| 1. |
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| 2. |
- Fischer, S, et al.
(författare)
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Collector test method under quasi dynamic conditions according to the European Standard EN 12975-2
- 2004
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X. ; 76, s. 117-123
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Konferensbidrag (refereegranskat)abstract
- In April 2001 the new European Standard EN 12975:2000: ''Thermal solar systems and components--Solar Collectors'' was established. With the publication of this European standard all national standards, related to the same topic, have to be withdrawn by the nations of the European Community. Now only one standard for testing solar collectors is valid throughout Europe.This European Standard specifies test methods for validating the durability, reliability and safety requirements for liquid heating collectors. The standard also includes two alternative test methods for the thermal performance characterization for liquid heating collectors. Apart from the well-known test method under steady-state conditions according to ISO 9806-1, ISO 9806-3 and ASHRAE 93-77 the EN 12975 permits a quasi-dynamic test method for the thermal performance characterization of solar thermal collectors.This paper presents the improved approach to outdoor performance testing of solar thermal collectors under quasi-dynamic test conditions. The test requirements and collector theory are closely connected to those long agreed on for steady-state testing, as described in the ISO and ASHRAE standards mentioned above. The most important effects for the all day performance of the collector are taken into account. The test method covers most collector designs on the market today (except ICS type). Only some correction terms are added to the basic collector models of the present steady-state test methods. Still this limited change will allow test data to be collected and used from whole days.An important fact is that the collector model used for the parameter identification is written so that the error in collector output power is minimized. Therefore an accurate long-term prediction of the collector performance can be an integral part of the test method, where the same collector model and parameters are used for both testing and prediction.
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| 3. |
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| 4. |
- Adsten, Monika, et al.
(författare)
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The influence of climate and location on collector performance
- 2002
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Ingår i: Renewable energy. - 0960-1481 .- 1879-0682. ; 25:4, s. 499-509
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Tidskriftsartikel (refereegranskat)abstract
- The influence of annual climate variations on the performance of solar thermal collectors in the northern part of Europe has been investigated. The annual solar collector energy output has been calculated with the MINSUN simulation program using hourly, measured climatic data for the years 1983–98 for three cities situated in the south (Lund), central (Stockholm) and north (Luleå) of Sweden. A synthetic year created with the Meteonorm weather simulation program was also used in the simulations. Two solar thermal collectors were modelled: a flat plate solar collector and a tubular vacuum collector, both of commercial standard.The thermal energy output is strongly correlated to the annual global irradiation at a horizontal surface. The annual average energy delivered from the flat plate collector was 337 kWh/m2 for Stockholm (337 for Lund and 298 for Luleå), and from the vacuum tube collector 668 kWh/m2 for Stockholm (675 for Lund and 631 for Luleå) at an operating temperature of T=50°C. Maximum deviations from the average value for this 16-year period are around 20% for the flat plate and 15% for the vacuum tube collector, at T=50°C.The relation between global irradiation on a horizontal surface and the annually collected thermal energy at a constant operating temperature could be fitted to a linear equation: qu=aG(0°)+bT, where qu is the energy output from the collector, G(0°) the global irradiation at a horizontal surface, T the average temperature of the collector fluid, and a and b fitting parameters in a double linear regression analysis.
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| 5. |
- Ahlgren, Benjamin, et al.
(författare)
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A simplified model for linear correlation between annual yield and DNI for parabolic trough collectors
- 2018
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Ingår i: Energy Conversion and Management. - : Elsevier. - 0196-8904 .- 1879-2227. ; 174, s. 295-308
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a simple method for estimating annual thermal performance of parabolic trough collectors (PTCs) based on a linear relation with annual DNI for a certain latitude. A case study with simulations for a novel concentrating solar collector in 316 locations for three operating temperature scenarios worldwide was carried out and showed promising results for the latitudes and continents investigated. For a certain latitude and mean operating temperature, the annual yield of a PTC was found to be linearly proportional to yearly DNI. The proposed method will serve as a simplified alternative to the steady-state and quasi-dynamic methods already used. Estimating performance based on yearly DNI can be used by design engineers to do quick preliminary planning of solar plants. Customers can also use this method to evaluate existing solar collector installations. A TRNSYS/TRNSED tool that uses a steady-state model has been developed to carry out the simulations and it has been validated against a PTC array at Technical University of Denmark (DTU). The results show that the simplified method can give reliable estimates of long-term performance of parabolic trough collectors.
