The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform

Bijan Adl-zarrabi - One of the best experts on this subject based on the ideXlab platform.

  • Long-term performance of vacuum insulations panels in buildings and building systems
    2017
    Co-Authors: Pär Johansson, Bijan Adl-zarrabi, Axel Berge
    Abstract:

    The extremely low thermal conductivity of vacuum insulation panels (VIP) leads to less required insulation thickness in different applications. This paper aims to present our research findings related to the long-term performance of VIPs based on measurements during the last five years. The measurements were performed both in laboratory and in field where the real condition are present. The performance of an exterior wall retrofitted with VIPs and a hybrid insulated District Heating Pipe were observed. The expected service life of both application are more than 50 years. Thus, the long-term performance of the VIPs is of interest. The results of the evaluation indicate that there is no considerable performance degradation after five years in the wall application and after three years in the hybrid insulated Pipes. The results are promising. However, it is still too soon to make final conclusions of the entire service life performance of the applications.

  • Influence of oxidation on radiative heat transfer in polyurethane insulation used for District Heating Pipes
    Energy Procedia, 2017
    Co-Authors: Fredrik Domhagen, Bijan Adl-zarrabi
    Abstract:

    Thermal conductivity of cellular rigid polyurethane foam (PUR) increases by time which leads to higher heat energy losses in District Heating Pipe networks. The main reason for increased thermal conductivity is diffusion of low conductive gases out of the PUR and diffusion of surrounding air into the PUR. However, oxidation of the PUR occurs during the service-life of the PUR and is accelerated by the higher temperatures close the fluid Pipe. The effect that oxidation has on the thermal conductivity is not yet fully understood and existing models for prediction of long-term thermal performance of PUR insulation in District Heating applications does not take oxidation processes into account. It is possible that the radiative heat transfer is affected by the oxidation and changes over the service-life of the PUR. In order to investigate the influence of oxidation on thermal conductivity, the extinction coefficient was therefore calculated for samples subjected to different levels of ageing. The input data for the calculations were measured by FTIR. The extinction coefficients were then used to calculate the overall thermal conductivity of the PUR with typical gas compositions. Results indicated that the extinction coefficient was 22 % higher in the samples exposed to lower temperatures. However, the effect on the overall thermal conductivity of the same samples was an increase of about 1.8 %. Since the comparison was made between two samples subjected to different levels of ageing, the increase in total thermal conductivity should be interpreted as a minimum if considering the total service lifetime of the PUR insulation.

  • Field measurements on a District Heating Pipe with vacuum insulation panels
    Renewable Energy, 2016
    Co-Authors: Axel Berge, Carl-eric Hagentoft, Bijan Adl-zarrabi
    Abstract:

    In Swedish District Heating networks, around 10% of the supplied thermal energy is lost in the distribution system. One solution to decrease the losses is to use hybrid insulation District Heating Pipes, a concept where the innermost part of the thermal insulation consists of vacuum insulation panels, held in place by polyurethane foam. One problem with vacuum insulation panels are their sensitivity to high temperatures. This paper presents field measurements on a hybrid insulation District Heating Pipe where the temperatures have been measured continuously at various positions of a Pipe section. The measurements show consistency and a large difference between hybrid insulation parts and reference parts without vacuum insulation panels. A superposition model has been used to calculate the temperature in a point and compare it to the measurement. The results are compared to the same calculation on the results from finite element simulations. The results show clearly that the vacuum panels in the Pipes have not collapsed. A slow deterioration of the panels is harder to find with this model. Changes in the system, such as a return temperature which decreases over time, can give a larger impact, concealing the change in the panel performance.

  • Assessing the Thermal Performance of District Heating Twin Pipes with Vacuum Insulation Panels
    Energy Procedia, 2015
    Co-Authors: Axel Berge, Bijan Adl-zarrabi, Carl-eric Hagentoft
    Abstract:

    In Sweden, around 10% of the energy supplied to the District Heating networks are lost through heat losses from the distribution Pipes. In cylindrical geometries it is preferable to improve the insulation as close to the center as possible. This has resulted in a hybrid insulation District Heating Pipe concept with a combination of vacuum insulation panels at the center, held in place by polyurethane foam. In the twin Pipe concept, the vacuum insulation panel cover the supply Pipe. This creates a complex temperature profile over the section and measured results on single Pipes might not be applicable. Therefore, there is a need for a method to evaluate the improvement of hybrid insulation twin Pipes in the laboratory. This paper presents a method where two guarded hot Pipe apparatuses is used, one Heating rod for each Pipe, to measure the heat losses from hybrid Pipes and compare to a conventional polyurethane Pipe. The measurements indicate an improvement in thermal performance by 12%-18% for the total losses and by 29% -39% for the supply Pipe losses.

