The Influence of the Shape of Granite on the Heat Storage Process in a Rock Bed

Nemś, Magdalena; Nemś, Artur; Gębarowska, Kamila

doi:10.3390/en13215662

Cited by 2 publications

(3 citation statements)

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“…The computational algorithm numerically solved a total of 26 equations. It was described in detail by the author in [15]. The calculation algorithm presented in this chapter enabled the following parameters to be determined: flow parameters, such as: air velocity in the bed storage , and the Reynold number Re, as well as thermal parameters, such as: the heat transfer rate between the flowing air and the storage material , the heat transfer coefficient into the material ℎ , and the Nusselt number Nu.…”

Section: Of 16mentioning

confidence: 99%

“…In addition, the discharge temperature curve was of a different nature, which was especially visible in the first two hours of the bed storage's charging process. Such a situation occurred despite the fact that the tested elements had the same equivalent diameter [15]. Due to these discrepancies, the author of the paper decided to continue research on crushed granite as a filling material.…”

Section: Introductionmentioning

confidence: 99%

“…Such an assumption means, in model calculations, that the storage material in the form of spheres and crushed stone will equally absorb heat from the working medium. The author noted, in the studies described in [15], that there are significant differences in the charging of a bed storage filled with spheres and those filled with crushed rock. The obtained differences in the 1st and the 2nd law efficiency show that the geometry of the rock has an impact on the heat transfer process.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Determination of the Influence of Shape on the Heat Transfer Process in a Crushed Granite Storage Bed

Nemś¹

2020

Energies

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The article presents the problem of modelling the charging of a constant-phase bed storage in the first hours of the process. The places of errors in the heat transfer calculations for the packed beds were indicated. Granite in the shape of spheres and crushed rocks, with a characteristic dimension of 50 mm, was used for the experimental tests. The material was subjected to tomographic examination and then used as a storage material. The charging process was carried out for three flow rates: 0.006, 0.008 and 0.010 m3/s. After three hours of testing, the temperature of the outlet air for the granite sphere as the storage material was the same as for the granite crushed rock. However, the biggest differences occurred after 1 h of charging. They were equal to: 40.4% for the flow rate of 0.006 m3/s, 22.0% for the flow rate of 0.008 m3/s, and 18.5% for the flow rate of 0.010 m3/s. The differences were greater than the uncertainty of the measurements. As a result, different temperatures of the storage material were obtained. After three hours, they were equal to: 25.2%, 12.3% and 8.6% for the lowest, medium, and highest airflow, respectively. The conducted heat transfer analysis and the relationship Nu = f(Re) was determined. The influence of the calculated and actual surface of the crushed rock on the heat exchange process was explained. For all the tested air flow rates through the bed, higher thermal parameters were obtained for the crushed rock than for the sphere. The maximum differences in the Nu number were: 222.6%, 151.4% and 161.3% for the flow of 0.006, 0.008 and 0.010 m3/s, respectively. This means that the description of the heat exchange process in the piled beds would require a parameter that takes into account the geometry of the storage material.

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Section: Of 16mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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