| 1. |
- Yan, A., et al.
(författare)
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Hydraulic performance of a new district heating systems with distributed variable speed pumps
- 2013
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 112, s. 876-885
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Tidskriftsartikel (refereegranskat)abstract
- The application of distributed variable speed pumps (DVSP) in the district heating (DH) network has been considered as a technology improvement that has a potential of saving energy, compared to the conventional central circulating pump (CCCP) DH system. A hydraulic model was developed to simulate the hydraulic performance of such a DVSP DH system, based on Kirchhoff's laws. It was applied to a real DH network in Kuerle, China. In order to improve the model accuracy, a new parameter called resistance ratio was proposed by comparing the measured data and the simulated result. The validation result shows that the model has the ability to predict the hydraulic behavior of the DVSP system. The results show that when the rotational speeds of all substation pumps are synchronously decreased by the same percentage, the pump heads and the flow rates are also reduced synchronously and almost in the same degree in all loops. In addition, two operation cases of DH were investigated, including (I) the flow rate varies in all of the loops simultaneously, and (II) the flow rate varies only in one of the loops. For both cases, the DVSP system has a better performance of saving energy at least 30% than the CCCP system. Compared to the CCCP system, the installed pump capacities can be smaller in the DVSP system. Hence, applying DSVP, especially at a low flow rate, can save quite much electricity. Based on the example network in Kuerle, the DVSP system consumes electricity 71% and 31% less than the CCCP system for Cases I and II respectively.
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| 2. |
- Dong, X., et al.
(författare)
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A novel design of a metal hydride reactor integrated with phase change material for H2 storage
- 2024
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 367
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Tidskriftsartikel (refereegranskat)abstract
- Using metal hydride for hydrogen storage in stationary applications and for transportation is a promising technology due to its advantages of large hydrogen storage capacity, low pressure and low energy consumption. Combining the metal hydride reactor with PCM is expected to recover the heat generated during the hydrogen absorption and use it for hydrogen desorption, thus improving the energy efficiency of the system. This paper proposes a metal hydride reactor integrated with honeycomb fins and PCM to enhance heat transfer. Based on simulations, the results show that the achieved hydrogen storage capacity is 1.326 wt%, the gravimetric and volumetric storage densities are 0.411% and 14.76 kg of H2 per m3, respectively, and the mean saturated rates are 1.222 × 10−3 g s−1 and 0.773 × 10−3 g s−1 for absorption and desorption processes. Compared with the reactor without fins, the mass and volume of the reactor using honeycomb fins are increased, resulting in a decrease in gravimetric and volumetric storage density, but a increase in reaction rate during hydrogen absorption and desorption processes. Based on this structure, we also propose a honeycomb fin reactor filled with sandwich PCM to further accelerate the heat transfer in the reaction process. Compare to the reactor with PCM only filled on the periphery of the honeycomb fins, the hydrogen absorption and desorption times are shortened by about 86.4% and 81.1%, respectively. In addition, different reactor structures are compared using multiple KPIs to provide relevant suggestions for the reactor optimization. The obtained research results can provide a reference for effective thermal management methods in MH storage systems.
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| 3. |
- 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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| 4. |
- Nagaraja, Ch., et al.
(författare)
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Opening remarks
- 2016
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Konferensbidrag (refereegranskat)
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| 5. |
- Song, C., et al.
(författare)
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Alternative pathways for efficient CO2 capture by hybrid processes—A review
- 2018
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier Ltd. - 1364-0321 .- 1879-0690. ; 82, s. 215-231
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Tidskriftsartikel (refereegranskat)abstract
- CO2 capture and storage technologies have been recognized as the primary option to mitigate the issue of climate change caused by the utilization of fossil fuels. In the last decades, several CO2 capture approaches have been developed, such as absorption, adsorption, membrane, cryogenic, hydrate and chemical looping combustion etc. However, the energy penalty is a general challenge for each technology. To overcome the disadvantages of standalone technology, the combination of two or more approaches (namely hybrid CO2 capture processes) has been considered as a potential option. In this work, the status and development of hybrid CO2 capture processes is presented in a classification of primary technology as absorption-based, adsorption-based, membrane-based and cryogenic-based. The detail configuration of each hybrid process is introduced. Simultaneously, the characteristics, advantages and potential challenges of each hybrid process are also summarized. Compared to the standalone methods, hybrid processes showed the superiority not only in CO2 recovery and energy penalty, but also in the installation investment. Therefore, hybrid processes can be a promising alternative to conventional CO2 capture technologies in future.
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