| 1. |
- Wang, K., et al.
(författare)
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Amended soils with weathered coal exhibited greater resistance to aggregate breakdown than those with biochar : From the viewpoint of soil internal forces
- 2024
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Ingår i: Soil & Tillage Research. - : Elsevier B.V.. - 0167-1987 .- 1879-3444. ; 244
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Tidskriftsartikel (refereegranskat)abstract
- Soil erosion is the first threat to soil functions. Reducing the soil aggregate breakdown strength is a key step to improve the soil's ability to resist rainfall splash erosion. Soil internal forces have been found to be the initial and important forces driving aggregate turnover. The application of exogenous organic materials can effectively improve soil aggregate stability and the resistance to rainfall erosion of agricultural soils. However, from the perspective of soil internal forces, information about the reduction effects of the exogenous organic materials application on soil aggregate breakdown is scarce, especially in comparing the effects of different materials. In this study, weathered coal and biochar were individually applied to loamy clay soil at rates of 0 %, 1 %, 2 %, and 3 % (w/w). Soil internal forces, aggregate breakdown strength, and splash erosion rate of different amended soils were then examined after four years. The results showed that compared with unamended soils (0 %), both weathered coal and biochar applications clearly increased the van der Waals attractive pressure and thus decreased the positive net pressure between soil particles. Additionally, these materials reduced soil aggregate breakdown strength and splash erosion rate. The application effects of the two materials were increased with their application rates. Under a lower electrolyte concentration in soil solution (0.0001 mol L−1), the aggregate breakdown strength in the soils amended with weathered coal was lower than that with biochar by 9.6 %, 23.2 %, and 17.7 % (when the diameter of broken aggregate was < 10 μm) and by 10.3 %, 20.8 %, and 17.5 % (when the diameter of broken aggregate was < 20 μm) at the 1 %, 2 %, and 3 % application rates, respectively (P < 0.05). Additionally, soils amended with weathered coal exhibited lower splash erosion rates compared to those amended with biochar, particularly at the higher application rate of 3 %. From the viewpoint of soil internal forces, weathered coal appears to be a suitable exogenous organic material for improving soil aggregate stability and anti-erosion ability during rainfall events. Our findings provide valuable insights into utilizing exogenous materials to improve soil resistance to rainfall splash erosion, assisting agricultural soil management in areas frequently affected by rainfall erosion.
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| 2. |
- Chen, S., et al.
(författare)
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Investment decision on shallow geothermal heating & cooling based on compound options model : A case study of China
- 2019
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 254
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Tidskriftsartikel (refereegranskat)abstract
- Developing shallow geothermal energy is expected to play an important role to supply affordable, clean and reliable heating by many countries in the world. However, the development is mainly hindered by the high upfront investment costs and various risks involved in the exploration, construction and operation phases. The present study proposed a compound options model to explore the optimal investment timing and value based on the consideration of both investment and operational flexibilities. The Least Square Monte Carlo and Markov Chain Monte Carlo methods were employed in the model to find the solutions. A case study was carried out for China, and five scenarios were simulated to understand the effects of different policies including subsidy, carbon trading mechanism, preferential taxation and preferential electricity price. The obtained results show that, (i) the incentive policies are essential for the development of shallow geothermal energy, which can attract more investment before 2030; (ii) the government is suggested to carry out a preferential electricity price for shallow geothermal development, rather than increase the subsidy; (iii) the application of compound options method increases the investment value in all five scenarios, but its impact on investment timing varies.
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| 3. |
- Li, Hailong, 1976-, et al.
