Spray and combustion characterization for internal combustion engines using optical measuring techniques - A review

The number of studies on spray and combustion characteristics in IC (internal combustion) engines using optical techniques has rapidly increased in the past few years due to an increase in the number of alternative fuels and stricter emission standard regulations. This study investigates better ways of controlling the combustion process, thus ensuring optimum performance and minimum emission levels produced during the combustion process. Alternative fuels such as CNG (compressed natural gas), biodiesel and hydrogen have been studied by many researchers due to their relative low environmental impact. Meanwhile, for conventional fuels such as gasoline and diesel, studies have focused on spray characteristics to provide better air/fuel mixtures in order to produce a cleaner combustion process. Few experimental works have investigated the effects of modifications to the injector itself, for example, varying the injection rate, injection pressure, etc. In order to provide a better understanding of spray and combustion characteristics, researchers have studied macroscopic and microscopic parameters using optical techniques. This paper presents the significance of spray and combustion study with optical techniques that have been reported by previous researchers in order to provide in depth knowledge as assistance to readers interested in this research area.     

Fabrication and characterisation of triangle-faced single crystal diamond micro-cantilevers

Single crystal diamond offers superior properties for MEMS applications to polycrystalline forms of this material. Here, a process based solely on focussed ion beam milling (Ga), has been used to fabricate nanometre-width diamond cantilevers we lengths of several tens of microns. The procedure results in low damage structures with little Ga incorporation, following post-fabrication annealing. The triangular profile of a cantilever produced using this technique is shown, theoretically, to have a factor of three improved defection response to a load typically encountered during chemical sensing compared to a conventional rectangular lever of similar dimensions.     

Thermal,mechanical, and morphological characterization of biobased thermoplastic starch from agricultural waste/polypropylene blends

The thermal, mechanical, and morphological properties of biobased thermoplastic starch (TPS) obtained from agricultural waste seed (AWS) and agricultural waste tuber (AWT) blended with polypropylene (PP) were investigated in this article. The grounded (pulverized) AWS and AWT were different in amylose/amylopectin ratios and contained relatively low starch content (≤50%). The commercial grade of TPS (CS) and native tapioca starch blended PP (NTS/PP) were also prepared for comparison. The performances of the TPS/PP blends were dependent on the starch composition (e.g., amylose‐to‐amylopectin ratio), particle size, dispersion, and interfacial adhesion with matrix. The high‐amylopectin starch blend (i.e., AWS/PP) was more susceptible to thermal degradation than the amylose‐rich material (i.e., NTS/PP). The addition of starch to PP not only led to a stiffening effect (i.e., increase in storage modulus), but it also affected the relaxation of polymer matrix by shifting the thermal transition (i.e., glass transition temperature) to a higher temperature. POLYM. ENG. SCI., 54:1357–1365, 2014. © 2013 Society of Plastics Engineers     

Syngas production from methane dry reforming over Ni/SBA-15 catalyst: Effect of operating parameters

The influence of operating conditions including reactant partial pressure and reaction temperature on the catalytic performance of 10%Ni/SBA-15 catalyst for methane dry reforming (MDR) reaction has been investigated in this study. MDR reaction was carried out under atmospheric pressure at varying CH₄/CO₂ volume ratios of 3:1 to 1:3 and 923–1023 K in a tubular fixed-bed reactor. SBA-15 supported Ni catalyst exhibited high specific surface area of 444.96 m² g^?1 and NiO phase with average crystallite size of 27 nm was detected on catalyst surface by X-ray diffraction and Raman measurements. H₂ temperature-programmed reaction shows that NiO particles were reduced to metallic Ni⁰ phase with degree of reduction of about 90.1% and the reduction temperature depended on the extent of metal-support interaction and confinement effect of mesoporous silica support. Catalytic activity appeared to be stable for 4 h on-stream at 973–1023 K whilst a slight drop in activity was observed at 923 K probably due to deposited carbon formed by thermodynamically favored CH₄ decomposition reaction. Both CH₄ and CO₂ conversions increased with rising reaction temperature and reaching about 91% and 94%, respectively at 1023 K with CO₂ and CH₄ partial pressure of 20 kPa. CH₄ conversion improved with increasing CO₂ partial pressure, ${\mathit{P}}_{\mathit{C}{\mathit{O}}_{\mathit{2}}}$ and exhibited an optimum at ${\mathit{P}}_{\mathit{C}{\mathit{O}}_{\mathit{2}}}$ of 30–50 kPa depending on reaction temperature whilst a substantial decline in CO₂ conversion was observed with growing ${\mathit{P}}_{\mathit{C}{\mathit{O}}_{\mathit{2}}}$. Additionally, CH₄ and CO₂ conversions decreased significantly with rising CH₄ partial pressure because of increasing carbon formation rate via CH₄ cracking in CH₄-rich feed. Post-reaction characterization shows that active Ni metal phase was not re-oxidized to inactive metal oxide during MDR reaction. The heterogeneous nature of deposited carbons including carbon nanofilament and graphite was detected on catalyst surface by Raman measurement.     

