Detail publikace

Influence of Underpressure on Heat Transfer And Temperature Field at Sprinkled Tube Bundle

Originální název

Influence of Underpressure on Heat Transfer And Temperature Field at Sprinkled Tube Bundle

Anglický název

Influence of Underpressure on Heat Transfer And Temperature Field at Sprinkled Tube Bundle

Jazyk

en

Originální abstrakt

Sprinkled tube bundles with a thin liquid film flowing over them are used in various technology processes where it is necessary to separate the vapour and liquid phases quickly and efficiently at low temperatures with a corresponding decrease of pressure around the tube bundle. In ideal conditions water boils at the whole surface of an exchanger, but in practice it must be considered that in original spots of contact between water and the exchanger wall the water will not boil at the tubes' surface but the cooling liquid will merely be heated-up. The article focuses on these processes. Experiments have been carried out at a tube bundle consisting of copper tubes of 12 mm diameter placed horizontally one above another that have been heated by water of an average input temperature approx. 40 °C. This bundle has been sprinkled by cool water at temperature of 15 °C and pressure has been gradually decreased using an exhauster at constant flow rates of heating and falling film liquid inside an experimental device's chamber. Was tested flow of sprinkled liquid in the range of 4-9 liters per minute, which corresponds to the range of Reynolds numbers of about 300 to 600 [-]. The result of these experiments is a studied heat transfer coefficient at the surface of a sprinkled tube bundle during heating of the cooling liquid with a transition into boiling of the liquid at the bundle. At a flow of 8 liters per minute were acquired sequence thermal camera FLIR SC 660. After evaluation of the sequences were generated maps of the temperature field according to decreasing the pressure and its standard deviation. From the contour graphs can evaluate the thermal stability of the liquid film on the spray tube bundle.

Anglický abstrakt

Sprinkled tube bundles with a thin liquid film flowing over them are used in various technology processes where it is necessary to separate the vapour and liquid phases quickly and efficiently at low temperatures with a corresponding decrease of pressure around the tube bundle. In ideal conditions water boils at the whole surface of an exchanger, but in practice it must be considered that in original spots of contact between water and the exchanger wall the water will not boil at the tubes' surface but the cooling liquid will merely be heated-up. The article focuses on these processes. Experiments have been carried out at a tube bundle consisting of copper tubes of 12 mm diameter placed horizontally one above another that have been heated by water of an average input temperature approx. 40 °C. This bundle has been sprinkled by cool water at temperature of 15 °C and pressure has been gradually decreased using an exhauster at constant flow rates of heating and falling film liquid inside an experimental device's chamber. Was tested flow of sprinkled liquid in the range of 4-9 liters per minute, which corresponds to the range of Reynolds numbers of about 300 to 600 [-]. The result of these experiments is a studied heat transfer coefficient at the surface of a sprinkled tube bundle during heating of the cooling liquid with a transition into boiling of the liquid at the bundle. At a flow of 8 liters per minute were acquired sequence thermal camera FLIR SC 660. After evaluation of the sequences were generated maps of the temperature field according to decreasing the pressure and its standard deviation. From the contour graphs can evaluate the thermal stability of the liquid film on the spray tube bundle.

Dokumenty

BibTex


@article{BUT122532,
  author="Petr {Kracík} and Jiří {Pospíšil}",
  title="Influence of Underpressure on Heat Transfer And Temperature Field at Sprinkled Tube Bundle",
  annote="Sprinkled tube bundles with a thin liquid film flowing over them are used in various technology processes where it is necessary to separate the vapour and liquid phases quickly and efficiently at low temperatures with a corresponding decrease of pressure around the tube bundle. In ideal conditions water boils at the whole surface of an exchanger, but in practice it must be considered that in original spots of contact between water and the exchanger wall the water will not boil at the tubes' surface but the cooling liquid will merely be heated-up. The article focuses on these processes. Experiments have been carried out at a tube bundle consisting of copper tubes of 12 mm diameter placed horizontally one above another that have been heated by water of an average input temperature approx. 40 °C. This bundle has been sprinkled by cool water at temperature of 15 °C and pressure has been gradually decreased using an exhauster at constant flow rates of heating and falling film liquid inside an experimental device's chamber. Was tested flow of sprinkled liquid in the range of 4-9 liters per minute, which corresponds to the range of Reynolds numbers of about 300 to 600 [-]. The result of these experiments is a studied heat transfer coefficient at the surface of a sprinkled tube bundle during heating of the cooling liquid with a transition into boiling of the liquid at the bundle. At a flow of 8 liters per minute were acquired sequence thermal camera FLIR SC 660. After evaluation of the sequences were generated maps of the temperature field according to decreasing the pressure and its standard deviation. From the contour graphs can evaluate the thermal stability of the liquid film on the spray tube bundle.",
  address="Trans Tech Publications",
  chapter="122532",
  doi="10.4028/www.scientific.net/AMM.832.200",
  howpublished="online",
  institution="Trans Tech Publications",
  number="832",
  year="2016",
  month="april",
  pages="200--206",
  publisher="Trans Tech Publications",
  type="journal article - other"
}