The Experts below are selected from a list of 75 Experts worldwide ranked by ideXlab platform

Simon Furbo - One of the best experts on this subject based on the ideXlab platform.

  • Demonstration of a Solar Combi-System utilizing stable supercooling of sodium acetate trihydrate for heat storage
    Applied Thermal Engineering, 2020
    Co-Authors: Gerald Englmair, Simon Furbo, Weiqiang Kong, Jakob Brinkø Berg, Jianhua Fan
    Abstract:

    Abstract Achieving a high fraction of Solar heat in heat supply for domestic buildings would reduce the use of fossil fuels for heat generation and has been a goal for a long time. Combined short and long-term heat storage has been identified as one way of achieving Solar fractions higher than 50 percent in heat supply for domestic buildings. To this end, a laboratory Solar heating System was built with heat-pipe tubular collectors 22.4 m2 in aperture and a heat-storage prototype consisting of a 735 L water tank and four PCM units each containing 200 kg sodium acetate trihydrate (SAT) composite. The SAT composite was utilized as sensible heat storage with the additional ability to release heat of fusion on demand. Operation was demonstrated with the space heating and hot water demand patterns of a standard-size Passive House in the Danish climate. A strategy was developed to control the System. Seven operation modes enabled Combined charging of water tank and PCM units, heat transfer from PCM units to the water tank when heat was in demand, and the right timing of auxiliary heating. We present the controller settings identified and the heat transfer fluid flow rates applied. Sequences of water tank charging, and single and parallel PCM unit charging were used to match the collector power available and the heat transfer limitations of the stores. During the charging of PCM units, the flow temperature was kept between 70 and 95 °C to allow continuous heat transfer rates of up to 16 kW. Peaks of up to 36 kW occurred when PCM units were added to the charging circuit. During heat transfer from PCM units to the water tank, flow temperatures were close to the SAT composite temperature and thermal power of up to 6 kW was measured. The heat stores were efficiently utilized in spring and autumn. The developed control strategy and measurement data from System demonstration will form the basis for numerical performance investigations.

  • A Solar Combi-System utilizing stable supercooling of sodium acetate trihydrate for heat storage: Numerical performance investigation
    Applied Energy, 2019
    Co-Authors: Gerald Englmair, Jianhua Fan, Christoph Moser, Hermann Schranzhofer, Simon Furbo
    Abstract:

    Abstract To reduce the energy consumption of buildings significantly, a novel Solar Combi-System with short and long-term heat storage has been developed. A System prototype with 22.4 m2 (aperture) evacuated tubular collectors, a 735 L water tank and 4 phase change material (PCM) units each containing 150 L sodium acetate trihydrate composite has been built. Experimental investigation has shown advantages of utilization of stable supercooling of sodium acetate trihydrate in spring and autumn. In this paper, a newly developed numerical model was used to investigate the performance potential of the System with Combined utilization of the water tank and the PCM units, including on-demand crystallization of supercooled sodium acetate trihydrate composites. PCM units, the water tank and the collector circuit models were validated with measurement data from System demonstration. Space heating and hot water demand patterns of a Danish single-family Passive House with a yearly heat demand of 3723 kWh were applied. Results showed that a 56% annual Solar fraction of heat supply was achieved with the prototype specifications. A 69% Solar fraction could be achieved with an optimized scenario including a 15% increased hot water demand. Sensitivity analysis of component sizing showed that PCM units of 200 L can be more efficiently used with a 0.6 m3 water tank. Optimal Solar collector array tilt was 70°. Aperture areas between 12.8 and 22.4 m2 were found adequate for frequent utilization of a PCM volume up to 1 m3. Thus, the PCM heat storage capacity could be utilized at least 5.5 times a year. With a 22.4 m2 collector area and 5 PCM units of 200 L each, a Solar fraction of 71% was calculated for the annual heat supply. Assuming full charge of a 0.6 m3 water tank and 2.8 m3 of sodium acetate trihydrate composite by electricity at the beginning of the year, the System could run 18 days without need for auxiliary heating. Thus, in periods without Solar collector power available, generation maxima of wind power could be utilized. In conclusion, building heat demand could be covered close to 100% by renewable energy resources.

