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Dahl, Jan
Publications (10 of 84) Show all publications
Mattsson, J., Hedström, A., Westerlund, L., Dahl, J., Ashley, R. & Viklander, M. (2018). Impacts on rural wastewater systems in subarctic regions due to changes in inputs from households (ed.). Journal of cold regions engineering, 32(1), Article ID 04017019.
Open this publication in new window or tab >>Impacts on rural wastewater systems in subarctic regions due to changes in inputs from households
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2018 (English)In: Journal of cold regions engineering, ISSN 0887-381X, E-ISSN 1943-5495, Vol. 32, no 1, article id 04017019Article in journal (Refereed) Published
Abstract [en]

The use of water-saving appliances and heat exchangers is becoming increasingly popular to decrease water consumption and recover energy from preheated water. However, such in-household changes can bring particular implications for subarctic rural areas, in terms of solids deposition in sewers and drops in performance of wastewater treatment plants (WWTPs), because these are already experiencing diminishing wastewater flows due to depopulation and seasonal dips in wastewater temperature resulting from infiltration into sewers. Hence, this study has considered two communities in Sweden, postulating three different cases with various scales of retrofitting and usage. The results indicate that the decrease in in-pipe velocities when all households are retrofitted with water-saving appliances could be counteracted by sewer relining, but not by the inclusion of a conventional estimate of infiltration. However, for the case in which retrofitting was combined with decreased usage of the appliances, the decrease in self-cleansing capacity could not be counteracted. The retrofitting of heat exchangers under shower trays in all households did not have a significant effect on treatment processes at the WWTP.

Place, publisher, year, edition, pages
American Society of Civil Engineers (ASCE), 2018
National Category
Water Engineering Energy Engineering
Research subject
Urban Water Engineering; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-14539 (URN)10.1061/(ASCE)CR.1943-5495.0000145 (DOI)000428257200005 ()2-s2.0-85030121882 (Scopus ID)de948167-31d8-4bac-a3d7-ca6af781096b (Local ID)de948167-31d8-4bac-a3d7-ca6af781096b (Archive number)de948167-31d8-4bac-a3d7-ca6af781096b (OAI)
Note

Validerad;2017;Nivå 2;2017-09-25 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-04-20Bibliographically approved
Vesterlund, M., Toffolo, A. & Dahl, J. (2017). Optimization of multi-source complex district heating network, a case study. Energy, 126, 53-63
Open this publication in new window or tab >>Optimization of multi-source complex district heating network, a case study
2017 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 126, p. 53-63Article in journal (Refereed) Published
Abstract [en]

The level of complexity for a district heating network increases with the maturity of the network, and this affects the pattern of the distribution of the hot water from the heat production sites to the end users. The majority of district heating systems are also multi-source networks, typically supported with heat from one main production site and other smaller satellite sites that are activated when required. In general, local energy companies have a lack of knowledge regarding how a meshed network behaves when different production sites are operated. The schedule of heat generation at the different sites is often based on staff experience and some general rules of thumb.

In this paper a method for modeling and simulating complex district networks is further developed in order to optimize the total operating costs of a multi-source network, with constraints on the pressure and temperature levels in the user areas and on the heat generation characteristics at each production site.

The optimization results show that the usage of the cheapest resources is preferred to a distributed generation of heat, even if some of the pipes may exceed the recommended thermal load capacity. The main site water supply temperature is found to be the lowest allowed by the constraint on the temperature of the water supplied to the end users, since the decrease of the costs associated with the lower thermal losses in the network is not counterbalanced by the increase of those associated with the pumping power of a larger water mass flow rate.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62320 (URN)10.1016/j.energy.2017.03.018 (DOI)000404305900006 ()2-s2.0-85014911271 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-03-15 (rokbeg)

Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2018-07-10Bibliographically approved
Pericault, Y., Hedström, A., Dahl, J., Vesterlund, M. & Olsson, G. (2016). District heat tracing of water and sewer lines in Kiruna, Sweden (ed.). Paper presented at Sanitation in Cold Climate Regions : 12/04/2016 - 14/04/2016. Paper presented at Sanitation in Cold Climate Regions : 12/04/2016 - 14/04/2016.
Open this publication in new window or tab >>District heat tracing of water and sewer lines in Kiruna, Sweden
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2016 (English)Conference paper, Oral presentation only (Other academic)
National Category
Water Engineering Energy Engineering
Research subject
Urban Water Engineering; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-35022 (URN)9642777e-1d16-404d-9344-4e07c651bbba (Local ID)9642777e-1d16-404d-9344-4e07c651bbba (Archive number)9642777e-1d16-404d-9344-4e07c651bbba (OAI)
Conference
Sanitation in Cold Climate Regions : 12/04/2016 - 14/04/2016
Note
Godkänd; 2016; 20160125 (youper)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Johansson, T., Vesterlund, M., Olofsson, T. & Dahl, J. (2016). Energy performance certificates and 3-dimensional city models as a means to reach national targets: A case study of the city of Kiruna (ed.). Paper presented at . Energy Conversion and Management, 116, 42-57
Open this publication in new window or tab >>Energy performance certificates and 3-dimensional city models as a means to reach national targets: A case study of the city of Kiruna
2016 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 116, p. 42-57Article in journal (Refereed) Published
Abstract [en]

Enhanced dissemination of information regarding energy saving and climate change targeted toward property owners is considered to be an important strategy in order to reach the Swedish national target of energy efficiency in the building sector by 2050. Here the municipality energy advisors and the national register for energy performance certificates can facilitate the mitigation of energy use in the building stock. So far few studies have focused on the practical road map to the national target of energy use on the city/district level and to the communication aspects with stakeholders in the creation of energy city models.In this paper a city energy model is developed based on the requests and need for visualization from a group of energy advisors. Six different scenarios are studied in order to analyze the possibility of reaching the energy targets specified by the government in the town of Kiruna. The results show that: (1) it is possible to automatically create city energy models using extract, transform and load tools based on spatial and non-spatial data from national registers and databases; (2) city energy models improve the understanding of energy use in buildings and can therefore be a valuable tool for energy advisors, real estate companies and urban planners. The case study of Kiruna showed that the proposed energy saving measures in the energy performance certificates need to be implemented and new buildings in the urban transformation must be of high energy standard in order to reach the national target in Kiruna.

National Category
Construction Management Energy Engineering
Research subject
Construction Engineering and Management; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-14165 (URN)10.1016/j.enconman.2016.02.057 (DOI)000373749800005 ()2-s2.0-84960080826 (Scopus ID)d82fcec8-829a-4bc9-a429-8e0d2c0bcef3 (Local ID)d82fcec8-829a-4bc9-a429-8e0d2c0bcef3 (Archive number)d82fcec8-829a-4bc9-a429-8e0d2c0bcef3 (OAI)
Note
Validerad; 2016; Nivå 2; 20160310 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vesterlund, M., Toffolo, A. & Dahl, J. (2016). Optimization of multi-source complex district heating network: a case study. In: Proceeding of 29th International Conference on efficiency, Cost, Optimization, Simulation and Enviromental Impact of Energy Systems: . Paper presented at 29th international conference on Efficiency, Cost, Optimisation, Simulation and Environmental Impact of Energy Systems, ECOS 2016, Portorož, Slovenia, June 19. - 23. 2016.
Open this publication in new window or tab >>Optimization of multi-source complex district heating network: a case study
2016 (English)In: Proceeding of 29th International Conference on efficiency, Cost, Optimization, Simulation and Enviromental Impact of Energy Systems, 2016Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The level of complexity for a district heating network increases with the maturity of the network, and this affects the pattern of the distribution of the hot water from the heat production sites to the end users. The majority of district heating systems are also multi-source networks, typically supported with heat from one main production site and other smaller satellite sites that are activated when required. In general, local energy companies have a lack of knowledge regarding how a meshed network behaves when different production sites are operated. The schedule of heat generation at the different sites is often based on staff experience and some general rules of thumb.