  • Evaluation of Long-term Performance of VIPs☆
    Energy Procedia, 2015
    Co-Authors: Pär Johansson, Bijan Adl-zarrabi, Axel Berge
    Abstract:

    Apart from the higher initial cost for using vacuum insulation panels (VIPs) in buildings there is still hesitation among architects and engineers whether these materials will withstand long-term use in buildings with a service life of 80-100 years. To evaluate the long-term performance, further investigations are needed. VIPs have been used in buildings since the 1990s and there already exists experience from using them in various applications. This paper presents the experiences from two field studies of a previously non-insulated wall with VIPs and a District Heating Pipe with hybrid VIP/PUR insulation. Measurements of the relative humidity in the wall showed that there is low risk of condensation in the VIP layer. Temperature measurements in the wall during the period 2010 to 2015 show no signs of deterioration of the VIPs. The same conclusion was made based on the temperature profiles in the District Heating Pipes during the period 2012 to 2015. The measurements are on-going to determine the long-term performance of the VIPs in different applications.

Axel Berge - One of the best experts on this subject based on the ideXlab platform.

  • Long-term performance of vacuum insulations panels in buildings and building systems
    2017
    Co-Authors: Pär Johansson, Bijan Adl-zarrabi, Axel Berge
    Abstract:

    The extremely low thermal conductivity of vacuum insulation panels (VIP) leads to less required insulation thickness in different applications. This paper aims to present our research findings related to the long-term performance of VIPs based on measurements during the last five years. The measurements were performed both in laboratory and in field where the real condition are present. The performance of an exterior wall retrofitted with VIPs and a hybrid insulated District Heating Pipe were observed. The expected service life of both application are more than 50 years. Thus, the long-term performance of the VIPs is of interest. The results of the evaluation indicate that there is no considerable performance degradation after five years in the wall application and after three years in the hybrid insulated Pipes. The results are promising. However, it is still too soon to make final conclusions of the entire service life performance of the applications.

  • Field measurements on a District Heating Pipe with vacuum insulation panels
    Renewable Energy, 2016
    Co-Authors: Axel Berge, Carl-eric Hagentoft, Bijan Adl-zarrabi
    Abstract:

    In Swedish District Heating networks, around 10% of the supplied thermal energy is lost in the distribution system. One solution to decrease the losses is to use hybrid insulation District Heating Pipes, a concept where the innermost part of the thermal insulation consists of vacuum insulation panels, held in place by polyurethane foam. One problem with vacuum insulation panels are their sensitivity to high temperatures. This paper presents field measurements on a hybrid insulation District Heating Pipe where the temperatures have been measured continuously at various positions of a Pipe section. The measurements show consistency and a large difference between hybrid insulation parts and reference parts without vacuum insulation panels. A superposition model has been used to calculate the temperature in a point and compare it to the measurement. The results are compared to the same calculation on the results from finite element simulations. The results show clearly that the vacuum panels in the Pipes have not collapsed. A slow deterioration of the panels is harder to find with this model. Changes in the system, such as a return temperature which decreases over time, can give a larger impact, concealing the change in the panel performance.

  • Assessing the Thermal Performance of District Heating Twin Pipes with Vacuum Insulation Panels
    Energy Procedia, 2015
    Co-Authors: Axel Berge, Bijan Adl-zarrabi, Carl-eric Hagentoft
    Abstract:

    In Sweden, around 10% of the energy supplied to the District Heating networks are lost through heat losses from the distribution Pipes. In cylindrical geometries it is preferable to improve the insulation as close to the center as possible. This has resulted in a hybrid insulation District Heating Pipe concept with a combination of vacuum insulation panels at the center, held in place by polyurethane foam. In the twin Pipe concept, the vacuum insulation panel cover the supply Pipe. This creates a complex temperature profile over the section and measured results on single Pipes might not be applicable. Therefore, there is a need for a method to evaluate the improvement of hybrid insulation twin Pipes in the laboratory. This paper presents a method where two guarded hot Pipe apparatuses is used, one Heating rod for each Pipe, to measure the heat losses from hybrid Pipes and compare to a conventional polyurethane Pipe. The measurements indicate an improvement in thermal performance by 12%-18% for the total losses and by 29% -39% for the supply Pipe losses.

