Numerical investigation towards a HiTAC condition in a 9MW heavy fuel-oil boiler

In this study, several conditions in a 9 MW heavy fuel-oil boiler were numerically studied in order to get a better understanding of the application of HiTAC in such a boiler. Simulations were done with an Euler- Lagrange approach. The Eddy Dissipation model was used for combustion. Simulation results showed that by recycling various ratios of flue gas into the primary and secondary air, a more uniform temperature distribution can be achieved. Besides, thermal NOX can be reduced to a lower level. Radiation from soot has shown to have a considerable influence on the predicted temperature profiles. It can reduce the peak temperature by 140 K in the case with hot combustion air

Numerical investigation of spray combustion towards HITAC conditions

The features of High Temperature Air Combustion (HiTAC), i.e. high-efficiency combustion processes creating a uniform temperature distribution with low NOX and CO emissions, lend itself ideally for the combustion of all sorts of "difficult” fuels, ranging from low-calorific gases such as waste-gases, to heavy fuel-oils. However, to date most of the applications of HiTAC are for gaseous fuels and solid fuels, while little has been investigated on liquid fuel spray combustion in such combustion regimes. The objective of the research presented in this thesis is to identify and specify the important parameters for achieving good model performance and to understand how HiTAC conditions can be achieved for spray combustion. For this purpose numerical investigations have been performed on the NIST (National Institute of Standards and Technology) methanol spray flame under a conventional condition, the DSHC (Delft Spray-in-Hot-Coflow) ethanol spray flames in both cold and hot co-flow conditions, and the heavy fuel oil spray combustion in a 9 MW boiler with flue gas recirculation using Stork Double Register Burner (DRB). The NIST methanol spray flame was numerically studied using an Eulerian- Lagrangian RANS model. With steady laminar flamelet model good agreements between experimental data and numerical results were observed. Then we extended the validated models and methods to the the simulation of DSHC flames, and also extended the limited co-flow conditions of experiment to a series of combinations of temperatures and O2 concentrations for comparative study. The results showed that the low O2 concentration plays a key role in the reduction of peak temperature and thus thermal NOX emissions. The flame profiles and SMD at various elevations showed good agreements with experimental data under the similar conditions. The analysis of spray trajectories has been discussed in order to perform proper model validation. Heavy fuel-oil combustion in a 9MW boiler was numerically investigated with the Euler-Lagrange method as well. For Combustion, Eddy Dissipation model with a two-step global reaction mechanism was used instead. The results showed that a more uniform temperature distribution in the boiler can be achieved by diluting the primary and secondary air flow with flue gas recirculation. In this way the thermal NOX can be effectively reduced, while the remained fuel NOX formation is mainly dependent on the local combustion characteristics and the initial concentration of nitrogen-bound compounds. Besides, soot formation should be included in the simulation since it shows considerable influence on peak temperature and NOX formation. It is also concluded that the realization of HiTAC-like conditions in heavy fuel-oil combustion depends on the possibility to guarantee a sufficiently high level of flue gas recirculation flow into the evaporating spray jet

Eulerian–Lagrangian RANS Model Simulations of the NIST Turbulent Methanol Spray Flame

A methanol spray flame in a combustion chamber of the NIST was simulated using an Eulerian–Lagrangian RANS model. Experimental data and previous numerical investigations by other researchers on this flame were analyzed to develop methods for more comprehensive model validation. The inlet boundary conditions of the spray were generated using semi-empirical models representing atomization, collision, coalescence, and secondary breakup. Experimental information on the trajectory of the spray was used to optimize the parameters of the pressure-swirl atomizer model. The standard k-ϵ turbulence model was used with enhanced wall treatment. A detailed reaction mechanism of gaseous combustion of methanol was used in the frame of the steady laminar flamelet model. The radiative transfer equations were solved using the discrete ordinates method. In general, the predicted mean velocity components of the gaseous flow and the droplets, the droplet number density, and the Sauter mean diameter (SMD) of the droplets at various heights in the present study show good agreement with the experimental data. Special attention is paid to the relative merits of the employed method to set inlet boundary conditions compared to the alternative method of using a measured droplet size and velocity distributio

Phytochemical Properties and In Vitro Biological Activities of Phenolic Compounds from Flower of Clitoria ternatea L.