In this paper a method for modeling and simulating complex district networks is further developed in order to optimize the total operating costs of a multi-source network, with constraints on the pressure and temperature levels in the user areas and on the heat generation characteristics at each production site.

The optimization results show that the usage of the cheapest resources is preferred to a distributed generation of heat, even if some of the pipes may exceed the recommended thermal load capacity. The main site water supply temperature is found to be the lowest allowed by the constraint on the temperature of the water supplied to the end users, since the decrease of the costs associated with the lower thermal losses in the network is not counterbalanced by the increase of those associated with the pumping power of a larger water mass flow rate.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-60957 (URN)
Conference
29th international conference on Efficiency, Cost, Optimisation, Simulation and Environmental Impact of Energy Systems, ECOS 2016, Portorož, Slovenia, June 19. - 23. 2016
Available from: 2016-12-07 Created: 2016-12-07 Last updated: 2017-11-24Bibliographically approved
Vesterlund, M., Toffolo, A. & Dahl, J. (2016). Simulation and analysis of a meshed district heating network (ed.). Paper presented at . Energy Conversion and Management, 122, 63-73
Open this publication in new window or tab >>Simulation and analysis of a meshed district heating network
2016 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 122, p. 63-73Article in journal (Refereed) Published
Abstract [en]

The flow distribution in a district heating network tends to become no longer obvious when system design is developed and its complexity increased. As a consequence, the network owner, often the local energy company, is in need of a simulation program to have the possibility of analysing network behaviour and expand the understanding about the operation of district heating system. In this paper, a simulation tool developed in MATLAB/Simulink is applied in order to analyse the flow distribution in the district heating network of the town of Kiruna (Sweden). The network in Kiruna has been developing since the 60s and is today a complex network with a meshed structure, i.e. it is formed by a set of loops from which secondary branches depart. The simulation tool is part of a methodology that has specifically been developed to analyse the flow pattern in such kind of networks without altering their physical structure, and it is expected to be a valuable tool for the redesign of the network in the forthcoming relocation of some of the urban districts. The results about the current network configuration show that only a few pipes in the network are exceeding the levels of heat flow recommended by pipe manufacturers. The largest drops in pressure and temperature from the heat production site to the nodes serving the main consumer areas are within 1.2 bar and 9 °C in the days of highest demand.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-5877 (URN)411b63db-cfe4-4756-852e-77f5593f749f (Local ID)411b63db-cfe4-4756-852e-77f5593f749f (Archive number)411b63db-cfe4-4756-852e-77f5593f749f (OAI)
Note
Validerad; 2016; Nivå 2; 20160530 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Vesterlund, M. & Dahl, J. (2015). A method for the simulation and optimization of district heating systems with meshed networks (ed.). Paper presented at . Energy Conversion and Management, 89, 555-567
Open this publication in new window or tab >>A method for the simulation and optimization of district heating systems with meshed networks
2015 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 89, p. 555-567Article in journal (Refereed) Published
Abstract [en]

There are two main methods nowadays for modeling district heating systems, but a key disadvantage of both is that a real network containing loops cannot be described without artificial simplifications in order to eliminate those distinguishing features. However, loops are very common in mature networks that have developed a meshed structure, and make the distribution of mass and heat flows quite characteristic. For this reason, a new process integration method for modeling complex district heating systems containing loops is described in this paper. This method makes it possible to analyze how loops and bottlenecks affect the behavior of the network, as well as the distribution path of the thermal energy in it. The district heating system in the town of Kiruna (located in the north of Sweden) has a complex design with several loops and part of it is used in the paper as an example of application.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-9152 (URN)10.1016/j.enconman.2014.10.002 (DOI)000346552200053 ()2-s2.0-84908374425 (Scopus ID)7b800504-b27d-4e1c-ba92-dcf3a103f468 (Local ID)7b800504-b27d-4e1c-ba92-dcf3a103f468 (Archive number)7b800504-b27d-4e1c-ba92-dcf3a103f468 (OAI)
Note
Validerad; 2015; Nivå 2; 20141029 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Risberg, D., Vesterlund, M., Westerlund, L. & Dahl, J. (2015). CFD simulation and evaluation of different heating systems installed in low energy building located in sub-arctic climate (ed.). Paper presented at . Building and Environment, 89, 160-169
Open this publication in new window or tab >>CFD simulation and evaluation of different heating systems installed in low energy building located in sub-arctic climate
2015 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 89, p. 160-169Article in journal (Refereed) Published
Abstract [en]

