Application of Parallel Compution on Numerical Simulation for the Fluid Flow Field of Fan

Abstract-In this paper, Numerical simulation and analysis was conducted on the flow field of axial fan by FLUENT software and the solved speeds of serial and parallel solver has been compared, and the effect of different number of nodes on the speed of parallel computation was discussed. The results showed that the convergence time used with the parallel solver is reduced by nearly 40% than that of the serial solver; with the increase of the number of nodes in parallel computation, the time required for convergence first decreased and then increased. The convergence time is the least when it is 6 nodes. On this basis, three-dimensional time average N-S equation was solved by the parallel algorithm, and the flow field of axial fan was simulated. The results show that when air flows through the impeller, vortex flow is generated at the rear of wheel, and the flow resistance increase; The "C" type distribution of pressure gradient is formed at leaf blade surface which can better improve the air distribution in the channel

Analysis of heat exchanger network for temperature fluctuation

Subject to temperature disturbance, exchangers in heat exchanger network will interact. It is necessary to evaluate the degree of temperature fluctuation in the network. There is inherently linear relationship between output and inlet temperatures of heat exchanger network. Based on this, the concept of temperature-change sensitivity coefficient was put forward. Quantitative influence of temperature fluctuation in the network was carried out in order to examine transmission character of temperature fluctuation in the system. And the information was obtained for improving the design quality of heat exchanger network. Favorable results were obtained by the introduced method compared with the experimental results. These results will assist engineers to distinguish primary and secondary influencing factors, which can be used in observing and controlling influencing factors accurately

Advancing thermal performance through vortex generators morphing

Abstract The design of rigid vortex generators (RVG) influences the thermal performance of various technologies. We employed Discrete Adjoint-Based Optimization to show the optimal development of vortex generators. Under turbulent flow conditions, different bi-objective functions on the RVG design were examined. Specifically, we aimed at an optimal RVG shape that minimizes the pressure drop and maximizes the local heat transfer in a rectangular channel. We show that an optimal design of an RVG can be obtained using computational fluid dynamics in conjunction with the Pareto Front at a computational cost of the order ~ $$O(10^{-1})$$ O ( 10 - 1 ) . We obtained three essential vortex generator shapes based on the RVG morphing technique. Compared to the baseline geometry of a delta winglet pair DWP, the first morphed design reduced the pressure drop by $$39\%$$ 39 % , however, at the expense of a $$21\%$$ 21 % reduction in the Nusselt number. The second vortex generator design enhanced the heat transfer by $$18\%$$ 18 % , however, at the cost of a significant increase in pressure drop of about $$40\%$$ 40 % . The final morphed design achieved the highest thermal performance factor of 1.28, representing a heat transfer enhancement of $$6\%$$ 6 % with a moderate increase in pressure drop of about $$13\%$$ 13 % compared to DWP vortex generators. Furthermore, we investigated the effect of introducing different size holes on the mass reduction of vortex generators and their thermal performances. The mass of vortex generators can be reduced by $$9\%$$ 9 % and with an increase of $$7\%$$ 7 % in thermal performance factor concerning the DWP baseline. The findings of this study will lead to highly efficient lightweight heat exchangers

Optimal shape design and performance investigation of helically coiled tube heat exchanger applying MO-SHERPA

International audienc

Expressions and Regulatory Effects of P38/ERK/JNK Mapks in the Adipogenic Trans-Differentiation of C2C12 Myoblasts

Background/Aims: Myoblasts and muscle satellite cells have the potential to transdifferentiate into adipocytes or adipocyte-like cells. Previous studies suggest that mitogen-activated protein kinase (MAPK) is critical to adipogenic trans-differentiation of muscle cells. ERK1/2, P38 and JNK are three major MAPK family members; their activation and regulatory functions during adipogenic trans-differentiation of myoblasts are investigated. Methods: C2C12 myoblasts were cultured and induced for adipogenic trans-differentiation. Activation patterns of MAPKs were assayed using protein microarray and Western blot. Three specific MAPK blockers, U0126, SB20358 and SP600125, were used to block ERK1/2, P38 and JNK during trans-differentiation. Cellular adipogenesis was measured using staining and morphological observations of cells and expression changes in adipogenic genes. Results: Inhibitors reduced phosphorylation of corresponding MAPK and produced unique cellular effects. Suppressing P38 promoted adipogenic trans-differentiation and intensified adipolytic metabolism in differentiated cells. However, inhibition of ERK1/2 had the opposite effects on adipogenesis and no effect on adipolysis. Blocking JNK weakly blocked trans-differentiation but stimulated adipolysis and induced apoptosis. Conclusion: Three MAPKs participate in the regulation of myoblast adipogenic trans-differentiation by controlling adipogenic and adipolysis metabolism

Devolatilization characteristics of Oedogonium sp., Loy Yang coal and their blends using thermogravimetric analysis