Mean drop size correlations and population balance models for liquid—liquid dispersion

Reliable models are required for accurate estimation of drop sizes which govern the interfacial area and rate of mass transfer in a system where various correlations and models have been improved for better accuracy and wider application breath. In this article, relevant semiempirical equations and population balance equation (PBE) models are reviewed. Semiempirical correlations are highly system dependent and limited to prediction of steady‐state drop size while PBE models could estimate transient drop size with considerations of inhomogeineity and flow spatial variation during drop size evolution. With appropriate model parameters determination, different PBE models can be used to reproduce experimental data for a similar system. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1129–1145, 2015     

Microwave-Assisted Aging of Organic–Inorganic Hybrid Nanocomposite of α-Naphthaleneacetate in the Lamella of Zn-Al-Layered Double Hydroxide

Microwave-assisted aging Zn-Al-layered double hydroxide with nitrate as the interlayer anion (ZANOL) and its nanohybrid with an organic moiety, -naphthaleneacetate (ZANAN), was done and the resulting properties of the materials compared. The results showed that intercalation of the -naphthaleneacetate (NAA) anion into the Zn-Al layered double hydroxide lamella is readily accomplished, resulting in the expansion of the interlayer spacing from 9.0 Å in the layered double hydroxide to 20.0 Å in the nanohybrid. This expansion accommodates the NAA anion of larger size than nitrate, as indicated by its molecular structure. For both methods, the resulting materials afforded a well-ordered organic–inorganic nanolayered structure. The Zn to Al ratio of the resulting nanocomposite is lower than the ratio present in the mother liquor at the beginning of the reaction, which implied less incorporation of aluminum ions from the mother liquor into the inorganic metal hydroxide layers. By using the microwave-assisted method, however, slightly more Al³⁺ ions were incorporated into the inorganic metal double hydroxide layers. In general, there is not much difference in the physicochemical properties of ZANANs aged by either the microwave or the conventional oil bath method. For both methods, longer aging time slightly enriched the organic content of the resulting nanohybrid and the inorganic Zn to Al ratio remained the same, independent of the aging time.     

Self-assembled nanocomposite of organic-inorganic hybrid: 2,4-dichlorophenoxyacetate in Zn-Al hydrotalcite-like layers

Hydrotalcite-like inorganic layers of Zn-Al, a host containing an organic moiety, 2,4-dichlorophenoxy-acetate, as a guest, was prepared by the spontaneous self-assembly method from an aqueous solution for the formation of a new layered organic-inorganic hybrid nanocomposite material. In this synthesis, the host- and guest-forming species were simultaneously included in the mother liquor, aged, and separated. Various Zn/Al ratios (R = 2, 3, and 4), concentrations of 2,4-dichlorophenoxyacetic acid (0.03-0.1 M), and pH (7 and 10) were studied to optimize the formation of the layered nancomposite. It was found that the optimum conditions for the formation of the nanocomposite were R = 4, pH 7, and concentration of 2,4-dichlorophenoxyacetic acid = 0.08 M. X-ray diffraction shows that this sample affords a nanolayered structure with a basal spacing of 24.6 A.     

Surface modification of ZnO nanorods with CdS quantum dots for application in inverted organic solar cells: effect of deposition duration

Incorporating cadmium sulfide quantum dots (CdS QDs) onto ZnO nanorod (ZNRs) has been investigated to be an efficient approach to enhance the photovoltaic performance of the inverted organic solar cell (IOSC) devices based on ZNRs/poly (3-hexylthiophene) (P3HT). To synthesize CdS/ZNRs, different durations of deposition per cycle from 1 to 9 min were used to deposit CdS via SILAR technique onto ZNRs surface grown via hydrothermal method at low temperature on FTO substrate. In typical procedures, P3HT as donor polymer were spun-coating onto CdS/ZNRs to fabricate IOSC devices, followed by Ag deposition as anode by magnetron sputtering technique. Incorporation of CdS QDs has modified the morphological, structural, and optical properties of ZNRs. Incorporation of CdS QDs onto ZNRs also led to higher open circuit voltage (V_oc) and short circuit current density (J_sc) of optimum ZNRs/CdS QDs devices due to the increased interfacial area between ZNRs and P3HT for more efficient exciton dissociation, reduced interfacial charge carrier recombination as a result of lower number of oxygen defects which act as electron traps in ZnO and prolonged carrier recombination lifetime. Therefore, the ZNRs/CdS QDs/P3HT device exhibited threefold higher PCE (0.55%) at 5 min in comparison to pristine ZNR constructed device (0.16%). Overall, our study highlights the potential of ZNRs/CdS QDs to be excellent electron acceptors for high efficiency hybrid optoelectronic devices.     

Effects of annealing temperature on the structural,morphology, optical properties and resistivity of sputtered CCTO thin film

CaCu₃Ti₄O₁₂ (CCTO) thin films with a thickness of 200 nm were deposited on ITO substrates by RF magnetron sputtering using a pure CCTO target. After the deposition, thin films were annealed at 400, 450, 500 and 550?°C, respectively, for 1 h. The effects of annealing temperature on the structural, surface morphology, optical properties and resistivity of (CCTO) thin films were investigated. The X-ray diffractometer results show that the thin films are polycrystalline in nature and are assigned to body-centered cubic perovskite configuration with a space group of Im-3. The intensity of the peaks and crystallinity gradually increased with the increase in annealing temperature. Microstructural investigation through FESEM showed that the grain size increased with increase in annealing temperature from 32 to 85 nm. The root mean square and roughness (Ra) were also enhanced with higher annealing temperatures, from 3.8 to 6.2 nm and from 4.7 to 7.7 nm, respectively, as confirmed by AFM. Increase in annealing temperature also affected the optical transmittance values which decreased to almost 60% at the visible range (550–850), as well as the optical energy band gap which decreased from 3.86 to 3.39 eV. The relevance between resistance behaviors and film microstructure is discussed. Therefore, it can be concluded that the desirable crystallinity, surface roughness, energy band gap and resistivity for 200 nm thick CCTO thin films deposited by RF magnetron sputtering can be achieved through the annealing process.