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| 6. |
- Bales, Chris, et al.
(författare)
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Dimensioning of Solar Combisystems
- 2003
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Ingår i: Solar heating systems for houses. - London : James & James. - 1902916468
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Bernardo, Ricardo, et al.
(författare)
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Evaluation of a Parabolic Concentrating PVT System
- 2008
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Ingår i: Proceedings of the 7th EUROSUN Conference. - 9781617822285
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study was testing and performance simulation of an innovative tracking hybrid solar system being developed by the Swedish Company Arontis. The Solar8 collector produces both electrical and thermal energy in one system. Its performance was compared with conventional photovoltaic panels and solar thermal collectors working side-by-side which are already on the market. The solar8 sample tested in Lund is a prototype designed for small demonstration projects and further development is ongoing. The evaluation shows that the thermal collector has an overall heat loss coefficient of 3.1 W/(m2.ºC), an optical efficiency of 65% and an electrical efficiency at 25ºC of 8% per active glazed area. If we account the total glazed area instead, the thermal collector has an overall heat loss coefficient of 2.5 W/(m2.ºC), an optical efficiency of 52% and an electric efficiency at 25ºC of 6%. The electric efficiency of the bare cells is 16%. Annual performance simulations were carried out for the Swedish (Stockholm), Portuguese (Lisbon) and Zambian (Lusaka) climate. From the simulations one can conclude that: Solar8 can be replaced by a traditional PV-thermal collector side-by-side system using less space and producing the same electric and thermal outputs; tracking around one axis placed in North-South direction is considerably better then tracking around an axis set on East-West direction; the global irradiation on a static surface is always higher when compared with the beam irradiation towards a tracking concentrating surface; the ratio between electric and thermal output decreases when Solar8 is moved to the equator.
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| 8. |
- Bernardo, Ricardo, et al.
(författare)
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Performance evaluation of low concentrating photovoltaic/thermal systems: A case study from Sweden
- 2011
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X. ; 85:7, s. 1499-1510
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Tidskriftsartikel (refereegranskat)abstract
- Some of the main bottlenecks for the development and commercialization of photovoltaic/thermal hybrids are the lack of an internationally recognized standard testing procedure as well as a method to compare different hybrids with each other and with conventional alternatives. A complete methodology to characterize, simulate and evaluate concentrating photovoltaic/thermal hybrids has been proposed and exemplified in a particular case study. By using the suggested testing method, the hybrid parameters were experimentally determined. These were used in a validated simulation model that estimates the hybrid outputs in different geographic locations. Furthermore, the method includes a comparison of the hybrid performance with conventional collectors and photovoltaic modules working side-by-side. The measurements show that the hybrid electrical efficiency is 6.4% while the optical efficiency is 0.45 and the U-value 1.9 W/m(2) degrees C. These values are poor when compared with the parameters of standard PV modules and flat plate collectors. Also, the beam irradiation incident on a north south axis tracking surface is 20-40% lower than the global irradiation incident on a fixed surface at optimal tilt. There is margin of improvement for the studied hybrid but this combination makes it difficult for concentrating hybrids to compete with conventional PV modules and flat plate collectors. (C) 2011 Elsevier Ltd. All rights reserved.
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| 9. |
- Campana, Pietro Elia, 1984-
(författare)
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PV water pumping systems for grassland and farmland conservation
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Grassland degradation is considered as one of the worst environmental and economic problems in China because of the negative impacts on water and food security. The application of the photovoltaic water pumping (PVWP) technology for irrigation is an innovative and sustainable solution to curb the progress of grassland desertification and to promote the conservation of farmland in remote areas. The combination of PVWP with water saving irrigation techniques and the sustainable management of the water resources enhances the grass productivity enabling to halt wind and rainfall erosion and to provide higher incomes and better living conditions for farmers. PVWP systems have been used for more than 40 years especially for drinking purposes, livestock watering and irrigation in small-medium size applications. Nevertheless, several knowledge gaps still exist and system failures still occur, which are mainly bounded to the system design procedure and optimization. The technical and economic feasibilities related to the system implementation, especially effectiveness and profitability, need to be addressed. Moreover, irrigation in remote areas constrained by availability of water resources has to be investigated for a better understanding of PVWP system integration with the environment and for optimization purposes. This thesis is to bridge the current knowledge gaps, optimize system implementation and prevent system failures Validation of the models adopted and optimization of the system on the basis of solar energy resources and exploitable groundwater has been performed for a pilot PVWP system in Inner Mongolia. The match between the water supplied through the pumping system and the grass water demand has been studied, and the effects of pumping on the available resources and the crop productivity have been evaluated. The economic analyses have also been conducted in order to establish the most cost effective solution to provide water for irrigation and to evaluate the project profitability. In addition, the CO2 emission reductions by using PV technology have been assessed as well. It was found that the proper designed PVWP system represents the best technical and economic solution to provide water for irrigation in the remote areas compared to other water pumping technologies, such as diesel water pumping and wind power water pumping due to the high positive net present values and short payback periods.