  • Evaluation of Long-term Performance of VIPs☆
    Energy Procedia, 2015
    Co-Authors: Pär Johansson, Bijan Adl-zarrabi, Axel Berge
    Abstract:

    Apart from the higher initial cost for using vacuum insulation panels (VIPs) in buildings there is still hesitation among architects and engineers whether these materials will withstand long-term use in buildings with a service life of 80-100 years. To evaluate the long-term performance, further investigations are needed. VIPs have been used in buildings since the 1990s and there already exists experience from using them in various applications. This paper presents the experiences from two field studies of a previously non-insulated wall with VIPs and a District Heating Pipe with hybrid VIP/PUR insulation. Measurements of the relative humidity in the wall showed that there is low risk of condensation in the VIP layer. Temperature measurements in the wall during the period 2010 to 2015 show no signs of deterioration of the VIPs. The same conclusion was made based on the temperature profiles in the District Heating Pipes during the period 2012 to 2015. The measurements are on-going to determine the long-term performance of the VIPs in different applications.

  • EVALUATION OF VACUUM INSULATION PANELS USED IN HYBRID INSULATION District Heating PipeS
    2014
    Co-Authors: Axel Berge, Bijan Adl-zarrabi
    Abstract:

    It is of interest to lower the energy losses from District Heating Pipes both for economic and environmental reasons. This paper evaluates a hybrid insulation solution where Vacuum Insulation Panels (VIP) are put around the supply Pipe in a District Heating Pipe and the rest of the casing Pipe is filled with polyurethane foam (PUR). The apparatus for the “guarded hot Pipe” method was used to estimate the thermal properties of single Pipes, which have been used as input in finite element models for simulation of twin Pipes in field. The simulations indicate a total reduction in the energy loss between 18% and 32% compared to Pipes of the same size with pure PUR insulation. Furthermore, the losses from the supply Pipe decrease by up to 56%. To achieve the low energy losses, the vacuum in the panels has to be preserved over the life span of the VIP. In field measurements, a hybrid Pipe prototype was connected to the District Heating grid in Varberg (southwest Sweden). After almost two years, the Pipe is still working without any detectable deterioration of the insulation performance. The panels have also been tested at high temperatures in laboratory with promising results.

Magdalena Svanström - One of the best experts on this subject based on the ideXlab platform.

  • Life Cycle Assessment of the District Heat Distribution System. Part 3: Use Phase and Overall Discussion (10 pp)
    The International Journal of Life Cycle Assessment, 2006
    Co-Authors: Camilla Persson, Morgan Fröling, Magdalena Svanström
    Abstract:

    - Part 1: Pipe Production [Int J LCA 9 (2) 130-136 (2004)] Part 2: Network Construction [Int J LCA 10 (6) 425-435 (2005)] Part 3: Use Phase and Overall Discussion [DOI: http://dx.doi.org/10.1065/lca2005.08.225] - Preamble. This series of three papers is based on research performed for the Swedish District Heating Association with the purpose of mapping the environmental life cycle impacts from the different phases involved in District heat distribution. Part 1 concerns production of the District Heating Pipes while Part 2 describes construction of the District Heating Pipe network. In Part 3, the use phase is evaluated based on heat losses from the network during heat distribution. Part 3 also includes a discussion in which the three evaluated life cycle phases are compared. Goal, Scope and Background The idea of District Heating is to transport centrally produced heat to buildings where it is used for space Heating and for domestic hot water generation. Water is used as a heat carrier. Many different heat sources are used to supply District Heating networks with hot water. In literature, environmental studies on District Heating mainly consider emissions from the heat generation; environmental impacts from the distribution system are seldom discussed. This paper is the third in an article series on the environmental impacts from the District heat distribution system. The paper presents an evaluation of the use phase of District heat distribution, focusing on long-term thermal performance of different District Heating Pipes. An overall discussion, in which environmental impacts from the different life cycle phases of District heat distribution are compared, is also presented. Methods for the Use Phase Study. Environmental impacts from use of District heat distribution systems were evaluated based on heat losses from the networks, which depend on the long-term thermal performance of the District Heating Pipes. The heat losses cause environmental impacts from extra heat generation needed to cover the losses. - The long-term thermal performance of preinsulated bonded District Heating Pipes with steel tube, polyurethane foam insulation and polyethylene casing, depends on the thickness and quality of both the insulation and the casing. One important attribute of the foam is the blowing agent used. The blowing agent influences both the initial insulating capacity of the foam and the ageing characteristics, due to differences in migration rates of different substances through the materials. - Heat losses were calculated for different District Heating Pipe dimensions (DN25 twin Pipe, and DN25, DN100 and DN500 Series 2 single Pipes). Pipes with two different foam blowing agents (cyclopentane and carbon dioxide) were studied, taking into account the differences in long term thermal performance of the foams. Concerning emissions from heat generation, two heat sources were considered: heat generation according to the average District Heating fuel mix used in Sweden in the year of 2000, and heat generation using natural gas heat only boilers. The functional unit used is 100 m of District heat distribution network during 30 years of use. Results and Discussion on the Use Phase. A short description of the inventory, some inventory results and a life cycle impact assessment are presented. Characterizations according to GWP, AP, POCP and resource depletion are given as well as two weightings: EcoIndicator99 and Ecoscarcity. The DN25 twin Pipe network has about 25% lower environmental impacts from use than the DN25 Series 2 single Pipe network. The District Heating Pipes insulated with cyclopentane blown polyurethane foam have a better environmental performance during use compared to those insulated with carbon dioxide blown foam (6-13%). This is partly dependent on a higher initial insulating capacity of the cyclopentane blown foam, but also due to a slower deterioration of the insulating capacity over time. For the two heat sources considered, different impact assessments give different indications to which option that is environmentally preferable. - Overall Results and Discussion on Pipe Production, Network Construction and Network Use Phases. A comparison of the three life cycle phases studied in this article series was made concerning four emissions, the four characterizations and the two weightings. The use phase represents over half of the total environmental impact for most, but not all, environmental parameters studied. It is important to keep the heat losses from the network down and to strive for heat sources with low environmental impacts. The larger the Pipe, the larger is the relative impact from Pipe production. The network construction phase has a relatively small contribution to the total environmental impact in most systems studied. However, the emissions during network construction often occur in residential areas and may therefore not be neglected when immediate nuisances and health aspects are considered. - A very small change of the material flows in the production phase, the change between two different blowing agents (cyclopentane and carbon dioxide), can give dramatic results for the total environmental outcome for the District Heating network because of a large change in influence on environmental impacts during use. The DN25 twin Pipe network proves to be environmentally advantageous compared to the DN25 Series 2 single Pipe network during all of the studied life cycle phases. Recommendations and Perspective . It is important to make sure that improvements in the production and construction phases do not lower the insulating capacity of the District Heating system. A good initial insulating capacity, maintained over time, is important for the environmental performance of a District heat distribution network. Using DN25 twin Pipes instead of DN25 Series 2 single Pipes is a better choice, when possible, regarding all studied life cycle phases. The environmental impact from use of the District heat distribution system depends heavily on the type of energy source that is utilized to supply the network with heat.

