Determination of the first critical thermal flux on flat heaters

Kirichenko, Yu. A.; Chernyakov, P. S.

doi:10.1007/bf01122589

“…(2) agrees fairly well with the data within the 20  60 range, and predicts higher values than the data for  <20 and 60< . Further, as stated by Kirichenko and Chernyakov (1971) predicts the CHF for a vertical surface ( =90) as 40% lower than the CHF for a horizontal surface ( =0). According to the results by Howard and Mudawar (1999) and Brusster (1997), where the effect of surface orientation on CHF was examined with water and FC-72, the CHF is little affected by angle of inclination and takes similar values from  =0 to 90.…”

Section: Critical Heat Fluxessupporting

confidence: 75%

“…The conclusions obtained in the present study may be summarized as follows: Fig.13 Plot of the present data for water with the predicted results by Eq. (2) by Kirichenko and Chernyakov (1971) (1) For the boiling in ethanol, R141b, and water, CHF occurs accompanied by the formation of large vapor masses that cover most of the heating surface in the whole range of pressures in the present experiments. This would suggest that the trigger of the CHF at high pressures is closely related to the dryout of the liquid layer (macrolayer) formed beneath the large vapor masses.…”

Section: Discussionmentioning

confidence: 92%

“…In Fig. 11, the values of the contact angles are different at different measurements, but the temperature dependence of the data by Hazuku et al and Correlations for CHF incorporating the effect of the surface wettability have been proposed by Kirichenko andChernyakov (1971), andKandlikar (2001). Kirichenko and Chernyakov assumed that hydrodynamic instability is responsible for the occurrence of the CHF and proposed the following correlation by considering the effect of the contact angle on the instability wave length, as …”

Section: Critical Heat Fluxesmentioning

confidence: 99%

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Critical heat flux on a vertical surface in saturated pool boiling at high pressures

Sakashita

¹

2016

JTST

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This paper investigates the CHF in saturated pool boiling of ethanol, R141b, and water on a 7 mm diameter vertical copper surface at high pressures. The pressures are from 0.1 to 3 MPa for ethanol, 0.1 to 1.5 MPa for R141b, and 0.1 to 0.8 MPa for water. The results show that the occurrence of CHF is accompanied by the formation of large vapor masses covering most of the heating surface with all three liquids over the whole range of pressures investigated here. The well-known Kutateladze-type CHF correlation explains the variations in the CHF with pressure well for ethanol and R141b, and underestimates the pressure dependence of the CHF for water. A correlation considering the effect of surface wettability on the CHF agrees fairly well with the CHF for water in the whole range of pressures here, when the temperature dependence of the contact angle determined from available data is incorporated into the correlation. This suggests that it is necessary to consider changes in surface wettability with pressure to be able to predict the CHF of water at high pressures.

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“…(2) agrees fairly well with the data within the 20°≤ θ ≤60° range, and predicts higher values than the data for θ <20° and 60°< θ. Further, as stated by Kirichenko and Chernyakov (1971) predicts the CHF for a vertical surface (φ =90°) as 40% lower than the CHF for a horizontal surface (φ =0°). According to the results by Howard and Mudawar (1999) and Brusster (1997), where the effect of surface orientation on CHF was examined with water and FC-72, the CHF is little affected by angle of inclination and takes similar values from φ =0° to 90°.…”

Section: Critical Heat Fluxesmentioning

confidence: 99%

“…According to Fig. 2 in the original paper by Kirichenko and Chernyakov (1971), where Eq. (2) is compared with the CHF for water at 0.1MPa measured by varying the contact angles, Eq.…”

Section: Critical Heat Fluxesmentioning

confidence: 99%

Critical Heat Flux on a Vertical Surface in Saturated Pool Boiling at High Pressures

Sakashita

¹

2016

The Proceedings of the Thermal Engineering Conference

0

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This paper investigates the CHF in saturated pool boiling of ethanol, R141b, and water on a 7 mm diameter vertical copper surface at high pressures. The pressures are from 0.1 to 3 MPa for ethanol, 0.1 to 1.5 MPa for R141b, and 0.1 to 0.8 MPa for water. The results show that the occurrence of CHF is accompanied by the formation of large vapor masses covering most of the heating surface with all three liquids over the whole range of pressures investigated here. The well-known Kutateladze-type CHF correlation explains the variations in the CHF with pressure well for ethanol and R141b, and underestimates the pressure dependence of the CHF for water. A correlation considering the effect of surface wettability on the CHF agrees fairly well with the CHF for water in the whole range of pressures here, when the temperature dependence of the contact angle determined from available data is incorporated into the correlation. This suggests that it is necessary to consider changes in surface wettability with pressure to be able to predict the CHF of water at high pressures.

show abstract