| 1. |
- Månsson, Sara, et al.
(författare)
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A fault handling process for faults in district heating customer installations
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 14:11
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Tidskriftsartikel (refereegranskat)abstract
- Faults in district heating (DH) customer installations cause high return temperatures, which have a negative impact on both current and future district heating systems. Thus, there is a need to detect and correct these faults soon after they occur to minimize their impact on the system. This paper, therefore, suggests a fault handling process for the detection and elimination of faults in DH customer installations. The fault handling process is based on customer data analysis since many faults manifest in customer data. The fault handling process was based on an analysis of the results from the previous fault handling studies, as well as conducting a workshop with experts from the DH industry. During the workshop, different organizational and technical challenges related to fault handling were discussed. The results include a presentation of how the utilities are currently working with fault handling. The results also present an analysis of different organizational aspects that would have to be improved to succeed in fault handling. The paper also includes a suggestion for how a fault handling process based on fault detection using data analysis may be designed. This process may be implemented by utilities in both current and future DH systems that interested in working more actively with faults in their customer installations.
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| 2. |
- Månsson, Sara, et al.
(författare)
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A taxonomy for labeling deviations in district heating customer data
- 2021
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Ingår i: Smart Energy. - : Elsevier BV. - 2666-9552. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- This paper suggests a taxonomy for labeling deviating patterns in district heating (DH) customer data. The taxonomy contains several fault labels intended to register information about faults in the DH systems that cause deviations in customer data. This taxonomy is needed because the DH industry is currently missing a unanimous way to label identified faults. The lack of a taxonomy makes it hard to develop automated fault detection and diagnosis methods based on the analysis of DH customer data. Such methods usually require training on historical data sets known to contain deviating data patterns caused by specific faults. By developing a taxonomy for labeling these faults, this study aims to create value for DH utilities in current and future DH systems. The taxonomy structure was based on literature studies, workshops, and discussions with partners within the Swedish FutureHeat collaboration organization Smart Energi. Once the basic structure was decided, it was sent out for evaluation amongst Swedish DH utilities. The evaluation was carried out as a survey study. The results from the survey were compiled, and the finalized version of the deviation cause taxonomy was produced. The study includes the results of the survey study and the finalized version of the deviation cause taxonomy.
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| 3. |
- Qi, Yuanxin, et al.
(författare)
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Dynamic modelling and controlling strategy of polymer electrolyte fuel cells
- 2020
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 45:54, s. 29718-29729
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive dynamic control oriented model of a polymer electrolyte fuel cell (PEFC) is developed, considering the mixed effects of temperature, gas flow and capacitance. The fractional relationship between the dynamic output voltage and the capacitance, which escaped the attention in most previous studies is also addressed. Moreover, based on the developed PEFC model, a proportional integral and derivative (PID) controller is designed to stabilize the output voltage at a determined value by regulating the input hydrogen mass flow rate under a series of disturbance in the input. The dynamic PEFC model and controller are simulated in Matlab/Simulink. The simulation results illustrate that the PEFC system model is capable of characterizing dynamic properties of PEFCs. Additionally, the developed PID controller is effective in stabilizing the output voltage with a rather small overshoot and rather faster response, which also proves that the developed model is suitable for PEFC control algorithms development.
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| 4. |
- Sánchez-García, Luis, 1989-
(författare)
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Modelling District Heating Network Costs
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The solution of the undergoing climate and energy crises requires a radical transformation of the energy system, in which sustainability, no carbon emissions and energy efficiency ought to play a paramount role. This revolution should extend to all areas of the energy system, including the space heating and cooling sector, which accounts for a third of the European final energy demand and, in the European continent, it is still mostly supplied by fossil fuels.District heating is a simple but powerful technology that can contribute to tackle this challenge. As a network infrastructure, it is characterised by the flexibility of the heat production, allowing the incorporation of a wide range of heat sources over time. Furthermore, it enables the recycling of heat that would otherwise be wasted and the use of local heat sources in a more cost-effective manner. Moreover, its coupling with the electricity sector can facilitate the increase of intermittent electric renewable energy sources. Nevertheless, at the moment, district heating only covers a tenth of the European space heating and cooling needs, albeit with significant differences among countries. In addition, the development of new district heating networks is capital intensive and can only be justified in those areas where the concentration of the heat demand is sufficiently high to deliver a lower cost to society than an individual alternative. Therefore, it is crucial to assess the potential of district heating and to identify the target areas for in-depth investigations. This necessity demands easy and straightforward tools, which can provide a first order approximation of the construction cost of new networks. One of these tools is the capital cost model developed by Persson & Werner, which is based on, among others, the effective width parameter. This is an indicator of the required trench length in an area supplied by district heating and has been related to the building density. This work has contributed to the understanding of the effective width parameter in a wide range of building densities, taking advantage of one of the largest district heating networks in Denmark, and provided new equations that relate it to various indicators of building density. Furthermore, the average pipe diameter of district heating pipes has been linked to another crucial parameter in district heating technology, the linear heat density, extending prior work conducted by Persson and Werner. In addition, Persson and Werner's model and the newly found empirical expressions have been validated in various Danish district heating networks, showing that the model provides relatively accurate results on an aggregate level and large areas but dismally fails in low-extension areas. Finally, the model has been applied to the European Union showing that district heating networks could potentially supply a third of the heat demand in 2050.
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