  • Life Cycle Assessment of the District Heat Distribution System - Part 2: Network Construction (11 pp)
    The International Journal of Life Cycle Assessment, 2005
    Co-Authors: Morgan Fröling, Magdalena Svanström
    Abstract:

    - Part 1: Pipe Production [Int J LCA 9 (2) 130–136 (2004)] Part 2: Network Construction [Int J LCA 10 (6) 425-435 (2005)] Part 3: Use Phase and Overall Discussion [DOI: http://dx.doi.org/10.1065/lca2005.08.225] - Preamble. This series of three papers is based on research performed for the Swedish District Heating Association with the purpose of mapping the environmental life cycle impacts from the different phases involved in District heat distribution. Part 1 concerns production of District Heating Pipes while Part 2 describes construction of the District Heating Pipe network. In Part 3, the use phase is evaluated based on heat losses from the network during heat distribution. Part 3 also includes a discussion in which the three evaluated life cycle phases are compared. Goal, Scope and Background In a District Heating network, hot water is transported from a central heat generation plant to buildings where the heat is utilised for space Heating and domestic hot water generation. This paper presents a life cycle assessment of the construction of District Heating Pipe networks, based on a gate-to-gate life cycle inventory commissioned by the Swedish District Heating Association. In the literature, environmental studies on District Heating mainly consider emissions from heat generation; environmental impacts from construction of the distribution system are seldom discussed. The purpose of the study is to identify environmentally significant parts in the construction of District heat distribution networks and to provide information for a larger study including more parts of the life cycle of such District heat distribution. No external review has been performed, but a reference group of District Heating experts familiar with the practice was involved in the choice of systems to be studied as well as in reviewing parts of the study. Methods The study covers construction of the main Pipe system according to the guidelines from the Swedish District Heating Association. Construction of the Pipe system was assumed to take place in Sweden by Swedish entrepreneurs during the time period 1999–2000. Transport of the District Heating Pipes from the factory to the excavation site is included in this study, but not the production of the Pipes. The functional unit used in the study is 100 metres of Pipe system (flow and return Pipe). The studied systems are: twin Pipe of the dimension DN25 and single Pipes of the dimensions DN25, DN100 and DN500. Two different surroundings were studied: urban environment, characterised by the need to break open and to restore asphalt cover and to remove excavated material from the site, and green areas, without any asphalt and where some of the excavated material might be left at the site and reused. Results and Discussion A short description of the inventory, some inventory results and life cycle impact assessments are presented. Characterisations according to GWP, AP, POCP and resource depletion are given as well as two weightings: EcoIndicator99 and Ecoscarcity. Emissions from production and use of the diesel needed for excavation of the Pipe trench gives rise to a dominating part of the environmental impact. Recommendations and Perspective To minimise the need for excavation is the most important feature in order to reduce the environmental impact from construction of the District Heating Pipe network. A twin Pipe uses a narrower Pipe trench than the equivalent two single Pipes, and is an already available option. Co-utilising the trenches with cables for electricity, for instance, will not make the environmental impact from the trench any smaller, but will decrease the total need for excavation in society. It is important to make sure that environmental improvements from changes in the network construction phase are not off-set by other effects in the total life cycle of District heat distribution.

