| 1. |
- Wang, Y., et al.
(författare)
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Minimum Air Cooling Requirements for Different Lithium-Ion Battery Operating Statuses
- 2024
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Ingår i: ASME Journal of Heat and Mass Transfer. - : ASME Press. - 2832-8450. ; 146:10
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Tidskriftsartikel (refereegranskat)abstract
- Battery energy storage systems (BESSs) play an important role in increasing the use of renewable energy sources. Owing to the temperature sensitivity of lithium-ion batteries (LIBs), battery thermal management systems (BTMSs) are crucial to ensuring the safe and efficient operation of BESSs. Previous works mainly focused on evaluating the performance of BTMS; however, little attention has been paid to the minimum cooling requirements of BESSs, which are important for optimizing the design and operation of BTMSs. To bridge the knowledge gap, this work investigated the performance of air cooling for a battery cabin under different charge/discharge (C) rates by using a computational fluid dynamics (CFD) model, which is coupled with a battery model. Simulation results show that the inlet airflow rate has the strongest influence. For the studied cases, when the battery operates at C-rates lower than 3, the inlet temperature should be controlled below 35 °C, and the gap between the batteries should be greater than 3 mm to meet the minimum heat dissipation requirement. At a C-rate of 0.5C, natural convection is sufficient to meet the cooling need, whereas at 1C or higher C-rates, forced convection has to be used. Increasing the number of batteries, for example, from 6 to 8, has negligible impact on the inlet flow required to assure the heat dissipation.
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| 2. |
- Huang, C., et al.
(författare)
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Understanding the water-energy nexus in urban water supply systems with city features
- 2018
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Ingår i: CLEANER ENERGY FOR CLEANER CITIES. - : Elsevier. ; , s. 265-270
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Konferensbidrag (refereegranskat)abstract
- The water-energy nexus has been introduced into urban water supply systems (WSSs) to improve the current plight of scarce resources and greenhouse effect in recent years. Urban water-energy integrated management is limited by the characteristics and reality of each city. In this paper, we characterize the comprehensive influence factors of energy use in China urban WSSs including geographic differences and city forms. The results indicate that the pressure of pipeline network and plain area ratio restricted by geomorphology would significantly impact the energy consumption during conveyance and distribution stage. For the city form aspect, the total volume of urban water supply and the leakage rate of pipeline networks play important roles in energy consumption of urban WSSs in China. In this study, the specific electricity consumption in WSSs was quantified, and several factors affected by city features which show strong correlation with energy use were determined. The results are of great significance to the energy saving in water supply systems in urban areas.
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| 3. |
- Yang, X., et al.
(författare)
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Effect of fin number on the melting phase change in a horizontal finned shell-and-tube thermal energy storage unit
- 2022
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier B.V.. - 0927-0248 .- 1879-3398. ; 236
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the enhanced heat transfer of adding longitudinal fins in a horizontal shell-and-tube heat storage unit. A two-dimensional numerical model is established and validated through comparing with experimental data in literature. Under the same ratio of fin volume to phase change materials (PCMs), the melting thermal performance is optimized by changing the fin thickness, interval and the number. Results demonstrate that adding longitudinal fins is a simple and effective method to enhance the thermal energy storage efficiency. The number of fins greatly affects the complete melting time, and the maximum time difference caused by the number of fins is as high as 72.85% under the same phase change material (PCM) filling mass. At the same time, increasing the number of fins will weaken the local natural convection. In this paper, the optimal number of fins in the limited research range is given, and the effectiveness of longitudinal fins in improving melting speed is quantified, which has certain practical significance for the engineering application research of phase change energy storage. © 2021 Elsevier B.V.
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| 4. |
- Zhang, X., et al.
(författare)
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Greater mineral and aggregate protection for organic carbon in the soil amended by weathered coal than by biochar : Based on a 3-year field experiment
- 2023
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Ingår i: Geoderma. - : Elsevier B.V.. - 0016-7061 .- 1872-6259. ; 438
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Tidskriftsartikel (refereegranskat)abstract
- Soil carbon pool stability plays an important role in reaching carbon neutrality and mitigating global warming. Applying soil amendments is a practical strategy in agricultural production to improve soil environment. Weathered coal (WC) is an organic amendment that can be used to improve soil quality. However, the effects of WC application on soil organic carbon pool stability, and its differences from the effects of biochar (BC, a common amendment) application remains unclear. In this study, BC was selected as a comparison to further evaluate the potential of WC based on a 3-year field experiment, in which WC and BC were individually applied into a loamy clay soil at 0%, 1%, and 3% (w/w) rates. Soil organic carbon and its fractions (including particulate organic carbon and mineral-bound organic carbon), soil aggregate fractions and its stability, and the organic carbon content in aggregates were examined. The results showed that both WC and BC significantly increased soil total organic carbon, particulate and mineral-bound organic carbon (P < 0.05). The mineral-bound organic carbon content in WC treatment was significantly higher than that in BC treatment (by 32% under the 3% rate) (P < 0.05), whereas, there were no significant differences in soil total organic carbon content. Both WC and BC increased the soil organic carbon content in all aggregate fractions. While only the WC improved the soil aggregate stability, and which was 15% (under 1% rate) and 28% (under 3% rate) higher in WC treatments than in BC treatments (P < 0.05). The proportion of mineral-bound organic carbon to soil total organic carbon content and the soil aggregate stability were obviously related the soil C/N, and the WC treatments had a higher proportion of mineral-bound organic carbon and soil aggregate stability than BC treatments under the same soil C/N. The results indicated that the application of WC may be more effective than BC in increasing mineral and aggregate protection for soil organic carbon and thus improving soil carbon pool stability. Additionally, the purchase cost of WC was clearly lower than that of BC. Combined with the low cost and the benefits in soil structure and carbon pool stability, the application of WC appeared to have advantages over BC. Our findings provide robust evidence that WC is more effective than BC in improving soil carbon pool stability.