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| 10. |
- Davidsson, Henrik, et al.
(författare)
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Performance of a multifunctional PV/T hybrid solar window
- 2010
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X. ; 84:3, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- A building-integrated multifunctional PV/T solar window has been developed and evaluated. It is constructed of PV cells laminated on solar absorbers placed in a window behind the glazing. To reduce the cost of the solar electricity, tiltable reflectors have been introduced in the construction to focus radiation onto the solar cells. The reflectors render the possibility of controlling the amount of radiation transmitted into the building. The insulated reflectors also reduce the thermal losses through the window. A model for simulation of the electric and hot water production was developed. The model can perform yearly energy simulations where different features such as shading of the cells or effects of the glazing can be included or excluded. The simulation can be run with the reflectors in an active, up right, position or in a passive, horizontal, position. The simulation program was calibrated against measurements on a prototype solar window placed in Lund in the south of Sweden and against a solar window built into a single family house, Solgården, in Älvkarleö in the central part of Sweden. The results from the simulation shows that the solar window annually produces about 35% more electric energy per unit cell area compared to a vertical flat PV module.
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| 11. |
- Davidsson, Henrik, et al.
(författare)
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Performance of a multifunctional PV/T hybrid solar window
- 2008
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Ingår i: [Host publication title missing]. ; , s. 44-51
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Konferensbidrag (refereegranskat)abstract
- A PV/T collector have been developed and evaluated at the department of Energy and Building Design at the Technical University of Lund, LTH in Sweden. The PV/T, a “multifunctional solar window” made of PV cells laminated on solar absorbers, is placed in a window behind the glazing. The solar window is built into a single family house, Solgården, in Älvkarleö outside Gävle in the eastern part of Sweden. To reduce the costs of the solar electricity, reflectors have been placed in the construction to focus the radiation onto the solar cells. In this way expensive solar cells can be replaced by considerably cheaper reflector material. The tiltable reflectors give the user a possibility to control the amount of radiation being transmitted into the building. The reflectors can also be used to reduce the thermal losses through the window. A model for electric and hot water production was developed. The simulation program, in Excel, can perform yearly energy simulations where different effects such as shading of the cells or the glazing effects can be included or excluded. The simulation can be run with the reflectors in an active, up right, position or with the reflectors in a passive, horizontal, position. The simulation program was calibrated against a prototype window placed in Lund in the south of Sweden and against the solar window in Solgården. The calculation model serves as a basis for the module written for the simulation program TRNSYS. A “TRNSYS-deck” was built and calibrated for the building Solgården. Yearly simulations of the energy balance for a house with the solar window was compared to simulations where the 16m2 solar window was replaced with an 8m2 normal window. The results show that the annual amount of auxiliary energy is lower with a developed solar window, including low-e coating on the glazing, compared to the normal window case. The developed solar window has considerable lower U-values than the existing solar window.
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| 12. |
- Davidsson, Henrik, et al.
(författare)
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Performance of a multifunctional PV/T hybrid solar window
- 2008
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Ingår i: EuroSun 2008 Proceedings.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A building-integrated multifunctional PV/T collector have been developed and evaluated. The PV/T solar window is constructed of PV cells laminated on solar absorbers and is placed in a window behind the glazing. To reduce the costs of the solar electricity, reflectors have been introduced in the construction to focus radiation onto the solar cells. The tiltable reflectors render a possibility to control the amount of radiation transmitted into the building. The insulated reflectors also reduce the thermal losses through the window. A model for simulation of the electric and hot water production was developed. The model can perform yearly energy simulations where different effects such as shading of the cells or effects of the glazing can be included or excluded. The simulation can be run with the reflectors in an active, up right, position or with the reflectors in a passive, horizontal, position. The simulation program was calibrated against measurements on a prototype solar window placed in Lund in the south of Sweden and against a solar window built into a single family house, Solgården, in Älvkarleö in the middle of Sweden. The results from the simulation shows that the solar window produces about 56% more electric energy per unit cell area compared to a vertical flat PV module.
