Effect of heat loss on the syngas production by fuel-rich combustion in a divergent two-layer burner

The effect of heat loss on the syngas production from partial combustion of fuel-rich in a divergent two-layer burner is numerically studied using two-dimensional model with detailed kinetics GRI-Mech 1.2. Both the radiation and wall heat losses to the surrounding are considered in the computations. It is shown that two types heat losses have different effects on the syngas production. The radiation heat loss has significant effect on the syngas temperature and the syngas temperature is dropped as radiation heat loss is increased, but it has neglected effect on the reforming efficiency and methane conversion efficiency. The wall heat loss has a comprehensive effect on the syngas production. The wall heat loss not only reduces the conversion efficiency, but also significantly decreases the syngas temperature. The effect of wall heat loss becomes weak as the equivalence is increased. The reforming efficiency drops from 0.440 to 0.424 for equivalence ratio of 2 and mixture velocity of 0.17 m/s for the predictions between adiabatic wall and non-adiabatic conditions.     

Investigating measurements of fine particle (PM2.5) emissions from the cooking of meals and mitigating exposure using a cooker hood

There is growing awareness that indoor exposure to particulate matter with diameter ≤ 2.5 μm (PM_2.5) is associated with an increased risk of adverse health effects. Cooking is a key indoor source of PM_2.5 and an activity conducted daily in most homes. Population scale models can predict occupant exposures to PM_2.5, but these predictions are sensitive to the emission rates used. Reported emission rates are highly variable and are typically for the cooking of single ingredients and not full meals. Accordingly, there is a need to assess PM_2.5 emissions from the cooking of complete meals. Mean PM_2.5 emission rates and source strengths were measured for four complete meals. Temporal PM_2.5 concentrations and particle size distributions were recorded using an optical particle counter (OPC), and gravimetric sampling was used to determine calibration factors. Mean emission rates and source strengths varied between 0.54—3.7 mg/min and 15—68 mg, respectively, with 95% confidence. Using a cooker hood (apparent capture efficiency > 90%) and frying in non‐stick pans were found to significantly reduce emissions. OPC calibration factors varied between 1.5 and 5.0 showing that a single value cannot be used for all meals and that gravimetric sampling is necessary when measuring PM_2.5 concentrations in kitchens.     

Combustion Wave Propagation of a Modular Porous Burner with Annular Heat Recirculation

A numerical investigation of the different arrangements of porous media in a combustor with annular heat recirculation is conducted.The effect of annular heat recirculation and porous block arrangement on the characteristics of combustion wave propagation is numerically studied.Results show that power input,heat capacity of porous matrix,arrangement of porous blocks,and annular heat recirculation are major factors that influence the propagation of combustion wave.The overall temperature of ceramic porous burner is higher than that of ceramic-metal type burner due to the lower heat storage capacity of the former,especially for the temperature downstream.The flame temperature is higher upstream and lower downstream with metal foams in the annulus than that without metal foams.The flame temperature of uniformity type burner is more uniform than that of gradually-varied and modular type burners.The flame front moves more slowly with metal foams in the annulus than that without metal foams due to the better preheating effect of metal foams.The flame position moves downstream,and the flame temperature gradually decreases and is eventually extinguished due to the low preheating temperature.     

Experimental investigation on gasification characteristics of polycarbonate (PC) microplastics in supercritical water

In order to solve the problem of marine microplastics and realize the harmless resource utilization of plastics, the gasification experiments of polycarbonate (PC) microplastics were carried out in supercritical water and a novel seawater gasification of microplastic experiment was investigated. In this paper, the effects of different operating conditions (temperature, time, feedstock concentration, pressure) on gasification performance were discussed. The gasification kinetic of microplastics in supercritical water was calculated. The experimental results showed that the increase in gasification temperature and time enhanced the cracking reaction and free radical reaction of the microplastics to increase the gasification efficiency, while the reduction in feedstock concentration improved the gasification efficiency by increasing the gasification level of unit feedstock. The change in pressure had no significant effect on gasification due to the fact that the properties of the supercritical water were not significantly changed. It was found that the valuable results that all alkali metal salts in seawater promote hydrogen conversion, while in terms of carbon conversion, only KCl, CaCl₂, NaHCO₃ and seawater had a significant catalytic effect on the gasification. Seawater gasification of microplastics was a potential resource utilization method. Finally, it was considered that the PC plastic gasification conformed to the random nucleation and subsequent growth model (n = 3), and the reaction activation energy was 230.45 kJ/mol, which was smaller than that of traditional pyrolysis.     

