in reduction of NOx and N2O1 emission formation in an oxy-fired fluidized bed boiler

Fossil fuel combustion is one of the major means to meet the mounting global energy demand. However, the increasing NO_x and N₂O emissions arising from fossil fuel combustion process have hazardous effects. Thus, mitigating these gases is vital to attain a sustainable environment. Interestingly, oxy-fuel combustion in fluidized bed for carbon capture and minimized NO_x emissions is strongly sustainable compare to the other approaches. It was assessed that NO_x formation and fuel-N conversion have significant limitation under oxy-fluidized bed compared to air mode and the mechanism of NO_x formation is still deficient and requires further development. In addition, this review paper discussed the potential of primary measure as low emission process with others supplementary techniques for feasible NO_x reduction. The influences of combustion mode, operating parameters, and reduction techniques such as flue gas recirculation, oxygen staging, biomass co-firing, catalyst, influence of fluidized bed design and structure, decoupling combustion and their merges are respectively evaluated. Findings show that significant minimization of NO_x emission can be achieved through combination of primary and secondary reduction techniques.     

A new latent accelerator and study of its effect on physical,mechanical and shelf-life of carbon fiber epoxy prepreg

The effects of a new latent accelerator and those of two common accelerators of 1-methyl imidazole and 2,4,6-tris(dimethylaminomethyl)phenol (DMP) have been studied in relation to the properties of dicyandiamide (dicy) cured epoxy resin and its prepregs with unidirectional carbon fiber. The new prepared accelerator is an adduct based on DMP (A_DMP). The results showed that the curing behavior of epoxy/dicy did not change when the appropriate amount of new accelerator was used. The amount of 5 phr of new latent accelerator is equal to the amount of 0.6 phr of DMP accelerator and by increasing the amount of new accelerator, the curing reaction of epoxy/dicy increased significantly. Viscosity build-up results and gel time measurements showed the high pot-life of resin system (epoxy/Dicy/A_DMP) and the high shelf-life of their prepreg. The results showed that the lap shear strength of sample containing 5 phr of the new accelerator (A_DMP5) was increased by 127% in comparison to the sample containing 0.6 phr of DMP. Transverse tensile strength and strain-at-break were increased by 27% and 31.7%, respectively. Transverse flexural strength, flexural strain-at-break and flexural modulus increased by 52%, 11% and 60%, respectively. On the other hand, fracture toughness and fracture energy increased significantly by 214% and 700%, respectively. This increase in mechanical properties was due to the bulkiness of the new latent accelerator acting as a toughening agent and also the good adhesion of fiber to the matrix as revealed by scanning electron microscopy.

     

The influence of Ohmic-vacuum heating on phenol,ascorbic acid and engineering factors of kiwifruit juice concentration process

The antioxidant, phenol, ascorbic acid, electrode corrosion and engineering factors of concentration process of kiwifruit juice by ohmic heating-vacuum conditions (OHVC) were evaluated and compared with ohmic heating under atmospheric conditions (OHAC). Results showed that the total phenol content was decreased with an increasing voltage gradient for both heating modes. The OHVC can better save the antioxidant capacity and ascorbic acid of concentrated samples than the OHAC. The processing time of OHVC was significantly higher than the OHAC at the same voltage gradient (P < 0.05). The electrode corrosion rate at the vacuum mode was 7- to 40-fold higher than the atmospheric mode. The energy efficiency at OHAC was lower than the OHVC. The energy consumption was found in the range of 3.37 to 3.75 MJ kg⁻¹ water for OHAC and 4.08 to 11.09 MJ kg⁻¹ water for OHVC. The electrical conductivity under the vacuum mode was lower than the atmospheric mode.     

Preparation and properties of polyester nanocomposites: Effects of mixing

A multistep mixing technique to manufacture highly intercalated/exfoliated nanocomposites of layered silicates in thermosetting resins was developed and successfully tested up to 9% nanoparticle content. We investigated the influences of mixing conditions on linear and nonlinear viscoelastic properties of processed clays and polyester suspensions. The effects of shear and mechanical mixing on the state of dispersion and microstructure of the cured nanocomposites were examined by the XRD and TEM techniques. Transient viscosities and linear viscoelastic data for the nanocomposites demonstrated significant enhancement by increasing speed and time of mechanical mixing. The solid state characterization techniques confirm mixed to highly exfoliated and delaminated microstructures were attained by the proposed method. Our observations indicate that the multistage mechanical mixing following a stationary step can be used to produce thermosetting and thermoplastic nanoparticles with the improved properties. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Curing behavior of dicyandiamide/epoxy resin system using different accelerators