(författare)
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A dynamic price model based on levelized cost for district heating
- 2019
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Ingår i: Energy, Ecology and Environment. - : Joint Center on Global Change and Earth System Science of the University of Maryland and Beijing Normal University. - 2363-7692 .- 2363-8338. ; 4:1, s. 15-25
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Tidskriftsartikel (refereegranskat)abstract
- District Heating (DH) is facing a tough competition in the market. In order to improve its competence, an effective way is to reform price models for DH. This work proposed a new dynamic price model based on the levelized cost of heat (LCOH) and the predicted hourly heat demand. A DH system in Sweden was used as a case study. Three methods were adopted to allocate the fuel cost to the variable costs of heat production, including (1) in proportion to the amount of heat and electricity generation; (2) in proportion to the exergy of generated heat and electricity; and (3) deducting the market price of electricity from the total cost. Results indicated that the LCOH-based pricie model can clearly reflect the production cost of heat. Through the comparison with other market-implemented price models, it was found that even though the market-implemented price models can, to certain extent, reflect the variations in heat demand, they cannot reflect the changes in production cost when different methods of heat production are involved. In addition, price model reforming can lead to a significant change in the expense of consumers and consequently, affect the selection of heating solution.
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| 4. |
- Qiu, R., et al.
(författare)
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A model-experience-driven method for the planning of refined product primary logistics
- 2022
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Ingår i: Chemical Engineering Science. - : Elsevier Ltd. - 0009-2509 .- 1873-4405. ; 254
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Tidskriftsartikel (refereegranskat)abstract
- Logistics planning is regarded as the most complex part of supply chain management for refined products. A vital knowledge gap still exists in understanding the trade-offs between the economy and the practicability of logistics schemes. Focus on this issue, this paper proposes a model-experience-driven method for the planning of refined product primary logistics. The method couples three sub-modules: (1) use coordinator's preference information and convex function interpolation to construct satisfaction indicator; (2) set up a multi-objective model for logistics coordination and optimization considering supply adjustment and secondary delivery; (3) adopt the augmented ɛ-constraint method to obtain the Pareto solutions and balance the economy and satisfaction indicators. The method is verified by a small-scale system, where the satisfaction degree increases by 77% while the logistics cost remains unchanged. The method is also successfully applied to a large-scale system with 29 refineries and 196 market depots, where Pareto logistics schemes are obtained and the supply–demand imbalance is greatly eased. The proposed method can help provide theoretical guidance for real-world logistics planning.
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| 5. |
- Sun, Q., et al.
(författare)
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A Comprehensive Review of Smart Energy Meters in Intelligent Energy Networks
- 2016
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Ingår i: IEEE Internet of Things Journal. - 2327-4662. ; 3:4, s. 464-479
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Tidskriftsartikel (refereegranskat)abstract
- The significant increase in energy consumption and the rapid development of renewable energy, such as solar power and wind power, have brought huge challenges to energy security and the environment, which, in the meantime, stimulate the development of energy networks toward a more intelligent direction. Smart meters are the most fundamental components in the intelligent energy networks (IENs). In addition to measuring energy flows, smart energy meters can exchange the information on energy consumption and the status of energy networks between utility companies and consumers. Furthermore, smart energy meters can also be used to monitor and control home appliances and other devices according to the individual consumer's instruction. This paper systematically reviews the development and deployment of smart energy meters, including smart electricity meters, smart heat meters, and smart gas meters. By examining various functions and applications of smart energy meters, as well as associated benefits and costs, this paper provides insights and guidelines regarding the future development of smart meters.
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| 6. |
- Wei, X., et al.
(författare)
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Assessing benefits in the flexibility of refined oil logistics from pipeline network integration reform : A case from South China
- 2022
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Ingår i: Chemical Engineering Science. - : Elsevier Ltd. - 0009-2509 .- 1873-4405. ; 253
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Tidskriftsartikel (refereegranskat)abstract
- The pipeline network integration reform enables unified management of pipelines from different entities. For refined oil logistics, this paper proposes a framework based on the MILP optimization model to quantify its flexibility. Considering the uncertainty, three disturbances occur in the logistics concurrently, and 10,000 simulations are performed to obtain the turnover cost. The ratio of pipeline transportation cost to the calculated average turnover cost is defined as the flexibility indicator. Taking China's largest refined oil pipeline network as an example, the results show that the flexibility rises 8.9% after the reform. The paper also quantifies the impact of the reform on logistics flexibility in South China, which is embodied in achieving lower freights and GHG emissions, lower impact by fluctuations, higher pipeline utilization, more efficient oil product turnover, and the avoiding of depot shortages when facing logistical disturbances. The underlying reasons for the results and 3E analysis are analyzed.