Electroactive polythiophene/polystyrene bottlebrushes as morphology compatibilizers in photovoltaic systems

Poly(3‐thiophene ethanol) (P3ThEt)‐graft‐polystyrene (PSt) bottlebrushes were synthesized and applied in active layers of poly(3‐hexylthiophene) (P3HT):phenyl‐C71‐butyric acid methyl ester (PC71BM) solar cells as morphology compatibilizers. In the presence of 15 wt% of P3ThEt‐graft‐PSt bottlebrush compatibilizers, the P3HT crystallite dimensions (D₍₁₀₀₎ = 45.67 nm and D₍₀₂₀₎ = 30.12 nm) and R_mean (38.96 nm) of PCBM clusters were the largest and the layer spacings were all the smallest (d₍₁₀₀₎ = 1.054 nm, d₍₀₂₀₎ = 0.301 nm and d_(PCBM) = 0.406 nm). These dimensional properties led to better hole (1.9 × 10^?3 cm² V^?1 s^?1) and electron (1.2 × 10^?2 cm² V^?1 s^?1) mobilities. The content of bottlebrushes was optimized at 15 wt%, and thereby the best photovoltaic results including the maximum cell efficiency of 5.37% were obtained for this turning point (12.75 mA cm^?2, 61%, 0.69 V). On exceeding the optimum weight percentage, all photovoltaic parameters decreased markedly and reached even less than that of pristine devices (1.92% versus 2.24%). After an optimum weight percentage of compatibilizers, further enhancement in bottlebrush content in active layers saturated and finally oversaturated the system and, consequently, the cell parameters significantly decreased. Accumulation of bottlebrushes in interfaces and donor/acceptor phases ruined the system function even with large and packed P3HT crystallites and PC71BM clusters. © 2019 Society of Chemical Industry     

小型蓄热式烧嘴的改进与应用

介绍了两种小型蓄热式烧嘴的改进过程、结构特点、工作原理以及在中小型加热炉、热处理炉上应用取得的显著效益。     

PLC控制在气力除灰系统的应用

本文根据攀钢发电厂除灰系统的控制性能要求,采用“上位机+PLC”组成的控制系统实现对除灰系统的控制.该控制系统具有抗干扰能力强、可靠性高、操作简便、扩展方便等优点.     

Dynamic viscoelasticity and molecular orientation in uniaxially drawn PC/PET blends

The dependence of dynamic viscoelasticity on molecular orientation of the hot-drawn polycarbonate (PC)/poly(ethylene terephthalate) blends was studied experimentally. The oriented states of samples were investigated by wide-angle X-ray diffraction and quantified by Hermans' factor. The viscoelasticity was probed by dynamic mechanical analysis. For the fitting curves of dynamic modulus versus orientation, the PC-rich blends with different compositions had an opposite concavity and convexity compared with the neat PC. The difference revealed the influence of molecular mobility on orientation and viscoelasticity. The assumption on the phase morphological change from sea-island to local sandwich-like structure in blends was proposed and used to interpret the variation of slope of fitting curves. The relationship between orientation and viscoelasticity was observed in PC-rich blends, which can help understand the mechanism of molecular orientation and develop the constitutive relations for simulation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47514.     

Improved stability in P3HT:PCBM photovoltaics by incorporation of well‐designed polythiophene/graphene compositions

Morphological and photovoltaic stabilities of poly(3‐hexylthiophene) (P3HT):phenyl‐C₆₁‐butyric acid methyl ester (PC₇₁BM) solar cells were investigated in pristine and modified states. To this end, four types of patterned/assembled nanostructures, namely reduced graphene oxide (rGO)‐g‐poly(3‐dodecylthiophene)/P3HT patched‐like pattern, rGO–polythiophene/P3HT/PC₇₁BM nanofiber, rGO‐g‐P3HT/P3HT cake‐like pattern and supra(polyaniline (PANI)‐g‐rGO/P3HT), were designed on the basis of rGO and various conjugated polymers. Intermediately covered rGO nanosheets by P3HT crystals (supra(PANI‐g‐rGO/P3HT)) performed better than sparsely (patched‐like pattern) and fully (cake‐like pattern) covered ones in P3HT:PC₇₁BM solar cell systems. Supra(PANI‐g‐rGO/P3HT) nanohybrids largely phase‐separated in active layers (root mean square = 0.88 nm) and also led to the highest performance (power conversion efficiency of 5.74%). The photovoltaic characteristics demonstrated decreasing trends during air aging for all devices, but with distinct slopes. The steepest decreasing plots were obtained for the unmodified P3HT:PC₇₁BM devices (from 1.77% to 0.28%). The two supramolecules with the most ordered structures, that is, cake‐like pattern (10.12 mA cm^?2, 51%, 0.58 V, 2.2 × 10^?6 cm² V^?1 s^?1, 4.3 × 10^?5 cm² V^?1 s^?1, 0.69 nm and 2.99%) and supra(PANI‐g‐rGO/P3HT) (12.51 mA cm^?2, 57%, 0.63 V, 1.2 × 10^?5 cm² V^?1 s^?1, 3.4 × 10^?4 cm² V^?1 s^?1, 0.82 nm and 4.49%), strongly retained morphological and photovoltaic stabilities in P3HT:PC₇₁BM devices after 1 month of air aging. According to the morphological, optical, photovoltaic and electrochemical results, the supra(PANI‐g‐rGO/P3HT) nanohybrid was the best candidate for stabilizing P3HT:PC₇₁BM solar cells. © 2020 Society of Chemical Industry