Various amounts of dicyandiamide (Dicy), two grades of epoxy resins, i.e. Epiran 06 and Epikote 828, and three different accelerators including benzyl dimethyl amine (BDMA), 3-(4-chlorophenyl)-1,1-dimethyl urea (Monuron) and 2-methyl imidazole (Im) were used in curing of Dicy/epoxy resin system. Both of the used epoxy resins were based on diglycidyl ether of bisphenol A (DGEBA). The effects of type and concentration of accelerators on curing behavior were studied by differential scanning calorimetry (DSC) method in dynamic or non-isothermal mode. The optimum concentration of Dicy for curing of epoxy resins was obtained based on the glass transition temperature of the cured epoxy/Dicy formulations. The maximum glass transition temperature of 139 °C was obtained at the stoichiometric ratio of Dicy to epoxy of 0.65. The results showed that BDMA has a broader curing peak in DSC and starts the cure reaction earlier than the others. However, Monuron has a narrow curing reaction peak with good cure latency. The tensile properties of Dicy-cured Epiran 06 and Epikote 828 epoxy resins reinforced with chopped strand mat showed that these two epoxy resins have similar mechanical properties. For composites based on the Epiran 06 and Epikote 828 reinforced with 40 wt % glass chopped strand mat, tensile strength and modulus were 156 and 153.4 MPa and 11.6 and 12.4 GPa, respectively.     

Real-Time Control System Adopted to Energy Storage for Smart Grid Low Wind Applications: A Part of Distributed Renewables in Smart City

In this paper, extensive efforts have been undertaken to design and develop a control system, which is incorporated with an energy storage device that can store energy from low-voltage renewable sources. The developed device acts as a storage element, which can be used to charge small-scale batteries, cellular devices, and other applications in remote places where the grid connection is not available. The circuit is developed using a case-by-case analysis. In order to solve the low output voltage problem, a bipolar junction transistor-metal oxide semiconductor field-effect transistor (BJT-MOSFET) based switch control technology with the Arduino microcontroller has been implemented. The developed control system is extremely efficient in charging batteries through a supercapacitor for low-voltage sources. In this research, a small-scale 200-W portable vertical axis wind turbine is used at a wind speed of 3 m/s. The result shows the efficiency of the proposed system as compared with the conventional systems. The proposed system can be an important tool of the latest distributed energy generation technology which is an important part of a smart city. Lastly, the limitations and future scopes of the development of the control device are discussed for the future barrier. An important future scope identified is to integrate the Internet of Things based mobile interface for remote monitoring for any kind of pandemic situation like COVID-19. Now, it is high time to get our smart city concept aligned with the post COVID pandemic situation and get us prepared smartly for similar future occurrences.     

Novel Euler-LaCoste linkage as a very low frequency vertical vibration isolator

LaCoste linkage vibration isolators have shown excellent performance for ultra-low frequency vertical vibration isolation. However, such isolators depend on the use of conventional pre-stressed coil springs, which suffer from creep. Here, we show that compressional Euler springs can be configured to create a stable tension unit for use in a LaCoste structure. In a proof of concept experiment, we demonstrate a vertical resonance frequency of 0.15 Hz in an Euler-LaCoste configuration with 200 mm height. The system enables the use of very low creep maraging steel as spring elements to eliminate the creep while minimising spring mass and reducing the effect of parasitic resonances. Larger scale systems with optimized Euler spring boundary conditions should achieve performance suitable for applications on third generation gravitational wave detectors such as the proposed Einstein telescope.     

Assessment of hydraulic conductivity in the multi-layered aquifer system of the Bengal Basin,Bangladesh, by performing slug tests

Bulletin of Engineering Geology and the Environment - Various studies have described upon importance of the performance of multilevel slug tests to assess hydraulic conductivity of aquifer...     

All-optical switchable holographic Fresnel lens based on azo-dye-doped polymer-dispersed liquid crystals

Fabrication of an all-optical switchable holographic liquid crystal (LC) Fresnel lens based on azo-dye-doped polymer-dispersed LCs is reported using a Michelson interferometer. It is found that, upon circularly polarized photoirradiation, the diffraction efficiency of the fabricated Fresnel lens was increased significantly in a reversible manner. We believe this is due to the anisotropy induced by reorientation of the LC molecules coupled with azo-dye molecule orientation due to trans-cis-trans photoisomerization, which modulates the refractive index of the LC-rich regions. We also studied the effect of azo dye on the polarization dependency of the fabricated lens.