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| 7. |
- Yang, Xiaohu, et al.
(författare)
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Thermal and economic analysis of charging and discharging characteristics of composite phase change materials for cold storage
- 2018
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 225, s. 585-599
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Tidskriftsartikel (refereegranskat)abstract
- This study conducted both experimental and numerical investigations on the solidification behavior in a metal foam composite phase change material (PCM) for cold storage. Volume-average-method was adopted with the help of Forchheimer-Darcy equation to model the fluid flow through porous media. Experimental measurements were performed to validate the analytical model and the numerical method, with good agreement achieved. Local thermal equilibrium and non-equilibrium states were justified numerically and experimentally. Effect of pore morphological parameters (porosity and pore density) upon the solidification features of composite PCM were investigated. For the appliance of composite PCM to cold storage, techno-economic characteristics was also assessed. Results demonstrated that the full solidification time for metal foams with a porosity of 0.93 and 0.97 can be saved 87.5% and 76.7% respectively compared with pure water. It indicated that porosity of metal foam played a dominant role in heat transfer enhancement; while pore density seemed to have little influence on phase change behavior according to the results. Local natural convection in the unsolidified phase caused a remarkable promotion of the interface evolution, and the full solidification time with natural convection considered can be saved by 14.3% compared with pure conduction for the case with the same porosity of 0.97. The economic analyses indicated that using composite PCM was profitable with a short payback period less than 2 years.
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| 8. |
- Yang, Xiaohu, et al.
(författare)
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Thermal performance of a shell-and-tube latent heat thermal energy storage unit : Role of annular fins
- 2017
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 202, s. 558-570
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Tidskriftsartikel (refereegranskat)abstract
- This study conducts numerical investigations on melting process in a shell-and-tube latent heat thermal energy storage (LHTES) unit with annular fins. Commercial grade paraffin is employed as the phase change material (PCM) and water serves as the heat transfer fluid (HTF). Finite-volume-method (FVM) based numerical simulations are performed to investigate the effects of fin number, height and thickness on the phase change process. Particular attention is made to justify the contribution of local natural convection to the overall phase change process. Results demonstrate that the full melting time could be maximally reduced by 65% by inserting annular fins into PCM. For maximizing thermal performance, an optimal group fin parameter (fin number N = 31, thickness t/l = 0.0248 and interval l/L = 0.0313) is recommended for the present study.
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| 9. |
- Zhang, L., et al.
(författare)
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A nearly end-to-end deep learning approach to fault diagnosis of wind turbine gearboxes under nonstationary conditions
- 2023
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Ingår i: Engineering applications of artificial intelligence. - : Elsevier Ltd. - 0952-1976 .- 1873-6769. ; 119
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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.
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| 10. |
- Zou, X., et al.
(författare)
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Roadmap to urban energy internet : Techno-enviro-economic analysis of renewable electricity and natural gas integrated energy system
- 2022
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 373
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Tidskriftsartikel (refereegranskat)abstract
- The integrated energy system which coordinates natural gas, renewable energy, and other energy subsystems is an effective way to promote a low-carbon economy. An effective framework for system assessment and optimisation is a critical issue. This paper takes a natural gas-wind-photovoltaic integrated energy system as the research object and uses the simulation software to analyse its techno-enviro-economic feasibility. Firstly, a mathematical model is customised to optimise the system installation and operation plans. Renewable electricity replaces some natural gas, resulting in pipeline pressure fluctuation. Here, the Stoner Pipeline Simulator software is used to simulate pipeline network operation to quantify the aforementioned pressure fluctuations. The proportion of renewable energy is gradually reduced until the network pressure fluctuation is less than 20% to ensure the stability of pipeline operation. Then, the optimal operation scheme can be determined. Taking three cities in Shandong, China, as cases, the results show that the proposed system is beneficial for urban energy internet development: (i) the total net present cost is reduced by 19.7%, 19.8%, and 20.8%, (ii) annual CO2 emission is reduced by 23.7%, 18.4%, and 12.2%; (iii) the levelised cost of energy is 0.142 $/kWh, 0.143$/kWh, and 0.153$/kWh.
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