Computational Fluid Dynamics (CFD) simulations were used to study the indoor climate in a low energy building in northern Sweden. The building’s low heat requirement raise the prospect of using a relatively simple and inexpensive heating system to maintain an acceptable indoor environment, even in the face of extremely low outdoor temperature. To explore the viability of this approach, the indoor climate in the building was studied considering three different heating systems: a floor heating system, air heating through the ventilation system and an air heat pump installation with one fan coil unit. The floor heating system provided the most uniform operative temperature distribution and was the only heating system that fully satisfied the recommendations to achieve tolerable indoor climate set by the Swedish authorities. On the contrary, air heating and the air heat pump created a relatively uneven distribution of air velocities and temperatures, and none of them fulfills the specified recommendations. From the economic point of view, the air heat pump system was cheaper to be installed but produced a less pleasant indoor environment than the other investigated heating systems.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-11144 (URN)10.1016/j.buildenv.2015.02.024 (DOI)000364440600014 ()2-s2.0-84924737867 (Scopus ID)a0dde22a-a36f-4f00-a108-d848722aa479 (Local ID)a0dde22a-a36f-4f00-a108-d848722aa479 (Archive number)a0dde22a-a36f-4f00-a108-d848722aa479 (OAI)
Note
Validerad; 2015; Nivå 2; 20150305 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vesterlund, M., Toffolo, A. & Dahl, J. (2015). Simulation and analysis of a meshed district heating network (ed.). In: (Ed.), (Ed.), ECOS 2015: 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. Paper presented at International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems : 29/06/2015 - 03/07/2015. : International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems
Open this publication in new window or tab >>Simulation and analysis of a meshed district heating network
2015 (English)In: ECOS 2015: 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems , 2015Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, 2015
Keywords
Engineering mechanics - Mechanical and thermal engineering, District heating, Meshed network, Simulation, Flow pattern, Heat distribution, Teknisk mekanik - Mekanisk och termisk energiteknik
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-35687 (URN)84978906340 (Scopus ID)a55e3550-6ae9-4a4b-a498-54300fcc8a7a (Local ID)9782955553909 (ISBN)a55e3550-6ae9-4a4b-a498-54300fcc8a7a (Archive number)a55e3550-6ae9-4a4b-a498-54300fcc8a7a (OAI)
Conference
International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems : 29/06/2015 - 03/07/2015
Note
Godkänd; 2015; 20150604 (matves)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Risberg, D., Vesterlund, M., Risberg, M., Hedström, A., Dahl, J. & Westerlund, L. (2014). Hållbara, integrerade energi- och VA-system (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Hållbara, integrerade energi- och VA-system
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2014 (Swedish)Report (Other academic)
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2014. p. 30
Series
Rapportserie Attract ; 2014:04
National Category
Energy Engineering Water Engineering
Research subject
Energy Engineering; Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-23505 (URN)73e3908f-5847-4f04-af09-6f9adbcefebe (Local ID)978-91-7583-284-5 (ISBN)978-91-7583-285-2 (ISBN)73e3908f-5847-4f04-af09-6f9adbcefebe (Archive number)73e3908f-5847-4f04-af09-6f9adbcefebe (OAI)
Note
Godkänd; 2014; 20150326 (danris)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-02-21Bibliographically approved
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