  • Long term thermal energy storage with stable supercooled sodium acetate trihydrate
    Applied Thermal Engineering, 2015
    Co-Authors: Mark Dannemand, Jorgen Munthe Schultz, Jakob Berg Johansen, Simon Furbo
    Abstract:

    Abstract Utilizing stable supercooling of sodium acetate trihydrate makes it possible to store thermal energy partly loss free. This principle makes seasonal heat storage in compact Systems possible. To keep high and stable energy content and cycling stability phase separation of the storage material must be avoided. This can be done by the use of the thickening agents carboxymethyl cellulose or xanthan rubber. Stable supercooling requires that the sodium acetate trihydrate is heated to a temperature somewhat higher than the melting temperature of 58 °C before it cools down. As the phase change material melts it expands and will cause a pressure built up in a closed chamber which might compromise stability of the supercooling. This can be avoided by having an air volume above the phase change material connected to an external pressure less expansion tank. Supercooled sodium acetate trihydrate at 20 °C stores up to 230 kJ/kg. TRNSYS simulations of a Solar Combi System including a storage with four heat storage modules of each 200 kg of sodium acetate trihydrate utilizing stable supercooling achieved a Solar fraction of 80% for a low energy house in Danish climatic conditions.

  • Solar Combi System based on a mantle tank
    2008
    Co-Authors: Eshagh Yazdanshenas, Simon Furbo
    Abstract:

    A Solar CombiSystem based on a mantle tank is investigated numerically and experimentally. Three different houses with four different radiator Systems are considered for the simulations. The needed temperature for the auxiliary heater is determined for different houses and radiator Systems. The thermal performance of the Solar CombiSystem is compared to the thermal performance of a Solar domestic hot water System based on a mantle tank. In the experimental study, tank temperatures and the heat transfer coefficient for the top mantle for a discharge test is determined. The investigations showed that the investigated concept is promising for low energy buildings.

  • theoretical comparison of Solar water space heating Combi Systems and stratification design options
    Journal of Solar Energy Engineering-transactions of The Asme, 2007
    Co-Authors: Elsa Andersen, Simon Furbo
    Abstract:

    A theoretical analysis of differently designed Solar Combi Systems is performed with weather data from the Danish Design Reference Year (55 deg N). Three Solar Combi System designs found on the market are investigated. The investigation focuses on the influence of stratification on the thermal performance under different operation conditions with different domestic hot water and space heating demands. The Solar Combi Systems are initially equipped with heat exchanger spirals and direct inlets to the tank. A step-by-step investigation is performed demonstrating the influence on the thermal performance of using inlet stratification pipes at the different inlets. Also, how the design of the space heating System, the control System of the Solar collectors, and the System size influence the thermal performance of Solar Combi Systems are investigated. The work is carried out within the Solar Heating and Cooling Programme of the International Energy Agency (IEA SHC), Task 32.

Dimitris Al. Katsaprakakis - One of the best experts on this subject based on the ideXlab platform.

  • introducing a Solar Combi System for hot water production and swimming pools heating in the pancretan stadium crete greece
    Energy Procedia, 2019
    Co-Authors: Dimitris Al. Katsaprakakis
    Abstract:

    Abstract National stadiums constitute large energy consuming infrastructures, exhibiting extended energy needs for lighting, indoor spaces heating, hot water production, swimming pools heating etc. In this article a Solar collectors – biomass heater System is studied to meet the final thermal energy needs for hot water and swimming pools heating for the Pancretan Stadium, Crete, Greece. Currently the above needs are covered with the consumption of 16,500 lt of diesel oil and 190 MWh of electricity annually. The introduced Solar-Combi System features as obvious option, given the abundant available Solar radiation and biomass, mainly from the by-products of the olive-oil trees cultivation. The proposed System’s operation was simulated with annual time series of average hourly values. Alternative dimensioning scenarios were executed, aiming at the total elimination of the diesel oil and the electricity for the particular uses. The economic feasibility of the introduced System is documented versus the avoiding energy resources procurement cost of the existing operation. With the concluded dimensioning, the Solar collectors annual penetration is 59.5% versus the annual final thermal energy consumption. The remaining thermal energy needs are covered from 31 tn of biomass pellets. The payback period of the proposed System is estimated at 5 years.

