The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Svend Svendsen - One of the best experts on this subject based on the ideXlab platform.
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ultra low temperature district Heating system with central heat pump and local boosters for low heat density area analyses on a real case in denmark
Energy, 2018Co-Authors: Xiaochen Yang, Svend SvendsenAbstract:Low temperature district Heating (DH) system gives easier access to the renewable energy as heat sources and improves the heat distribution efficiency. From the exergy point of view, low DH supply temperature also better matches the exergy demand of space Heating and domestic hot water. It is more beneficial to operate district Heating system under lower temperature level for the heat-sparse area where the distribution losses accounts for a large proportion in the total heat supply. In this study, the actual performance of a case ultra-low temperature district Heating (ULTDH) system in Denmark was investigated based on long-term measurements. The system combines the central heat pump and local boosters, while the impact of such configuration on the overall system performance was analysed. The energy, exergy and economy performances of the case system were compared to medium temperature district Heating system (MTDH) and low-temperature district Heating system (LTDH). The results show that the LTDH system without Supplementary Heating has the highest energy and exergy efficiency. While the ULTDH system has better performance compared to the MTDH system in energy, exergy and economy due to substantial savings from the distribution heat loss.
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Achieving low return temperature for domestic hot water preparation by ultra-low-temperature district Heating
Energy Procedia, 2017Co-Authors: Xiaochen Yang, Svend SvendsenAbstract:Abstract District Heating (DH) is a cost-effective method of heat supply, especially to area with high heat density. Ultra-low-temperature district Heating (ULTDH) is defined with supply temperature at 35-45 °C. It aims at making utmost use of the available low-temperature energy sources. In order to achieve high efficiency of the ULTDH system, the return temperature should be as low as possible. For the energy-efficient buildings in the future, it is feasible to use ULTDH to cover the space Heating demand. However, considering the comfort and hygiene requirements of domestic hot water (DHW) preparation, Supplementary Heating devices should be combined, which can affect the return temperature in different extents. This study analysed the return temperatures of different types of substations for DHW preparation with ULTDH, and developed improvements in the substation for better energy efficiency. Both the instantaneous and storage-type electric Heating methods were Long-term measured as Supplementary Heating for ULTDH in the case substations in Denmark. We analysed the seasonal impacts of the return temperature from the DHW loop on the overall return temperature of district Heating. To achieve lower return temperature and higher efficiency for DHW supply, an innovative substation was devised, which replaced the bypass with an instantaneous heat exchanger and a micro electric storage tank. The energy performance of the proposed substation and the resulting benefits for the DH system by the lower return temperature were investigated
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Evaluations of different domestic hot water preparing methods with ultra-low-temperature district Heating
Energy, 2016Co-Authors: Xiaochen Yang, Hongwei Li, Svend SvendsenAbstract:This study investigated the performances of five different substation configurations in single-family houses supplied with ULTDH (ultra-low-temperature district Heating). The temperature at the heat plant is 46 °C and around 40 °C at the substations. To avoid the proliferation of Legionella in the DHW (domestic hot water) and assure the comfortable temperature, all substations were installed with Supplementary Heating devices. Detailed measurements were taken in the substations, including the electricity demand of the Supplementary Heating devices. To compare the energy and economic performance of the substations, separate models were built based on standard assumptions. The relative heat and electricity delivered for preparing DHW were calculated. The results showed that substations with storage tanks and heat pumps have high relative electricity demand, which leads to higher integrated costs considering both heat and electricity for DHW preparation. The substations with in-line electric heaters have low relative electricity usage because very little heat is lost due to the instantaneous DHW preparation. Accordingly, the substations with in-line electric heaters would have the lowest energy cost for DHW preparation. To achieve optimal design and operation for the ULTDH substation, the electricity peak loads of the in-line electric heaters were analysed according to different DHW-Heating strategies.
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New counter flow heat exchanger designed for ventilation systems in cold climates
Energy and Buildings, 2007Co-Authors: Jesper Kragh, Jørgen Rose, Toke Rammer Nielsen, Svend SvendsenAbstract:Abstract In cold climates, mechanical ventilation systems with highly efficient heat recovery will experience problems with condensing water from the extracted humid indoor air. If the condensed water changes to ice in the heat exchanger, the airflow rate will quickly fall due to the increasing pressure drop. PreHeating the inlet air (outdoor air) to a temperature above 0 °C before it enters the exchanger is one solution often used to solve the problem, however, this method reduces the energy saving potential significantly. To minimize the energy cost, a more efficient way to solve the freezing problem is therefore desirable. In this paper, the construction and test measurements of a new counter flow heat exchanger designed for cold climates are presented. The developed heat exchanger is capable of continuously defrosting itself without using Supplementary Heating. Other advantages of the developed heat exchanger are low pressure loss, cheap materials and a simple construction. The disadvantage is that the exchanger is big compared with other heat exchangers. In this paper, the new heat exchanger's efficiency is calculated theoretically and measured experimentally. The experiment shows that the heat exchanger is capable of continuously defrosting itself at outside air temperatures well below the freezing point while still maintaining a very high efficiency. Further analysis and development of a detailed simulation model of a counter flow air-to-air heat exchanger will be described in future articles.