  • Life cycle assessment of the District heat distribution system
    The International Journal of Life Cycle Assessment, 2004
    Co-Authors: Morgan Fröling, Camilla Holmgren, Magdalena Svanström
    Abstract:

    Goal, Scope and Background District Heating, the utilization of centrally produced heat for space Heating and domestic hot water generation, has the potential to contribute to the eco-efficient use of energy resources in the parts of the world where space Heating is needed. In literature, environmental studies on District Heating mainly consider the emissions from heat generation; the environmental impact from the distribution system is seldom discussed. This paper presents a life cycle assessment of the production of District Heating Pipes, based on a cradle-to-gate life cycle inventory commissioned by the Swedish District Heating Association. No external review has been performed but a reference group of District Heating experts familiar with the practice was involved in the choice of cases as well as in reviewing parts of the study. Methods Manufacturing of District Heating Pipes at PowerPipe Systems AB, Göteborg, Sweden, was studied. Prefabricated polyurethane insulated District Heating Pipes were considered, with a steel tube and a protective casing made of high-density polyethylene. Production of Pipes during the time period 1999–2000 was investigated. The functional unit used in the study is production of one District Heating Pipe unit. The studied Pipes are: a twin Pipe of the dimension DN25 (12m long) and single Pipes of the dimensions DN25 (12m), DN100 (12m) and DN500 (16m). Results and Discussion A short description of the inventory, some inventory results and a life cycle impact assessment are presented. Characterizations according to GWP, AP, POCP and resource depletion are given as well as two weightings: EcoIndicator99 and Ecoscarcity. If the life cycle is grouped into ‘Materials production’, ‘Transports’, ‘Manufacturing’ and ‘Waste management’, the ‘Materials production’ gives rise to a dominating part of the environmental impact. Recommendation and Perspective To use materials in the Pipes as efficiently as possible is the most important feature in order to reduce the environmental impact from production of District Heating Pipes. Twin Pipes can be a more material efficient solution than single Pipes. It is important to make sure that environmental improvements from changes in the Pipe production phase are not offset by other effects in the total life cycle of the District Heating Pipe.

  • Carbon dioxide diffusion in District Heating Pipes
    Cellular Polymers, 1999
    Co-Authors: Magdalena Svanström, O Ramnäs, Morgan Fröling, Ulf Jarfelt
    Abstract:

    Measurements on the cell gas composition of old District Heating Pipes insulated with carbon dioxide-blown polyurethane foam and still in use, are reported. The Pipes had been in use for up to more than eight years at the latest date of measurement. The effective permeability coefficients for carbon dioxide in the District Heating Pipes at room temperature were calculated to be in the range 1.5 to 5.3.10 -16 mole.m -1 .s -1 .Pa -1 . For carbon dioxide, the major part of the resistance to diffusion was found in the polyethylene casing. The influence of the dimension of the District Heating Pipe and the temperature of the polyethylene casing is discussed.

  • Mass Transfer of Carbon Dioxide through the Polyethylene Casing of District Heating Pipes
    Journal of Thermal Insulation and Building Envelopes, 1997
    Co-Authors: Magdalena Svanström, O Ramnäs, Maria Olsson, Ulf Jarfelt
    Abstract:

    The mass transfer of carbon dioxide through the outer polyethylene casing of District Heating Pipes, at room temperature, was evaluated, using different test methods. The mass transfer either through polyethylene casings on polyurethane preinsulated District Heating Pipes or through polyethylene casings alone was mea sured. Permeability coefficients of different polyethylene casings were about 20 · 10-18 kg·m-1·s-1·Pa-1. Permeability coefficients for carbon dioxide in polyurethane foam is about 100 times lower, which means that the mass transfer resistance to car bon dioxide of the polyurethane foam in a District Heating Pipe is negligible in com parison with the polyethylene casing.

Morgan Fröling - One of the best experts on this subject based on the ideXlab platform.