  • optimized dimensioning and operation automation for a Solar Combi System for indoor space heating a case study for a school building in crete
    Energies, 2019
    Co-Authors: Dimitris Al. Katsaprakakis, Georgios Zidianakis
    Abstract:

    This article investigates the introduction of hybrid power plants for thermal energy production for the indoor space heating loads coverage. The plant consists of flat plate Solar collectors with selective coating, water tanks as thermal energy storage and a biomass heater. A new operation algorithm is applied, maximizing the exploitation of the available thermal energy storage capacity and, eventually, the thermal power production from the Solar collectors. An automation System is also designed and proposed for the realization of the newly introduced algorithm. The Solar-Combi System is computationally simulated, using annual time series of average hourly steps. A dimensioning optimization process is proposed, using as criterion the minimization of the thermal energy production levelized cost. The overall approach is validated on a school building with 1000 m2 of covered area, located in the hinterland of the island of Crete. It is seen that, given the high available Solar radiation in the specific area, the proposed Solar-Combi System can guarantee the 100% annual heating load coverage of the examined building, with an annual contribution from the Solar collectors higher than 45%. The annually average thermal power production levelized cost is calculated at 0.15 €/kWhth.

  • Optimized Dimensioning and Operation Automation for a Solar-Combi System for Indoor Space Heating. A Case Study for a School Building in Crete
    MDPI AG, 2019
    Co-Authors: Dimitris Al. Katsaprakakis, Georgios Zidianakis
    Abstract:

    This article investigates the introduction of hybrid power plants for thermal energy production for the indoor space heating loads coverage. The plant consists of flat plate Solar collectors with selective coating, water tanks as thermal energy storage and a biomass heater. A new operation algorithm is applied, maximizing the exploitation of the available thermal energy storage capacity and, eventually, the thermal power production from the Solar collectors. An automation System is also designed and proposed for the realization of the newly introduced algorithm. The Solar-Combi System is computationally simulated, using annual time series of average hourly steps. A dimensioning optimization process is proposed, using as criterion the minimization of the thermal energy production levelized cost. The overall approach is validated on a school building with 1000 m2 of covered area, located in the hinterland of the island of Crete. It is seen that, given the high available Solar radiation in the specific area, the proposed Solar-Combi System can guarantee the 100% annual heating load coverage of the examined building, with an annual contribution from the Solar collectors higher than 45%. The annually average thermal power production levelized cost is calculated at 0.15 €/kWhth

Jianhua Fan - One of the best experts on this subject based on the ideXlab platform.

  • Demonstration of a Solar Combi-System utilizing stable supercooling of sodium acetate trihydrate for heat storage
    Applied Thermal Engineering, 2020
    Co-Authors: Gerald Englmair, Simon Furbo, Weiqiang Kong, Jakob Brinkø Berg, Jianhua Fan
    Abstract:

    Abstract Achieving a high fraction of Solar heat in heat supply for domestic buildings would reduce the use of fossil fuels for heat generation and has been a goal for a long time. Combined short and long-term heat storage has been identified as one way of achieving Solar fractions higher than 50 percent in heat supply for domestic buildings. To this end, a laboratory Solar heating System was built with heat-pipe tubular collectors 22.4 m2 in aperture and a heat-storage prototype consisting of a 735 L water tank and four PCM units each containing 200 kg sodium acetate trihydrate (SAT) composite. The SAT composite was utilized as sensible heat storage with the additional ability to release heat of fusion on demand. Operation was demonstrated with the space heating and hot water demand patterns of a standard-size Passive House in the Danish climate. A strategy was developed to control the System. Seven operation modes enabled Combined charging of water tank and PCM units, heat transfer from PCM units to the water tank when heat was in demand, and the right timing of auxiliary heating. We present the controller settings identified and the heat transfer fluid flow rates applied. Sequences of water tank charging, and single and parallel PCM unit charging were used to match the collector power available and the heat transfer limitations of the stores. During the charging of PCM units, the flow temperature was kept between 70 and 95 °C to allow continuous heat transfer rates of up to 16 kW. Peaks of up to 36 kW occurred when PCM units were added to the charging circuit. During heat transfer from PCM units to the water tank, flow temperatures were close to the SAT composite temperature and thermal power of up to 6 kW was measured. The heat stores were efficiently utilized in spring and autumn. The developed control strategy and measurement data from System demonstration will form the basis for numerical performance investigations.

