| 1. |
- Markeby Ljungqvist, Hampus, et al.
(författare)
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A realistic view on heat reuse from direct free air-cooled data centres
- 2023
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Ingår i: Energy Conversion and Management. - : Elsevier. - 2590-1745. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the opportunities to reuse excess heat from direct free air-cooled data centres without incorporating heat pumps to upgrade the heat. The operation of a data centre in northern Sweden, Luleå, was simulated for a year. It was established that heat losses through the thermal envelope and from the humidification of the cooling airflow influenced the momentary energy reuse factor, iERF, with up to 7%. However, for the annual energy reuse factor, ERF, the heat losses could be neglected since they annually contributed to an error of less than 1%. It was shown that the ideal heat reuse temperature in Luleå was 13, 17, and 18 °C with an exhaust temperature of 30, 40 and 50 °C. The resulting ERF was 0.50, 0.59 and 0.66, meaning that a higher exhaust temperature resulted in potentially higher heat reuse. It could also be seen that raising the exhaust temperature lowered the power usage effectiveness, PUE, due to more efficient cooling. Using heat reuse applications with different heat reuse temperatures closer to the monthly average instead of an ideal heat reuse temperature for the whole year improved the ERF further. The improvement was 11–31% where a lower exhaust temperature meant a higher relative improvement.
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| 2. |
- Markeby Ljungqvist, Hampus, et al.
(författare)
-
Data center heated greenhouses, a matter for enhanced food self-sufficiency in sub-arctic regions
- 2021
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Ingår i: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 215
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the possibility of increasing Northern Sweden's degree of self-sufficiency in food supply, at the 65th latitude, by using a data center as a heating source for greenhouse production. A dynamic building energy simulation software was used to compute both the hourly exhaust air output from a 1 MW data center for one year and the corresponding heating demand for two different greenhouse sizes, 2000 m2 and 10 000 m2, and two different production scenarios. Partial year production, 1 Mars – 15 October, without grow lights and full-year production with grow lights. The study showed that 5.5–30.5% of the electrical input to a 1 MW data center could be recovered. The 2000 m2 greenhouse could operate almost entirely, 89.7–97.9%, on excess heat while only 50.0–61.5% of the 10 000 m2 greenhouse heating demand could be met for full- and partial-year production, respectively. Furthermore, it is concluded that the 10 000 m2 greenhouse with full year production was the most prominent case and would cost-effectively yield 7.6% of northern Sweden's vegetable self-sufficiency.
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| 3. |
- Pericault, Youen, 1992-, et al.
(författare)
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A novel freeze protection strategy for shallow buried sewer pipes : temperature modelling and field investigation
- 2016
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Ingår i: Proceedings of the 8th International Conference on Sewer Processes & Networks.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The burial of sewer and water pipes below the maximum ground frost depth can be very costly and laborious in regions with cold winters. If a freeze protection measure is applied, the utility lines can be installed in a shallower trench to reduce the excavation needs during construction and maintenance works. One freeze protection measure, so called heat tracing, consist in supplying heat along the pipes. In this work, the use of 4th generation district heating as a heat tracing solution was investigated at a pilot site in Kiruna, Sweden. The influence of the system on sewer and water pipes temperatures was studied experimentally and numerically at a snow-free and snow-covered cross section. The study showed that, under the climatic conditions of the experiment, a heat tracing temperature of 25 ˚C allowed to prevent freezing of the pipes while keeping drinking water pipes in safe temperature range at both cross sections. The other main result was that a finite volume model of the sections was developed and showed a good fitting to the experimental data.
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| 4. |
- Pericault, Youen, 1992-, et al.
(författare)
-
A novel freeze protection strategy for shallow buried sewer pipes : temperature modelling and field investigation
- 2017
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 76:2, s. 294-301
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Tidskriftsartikel (refereegranskat)abstract
- The burial of sewer and water pipes below the maximum ground frost depth can be very costly and laborious in regions with cold winters. If a freeze protection measure is applied, the utility lines can be installed in a shallower trench to reduce the excavation needs. One freeze protection measure, so called heat tracing, consists in supplying heat along the pipes. In this work, the use of 4th generation district heating as a heat tracing solution was investigated at a pilot site in Kiruna, Sweden. The influence of the system on sewer and water pipe temperatures was studied at a snow-free and snow-covered cross section. To this end, five heat tracing temperatures were tested and the corresponding sewer and water pipe temperatures were measured. The field experiment was also simulated with a two dimensional finite volume model. The study showed that, under the climatic conditions of the experiment, a heat tracing temperature of 25 °C allowed to prevent freezing of the pipes while keeping drinking water pipes in a safe temperature range at both cross sections. The other main result was that the developed finite volume model of the sections showed a good fitting to the experimental data
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| 5. |
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