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| 13. |
- Davidsson, Henrik, et al.
(författare)
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System analysis of a multifunctional PV/T hybrid solar window
- 2012
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X. ; 86:3, s. 903-910
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThe work presented in this article aims to investigate a PV/T hybrid solar window on a system level. A PV/T hybrid is an absorber on which solar cells have been laminated. The solar window is a PV/T hybrid collector with tiltable insulated reflectors integrated into a window. It simultaneously replaces thermal collectors, PV-modules and sunshade. The building integration lowers the total price of the construction since the collector utilizes the frame and the glazing in the window. When it is placed in the window a complex interaction takes place. On the positive side is the reduction of the thermal losses due to the insulated reflectors. On the negative side is the blocking of solar radiation that would otherwise heat the building passively. This limits the performance of the solar window since a photon can only be used once. To investigate the sum of such complex interaction a system analysis has to be performed. In this paper results are presented from such a system analysis showing both benefits and problems with the product. The building system with individual solar energy components, i.e. solar collector and PV modules, of the same size as the solar window, uses 1100 kW h less auxiliary energy than the system with a solar window. However, the solar window system uses 600 kW h less auxiliary energy than a system with no solar collector.
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| 14. |
- Davidsson, Henrik, et al.
(författare)
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Utveckling av Byggnadsintegrerade Solenergisystem för Energieffektiva Hus
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A PV/T collector has been developed and evaluated at the department of Energy and Building Design at the Technical University of Lund, LTH in Sweden. The PV/T, a “solar window” made of PV cells laminated on solar absorbers is placed in a window behind the glazing. The solar window is built into a single family house, Solgården, in Älvkarleö outside Gävle in the eastern part of Sweden. To reduce the costs of the solar electricity reflectors have been placed in the construction to focus light onto the solar cells. In this way expensive solar cells can be replaced by considerably cheaper reflector material. The tiltable reflectors give the user a possibility to control the amount of sunlight being let into the building. The reflectors can also be used to reduce the thermal losses through the window. A calculation model for electricity and hot water production was created. The simulation program, in Excel, can perform yearly energy simulations where different effects such as shading of the cells or the glazing effects can be included or excluded. The simulation can be run with the reflectors in an active, up right, position or with the reflectors in a passive, horizontal, position. The simulation programme was calibrated against a prototype window placed in Lund in the south of Sweden and against the solar window in Solgården Älvkarleö. The calculation model serves as a basis for the module written for the simulation program TRNSYS. A “TRNSYS-deck” was built and calibrated for the building Solgården. The energy balance for the system shows that the control of the reflectors is of great importance. A good control strategy for the reflectors can lower the annual energy demand and improve the indoor climate. A control mechanism that incorporates the indoor and outdoor temperatures can for instance decide to open the reflectors during summer nights to cool the building. Yearly simulations of the energy balance for a house with the solar window was compared to simulations where the 16 m2 solar window was replaced with a 8 m2 normal window. The results show the annual amount of auxiliary is lower with a developed solar window compared to the normal window case. The developed solar window has considerably lower U-values than the existing solar window. A simulation was run to investigate the over heating of the building using different control strategies for the reflectors. The simulation was also run for the normal window. The results show that the reflectors of the solar window work fine as a sun shade, keeping the overheating to a minimum. A normal window has to be supplemented with a sun shade of some kind to keep the over heating during the summer on an acceptable level. An Improvement of the solar window that can be of great importance is to add some sort of low-e coating on the glazing to reduce the U-value even further. However, it must be taken into account that the transmittance of the glazing will be affected in a negative way if low-e coating is added. Lower transmission means lower electricity and hot water production. Other improvements that can be made are better insulation of the reflector and the absorber. The most important way to improve the annual electricity production is to use better solar cells. Today cells of standard quality with an efficiency of about 16-17% can be obtained. The electric system at Solgården is built up around a battery bank that can be charged from the solar window, the Stirling generator or from the grid. To have continuous power for some time during a black out and also the relatively low fuse that is needed for the house are two advantages with this system. Simulations show that the day to day storage of electricity in the batteries evens out the power peaks from the load and the electric production, and that further storage is of limited use. Simulations show that the production of electric energy from a combination of solar cells and a Stirling generator is in good agreement with the load during the full