Enni Ruokamo - One of the best experts on this subject based on the ideXlab platform.
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household preferences of hybrid home Heating systems a choice experiment application
Energy Policy, 2016Co-Authors: Enni RuokamoAbstract:The residential Heating sector presents considerable energy savings potential, as numerous Heating solutions for reducing electricity consumption and utilizing renewable energy sources are available in the market. The aim of this paper is to examine determinants of household Heating system choices and to use this information for policy planning purposes. This paper investigates residential homeowner attitudes regarding innovative hybrid home Heating systems (HHHS) with choice experiment. Heating system scenarios are designed to represent the most relevant primary and Supplementary Heating alternatives currently available in Finland. The choice sets include six main Heating alternatives (district heat, solid wood, wood pellet, electric storage Heating, ground heat pump and exhaust air heat pump) that are described by five attributes (Supplementary Heating systems, investment costs, operating costs, comfort of use and environmental friendliness). The results imply that HHHSs generally appear to be accepted among households; however, several factors affect perceptions of these technologies. The results reveal differing household attitudes toward the main Heating alternatives and show that such views are affected by socio-demographic characteristics (age, living environment, education, etc.). The results suggest that households view Supplementary Heating systems (especially solar-based) favorably. The other attributes studied also play a significant role in decision making.
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Household preferences of hybrid home Heating systems – A choice experiment application
Energy Policy, 2016Co-Authors: Enni RuokamoAbstract:The residential Heating sector presents considerable energy savings potential, as numerous Heating solutions for reducing electricity consumption and utilizing renewable energy sources are available in the market. The aim of this paper is to examine determinants of household Heating system choices and to use this information for policy planning purposes. This paper investigates residential homeowner attitudes regarding innovative hybrid home Heating systems (HHHS) with choice experiment. Heating system scenarios are designed to represent the most relevant primary and Supplementary Heating alternatives currently available in Finland. The choice sets include six main Heating alternatives (district heat, solid wood, wood pellet, electric storage Heating, ground heat pump and exhaust air heat pump) that are described by five attributes (Supplementary Heating systems, investment costs, operating costs, comfort of use and environmental friendliness). The results imply that HHHSs generally appear to be accepted among households; however, several factors affect perceptions of these technologies. The results reveal differing household attitudes toward the main Heating alternatives and show that such views are affected by socio-demographic characteristics (age, living environment, education, etc.). The results suggest that households view Supplementary Heating systems (especially solar-based) favorably. The other attributes studied also play a significant role in decision making.
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Households' Attitudes Toward Alternative Heating Systems and Renewable Energy - a Choice Experiment Application
2014Co-Authors: Enni RuokamoAbstract:In this decade, hybrid home Heating systems (HHHS) have rapidly increased their popularity among households in Finland. This trend and the lack of thorough studies spurred us to investigate the innovative HHHS with choice experiment (CE). In our CE the Heating system scenarios are designed to represent the most relevant alternatives of the main and Supplementary Heating systems nowadays. Our study has three objectives. Firstly, we aim to provide information on households’ preferences toward hybrid home Heating systems. We are interested in what kind of Heating system choices the households make under new Heating system alternatives. In addition, we investigate what are the determinants of the adoption of hybrid home Heating systems. Secondly, this study examines the role of information in the Heating system decisions. Thirdly, the purpose of this study is to explain preference heterogeneity among respondents. In particular, we will elaborate the role of scale heterogeneity in the CE analysis. Normal 0 false false false FI X-NONE X-NONE
Xiaochen Yang - One of the best experts on this subject based on the ideXlab platform.
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ultra low temperature district Heating system with central heat pump and local boosters for low heat density area analyses on a real case in denmark
Energy, 2018Co-Authors: Xiaochen Yang, Svend SvendsenAbstract:Low temperature district Heating (DH) system gives easier access to the renewable energy as heat sources and improves the heat distribution efficiency. From the exergy point of view, low DH supply temperature also better matches the exergy demand of space Heating and domestic hot water. It is more beneficial to operate district Heating system under lower temperature level for the heat-sparse area where the distribution losses accounts for a large proportion in the total heat supply. In this study, the actual performance of a case ultra-low temperature district Heating (ULTDH) system in Denmark was investigated based on long-term measurements. The system combines the central heat pump and local boosters, while the impact of such configuration on the overall system performance was analysed. The energy, exergy and economy performances of the case system were compared to medium temperature district Heating system (MTDH) and low-temperature district Heating system (LTDH). The results show that the LTDH system without Supplementary Heating has the highest energy and exergy efficiency. While the ULTDH system has better performance compared to the MTDH system in energy, exergy and economy due to substantial savings from the distribution heat loss.
