| 1. |
- Nagaraja, Ch., et al.
(författare)
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Opening remarks
- 2016
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Konferensbidrag (refereegranskat)
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| 2. |
- Xiong, R., et al.
(författare)
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Key technologies for electric vehicles
- 2022
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Ingår i: Green Energy and Intelligent Transportation. - : Elsevier B.V.. - 2773-1537. ; 1:2
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Cornelissen, Johannes H C, et al.
(författare)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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| 4. |
- Guo, S., et al.
(författare)
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Mobilized thermal energy storage : Materials, containers and economic evaluation
- 2018
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Ingår i: Energy Conversion and Management. - : Elsevier Ltd. - 0196-8904 .- 1879-2227. ; 177, s. 315-329
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Tidskriftsartikel (refereegranskat)abstract
- The transportation of thermal energy is essential for users who are located far away from heat sources. The networks connecting them achieve the goal in efficient heat delivery and reasonable cost, especially for the users with large heat demands. However, it is difficult to satisfy the heat supply of the detached or emergent users with the existing pipelines. Therefore, a promising alternative, called mobilized thermal energy storage (M-TES), was proposed to deliver the heat flexibly without the restriction of networks. In this paper, a review of studies on M-TES is conducted in terms of materials, containers and economic evaluation. The potential candidates of materials, such as sugar alcohols, hydrated salts, alkalies and zeolite are reviewed and compared based on their thermophysical properties, price, advantages and disadvantages. Various containers, including the shell-and-tube, encapsulated, direct-contact, detachable and sorptive types, are discussed from the aspects of configuration, performance and utilization. Furthermore, the studies on the economic evaluation of M-TES systems are summarized and discussed based on the analysis of the economic indicators, including initial cost, operating cost, revenue, subsidy and energy cost. Finally, the challenges and future perspectives for developing M-TES are presented.
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| 5. |
- Rong, X., et al.
(författare)
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Experimental study on a multi-evaporator mutual defrosting system for air source heat pumps
- 2023
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 332
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Tidskriftsartikel (refereegranskat)abstract
- Air source heat pumps (ASHPs) are prone to frost when heating in a low-temperature and high-humidity environment, which deteriorates the heating performance of the unit. In this study, a new multi-evaporator mutual defrosting (MEMD) system was proposed to overcome the disadvantages of traditional defrosting methods: intermittent heating and inefficient defrosting. To validate the performance of the proposed defrosting technology, comparative tests were conducted in various outdoor environmental conditions. The experimental results showed that the MEMD system could continuously heat water during the defrosting period. In five experimental conditions, the MEMD system exhibited a lower water temperature drop range (2.1–2.8 °C) than that of a traditional reverse-cycle defrosting (RCD) system (6.0–7.3 °C). Due to the effective utilization of heat production during the heating period, the effective heat power (qe) of the unit increased by 0.7–1.4 kW, and the heat loss coefficient (HLC) of frosting and defrosting increased by an average of 6 % in the five experimental conditions, effectively reducing the heating capacity loss of the unit caused by defrosting. While defrosting, the MEMD system was able to utilize the remaining evaporators to absorb heat from the air and then deliver it to the defrosting evaporator. The equivalent defrosting energy efficiency (COPd) of the MEMD system was 17.5 % greater than that of the RCD system on average. During the heating and defrosting cycle, the energy saved when defrosting could increase the cycle coefficient of performance (CCOP) of heating by 3.7 %.
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| 6. |
- Wang, W., et al.
(författare)
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Experimental study on the direct/indirect contact energy storage container in mobilized thermal energy system (M-TES)
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 119, s. 181-189
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Tidskriftsartikel (refereegranskat)abstract
- A mobilized thermal energy storage (TES) system has been proposed to recover and use industrial waste or excess heat for distributed users. In this paper, lab-scale test facilities have been built to understand the mechanisms of heat charging and discharging processes. The facilities consist of a direct/indirect-contact thermal energy storage container, heat transfer oil (HTO)/water tanks, an electrical boiler, HTO/water pumps and a plate heat exchanger. The organic phase change material (PCM), erythritol, which is sugar alcohol, was chosen as the working material due to its large heat density (330. kJ/kg) and suitable melting point (118. °C) for industrial low-temperature heat recovery, as well as non toxic and corrosive. Although differential scanning calorimetry tests have shown that a large temperature range exists during the phase change of erythritol, it did not affect the heat discharging during the tests of system performance. Heat charging/discharging results show that for the direct-contact storage container, heat discharging process is much faster than charging process. At the initial stage of heat charging, heat transfer oil is blocked to enter the container, resulting in a slow charging rate. Meanwhile, the PCM attached on the container wall on the bottom always melts last. It has been found that increasing the flow rate of HTO can effectively enhance the charging/discharging processes. For the indirect-contact storage container, heat charging and discharging take almost the same time; and the flow rate of HTO does not show an obvious effect on the charging and discharging processes due to the weak thermal conductivity of the solid phase change material. Comparatively, using the direct-contact storage container may achieve shorter charging/discharging processes than using the indirect-contact storage container.
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| 7. |
- Yu, H., et al.
(författare)
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Improved triangle splitting based bi-objective optimization for community integrated energy systems with correlated uncertainties
- 2022
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Ingår i: Sustainable Energy Technologies and Assessments. - : Elsevier Ltd. - 2213-1388 .- 2213-1396. ; 49
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Tidskriftsartikel (refereegranskat)abstract
- Economic and environmental benefits are the most important in the operation of community integrated energy systems (CIES), modeled as a bi-objective optimization problem. In the case of the uncertainties from loads and renewable energy generators, the effectiveness of the operation strategies may be degraded in the practical applications of CIES. In this paper, an improved triangle splitting based bi-objective optimization method is proposed to search for the Pareto optimal solution of the CIES operation. The general preference of decision-makers in practical applications is utilized in the search process to reduce the detailed search interval and consequently improve the optimization efficiency. In addition, a bi-objective uncertain optimization framework is established for the economic-environmental operation of the CIES under uncertainties. The correlation between uncertainties is considered to generate the operation scenarios, in which the solution probability function is employed to determine the final operation strategy with robustness. A comprehensive case study is conducted based on a practical CIES in China, proving the feasibility and effectiveness of the proposed methods.
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| 8. |
- Zhang, Xinxin, et al.
(författare)
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China's coal-fired power plants impose pressure on water resources
- 2017
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Ingår i: Journal of Cleaner Production. - : ELSEVIER SCI LTD. - 0959-6526 .- 1879-1786. ; 161, s. 1171-1179
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Tidskriftsartikel (refereegranskat)abstract
- Coal is the dominant fuel for electricity generation around the world. This type of electricity generation uses large amounts of water, increasing pressure on water resources. This calls for an in-depth investigation in the water-energy nexus of coal-fired electricity generation. In China, coal-fired power plants play an important role in the energy supply. Here we assessed water consumption of coal-fired power plants (CPPs) in China using four cooling technologies: closed-cycle cooling, once-through cooling, air cooling, and seawater cooling. The results show that water consumption of CPPs was 3.5 km(3), accounting for 11% of total industrial water consumption in China. Eighty-four percent of this water consumption was from plants with closed-cycle cooling. China's average water intensity of CPPs was 1.15 l/kWh, while the intensity for closed-cycle cooling was 3-10 times higher than that for other cooling technologies. About 75% of water consumption of CPPs was from regions with absolute or chronic water scarcity. The results imply that the development of CPPs needs to explicitly consider their impacts on regional water resources.
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