year. Solgårdens two parallel electric systems, 230 V and 12 V, has many advantages such as electric security and low energy consumption. To save electric energy is of extra interest when solar cells are used as an energy source. Due to the high price for solar cells large energy saving investments ought to be made before a solar cell installation is economically interesting. To move the energy use from electricity to hot water use is profitable for a stand alone house since solar heating and bio fuel is considerably cheaper compared to solar electricity. Tumble driers, washing machines and dishwashers can for instance use a circulating hot water system instead of electricity in order to minimize the electric use. Normally the energy balance between produced electric energy and produced thermal energy is in better agreement if hot water is used instead of electric energy. Other important investments to make the electric usage more efficient are to use low energy light bulbs and modern kitchen appliances, pumps, fans and computers. This can save as much as 80% of the electricity compared to old standard techniques. Solgården is in practice working with the main fuses of the sizes of 3-4 A only. This can be accomplished because of the battery bank and since no equipment with a high current demand is connected to the power system. A high slope of the PV-modules has the advantage that the power during the summer is decreased. On the other hand a module tilt of 45° is to prefer both from an energy and a power view. A 45° tilted module gives a higher annual output in kWh per monitored kWp than a vertical module.
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| 15. |
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| 16. |
- Furbo, Simon, et al.
(författare)
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Best Practices for PVT Technology
- 2021
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Ingår i: SWC2021 Proceedings. - Freiburg, Germany : ISES.
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Konferensbidrag (refereegranskat)abstract
- The PVT technology combines solar PV and solar thermal in the same PVT panel. In this way, both electricity and heat are produced by the PVT panel. Compared to the PV technology and the solar heating technology the PVT technology is in the early market stage with only few small and weak industries active. Best practices for the PVT technology, which is still under rapid development, are summarized. Marketed systems with different PVT panel types, different PVT system types with different components for different applications are considered. The potential advantages for PVT systems and the needs for key actors in order to establish a successful sustainable future PVT market are given. Finally, recommendations for a subsidy scheme for PVT systems are given, so that a PVT market can be developed in parallel with the successful PV market.
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| 17. |
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| 18. |
- Hatwaambo, Sylvester, et al.
(författare)
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Projected beam irradiation at low latitudes using Meteonorm database
- 2009
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Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481. ; 34:5, s. 1394-1398
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Tidskriftsartikel (refereegranskat)abstract
- The quantitative analysis of beam radiation received on a solar concentrator may be understood by evaluating the projected solar height angle or profile angle along the north-south vertical plane. This means that all the sunrays projected along the north-south vertical plane will be intercepted by a collector provided the projection angle lies within the acceptance angle. The Meteonorm method of calculating solar radiation on any arbitrary oriented surface uses the globally simulated meteorological databases. Meteonorm has become a valuable too for estimating solar radiation where measured solar radiation data is missing or irregular. In this paper we present the projected beam solar radiation at low latitudes based on the standard Meteonorm calculations. The conclusion is that there is potential in using solar concentrators at these latitudes since the projected beam radiation is more during winter periods than in summer months. This conclusion is in conformity with the design principle of solar collectors for worst case conditions. (C) 2008 Elsevier Ltd. All rights reserved.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Kjellsson, Elisabeth, et al.
(författare)
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Combination of solar collectors and ground-source heat pump for small buildings
- 2005
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Ingår i: Proceedings of the 2005 Solar world Congress. - 0895531771
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The combination of solar heat and ground-source heat pumps in dwellings gives opportunities for optimising the use of renewable energy sources and minimize the share of bought energy. Solar collectors in the system may give advantages for the operational conditions both for the solar collectors and for the heat pump. The aim of this project was to analyse different variables such as energy demand, building types, climate, geological conditions, system design and control. The study has been carried out with TRNSYS simulations for Swedish climate and building conditions. The results from the computer simulations so far, shows that there is an obvious risk that the use of electricity for the circulation pumps is larger than the decrease of electricity use for the heat pump and the auxiliary heater. It is most important that the system is optimised in order to restrict the total use of electricity.
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| 25. |
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| 26. |
- Kjellsson, Elisabeth, et al.