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Achieving low return temperature for domestic hot water preparation by ultra-low-temperature district Heating
Energy Procedia, 2017Co-Authors: Xiaochen Yang, Svend SvendsenAbstract:Abstract District Heating (DH) is a cost-effective method of heat supply, especially to area with high heat density. Ultra-low-temperature district Heating (ULTDH) is defined with supply temperature at 35-45 °C. It aims at making utmost use of the available low-temperature energy sources. In order to achieve high efficiency of the ULTDH system, the return temperature should be as low as possible. For the energy-efficient buildings in the future, it is feasible to use ULTDH to cover the space Heating demand. However, considering the comfort and hygiene requirements of domestic hot water (DHW) preparation, Supplementary Heating devices should be combined, which can affect the return temperature in different extents. This study analysed the return temperatures of different types of substations for DHW preparation with ULTDH, and developed improvements in the substation for better energy efficiency. Both the instantaneous and storage-type electric Heating methods were Long-term measured as Supplementary Heating for ULTDH in the case substations in Denmark. We analysed the seasonal impacts of the return temperature from the DHW loop on the overall return temperature of district Heating. To achieve lower return temperature and higher efficiency for DHW supply, an innovative substation was devised, which replaced the bypass with an instantaneous heat exchanger and a micro electric storage tank. The energy performance of the proposed substation and the resulting benefits for the DH system by the lower return temperature were investigated
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Evaluations of different domestic hot water preparing methods with ultra-low-temperature district Heating
Energy, 2016Co-Authors: Xiaochen Yang, Hongwei Li, Svend SvendsenAbstract:This study investigated the performances of five different substation configurations in single-family houses supplied with ULTDH (ultra-low-temperature district Heating). The temperature at the heat plant is 46 °C and around 40 °C at the substations. To avoid the proliferation of Legionella in the DHW (domestic hot water) and assure the comfortable temperature, all substations were installed with Supplementary Heating devices. Detailed measurements were taken in the substations, including the electricity demand of the Supplementary Heating devices. To compare the energy and economic performance of the substations, separate models were built based on standard assumptions. The relative heat and electricity delivered for preparing DHW were calculated. The results showed that substations with storage tanks and heat pumps have high relative electricity demand, which leads to higher integrated costs considering both heat and electricity for DHW preparation. The substations with in-line electric heaters have low relative electricity usage because very little heat is lost due to the instantaneous DHW preparation. Accordingly, the substations with in-line electric heaters would have the lowest energy cost for DHW preparation. To achieve optimal design and operation for the ULTDH substation, the electricity peak loads of the in-line electric heaters were analysed according to different DHW-Heating strategies.
Johnny Iversen - One of the best experts on this subject based on the ideXlab platform.
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Integration of space Heating and hot water supply in low temperature district Heating
Energy and Buildings, 2016Co-Authors: Brian Elmegaard, Torben Schmidt Ommen, Michael Markussen, Johnny IversenAbstract:Abstract District Heating may supply many consumers efficiently, but the heat loss from the pipes to the ground is a challenge. The heat loss may be lowered by decreasing the network temperatures for which reason low temperature networks are proposed for future district Heating. The Heating demand of the consumers involves both domestic hot water and space Heating. Space Heating may be provided at low temperature in low energy buildings. Domestic hot water, however, needs sufficient temperatures to avoid growth of legionella. If the network temperature is below the demand temperature, Supplementary Heating is required by the consumer. We study conventional district Heating at different temperatures and compare the energy and exergetic efficiency and annual Heating cost to solutions that utilize electricity for Supplementary Heating of domestic hot water in low temperature district Heating. This includes direct electric Heating and three heat pump solutions applying R134a and R744. The results show that conventional solutions at lowest possible temperature have the highest exergetic efficiency of 28% and lowest annual cost of € 690 for a 159 m2 house. The best low temperature system is an R134a heat pump with hot water storage on the district Heating side, which reaches 25% exergetic efficiency.