  • Life Cycle Assessment of the District Heat Distribution System. Part 3: Use Phase and Overall Discussion (10 pp)
    The International Journal of Life Cycle Assessment, 2006
    Co-Authors: Camilla Persson, Morgan Fröling, Magdalena Svanström
    Abstract:

    - Part 1: Pipe Production [Int J LCA 9 (2) 130-136 (2004)] Part 2: Network Construction [Int J LCA 10 (6) 425-435 (2005)] Part 3: Use Phase and Overall Discussion [DOI: http://dx.doi.org/10.1065/lca2005.08.225] - Preamble. This series of three papers is based on research performed for the Swedish District Heating Association with the purpose of mapping the environmental life cycle impacts from the different phases involved in District heat distribution. Part 1 concerns production of the District Heating Pipes while Part 2 describes construction of the District Heating Pipe network. In Part 3, the use phase is evaluated based on heat losses from the network during heat distribution. Part 3 also includes a discussion in which the three evaluated life cycle phases are compared. Goal, Scope and Background The idea of District Heating is to transport centrally produced heat to buildings where it is used for space Heating and for domestic hot water generation. Water is used as a heat carrier. Many different heat sources are used to supply District Heating networks with hot water. In literature, environmental studies on District Heating mainly consider emissions from the heat generation; environmental impacts from the distribution system are seldom discussed. This paper is the third in an article series on the environmental impacts from the District heat distribution system. The paper presents an evaluation of the use phase of District heat distribution, focusing on long-term thermal performance of different District Heating Pipes. An overall discussion, in which environmental impacts from the different life cycle phases of District heat distribution are compared, is also presented. Methods for the Use Phase Study. Environmental impacts from use of District heat distribution systems were evaluated based on heat losses from the networks, which depend on the long-term thermal performance of the District Heating Pipes. The heat losses cause environmental impacts from extra heat generation needed to cover the losses. - The long-term thermal performance of preinsulated bonded District Heating Pipes with steel tube, polyurethane foam insulation and polyethylene casing, depends on the thickness and quality of both the insulation and the casing. One important attribute of the foam is the blowing agent used. The blowing agent influences both the initial insulating capacity of the foam and the ageing characteristics, due to differences in migration rates of different substances through the materials. - Heat losses were calculated for different District Heating Pipe dimensions (DN25 twin Pipe, and DN25, DN100 and DN500 Series 2 single Pipes). Pipes with two different foam blowing agents (cyclopentane and carbon dioxide) were studied, taking into account the differences in long term thermal performance of the foams. Concerning emissions from heat generation, two heat sources were considered: heat generation according to the average District Heating fuel mix used in Sweden in the year of 2000, and heat generation using natural gas heat only boilers. The functional unit used is 100 m of District heat distribution network during 30 years of use. Results and Discussion on the Use Phase. A short description of the inventory, some inventory results and a life cycle impact assessment are presented. Characterizations according to GWP, AP, POCP and resource depletion are given as well as two weightings: EcoIndicator99 and Ecoscarcity. The DN25 twin Pipe network has about 25% lower environmental impacts from use than the DN25 Series 2 single Pipe network. The District Heating Pipes insulated with cyclopentane blown polyurethane foam have a better environmental performance during use compared to those insulated with carbon dioxide blown foam (6-13%). This is partly dependent on a higher initial insulating capacity of the cyclopentane blown foam, but also due to a slower deterioration of the insulating capacity over time. For the two heat sources considered, different impact assessments give different indications to which option that is environmentally preferable. - Overall Results and Discussion on Pipe Production, Network Construction and Network Use Phases. A comparison of the three life cycle phases studied in this article series was made concerning four emissions, the four characterizations and the two weightings. The use phase represents over half of the total environmental impact for most, but not all, environmental parameters studied. It is important to keep the heat losses from the network down and to strive for heat sources with low environmental impacts. The larger the Pipe, the larger is the relative impact from Pipe production. The network construction phase has a relatively small contribution to the total environmental impact in most systems studied. However, the emissions during network construction often occur in residential areas and may therefore not be neglected when immediate nuisances and health aspects are considered. - A very small change of the material flows in the production phase, the change between two different blowing agents (cyclopentane and carbon dioxide), can give dramatic results for the total environmental outcome for the District Heating network because of a large change in influence on environmental impacts during use. The DN25 twin Pipe network proves to be environmentally advantageous compared to the DN25 Series 2 single Pipe network during all of the studied life cycle phases. Recommendations and Perspective . It is important to make sure that improvements in the production and construction phases do not lower the insulating capacity of the District Heating system. A good initial insulating capacity, maintained over time, is important for the environmental performance of a District heat distribution network. Using DN25 twin Pipes instead of DN25 Series 2 single Pipes is a better choice, when possible, regarding all studied life cycle phases. The environmental impact from use of the District heat distribution system depends heavily on the type of energy source that is utilized to supply the network with heat.