(författare)
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Optimization of systems with the combination of ground-source heat pump and solar collectors in dwellings
- 2010
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 35:6, s. 2667-2673
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Konferensbidrag (refereegranskat)abstract
- The use of ground-source heat pumps for heating and domestic hot water in dwellings is common in Sweden. The combination with solar collectors has been introduced to reduce the electricity demand in the system. In order to analyze different systems with combinations of solar collectors and ground-source heat pumps, computer simulations have been carried out with the simulation program TRNSYS. Large differences were found between the system alternatives. The optimal design is when solar heat produces domestic hot water during summertime and recharges the borehole during wintertime. The advantage is related to the rate of heat extraction from the borehole as well as the overall design of the system. The demand of electricity may increase with solar recharging, because of the increased operating time of the circulation pumps. Another advantage with solar heat in combination with heat pumps is when the boreholes or neighbouring installations are drilled so close that they thermally influence each other. This may lead to decreasing temperatures in the ground, which gives decreased performance of the heat pump and increased use of electricity. The net annual heat extraction from the ground is reduced by recharge from solar heat. (C) 2009 Elsevier Ltd. All rights reserved.
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| 27. |
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| 28. |
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| 29. |
- Kovacs, Peter, et al.
(författare)
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Comparison of five approaches to solar assisted cooling
- 2009
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Ingår i: 29th Biennial Solar World Congress of the International Solar Energy Society, ISES 2009; Johannesburg; South Africa; 11 October 2009 through 14 October 2009. - 9781617388521 ; 1, s. 423-430
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Konferensbidrag (refereegranskat)abstract
- Numerous different options are available for cooling buildings using solar energy. In this theoretical study, which is also a pre study for a pilot installation, five generic technologies are compared: 1. Conventional compressor chiller fed by electricity from PV panels 2. Absorption chiller fed by a combination of medium temperature solar heat and district heating 3. Absorption chiller fed by a combination of low to medium temperature solar heat and district heating 4. Evaporative cooling (tower) fed by electricity from PV panels 5. Desiccant cooling fed by medium temperature solar heat and district heating The financial viability of each technology will essentially depend on competing supply energy tariffs, local climate, time distribution of cooling loads, the internal cooling distribution system, subsidy levels and expected operational costs. Furthermore, the buyers' choice of a system will also be affected by the fact that the technologies are in different stages of maturity. From the point of view of the district heating provider potential impact on the heating network is also of great interest. The study compares the five technologies in the light of these different aspects. The paper describes the method in more detail as well as the results of the study. The best overall conditions were found for a combination of PV powered conventional chillers which, according to calculations have a significantly lower LCC than the reference district cooling, even if subsidies are not taken into account. The concept based on free cooling from a wet cooling tower powered by PV has a much lower cost than the chiller, but the technical feasibility of this new and very energy efficient technology is not yet considered to be proven. Results from the economical analysis of solar assisted district heating powered comfort cooling varies within a wide range depending on the tariff applied for the district heat.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
- Lennermo, Gunnar, et al.
(författare)
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Underlag för utökad besiktning av bio- och solvärmesystem : Formulär med analyshjälp
