| 1. |
- Li, Fangfang, et al.
(författare)
-
Combination of CO2 electrochemical reduction and biomass gasification for producing methanol : A techno-economic assessment
- 2024
-
Ingår i: Energy Conversion and Management. - : Elsevier Ltd. - 0196-8904 .- 1879-2227. ; 307
-
Tidskriftsartikel (refereegranskat)abstract
- Combining CO2 electrochemical reduction (CO2R) and biomass gasification for producing methanol (CH3OH) is a promising option to increase the carbon efficiency, reduce total production cost (TPC), and realize the utilization of byproducts of CO2R system, but its viability has not been studied. In this work, systematic techno-economic assessments for the processes that combined CO2R to produce CO/syngas/CH3OH with biomass gasification were conducted and compared to stand-alone biomass gasification and CO2R processes, to identify the benefits and analyze the commercialization potential of different pathways under current and future conditions. The results demonstrated that the process that combined biomass gasification with CO2R to CO represents a viable pathway with a competitive TPC of 0.39 €/kg-CH3OH under the current condition. For all the combined cases, electricity usage for CO2R accounts for 36–76% of total operating cost, which plays a key role for TPC. Sensitivity analysis confirmed that the process that combined biomass gasification with CO2R to CO is sensitive to the price of electricity, while both CO2R performance and prices of stack and electricity are important for the processes that combined with CO2R to syngas/CH3OH.
|
|
| 2. |
- Fan, Y., et al.
(författare)
-
Mechanical preparation of nano titanium dioxide powder and its optical properties
- 2007
-
Ingår i: Journal of the Chinese Ceramic Society. - 0454-5648. ; 35:7, s. 832-837
-
Tidskriftsartikel (refereegranskat)abstract
- mechanical preparation of the nano-sized particles of TiO2 powder by a stirred bead mill was investigated. The particle sizes of the ground products were determined by the acoustic particle sizer, the nitrogen gas adsorption method and a scanning electron microscopy. The diameter of the nano-sized particles, which were obtained after milling for 7 h, is about 50 nm and the specific surface area is up to 70 m2/g. The surface and structure of the samples have been investigated with X-ray diffraction. It is indicated that an intense comminution in the mill leads to a progressive loss in crystallinity of TiO2. The catalytic degradation of methyl orange in water was also studied by a photometer. The results show that the nano-sized particles of TiO2 powder prepared by milling possess photocatalysis effect and are capable of absorption of ultraviolet radiation
|
|
| 3. |
|
|
| 4. |
- Li, X. Y., et al.
(författare)
-
Collision Fluctuations of Lucky Droplets with Superdroplets
- 2022
-
Ingår i: Journal of the Atmospheric Sciences. - : American Meteorological Society. - 0022-4928 .- 1520-0469. ; 79:7, s. 1821-1835
-
Tidskriftsartikel (refereegranskat)abstract
- It was previously shown that the superdroplet algorithm for modeling the collision-coalescence process can faithfully represent mean droplet growth in turbulent clouds. An open question is how accurately the superdroplet algorithm accounts for fluctuations in the collisional aggregation process. Such fluctuations are particularly important in dilute suspensions. Even in the absence of turbulence, Poisson fluctuations of collision times in dilute suspensions may result in substantial variations in the growth process, resulting in a broad distribution of growth times to reach a certain droplet size. We quantify the accuracy of the superdroplet algorithm in describing the fluctuating growth history of a larger droplet that settles under the effect of gravity in a quiescent fluid and collides with a dilute suspension of smaller droplets that were initially randomly distributed in space ("lucky droplet model"). We assess the effect of fluctuations upon the growth history of the lucky droplet and compute the distribution of cumulative collision times. The latter is shown to be sensitive enough to detect the subtle increase of fluctuations associated with collisions between multiple lucky droplets. The superdroplet algorithm incorporates fluctuations in two distinct ways: through the random spatial distribution of superdroplets and through the Monte Carlo collision algorithm involved. Using specifically designed numerical experiments, we show that both on their own give an accurate representation of fluctuations. We conclude that the superdroplet algorithm can faithfully represent fluctuations in the coagulation of droplets driven by gravity.
|
|
| 5. |
- Liang, G-B, et al.
(författare)
-
Modified regularization method applied to the inversion of particle size distribution from light scattering data
- 2006
-
Ingår i: Guangdian Gongcheng. - 1003-501X. ; 33:12, s. 44-49
-
Tidskriftsartikel (refereegranskat)abstract
- Laser particle size analyzer is one of the instruments for particle size analysis. Recent developments focus on various algorithms for particle size analysis via light energy distribution based on the Mie scattering theory in the laser analyzer. The determination of the particle size distribution (PSD) from the analyzer requires the inversion of the Fredholm integral equation of the first kind. This equation is an ill-posed one, which can be analyzed by effective algorithms. This paper presents a modified regularization method applied to the inversion of the PSD with the independent models. The Generalized Cross-Validation (GCV) method was used for the selection of a regularization parameter. The Successive Over-Relaxation (SOR) iterative method was applied to improve the exactness and stability of the convergent result. The simulation with the models was carried out. The simulated results are in a good agreement with the data measured from nine standard particulate samples as well as their mixtures. It is indicated that this method can be feasible and effective for the simulation of the PSD from the corresponding light scattering data.
|
|
| 6. |
- Tang, C. A., et al.