  • A Solar Combi-System utilizing stable supercooling of sodium acetate trihydrate for heat storage: Numerical performance investigation
    Applied Energy, 2019
    Co-Authors: Gerald Englmair, Jianhua Fan, Christoph Moser, Hermann Schranzhofer, Simon Furbo
    Abstract:

    Abstract To reduce the energy consumption of buildings significantly, a novel Solar Combi-System with short and long-term heat storage has been developed. A System prototype with 22.4 m2 (aperture) evacuated tubular collectors, a 735 L water tank and 4 phase change material (PCM) units each containing 150 L sodium acetate trihydrate composite has been built. Experimental investigation has shown advantages of utilization of stable supercooling of sodium acetate trihydrate in spring and autumn. In this paper, a newly developed numerical model was used to investigate the performance potential of the System with Combined utilization of the water tank and the PCM units, including on-demand crystallization of supercooled sodium acetate trihydrate composites. PCM units, the water tank and the collector circuit models were validated with measurement data from System demonstration. Space heating and hot water demand patterns of a Danish single-family Passive House with a yearly heat demand of 3723 kWh were applied. Results showed that a 56% annual Solar fraction of heat supply was achieved with the prototype specifications. A 69% Solar fraction could be achieved with an optimized scenario including a 15% increased hot water demand. Sensitivity analysis of component sizing showed that PCM units of 200 L can be more efficiently used with a 0.6 m3 water tank. Optimal Solar collector array tilt was 70°. Aperture areas between 12.8 and 22.4 m2 were found adequate for frequent utilization of a PCM volume up to 1 m3. Thus, the PCM heat storage capacity could be utilized at least 5.5 times a year. With a 22.4 m2 collector area and 5 PCM units of 200 L each, a Solar fraction of 71% was calculated for the annual heat supply. Assuming full charge of a 0.6 m3 water tank and 2.8 m3 of sodium acetate trihydrate composite by electricity at the beginning of the year, the System could run 18 days without need for auxiliary heating. Thus, in periods without Solar collector power available, generation maxima of wind power could be utilized. In conclusion, building heat demand could be covered close to 100% by renewable energy resources.

Gerald Englmair - One of the best experts on this subject based on the ideXlab platform.

  • Demonstration of a Solar Combi-System utilizing stable supercooling of sodium acetate trihydrate for heat storage
    Applied Thermal Engineering, 2020
    Co-Authors: Gerald Englmair, Simon Furbo, Weiqiang Kong, Jakob Brinkø Berg, Jianhua Fan
    Abstract:

    Abstract Achieving a high fraction of Solar heat in heat supply for domestic buildings would reduce the use of fossil fuels for heat generation and has been a goal for a long time. Combined short and long-term heat storage has been identified as one way of achieving Solar fractions higher than 50 percent in heat supply for domestic buildings. To this end, a laboratory Solar heating System was built with heat-pipe tubular collectors 22.4 m2 in aperture and a heat-storage prototype consisting of a 735 L water tank and four PCM units each containing 200 kg sodium acetate trihydrate (SAT) composite. The SAT composite was utilized as sensible heat storage with the additional ability to release heat of fusion on demand. Operation was demonstrated with the space heating and hot water demand patterns of a standard-size Passive House in the Danish climate. A strategy was developed to control the System. Seven operation modes enabled Combined charging of water tank and PCM units, heat transfer from PCM units to the water tank when heat was in demand, and the right timing of auxiliary heating. We present the controller settings identified and the heat transfer fluid flow rates applied. Sequences of water tank charging, and single and parallel PCM unit charging were used to match the collector power available and the heat transfer limitations of the stores. During the charging of PCM units, the flow temperature was kept between 70 and 95 °C to allow continuous heat transfer rates of up to 16 kW. Peaks of up to 36 kW occurred when PCM units were added to the charging circuit. During heat transfer from PCM units to the water tank, flow temperatures were close to the SAT composite temperature and thermal power of up to 6 kW was measured. The heat stores were efficiently utilized in spring and autumn. The developed control strategy and measurement data from System demonstration will form the basis for numerical performance investigations.