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det är svårt att på ett genomarbetat sätt, kontrollera en solvärmeanläggning som är i drift och det blir svårare när solvärmesystemet skall samverka med en biobränsleanläggning, som har sina speciella egenheter. Det enklaste och, som det kan tyckas, bästa sättet att kontrollera om en solvärmeanläggning fungerar, är att beräkna utifrån en värmemängdsmätare, som förhoppningsvis finns i anläggningen, hur mycket energi per m2 aktiv area som solfångaren har producerat per år. Om produktionen ligger mellan 300 – 350 kWh/m2 så är det bra. Det är dock så att en solvärmeanläggning borde kunna producera betydligt mer värme om den bara ges lite bättre förutsättning eller att den faktiskt kan ge mindre, men ändå uppfylla de krav som ställdes. Det behöver inte nödvändigtvis vara antalet producerade solfångar-kWh värme som är högt utan det viktigaste kanske är att antalet inbesparade kWh biobränsle är många. För att kunna få ett grepp om hur en solvärmeanläggning fungerar i sitt sammanhang så bör det totala systemet redovisas framför allt med avseende på: -Värmedistributionssystemets uppbyggnad. Var och när finns kallt vatten som ska värmas samt hur mycket. -Energi- och effektnivåer för olika delar av systemet och fram för allt under sommaren -Vilka pannor och bränslen som används, framför allt med betoning på reglerbarhet Solvärmekretsen, som inte är speciellt annorlunda utformad än i andra lite större solvärmeanläggningar ges i den här rapporten relativt stort utrymme, eftersom den samlade kompetensen bland de som gör besiktningar och kontroller inte är så hög. De delar som berörs mest är: -Trycket i solvärmeanläggningen med avseende på expansionskärlets förtryck, systemets uppfyllnadstryck och driftsfunktioner -Flödet i anläggningen som inriktar sig på luftmedryckning, flödesfördelning och vanliga flödeshastigheter -Solfångarnas energi- och värmeeffektproduktion Huvuddelen av underlagsmaterialet bör ha samlats in före besöket, genom att försöka få tag på: -Förstudier för solvärme- och pannanläggning -Förfrågningsunderlag för i första hand solvärmeanläggningen -Driftstatistik -Data på hur det totala systemet ser ut. Dessa data bör bearbetas innan besöket på plats vilket skall inkludera en genomgång av driftsansvarig vilket kompletteras med en guidad tur genom anläggningen. Besöket bör också vara förberett hos driftsansvariga så att stegar för att komma åt solfångarna finns framtagna och de säkerhetsselar som skall finnas vid okulär inspektion finns tillgängliga. Efter avslutad på platsen kontroll ska en besiktningsrapport skrivas. Mycket underlagsberäkningar ska skickas med som bilaga samt en lista med punkter som syftar till att få en effektivare sol- och biobränsleanläggning.
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| 35. |
- Lennermo, Gunnar, et al.
(författare)
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Underlag för utökad besiktning av sol- och biovärmesystem
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det är svårt att på ett genomarbetat sätt, kontrollera en solvärmeanläggning som är i drift och det blir svårare när solvärmesystemet ska samverka med en biobränsleanläggning, som har sina speciella egenheter. Det enklaste och, som det kan tyckas, bästa sättet att kontrollera om en solvärmeanläggning fungerar, är att beräkna utifrån en värmemängdsmätare, som förhoppningsvis finns i anläggningen, hur mycket energi per m2 aktiv area som solfångaren har producerat per år. Om produktionen ligger mellan 300 – 350 kWh/m2 är det bra. Det är dock så att en solvärmeanläggning borde kunna producera betydligt mer värme om den bara ges lite bättre förutsättning eller att den faktiskt kan ge mindre, men ändå uppfylla de krav som ställdes. Det behöver inte nödvändigtvis vara antalet producerade solfångarkWh värme som är högt utan det viktigaste kanske är att antalet inbesparade kWh biobränsle är många. För att kunna få ett grepp om hur en solvärmeanläggning fungerar i sitt sammanhang bör det totala systemet redovisas framför allt med avseende på: • Värmedistributionssystemets uppbyggnad. Var, när och hur mycket kallt vatten ska värmas? • Energi- och effektnivåer för olika delar av systemet, framför allt under sommaren? • Vilka pannor och bränslen används, framför allt med betoning på reglerbarhet? Solvärmekretsen, som inte är speciellt annorlunda utformad än i andra lite större solvärmeanläggningar, ges i den här rapporten relativt stort utrymme, eftersom den samlade kompetensen bland de som gör besiktningar och kontroller inte är så hög. Mest berörda delar är: • Trycket i solvärmeanläggningen med avseende på expansionskärlets förtryck, systemets uppfyllnadstryck och driftsfunktioner • Flödet i anläggningen som inriktar sig på luftmedryckning, flödesfördelning och vanliga flödeshastigheter • Solfångarnas energi- och värmeeffektproduktion Huvuddelen av underlagsmaterialet bör ha samlats in före besöket, genom att försöka få tag på: • Förstudier för solvärme- och pannanläggning • Förfrågningsunderlag för i första hand solvärmeanläggningen • Driftstatistik • Data på hur det totala systemet ser ut Dessa data bör bearbetas innan besöket på plats, vilket ska inkludera en genomgång av driftsansvarig kompletterat med en guidad tur genom anläggningen. Besöket bör också vara förberett hos driftsansvariga så att stegar för att komma åt solfångarna finns framtagna och de säkerhetsselar, som ska användas vid okulär inspektion, finns tillgängliga. Efter avslutad på-platsen-kontroll ska en besiktningsrapport skrivas. Mycket underlagsberäkningar ska skickas med som bilaga samt en lista med punkter som syftar till att få en effektivare sol- och biobränsleanläggning.