Phenolic compounds from the flower of Clitoria ternatea L. (PCFCTL) were extracted using a high-speed shearing extraction technique and purified by AB-8 macroporous resins, and the phytochemical composition of the purified phenolic compounds from the flower of Clitoria ternatea L. (PPCFCTL) was then analyzed. Subsequently, its bioactivities including antioxidant properties, enzyme inhibitory activities, and antiproliferative activities against several tumor cell lines were evaluated. Results indicated that the contents of total phenolics, flavonoids, flavonols, flavanols, and phenolic acids in PPCFCTL were increased by 3.29, 4.11, 2.74, 2.43, and 2.96-fold, respectively, compared with those before being purified by AB-8 macroporous resins. The results showed PPCFCTL have significant antioxidant ability (measured by reducing power, RP, and ferric reducing antioxidant power method, FRAP) and good DPPH, ABTS+, and superoxide anion radical scavenging activities. They can also significantly inhibit lipase, α-amylase, and α-glucosidase. In addition, morphological changes of HeLa, HepG2, and NCI-H460 tumor cells demonstrated the superior antitumor performance of PPCFCTL. However, the acetylcholinesterase inhibitory activity was relatively weak. These findings suggest that PPCFCTL have important potential as natural antioxidant, antilipidemic, anti-glycemic and antineoplastic agents in health-promoting foods

Design, synthesis and biological evaluation of novel 9-N-substituted-13-alkylberberine derivatives from Chinese medicine as anti-hepatocellular carcinoma agents

A series of novel 9-N-substituted-13-alkylberberine derivatives from Chinese medicine were designed and synthesized with improved anti-hepatocellular carcinoma (HCC) activities. The optimal compound 4d showed strong activities against HepG2, Sk-Hep-1, Huh-7 and Hep3B cells with IC values of 0.58-1.15 μM, which were superior to positive reference cisplatin. Interestingly, 4d exhibited over 40-fold more potent activity against cisplatin-resistant HepG2/DPP cells while showing lower cytotoxicity in normal LX-2 cells. The mechanism studies revealed 4d greatly stabilized G-quadruplex DNA leading to intracellular c-MYC expression downregulation, blocked G2/M-phase cell cycle by affecting related p-cdc25c, cdc2 and cyclin B1 expressions, and induced apoptosis by a ROS-promoted PI3K/Akt-mitochondrial pathway. Furthermore, 4d possessed good pharmacokinetic properties and significantly inhibited the tumor growth in the H22 liver cancer xenograft mouse model without obvious toxicity. Altogether, the remarkably biological profiles of 4d both in vitro and in vivo would make it a promising candidate for HCC therapy. [Abstract copyright: Copyright © 2023 Elsevier Ltd. All rights reserved.

Downregulation of cardiac PIASy inhibits Cx43 SUMOylation and ameliorates ventricular arrhythmias in a rat model of myocardial ischemia/reperfusion injury

Abstract. Background:. Dysfunction of the gap junction channel protein connexin 43 (Cx43) contributes to myocardial ischemia/reperfusion (I/R)-induced ventricular arrhythmias. Cx43 can be regulated by small ubiquitin-like modifier (SUMO) modification. Protein inhibitor of activated STAT Y (PIASy) is an E3 SUMO ligase for its target proteins. However, whether Cx43 is a target protein of PIASy and whether Cx43 SUMOylation plays a role in I/R-induced arrhythmias are largely unknown. Methods:. Male Sprague–Dawley rats were infected with PIASy short hairpin ribonucleic acid (shRNA) using recombinant adeno-associated virus subtype 9 (rAAV9). Two weeks later, the rats were subjected to 45 min of left coronary artery occlusion followed by 2 h reperfusion. Electrocardiogram was recorded to assess arrhythmias. Rat ventricular tissues were collected for molecular biological measurements. Results:. Following 45 min of ischemia, QRS duration and QTc intervals statistically significantly increased, but these values decreased after transfecting PIASy shRNA. PIASy downregulation ameliorated ventricular arrhythmias induced by myocardial I/R, as evidenced by the decreased incidence of ventricular tachycardia and ventricular fibrillation, and reduced arrythmia score. In addition, myocardial I/R statistically significantly induced PIASy expression and Cx43 SUMOylation, accompanied by reduced Cx43 phosphorylation and plakophilin 2 (PKP2) expression. Moreover, PIASy downregulation remarkably reduced Cx43 SUMOylation, accompanied by increased Cx43 phosphorylation and PKP2 expression after I/R. Conclusion:. PIASy downregulation inhibited Cx43 SUMOylation and increased PKP2 expression, thereby improving ventricular arrhythmias in ischemic/reperfused rats heart