(författare)
-
A theoretical model for Kaiser effect in rocks
- 1997
-
Ingår i: Pure and Applied Geophysics. - : Springer Science and Business Media LLC. - 0033-4553 .- 1420-9136. ; 150:2, s. 203-215
-
Tidskriftsartikel (refereegranskat)abstract
- The mechanism of Kaiser effect was studied with the aid of a damage model for rock. Recognizing that the AE counts are transient elastic waves due to local damage of the rock, the quantitative relation between AE counts and statistical distribution of the local strength of the rock has been established. Subsequently, according to Damage Theory, an expression for Kaiser Effect under uniaxial stress state was derived from the model. This is found to be in good agreement with the experimental results.
|
|
| 7. |
- Zhang, L., et al.
(författare)
-
A nearly end-to-end deep learning approach to fault diagnosis of wind turbine gearboxes under nonstationary conditions
- 2023
-
Ingår i: Engineering applications of artificial intelligence. - : Elsevier Ltd. - 0952-1976 .- 1873-6769. ; 119
-
Tidskriftsartikel (refereegranskat)abstract
- Fault diagnosis of wind turbine gearboxes is crucial in ensuring wind farms’ reliability and safety. However, nonstationary working conditions, such as load change or speed regulation, may result in an accuracy deterioration of many existing fault diagnosis approaches. To overcome the issue, this research proposes a nearly end-to-end deep learning approach to fault diagnosis of wind turbine gearboxes using vibration signals. Concretely, we adopt Empirical Mode Decomposition (EMD) to decompose vibration signals into a series of Intrinsic Mode Functions (IMFs). Then, the multi-channel IMFs are fed into a 1D Convolutional Neural Network (CNN) for automatic feature learning and fault classification. Since EMD is a signal processing technique requiring no prior knowledge, the model architecture can be viewed as nearly end-to-end. The proposed approach was validated in a real-world dataset; it proved deep learning models have an overwhelming advantage in representation capacity over traditional shallow models. It also demonstrated that the introduction of EMD as a preprocessing step improves both the training efficiency and the generalization ability of a deep model, thus leading to a better fault diagnosis efficacy under variable working conditions.
|
|
| 8. |
- Zhang, Zhibo, et al.
(författare)
-
Application and Challenge of Ionic Liquids as Co-solvent for Electro-enzymatic Conversion of CO2 to Methanol
- 2021
-
Ingår i: Proceedings of the Chinese Society of Electrical Engineering. - : Chinese Society for Electrical Engineering. - 0258-8013. ; 41:11, s. 3657-3665
-
Tidskriftsartikel (refereegranskat)abstract
- Utilization of carbon dioxide (CO2) has attracted great research interests, because CO2 is both a typical greenhouse gas and renewable carbon resource. This review mainly summarized and reviewed the research work linked to the challenges in the enzymatic conversion of CO2, such as NADH regeneration and low CO2 conversion efficiency. Based on the summary on the electro-enzymatic conversion of CO2, ionic liquids for the enzymatic conversion of CO2, and ionic liquids for the electrochemical conversion of CO2, we suggested applying ionic liquids as co-solvent in the enzymatic conversion of CO2 to methanol and coupling it with the reduction of NAD+ to NADH by electrocatalysis, providing a novel pathway for producing methanol from CO2.
|
|
| 9. |
- Zhang, Z., et al.
(författare)
-
Electromagnetic wave-based analysis of laser–particle interactions in directed energy deposition additive manufacturing
- 2020
-
Ingår i: Additive Manufacturing. - : Elsevier. - 2214-8604 .- 2214-7810. ; 34
-
Tidskriftsartikel (refereegranskat)abstract
- A modified heat-source model based on electromagnetic wave theory was proposed to investigate the interactions between powder particles and a laser beam, considering the spatial distribution of particles inside the beam. The absorption of energy by these particles in laser directed energy deposition additive manufacturing was calculated using the proposed model, which was validated experimentally. Both numerical model and experiment were used to study the effects of powder velocities on the temperature variations in the additive manufacturing process. Results indicate that the direct heat transfer from the laser to a target can be increased if the size distribution is wider; it also increases with the velocity of the particles. However, with the increase of powder-flow rate, the rate of mass transfer decreases the heat transfer. Melt-pool depth in melting and re-melting processes can therefore be controlled by varying these parameters.
|
|
