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- Gehlin, Signhild, et al.
(författare)
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Backgroudn promoting TES systems in Sweden
- 2006
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Swedish nuclear plants are slowly being shut down as a result of a referendum in 1980. During the years after the referendum, four nuclear reactors were completed and taken into operation. The nuclear power then covered 50 % of the Swedish production capacity resulting in large over capacity, which meant inexpensive electricity. For many years thereafter direct electrical space heating was the only feasible option. This development continued until direct electrical heating was used for about 30 % of all space heating in Sweden. Swedish consumer prices were then about one third of that in most European countries. The much later deregulation of the electrical market and connection of the power grid to other European countries meant that Swedish consumer prices increased rapidly. Within a few years the prices are expected to be at the same level all over Europe and direct space heating is no longer a feasible alternative. This is why it is so attractive to Swedes to use heat pumps to reduce their electricity consumption. The present Swedish energy policy aims to a changeover from the use of prime energy sources to renewables. This is partly because of international agreements on the reduction of greenhouse emissions and partly to obtain a more independent energy system. Since the use of heat pumps mean that the electrical consumption is reduced by 70 % and also means less emission to the atmosphere, heat pump systems have been encouraged by subsidies. This present subsidy, which covers about 15 % of the investment, has been on and off during the last decades. Now, the new EU directive on energy efficient buildings offers a platform for the promotion of thermal energy
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| 2. |
- Gehlin, Signhild, et al.
(författare)
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Promoting TES Systems in Sweden
- 2006
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Ingår i: Thermal energy storage. - Pomona, NJ : Richard Stockton College of NJ.
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Konferensbidrag (refereegranskat)
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| 3. |
- Gustafsson, Anna-Maria, et al.
(författare)
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Influence of natural convection in water-filled boreholes for GCHP
- 2008
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Ingår i: ASHRAE Transactions. - 0001-2505. ; 114:1, s. 416-423
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Tidskriftsartikel (refereegranskat)abstract
- In groundwater filled borehole heat exchangers (BHE), convective flow inside the borehole water will affect the heat transfer. Since the convective flow is dependent of the temperature gradient, different injection rates and ground temperatures will result in different borehole thermal resistance. This paper describes the influence of natural convection in water-filled boreholes in impermeable bedrock for ground-coupled heat pump (GCHP) systems. An overview of groundwater-filled boreholes and the influence of groundwater movements are presented followed by numerical simulations and field measurements to further investigate the influence. The results from the simulations of the three-dimensional, steady-state model of a 9.8 ft (3 m) deep BHE are compared to evaluated results from performed thermal response test (TRT). The results show that convective flow in groundwater-filled BHE results in 5-9 times more efficient heat transfer compared to stagnant water when heat carrier temperatures are in the range of 50-86°F (10-30°C). The size of the convective flow depends on the temperature gradients in the borehole. This shows the importance of on-site investigation of thermal properties using appropriate power injection rates similar to those in the system to be built. This research is part of an on-going project to find ways to estimate the heat transfer including convective flow and to incorporate the findings into the design of GCHP systems. TRT are today a common way to determine heat transfer properties for a BHE and its surroundings. Performing TRT measurements with several injection rates is a way to evaluate the dynamic thermal response including the change in convective flow due to changes in temperature levels. If this dynamic response would be included in design tools a more thorough design of the BHE system is performed. Here, the early result of this research is presented
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| 5. |
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| 6. |
- Nordell, Bo, et al.
(författare)
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30 years of Stock Conferences
- 2009
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Ingår i: Abstract book and proceeding : Effstock 2009. - Stockholm : Energi- och Miljötekniska Föreningen / EMTF Förlag.
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Konferensbidrag (refereegranskat)
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