| 1. |
- Guo, Shaopeng, et al.
(författare)
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Techno-economic assessment of mobilized thermal energy storage for distributed users : A case study in China
- 2017
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Ingår i: Applied Energy. - : ELSEVIER SCI LTD. - 0306-2619 .- 1872-9118. ; 194, s. 481-486
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Tidskriftsartikel (refereegranskat)abstract
- The mobilized thermal energy storage (M-TES) system is a promising alternative to conventional heating systems to meet the heat demand for distributed users. This paper provided a techno-economic assessment of the M-TES system based on a case study in China. According to the analysis of the design specifications of the heating system, the suitability of matching the M-TES with existing heating systems was analyzed. The results show that the M-TES is appropriate for use with heating systems with a fan-coil unit and under-floor pipe. Containers and operating strategies for the M-TES with different transportation schemes were also designed. The maximum allowed load of the M-TES container is 39 t according to the discussion of transportation regulations on the road. The cost and income of the M-TES in the study case were estimated, and the net present value (NPV) and payback period (PBP) were also calculated. The best operating strategy is the use of 2 containers and 4 cycles of container transportation per day, with a PBP of approximately 10 years. The M-TES is applicable for middle and small-scale heat users in China.
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| 2. |
- Clark, Adam Thomas, et al.
(författare)
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General statistical scaling laws for stability in ecological systems
- 2021
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 24:7, s. 1474-1486
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Tidskriftsartikel (refereegranskat)abstract
- Ecological stability refers to a family of concepts used to describe how systems of interacting species vary through time and respond to disturbances. Because observed ecological stability depends on sampling scales and environmental context, it is notoriously difficult to compare measurements across sites and systems. Here, we apply stochastic dynamical systems theory to derive general statistical scaling relationships across time, space, and ecological level of organisation for three fundamental stability aspects: resilience, resistance, and invariance. These relationships can be calibrated using random or representative samples measured at individual scales, and projected to predict average stability at other scales across a wide range of contexts. Moreover deviations between observed vs. extrapolated scaling relationships can reveal information about unobserved heterogeneity across time, space, or species. We anticipate that these methods will be useful for cross-study synthesis of stability data, extrapolating measurements to unobserved scales, and identifying underlying causes and consequences of heterogeneity.
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| 3. |
- Guo, Shaopeng, et al.
(författare)
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Economic Assessment of Mobilized Thermal Energy Storage for Distributed Users : A Case Study in China
- 2016
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Ingår i: CUE 2015 - APPLIED ENERGY SYMPOSIUM AND SUMMIT 2015. - : Elsevier. ; 88, s. 656-661
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Konferensbidrag (refereegranskat)abstract
- Mobilized thermal energy storage (M-TES) system can be an alternative of the conventional heating system to meet the heat demand for distributed users. This paper conducted a case study of the M-TES system in China. The operating strategies (OS) of the M-TES with different transportation schemes were compared. Moreover, the economic assessment was performed based on the project's net present value (NPV) and payback period (PBP). The OS with 6 trips per day is the most profitable with pay-back time of about 2, 3 and 5 years if the waste heat costs at the level of 0 epsilon/MWh, 3300 epsilon/MWh, and 6600 epsilon/MWh, respectively.
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| 4. |
- Guo, Shaopeng, et al.
(författare)
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Numerical study of the improvement of an indirect contact mobilized thermal energy storage container
- 2016
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 161, s. 476-486
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the melting and solidification behaviours of the PCM in an indirect contact mobilized thermal energy storage (ICM-TES) container were numerically investigated to facilitate the further understanding of the phase change mechanism in the container. A 2D model was built based on the simplification and assumptions of experiments, which were validated by comparing the results of computations and measurements. Then, three options, i.e., a high thermal conductivity material (expanded graphite) addition, the tube diameter and the adjustment of the internal structure of the container and fin installation, were analyzed to seek effective approaches for the improvement of the ICM-TES performance. The results show that the optimal parameters of the three options are 10 vol.% (expanded graphite proportion), 22 mm (tube diameter) and 0.468 m(2) (fin area). When the three options are applied simultaneously, the charging time is reduced by approximately 74% and the discharging time by 67%.
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| 5. |
- Han, Ruiping, et al.
(författare)
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Review on Heat-Utilization Processes and Heat-Exchange Equipment in Biogas Engineering
- 2016
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Ingår i: Journal of Renewable and Sustainable Energy. - : AIP Publishing. - 1941-7012. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- With the increasing demand for environmental protection and renewable energy, bioenergy technology has been attracting considerable attention. Anaerobic digestion (AD) is the process to convert the low-grade biomass into bioenergy, in which both heat-recovery and -recycling should be treated carefully in order to improve the process efficiency. In this work, the heat-recovery and its utilization processes were reviewed, and different types of heat exchangers as well as their advantages in biogas engineering were surveyed. It shows that the recovery and utilization of the waste heat from biogas plants with an internal system, such as slurry effluent unit, the combined heat and power unit, the sanitation unit, and the internal recycle unit, are important for improving the AD efficiency of biogas production. For example, the recovery and recycling of waste heat from the effluent can result in a 2-3 °C temperature increase for the inlet manure slurry. For thermophilic AD, the heat recovery from effluent can save about 50% of the total heat requirement. The external heating process is more suitable for large- and medium-scale biogas plants, and the heat transfer coefficient of external heating (850-1000 W/m2 K-1) is almost two-times higher than that of the internal heating (300-400 W/m2 K-1). To utilize the waste heat in biogas plants, heat exchangers have been designed for biogas slurry. However, further improvement on the heat exchangers with anti-blockage, anti-fouling, high efficiency, and low investment is still needed. Moreover, the heat exchanger suitable for a low-temperature-difference system is specially needed in China, but the development is still in its infancy. Therefore, to tailor to the Chinese national conditions, special external heating processes should be designed and reoriented to the diversity of biomass, the climatic environmental conditions, and the renewable Chinese policies
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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. |
- Zhang, Helin, et al.
(författare)
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Dispersal network heterogeneity promotes species coexistence in hierarchical competitive communities
- 2021
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Ingår i: Ecology Letters. - : WILEY. - 1461-023X .- 1461-0248. ; 24:1, s. 50-59
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the mechanisms of biodiversity maintenance is a fundamental issue in ecology. The possibility that species disperse within the landscape along differing paths presents a relatively unexplored mechanism by which diversity could emerge. By embedding a classical metapopulation model within a network framework, we explore how access to different dispersal networks can promote species coexistence. While it is clear that species with the same demography cannot coexist stably on shared dispersal networks, we find that coexistence is possible on unshared networks, as species can surprisingly form self-organised clusters of occupied patches with the most connected patches at the core. Furthermore, a unimodal biodiversity response to an increase in species colonisation rates or average patch connectivity emerges in unshared networks. Increasing network size also increases species richness monotonically, producing characteristic species-area curves. This suggests that, in contrast to previous predictions, many more species can co-occur than the number of limiting resources.
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