In order to assess the potential of gasification for the utilisation of algal biomass, the devolatilisation characteristics of a fresh water macroalgae (Oedogonium sp.), a Victoria brown coal (Loy Yang) and their blends were investigated. The study indicated that Oedogonium sp. and Loy Yang coal exhibit quite different pyrolysis characteristics under the same pyrolysis conditions, the devolatization of Oedogonium sp. occurs mainly between 180-410 °C, while for Loy Yang coal pyrolysis occurs over a wider temperature zone. The effect of heating rate on the devolatilization characteristics of these two fuels was also studied; for heating rates of 10-40 °C /min it was found that pyrolysis shifts to higher temperatures as the heating rate increases for both fuels. There is no significant change in the residual mass for Loy Yang coal, however, the residual mass of Oedogonium sp. decreases slightly as the heating rate increases. The pyrolysis characteristics of blends of these two fuels were also investigated for different blending ratios. No interaction effects were observed to exist for the experimental conditions investigated. Based on this work, successful co-gasification of macroalgae and coal is not expected to be impeded by limitations occurring during the pyrolysis stage

Preparation of a Z-Type g-C3N4/(A-R)TiO2 Composite Catalyst and Its Mechanism for Degradation of Gaseous and Liquid Ammonia

In this study, an (A-R)TiO2 catalyst (ART) was prepared via the sol–gel method, and g-C3N4 (CN) was used as an amendment to prepare the g-C3N4/(A-R)TiO2 composite catalyst (ARTCN). X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, N2 adsorption–desorption curves (BET), UV–Vis diffuse absorption spectroscopy (UV–Vis DRS), and fluorescence spectroscopy (PL) were used to evaluate the structure, morphology, specific surface area, optical properties, and photocarrier separation ability of the catalysts. The results showed that when the modifier CN content was 0.5 g, the dispersion of the ARTCN composite catalyst was better, with stronger light absorption performance, and the forbidden band width was smaller. Moreover, the photogenerated electrons in the conduction band of ART transferred to the valence band of CN and combined with the holes in the valence band of CN, forming Z-type heterostructures that significantly improved the efficiency of the photogenerated electron-hole migration and separation, thus increasing the reaction rate. Gaseous and liquid ammonia were used as the target pollutants to investigate the activity of the prepared catalysts, and the results showed that the air wetness and initial concentration of ammonia had a great influence on the degradation of gaseous ammonia. When the initial concentration of ammonia was 50 mg/m3 and the flow rate of the moist air was 0.9 mL/min, the degradation rate of gaseous ammonia by ARTCN-0.5 reached 88.86%, and it had good repeatability. When the catalytic dose was 50 mg and the initial concentration of NH4+ was 100 mg/L, the degradation rate of liquid ammonia by ARTCN-0.5 was 71.60% after 3 h of reaction, and small amounts of NO3− and NO2− were generated. The superoxide anion radical (·O2−) and hydroxyl radical (·OH) were the main active components in the photocatalytic reaction process

MicroRNA-199a Targets the Fatty Acid Transport Protein 1 Gene and Inhibits the Adipogenic Trans-Differentiation of C2C12 Myoblasts

Background/Aims: Muscle cells are able to trans-differentiate into adipocytes with adipogenesis induction. MicroRNAs (miRNAs), a class of small non-coding RNAs, widely participate in the regulation of growth and development of cells. However, the expression and regulatory role of miRNAs in the trans-differentiation of muscle cell are largely unknown. Methods: C2C12 myoblasts were inducted to adipogenesis trans-differentiation and microarrays were used to assay the changes of expression profile of miRNAs. MiR-199a, a miRNA showed significant change in the trans-differentiation, was selected for the subsequent function study via over- expression and knock down. Results: Dozens of miRNAs showed different changes followed the adipogenesis trans-differentiation of C2C12 cells. In which, miR-199a was decreased in the adipogenic cells and miR-199a over-expression inhibited the trans-differentiation and decreased lipid accumulation in the cells. Moreover, Fatty acid transport protein 1 (Fatp1), a major regulator of trans-membrane transportation and the oxidative metabolism of free fatty acids, was showed to be a target of miR-199a by computational and luciferase reporter assays. Additionally, Fatp1 knock-down by small interfering RNA had similar inhibitory effects on the trans-differentiation in C2C12 cells. Conclusion: Our study reveals an important role for miR-199a in the regulation of adipogenic trans-differentiation in muscle cells via suppression of Fatp1 gene

Heterostructure Cu2O/(001)TiO2 Effected on Photocatalytic Degradation of Ammonia of Livestock Houses

In this paper, a heterogeneous composite catalyst Cu2O/(001)TiO2 was prepared by the impregnation-reduction method. The crystal form, highly active facet content, morphology, optical properties, and the photogenerated electron-hole recombination rate of the as-prepared catalysts were investigated. The performance of Cu2O/(001)TiO2 was appraised by photocatalytic degradation of ammonia under sunlight and was compared with lone P25, Cu2O, and (001)TiO2 at the same reaction conditions. The results showed that 80% of the ammonia concentration (120 ± 3 ppm) was removed by Cu2O/(001)TiO2, which was a higher degradation rate than that of pure P25 (12%), Cu2O (12%), and (001)TiO2 (15%) during 120 min of reaction time. The reason may be due to the compound’s (Cu2O/(001)TiO2) highly active (001) facets content that increased by 8.2% and the band gap width decreasing by 1.02 eV. It was also found that the air flow impacts the photocatalytic degradation of ammonia. Therefore, learning how to maintain the degradation effect of Cu2O/(001)TiO2 with ammonia will be important in future practical applications