  • Life Cycle Assessment of the District Heat Distribution System - Part 2: Network Construction (11 pp)
    The International Journal of Life Cycle Assessment, 2005
    Co-Authors: Morgan Fröling, Magdalena Svanström
    Abstract:

    - Part 1: Pipe Production [Int J LCA 9 (2) 130–136 (2004)] Part 2: Network Construction [Int J LCA 10 (6) 425-435 (2005)] Part 3: Use Phase and Overall Discussion [DOI: http://dx.doi.org/10.1065/lca2005.08.225] - Preamble. This series of three papers is based on research performed for the Swedish District Heating Association with the purpose of mapping the environmental life cycle impacts from the different phases involved in District heat distribution. Part 1 concerns production of District Heating Pipes while Part 2 describes construction of the District Heating Pipe network. In Part 3, the use phase is evaluated based on heat losses from the network during heat distribution. Part 3 also includes a discussion in which the three evaluated life cycle phases are compared. Goal, Scope and Background In a District Heating network, hot water is transported from a central heat generation plant to buildings where the heat is utilised for space Heating and domestic hot water generation. This paper presents a life cycle assessment of the construction of District Heating Pipe networks, based on a gate-to-gate life cycle inventory commissioned by the Swedish District Heating Association. In the literature, environmental studies on District Heating mainly consider emissions from heat generation; environmental impacts from construction of the distribution system are seldom discussed. The purpose of the study is to identify environmentally significant parts in the construction of District heat distribution networks and to provide information for a larger study including more parts of the life cycle of such District heat distribution. No external review has been performed, but a reference group of District Heating experts familiar with the practice was involved in the choice of systems to be studied as well as in reviewing parts of the study. Methods The study covers construction of the main Pipe system according to the guidelines from the Swedish District Heating Association. Construction of the Pipe system was assumed to take place in Sweden by Swedish entrepreneurs during the time period 1999–2000. Transport of the District Heating Pipes from the factory to the excavation site is included in this study, but not the production of the Pipes. The functional unit used in the study is 100 metres of Pipe system (flow and return Pipe). The studied systems are: twin Pipe of the dimension DN25 and single Pipes of the dimensions DN25, DN100 and DN500. Two different surroundings were studied: urban environment, characterised by the need to break open and to restore asphalt cover and to remove excavated material from the site, and green areas, without any asphalt and where some of the excavated material might be left at the site and reused. Results and Discussion A short description of the inventory, some inventory results and life cycle impact assessments are presented. Characterisations according to GWP, AP, POCP and resource depletion are given as well as two weightings: EcoIndicator99 and Ecoscarcity. Emissions from production and use of the diesel needed for excavation of the Pipe trench gives rise to a dominating part of the environmental impact. Recommendations and Perspective To minimise the need for excavation is the most important feature in order to reduce the environmental impact from construction of the District Heating Pipe network. A twin Pipe uses a narrower Pipe trench than the equivalent two single Pipes, and is an already available option. Co-utilising the trenches with cables for electricity, for instance, will not make the environmental impact from the trench any smaller, but will decrease the total need for excavation in society. It is important to make sure that environmental improvements from changes in the network construction phase are not off-set by other effects in the total life cycle of District heat distribution.

  • Life cycle assessment of the District heat distribution system
    The International Journal of Life Cycle Assessment, 2004
    Co-Authors: Morgan Fröling, Camilla Holmgren, Magdalena Svanström
    Abstract:

    Goal, Scope and Background District Heating, the utilization of centrally produced heat for space Heating and domestic hot water generation, has the potential to contribute to the eco-efficient use of energy resources in the parts of the world where space Heating is needed. In literature, environmental studies on District Heating mainly consider the emissions from heat generation; the environmental impact from the distribution system is seldom discussed. This paper presents a life cycle assessment of the production of District Heating Pipes, based on a cradle-to-gate life cycle inventory commissioned by the Swedish District Heating Association. No external review has been performed but a reference group of District Heating experts familiar with the practice was involved in the choice of cases as well as in reviewing parts of the study. Methods Manufacturing of District Heating Pipes at PowerPipe Systems AB, Göteborg, Sweden, was studied. Prefabricated polyurethane insulated District Heating Pipes were considered, with a steel tube and a protective casing made of high-density polyethylene. Production of Pipes during the time period 1999–2000 was investigated. The functional unit used in the study is production of one District Heating Pipe unit. The studied Pipes are: a twin Pipe of the dimension DN25 (12m long) and single Pipes of the dimensions DN25 (12m), DN100 (12m) and DN500 (16m). Results and Discussion A short description of the inventory, some inventory results and a life cycle impact assessment are presented. Characterizations according to GWP, AP, POCP and resource depletion are given as well as two weightings: EcoIndicator99 and Ecoscarcity. If the life cycle is grouped into ‘Materials production’, ‘Transports’, ‘Manufacturing’ and ‘Waste management’, the ‘Materials production’ gives rise to a dominating part of the environmental impact. Recommendation and Perspective To use materials in the Pipes as efficiently as possible is the most important feature in order to reduce the environmental impact from production of District Heating Pipes. Twin Pipes can be a more material efficient solution than single Pipes. It is important to make sure that environmental improvements from changes in the Pipe production phase are not offset by other effects in the total life cycle of the District Heating Pipe.