  • A Solar Combi-System utilizing stable supercooling of sodium acetate trihydrate for heat storage: Numerical performance investigation
    Applied Energy, 2019
    Co-Authors: Gerald Englmair, Jianhua Fan, Christoph Moser, Hermann Schranzhofer, Simon Furbo
    Abstract:

    Abstract To reduce the energy consumption of buildings significantly, a novel Solar Combi-System with short and long-term heat storage has been developed. A System prototype with 22.4 m2 (aperture) evacuated tubular collectors, a 735 L water tank and 4 phase change material (PCM) units each containing 150 L sodium acetate trihydrate composite has been built. Experimental investigation has shown advantages of utilization of stable supercooling of sodium acetate trihydrate in spring and autumn. In this paper, a newly developed numerical model was used to investigate the performance potential of the System with Combined utilization of the water tank and the PCM units, including on-demand crystallization of supercooled sodium acetate trihydrate composites. PCM units, the water tank and the collector circuit models were validated with measurement data from System demonstration. Space heating and hot water demand patterns of a Danish single-family Passive House with a yearly heat demand of 3723 kWh were applied. Results showed that a 56% annual Solar fraction of heat supply was achieved with the prototype specifications. A 69% Solar fraction could be achieved with an optimized scenario including a 15% increased hot water demand. Sensitivity analysis of component sizing showed that PCM units of 200 L can be more efficiently used with a 0.6 m3 water tank. Optimal Solar collector array tilt was 70°. Aperture areas between 12.8 and 22.4 m2 were found adequate for frequent utilization of a PCM volume up to 1 m3. Thus, the PCM heat storage capacity could be utilized at least 5.5 times a year. With a 22.4 m2 collector area and 5 PCM units of 200 L each, a Solar fraction of 71% was calculated for the annual heat supply. Assuming full charge of a 0.6 m3 water tank and 2.8 m3 of sodium acetate trihydrate composite by electricity at the beginning of the year, the System could run 18 days without need for auxiliary heating. Thus, in periods without Solar collector power available, generation maxima of wind power could be utilized. In conclusion, building heat demand could be covered close to 100% by renewable energy resources.

Georgios Zidianakis - One of the best experts on this subject based on the ideXlab platform.

  • optimized dimensioning and operation automation for a Solar Combi System for indoor space heating a case study for a school building in crete
    Energies, 2019
    Co-Authors: Dimitris Al. Katsaprakakis, Georgios Zidianakis
    Abstract:

    This article investigates the introduction of hybrid power plants for thermal energy production for the indoor space heating loads coverage. The plant consists of flat plate Solar collectors with selective coating, water tanks as thermal energy storage and a biomass heater. A new operation algorithm is applied, maximizing the exploitation of the available thermal energy storage capacity and, eventually, the thermal power production from the Solar collectors. An automation System is also designed and proposed for the realization of the newly introduced algorithm. The Solar-Combi System is computationally simulated, using annual time series of average hourly steps. A dimensioning optimization process is proposed, using as criterion the minimization of the thermal energy production levelized cost. The overall approach is validated on a school building with 1000 m2 of covered area, located in the hinterland of the island of Crete. It is seen that, given the high available Solar radiation in the specific area, the proposed Solar-Combi System can guarantee the 100% annual heating load coverage of the examined building, with an annual contribution from the Solar collectors higher than 45%. The annually average thermal power production levelized cost is calculated at 0.15 €/kWhth.

  • Optimized Dimensioning and Operation Automation for a Solar-Combi System for Indoor Space Heating. A Case Study for a School Building in Crete
    MDPI AG, 2019
    Co-Authors: Dimitris Al. Katsaprakakis, Georgios Zidianakis
    Abstract:

    This article investigates the introduction of hybrid power plants for thermal energy production for the indoor space heating loads coverage. The plant consists of flat plate Solar collectors with selective coating, water tanks as thermal energy storage and a biomass heater. A new operation algorithm is applied, maximizing the exploitation of the available thermal energy storage capacity and, eventually, the thermal power production from the Solar collectors. An automation System is also designed and proposed for the realization of the newly introduced algorithm. The Solar-Combi System is computationally simulated, using annual time series of average hourly steps. A dimensioning optimization process is proposed, using as criterion the minimization of the thermal energy production levelized cost. The overall approach is validated on a school building with 1000 m2 of covered area, located in the hinterland of the island of Crete. It is seen that, given the high available Solar radiation in the specific area, the proposed Solar-Combi System can guarantee the 100% annual heating load coverage of the examined building, with an annual contribution from the Solar collectors higher than 45%. The annually average thermal power production levelized cost is calculated at 0.15 €/kWhth