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| 5. |
- Li, X., et al.
(författare)
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Performance comparison regarding loop heat pipes with different evaporator structures
- 2019
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Ingår i: International journal of thermal sciences. - : Elsevier Masson SAS. - 1290-0729 .- 1778-4166. ; 136, s. 86-95
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Tidskriftsartikel (refereegranskat)abstract
- The design of evaporator can clearly affect the performance of loop heat pipes (LHPs). In order to understand the influence, three different designs of evaporators were compared, including embedding vapor channels on the heating surface (Config_1), embedding vapor channels in the wick (Config_2), and separating the wick from the heating surface (Config_3). Based on the validated model, the operating temperature, the start-up time, and the transport distance, as key performance indicators, were studied. Results show that, to improve the performance of LHP, it is of importance to reduce the contacting area between the wick and the heating surface. Due to the existence of the steam chamber, the wick was separated from the heating surface in Config_3, resulting in the lowest operating temperature and the shortest start-up time. The pressure head of evaporation is also an important component of the driving force. For Config_3, since the evaporation happened in the steam chamber rather than in the wick, it had a longer transport distance than Config_1 and Config_2 at the same heat load.
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| 6. |
- Liu, G., et al.
(författare)
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Numerical analysis of inner heating tube position for improving solid-phase transition in a shell-and-tube heat accumulator
- 2023
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Ingår i: Alexandria Engineering Journal. - : Elsevier B.V.. - 1110-0168 .- 2090-2670. ; 65, s. 771-784
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Tidskriftsartikel (refereegranskat)abstract
- Latent heat thermal storage (LHTS) system is vital to reduce environment pollution. In the shell-and-tube heat accumulator, the position of the inner heating tube plays a vital role in the thermal storage. To analyze the effect of the inner tube position on the phase transition, a two-dimensional numerical model is developed. The structure has the minimum full melting time of 3480 s when the inner tube is 12 mm (L = 12 mm) from the center. Compared with L = 0 mm, the full melting time at L = 12 mm can be reduced by 13.4%.
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| 7. |
- Shi, J., et al.
(författare)
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Capacity Fading Characteristics of Lithium Iron Phosphate Batteries Under Different Precooling Conditions
- 2023
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Ingår i: Lecture Notes in Electrical Engineering, vol. 1016. - : Springer Science and Business Media Deutschland GmbH. - 9789819910267 ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- The capacity fading of lithium iron phosphate batteries is related to its internal temperature and the growth of solid electrolyte (SEI). It is an effective way by controlling its internal temperature to mitigate capacity fading. This paper discusses the impact of pre-cooling and resting time on capacity fading and the growth of SEI. Results showed that the battery capacity increased and the thickness of SEI decreased if the pre-cooling was employed. Compared to 25 °C of ambient temperature, the thickness of SEI under 5 °C of pre-cooling temperature decreased by 404 nm, 386 nm, and 502 nm for 2C, 3C, and 5C discharge rate, respectively. The internal temperature of battery could be better cooled and therefore capacity increased with the increase of resting time. At 15 °C of pre-cooling temperature, the capacity increased by 3.8% if the resting time increased from 600 s to 2400 s. Therefore, the pre-cooling method could effectively mitigate capacity fading. The conclusion obtained in this paper could provide guidance for battery thermal management.
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| 8. |
- Si, P., et al.
(författare)
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An innovative building envelope with variable thermal performance for passive heating systems
- 2020
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 269
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Tidskriftsartikel (refereegranskat)abstract
- The integration of passive solar heating strategies into the existing buildings has been considered as an innovative and effective approach to mitigate energy and environmental issues. To balance the trade-off between solar heat gain and thermal insulation in traditional passive solar systems, this paper presented an innovative envelope with variable thermal performance for passive solar buildings. Field measurement was carried out to validate the feasibility of the transparent building envelope under step control operation strategy to building comfortable indoor environment especially in cold plateau areas. The experimental results show that, even under harsh climate conditions, the application of the proposed building envelope effectively increases the heat gain and maintains indoor temperature at a relatively comfortable level in the studied case. The average indoor air temperature of the studied rooms is at 13.0–14.0 °C, with the highest temperature up to 21 °C. Numerical simulation by DesignBuilder software was further developed to exploit the efficiency of the proposed building envelope under the step control operation strategy for increasing the indoor temperature. The simulation results show the same tendency with the filed measurement results. The operation strategy of opening indoor window at 10:00 am and closing at 5:00 pm can achieve the maximization of solar gain, significantly increasing the indoor temperature. Attributed to good balance between solar heat gain coefficient and thermal resistance, the average temperature of the room with the proposed envelope mode is 2.0 °C (sunny day) and 1.5 °C (cloudy day) higher than that of another three passive solar envelope operation modes, respectively. In general, the proposed building envelope with variable thermal performance has high potential to improve the indoor thermal environment in cold plateau areas at low cost. © 2020 Elsevier Ltd
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| 9. |
- 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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| 10. |
- 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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