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Nucleate boiling is a type of boiling that takes place when the surface temperature is hotter than the saturated fluid temperature by a certain amount but where the heat flux is below the critical heat flux. For water, as shown in the graph below, nucleate boiling occurs when the surface temperature is higher than the saturation temperature (TS) by between 10 and 30 °C (18 and 54 °F). The critical heat flux is the peak on the curve between nucleate boiling and transition boiling. The heat transfer from surface to liquid is greater than that in film boiling. Nucleate boiling is common in electric kettles and is responsible for the noise that occurs before boiling occurs. It also occurs in water boilers where water is rapidly heated. (en) 核沸騰(かくふっとう、英: Nucleate boiling)は、伝熱面温度から液体のを差し引いた伝熱面過熱度がある値を超えたところから生じる沸騰現象で、伝熱面上にランダムに分布した発泡点より気泡が発生する沸騰の形態である。伝熱面過熱度をさらに大きくすると気泡が合体するようになり、ある上限を超えると合体した気泡が伝熱を阻害するようになる。この核沸騰の上限を与える熱流束を限界熱流束(英: Critical heat flux, CHF)と呼ぶ。1気圧下の水の沸騰曲線の一例である下図の沸騰曲線では104℃ から 130℃ の範囲で核沸騰が生じており、グラフの変曲点として現れているのが限界熱流束点である。ただし、この温度は伝熱面の性状や寸法等によって変化するため、あくまで一例である。 (ja) |
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核沸騰(かくふっとう、英: Nucleate boiling)は、伝熱面温度から液体のを差し引いた伝熱面過熱度がある値を超えたところから生じる沸騰現象で、伝熱面上にランダムに分布した発泡点より気泡が発生する沸騰の形態である。伝熱面過熱度をさらに大きくすると気泡が合体するようになり、ある上限を超えると合体した気泡が伝熱を阻害するようになる。この核沸騰の上限を与える熱流束を限界熱流束(英: Critical heat flux, CHF)と呼ぶ。1気圧下の水の沸騰曲線の一例である下図の沸騰曲線では104℃ から 130℃ の範囲で核沸騰が生じており、グラフの変曲点として現れているのが限界熱流束点である。ただし、この温度は伝熱面の性状や寸法等によって変化するため、あくまで一例である。 (ja) Nucleate boiling is a type of boiling that takes place when the surface temperature is hotter than the saturated fluid temperature by a certain amount but where the heat flux is below the critical heat flux. For water, as shown in the graph below, nucleate boiling occurs when the surface temperature is higher than the saturation temperature (TS) by between 10 and 30 °C (18 and 54 °F). The critical heat flux is the peak on the curve between nucleate boiling and transition boiling. The heat transfer from surface to liquid is greater than that in film boiling. (en) |
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核沸騰 (ja) Nucleate boiling (en) |
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