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Integration of Space Heating and Hot Water Supply in Low Temperature District Heating
2015Co-Authors: Brian Elmegaard, Torben Schmidt Ommen, Michael Markussen, Johnny IversenAbstract:District Heating makes it possible to provide heat for many consumers in an efficient manner. In particular, district Heating based on combined heat and power production is highly efficient. One disadvantage of district Heating is that there is a significant heat loss from the pipes to the surrounding ground. In larger networks involving both transmission and distribution systems, the heat loss is most significant from the distribution network. An estimate is that about 80-90 % of the heat loss occurs in the distribution system. In addition, the heat loss is naturally highest from the forward pipes, where the water is at the highest temperature. The heat loss may be lowered by decreasing the temperatures in the network for which reason low temperature networks are proposed as a low loss solution for future district Heating. However, the Heating demand of the consumers involve both domestic hot water and space Heating. Space Heating may be provided at low temperature in modern low energy buildings. Domestic hot water, however, needs to reach sufficient temperatures to avoid growth of legionella bacteria. If the network temperature is below the temperature demand, Supplementary Heating is required by the consumer. In the present paper we study conventional district Heating at different temperature levels and compare the energy efficiency, the exergetic efficiency and annual Heating cost to solutions that utilize electricity for Supplementary Heating of domestic hot water in low temperature district Heating. Four different Supplementary Heating solutions are studied: direct electric Heating and three heat pump solutions. Heat pumps with R134a and R744 are studied. The results show that conventional solutions at lowest possible temperature have the highest exergetic efficiency of 28 % and lowest annual cost of C 690 (5200 DKK) for a 159 m 2 house. The best low temperature system is an R134a heat pump with hot water storage on the district Heating side. This system reaches an exergetic efficiency of 25 % with a heat pump COP of 4.0.
Brian Elmegaard - One of the best experts on this subject based on the ideXlab platform.
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Integration of space Heating and hot water supply in low temperature district Heating
Energy and Buildings, 2016Co-Authors: Brian Elmegaard, Torben Schmidt Ommen, Michael Markussen, Johnny IversenAbstract:Abstract District Heating may supply many consumers efficiently, but the heat loss from the pipes to the ground is a challenge. The heat loss may be lowered by decreasing the network temperatures for which reason low temperature networks are proposed for future district Heating. The Heating demand of the consumers involves both domestic hot water and space Heating. Space Heating may be provided at low temperature in low energy buildings. Domestic hot water, however, needs sufficient temperatures to avoid growth of legionella. If the network temperature is below the demand temperature, Supplementary Heating is required by the consumer. We study conventional district Heating at different temperatures and compare the energy and exergetic efficiency and annual Heating cost to solutions that utilize electricity for Supplementary Heating of domestic hot water in low temperature district Heating. This includes direct electric Heating and three heat pump solutions applying R134a and R744. The results show that conventional solutions at lowest possible temperature have the highest exergetic efficiency of 28% and lowest annual cost of € 690 for a 159 m2 house. The best low temperature system is an R134a heat pump with hot water storage on the district Heating side, which reaches 25% exergetic efficiency.
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Integration of Space Heating and Hot Water Supply in Low Temperature District Heating
2015Co-Authors: Brian Elmegaard, Torben Schmidt Ommen, Michael Markussen, Johnny IversenAbstract:District Heating makes it possible to provide heat for many consumers in an efficient manner. In particular, district Heating based on combined heat and power production is highly efficient. One disadvantage of district Heating is that there is a significant heat loss from the pipes to the surrounding ground. In larger networks involving both transmission and distribution systems, the heat loss is most significant from the distribution network. An estimate is that about 80-90 % of the heat loss occurs in the distribution system. In addition, the heat loss is naturally highest from the forward pipes, where the water is at the highest temperature. The heat loss may be lowered by decreasing the temperatures in the network for which reason low temperature networks are proposed as a low loss solution for future district Heating. However, the Heating demand of the consumers involve both domestic hot water and space Heating. Space Heating may be provided at low temperature in modern low energy buildings. Domestic hot water, however, needs to reach sufficient temperatures to avoid growth of legionella bacteria. If the network temperature is below the temperature demand, Supplementary Heating is required by the consumer. In the present paper we study conventional district Heating at different temperature levels and compare the energy efficiency, the exergetic efficiency and annual Heating cost to solutions that utilize electricity for Supplementary Heating of domestic hot water in low temperature district Heating. Four different Supplementary Heating solutions are studied: direct electric Heating and three heat pump solutions. Heat pumps with R134a and R744 are studied. The results show that conventional solutions at lowest possible temperature have the highest exergetic efficiency of 28 % and lowest annual cost of C 690 (5200 DKK) for a 159 m 2 house. The best low temperature system is an R134a heat pump with hot water storage on the district Heating side. This system reaches an exergetic efficiency of 25 % with a heat pump COP of 4.0.