  • Transport of 1,1,1,3,3-pentafluorobutane (HFC-365mfc) in rigid polyurethane foam and polyethylene
    Cellular Polymers, 2002
    Co-Authors: Sara Mangs, O Ramnäs, Morgan Fröling, Ulf Jarfelt
    Abstract:

    This study focuses on the mass transfer properties of 1,1,1,3,3-pentafluorobutane (HFC-365mfc) in the insulating system used in most District Heating Pipes produced today, namely rigid polyurethane (PUR) foam with a protective layer of polyethylene (HDPE). The solubility, permeability and diffusion coefficients for HFC-365mfc in PUR foam and HDPE have been determined. The coefficients for HFC-365mfc in PUR foam are very similar to those of cyclopentane, currently the most common blowing agent in PUR foams used for District Heating Pipes in Europe. The polyethylene casing is a better diffusion barrier for HFC-365mfc than it is for cyclopentane. However, the main mass transfer resistance of HFC-365mfc in a District Heating Pipe is found in the PUR foam.

  • Carbon dioxide diffusion in District Heating Pipes
    Cellular Polymers, 1999
    Co-Authors: Magdalena Svanström, O Ramnäs, Morgan Fröling, Ulf Jarfelt
    Abstract:

    Measurements on the cell gas composition of old District Heating Pipes insulated with carbon dioxide-blown polyurethane foam and still in use, are reported. The Pipes had been in use for up to more than eight years at the latest date of measurement. The effective permeability coefficients for carbon dioxide in the District Heating Pipes at room temperature were calculated to be in the range 1.5 to 5.3.10 -16 mole.m -1 .s -1 .Pa -1 . For carbon dioxide, the major part of the resistance to diffusion was found in the polyethylene casing. The influence of the dimension of the District Heating Pipe and the temperature of the polyethylene casing is discussed.

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  • Super insulation material in District Heating Pipes
    SURFACE, 2018
    Co-Authors: Adl-zarrabi Bijan
    Abstract:

    In Swedish District Heating systems, 10% of the produced energy is lost at the distribution network. It is of interest to lower the energy losses both for economic and environmental reasons. Since 2011 the feasibility of using superinsulation material for insulation of the District Heating Pipes were studied. Apparent thermal conductivity and long term performance of vacuum panels has been identified has the crucial challenge for using vacuum insulation panels. The estimated life time of a vacuum panel in building applications at 90 °C is about 50 years. The life time estimation is based on the climate condition valid for building application. However, peak temperature in a District Heating system can be about 140°C. Hybrid insulated Pipes with a Vacuum Insulated Panel (VIP) have been tested and evaluated by laboratory and field measurements. The results of numerical analyses of the measured data indicate a possible small degradation of the VIP at a similar rate as building application, even though the operative temperature is between 80-100 °C. In the laboratory a hybrid insulated Pipe has withstood exposure to one sided Heating at 115°C for over 5 years. The results indicate that hybrid insulated District Heating Pipes reduce heat losses by 20-30% for a twin Pipe and with more than 50% in a single Pipe. It can be concluded that VIP shows promising performance in District Heating Pipe application

  • Field measurements on a District Heating Pipe with vacuum insulation panels
    2016
    Co-Authors: Berge Axel, Adl-zarrabi Bijan, Hagentoft Carl-eric
    Abstract:

    © 2015 Elsevier Ltd. In Swedish District Heating networks, around 10% of the supplied thermal energy is lost in the distribution system. One solution to decrease the losses is to use hybrid insulation District Heating Pipes, a concept where the innermost part of the thermal insulation consists of vacuum insulation panels, held in place by polyurethane foam. One problem with vacuum insulation panels are their sensitivity to high temperatures. This paper presents field measurements on a hybrid insulation District Heating Pipe where the temperatures have been measured continuously at various positions of a Pipe section. The measurements show consistency and a large difference between hybrid insulation parts and reference parts without vacuum insulation panels. A superposition model has been used to calculate the temperature in a point and compare it to the measurement. The results are compared to the same calculation on the results from finite element simulations. The results show clearly that the vacuum panels in the Pipes have not collapsed. A slow deterioration of the panels is harder to find with this model. Changes in the system, such as a return temperature which decreases over time, can give a larger impact, concealing the change in the panel performance