| 1. |
- Huang, L., et al.
(författare)
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Carbon footprint of oil products pipeline transportation
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier B.V.. - 0048-9697 .- 1879-1026. ; 783
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Tidskriftsartikel (refereegranskat)abstract
- As climate issues gradually attract public attention worldwide, the operation and construction of oil product pipelines have been attached with new energy-saving and emission-reduction targets. Though previous studies concerning Life Cycle Assessment of oil and gas pipelines have estimated the carbon footprint to some extent, there is a lack of researches that take the characteristics of oil products pipelines into consideration. Oil products pipelines undertake the task of delivering various products to downstream demand locations, which differs greatly from other pipeline transportation systems as back-to-back sequential delivery is adopted. In this paper, a detailed Life Cycle Assessment model is established to analyze carbon emissions of oil products pipeline system from construction to disposal as well as its impact on soil environment. Data from practical pipes is adopted as the case study to reflect emissions produced in different stages, and the amount of total and unified emissions of different pipes provided through the proposed model is within the range of 2.78 to 4.70 tCO2e/t·km. Then, sensitivity analysis is carried out to identify the driving factors of emissions. According to the calculation results, pipe length, diameter and throughput turn out to be the dominating factors, and an empirical formula is derived for future planned pipes. Relevant recommendations are put forward based on the results to help reduce emissions from oil product pipe transportation.
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| 2. |
- Huang, X., et al.
(författare)
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Depth optimization of solidification properties of a latent heat energy storage unit under constant rotation mechanism
- 2023
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Ingår i: Energy and Buildings. - : Elsevier Ltd. - 0378-7788 .- 1872-6178. ; 290
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Tidskriftsartikel (refereegranskat)abstract
- Latent heat storage technology plays an important role in the effective utilization of clean energy such as solar energy in building heating, but the low thermal conductivity of heat storage medium (phase change material) affects its large-scale application. As a new heat storage enhancement technology, rotation mechanism has a good application prospect. In this paper, the solidification performance of a triplex-tube latent heat thermal energy storage unit at constant speed (0.5 rpm) is studied numerically. Different optimization design methods (Taguchi method and response surface method) are used for deep analysis. The influences of fin position, number, and material on solidification properties are explored by the Taguchi method. Then, the unit structure (fin angle, fin length, and fin width) is optimized by the response surface method. Compared with the original structure, the average heat release rate of 8 copper fins with all outer tubes is increased by 108.93%, and the solidification time is reduced by 52.06%. The optimal structure can further shorten the solidification time by 29.14% and increase the average heat release rate by 40.5%. Additionally, the study of wall temperature shows that increasing temperature difference makes solidification speed faster and heat energy release faster. This effect effectively eliminates the adverse effects of slow solidification during the later stages of the process on the system.
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| 3. |
- Wang, L., et al.
(författare)
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Full-scale utilization of geothermal energy : A high-efficiency CO2 hybrid cogeneration system with low-temperature waste heat
- 2023
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 403
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Tidskriftsartikel (refereegranskat)abstract
- The utilization of geothermal energy is becoming increasingly important in the current transition towards sustainable energy sources. Among the various methods of utilizing geothermal energy, the use of hybrid geothermal power plants that exploit CO2 fluid for preheating in electricity generation has been identified as an attractive approach. Additionally, the shallow ground source heat pump (SGSHP) has been proven to be superior in previous experimental studies. However, the full-scale utilization of geothermal energy, through generating electricity from geothermal power plants and applying waste heat with SGSHPs for auxiliary heating, needs further exploration. This study proposes a novel CO2 hybrid geothermal system that incorporates a GSHP heating system. The hybrid geothermal system uses CO2 as the underground working fluid, and the electricity and waste heat are used to assist the GSHP for heating, ventilation, and air conditioning. The proposed system can produce 11.41 MW of electricity, 80 °C of hot water, and 34.76 MW of cold energy by driving 50 MW of the geothermal heat. Through a comprehensive analysis of the economy, energy, exergy, and environment, the results demonstrate that the maximum exergy damage of the refrigeration power cycle is 37999.33 kW, which has the highest exergy losses. The exergy loss of the steam turbine heat power conversion in the geothermal power generation process is the highest, but this loss can be effectively reduced through heat integration. The optimal cooling temperature of the coupled system should be set at 8 °C, and it has a good investment prospect. In summary, the CO2 hybrid geothermal system can realize effective cogeneration and fully utilize geothermal energy. Therefore, it has great potential to contribute to the transition towards a sustainable energy future.
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| 4. |
- Wu, P., et al.
(författare)
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Interval Number-Based Safety Reasoning Method for Verification of Decentralized Power Systems in High-Speed Trains
- 2021
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Ingår i: Mathematical problems in engineering (Print). - : Hindawi Limited. - 1024-123X .- 1563-5147. ; 2021
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Tidskriftsartikel (refereegranskat)abstract
- Decentralized power systems are commonly used in high-speed trains. However, many parameters in decentralized power systems are uncertain and inevitably have errors. We present a reasoning method based on the interval numbers for decentralized power systems in high-speed trains. Uncertain parameters and their unavoidable errors are quantitatively described by interval numbers. We also define generalized linear equations with interval numbers (LAIs), which can be used to describe the movement of the train. Furthermore, it is proven that the zero sets of LAIs are convex. Therefore, the inside of the fault-tolerance area can be formed by their vertexes and edges and represented by linear inequalities. Consequently, we can judge whether the system is working properly by verifying that the current system state is in the fault-tolerance area. Finally, a fault-tolerance area is obtained, which can be determined by linear equations with an interval number, and we test the correctness of the fault-tolerance area through large-scale random test cases.
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