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| 36. |
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| 37. |
- Letz, Thomas, et al.
(författare)
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A new concept for combisystems characterization : the FSC method
- 2009
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Ingår i: Solar Energy. - : Elsevier. - 0038-092X .- 1471-1257. ; 83:9, s. 1540-1549
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Tidskriftsartikel (refereegranskat)abstract
- Solar combisystems are relatively complex systems with many different components and operational parameters. Before the beginning of IEA-SHC Task 26 ("solar combisystems"), no method was available with which they could be compared. The well known "f-chart" method was introduced by Duffie and Beckman already in the seventies, but was only useful for dimensioning generic combisystems, with a defined hydraulic scheme. It didn't give a method to compare different designs. The objective of this work was to develop a simple tool for characterizing the performance of these systems. The method used was to analyse the comprehensive simulation results of Task 26 and to look for relationships between the key external factors of climate and load, and the system performance. The result is a new and simple methodology for characterization of solar combisystems, called the fractional solar consumption (FSC) method. FSC is a dimensionless quantity, which takes simultaneously into account the climate, the space heating and domestic hot water loads, the collector size, its orientation and tilt angle, but which does not depend on the studied system design. The study shows that fractional energy savings, with and without parasitic energy included, can be expressed as a quadratic function of FSC. The relationship was shown to be valid for a wide range of conditions, but to be limited for certain parameters such as collector orientation and hot water load. The method has been used to create a nomogram and the computer design tool CombiSun.
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| 38. |
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| 39. |
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Perers, Bengt, et al.
(författare)
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A new tool for standardized collector performance calculations
- 2011
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Konferensbidrag (refereegranskat)abstract
- A new tool for standardized calculation of solar collector performance has been developed in cooperation between SP Borås Sweden, DTU Denmark and SERC Dalarna University. The tool is designed to calculate the annual performance for a number of representative cities in Europe on the basis of parameters from collector tests performed according to EN12975, without any intermediate conversions. The main target group for this tool is test institutes and certification bodies that intend to use it for conversion of collector model parameters derived from performance tests, into a more user friendly quantity i.e. the annual energy output. Energy output both per m2 and per collector module can be calculated.
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| 44. |
- Perers, Bengt, et al.
(författare)
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A simplified heat pump model for use in solar plus heat pump system simulation studies
- 2012
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 30, s. 664-667
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Tidskriftsartikel (refereegranskat)abstract
- Solar plus heat pump systems are often very complex in design, with sometimes special heat pump arrangements and control. Therefore detailed heat pump models can give very slow system simulations and still not so accurate results compared to real heat pump performance in a system. The idea here is to start from a standard measured performance map of test points for a heat pump according to EN 14825 and then determine characteristic parameters for a simplified correlation based model of the heat pump. By plotting heat pump test data in different ways including power input and output form and not only as COP, a simplified relation could be seen. By using the same methodology as in the EN 12975 QDT part in the collector test standard it could be shown that a very simple model could describe the heat pump test data very accurately, by identifying 4 parameters in the correlation equation found. © 2012 The Authors.
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| 45. |
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| 46. |
- Perers, Bengt, et al.
(författare)
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A tool for standardized collector performance calculations including PVT
- 2012
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 30, s. 1354-1364
-
Tidskriftsartikel (refereegranskat)abstract
- A tool for standardized calculation of solar collector performance has been developed in cooperation between SP Technical Research Institute of Sweden, DTU Denmark and SERC Dalarna University. The tool is designed to calculate the annual performance of solar collectors at representative locations in Europe. The collector parameters used as input in the tool are compiled from tests according to EN12975, without any intermediate conversions. The main target group for this tool is test institutes and certification bodies that are intended to use it for conversion of collector model parameters (derived from performance tests) into a more user friendly quantity: the annual energy output. The energy output presented in the tool is expressed as kWh per collector module. A simplified treatment of performance for PVT collectors is added based on the assumption that the thermal part of the PVT collector can be tested and modeled as a thermal collector, when the PV electric part is active with an MPP tracker in operation. The thermal collector parameters from this operation mode are used for the PVT calculations. © 2012 The Authors.
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