Abstract
The main results obtained at Grenoble during the last four years in the field of boiling mechanisms and related phenomena in nuclear reactors are reported. 1 - Observation Of Boiling: By the use of photography and ultrafast cinematography (8000 frames per second maximum), boiling in a vessel or a tube was observed up to 140 kg/cm{sup 2}. The populations of bubble-generating seeds (sites) were counted, and a correlation established giving their number per unit of surface area as a function of the thermal flux and the pressure. The diameter of the bubbles breaking of from the wall was studied up to 140 kg/cm{sup 2}: three types of bubble have been shown to exist: - those in equilibrium, their diameter following the formula of Fritz and Ende, - bubbles found by boiling, the diameters of which decrease rapidly with the pressure (1/100 mm to 140 kg/cm{sup 2}), - the coalescences which appear in saturated liquid above 15 W/cm{sup 2}, their proportion being independent of the pressure. Strioscopic observations were made of the movements of the thermal film associated with the generation of the seeds, at the initiation and condensation of the bubbles, the mechanisms responsible for the highly efficient heat transfer
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Mondin, H;
Lavigne, P;
Semeria, R
[1]
- Commissariat a l'Energie Atomique, Grenoble (France). Centre d'Etudes Nucleaires
Citation Formats
Mondin, H, Lavigne, P, and Semeria, R.
Some fundamental aspects of boiling in nuclear reactors; Quelques aspects fondamentaux de l'ebullition dans les reacteurs nucleaires.
France: N. p.,
1964.
Web.
Mondin, H, Lavigne, P, & Semeria, R.
Some fundamental aspects of boiling in nuclear reactors; Quelques aspects fondamentaux de l'ebullition dans les reacteurs nucleaires.
France.
Mondin, H, Lavigne, P, and Semeria, R.
1964.
"Some fundamental aspects of boiling in nuclear reactors; Quelques aspects fondamentaux de l'ebullition dans les reacteurs nucleaires."
France.
@misc{etde_20668372,
title = {Some fundamental aspects of boiling in nuclear reactors; Quelques aspects fondamentaux de l'ebullition dans les reacteurs nucleaires}
author = {Mondin, H, Lavigne, P, and Semeria, R}
abstractNote = {The main results obtained at Grenoble during the last four years in the field of boiling mechanisms and related phenomena in nuclear reactors are reported. 1 - Observation Of Boiling: By the use of photography and ultrafast cinematography (8000 frames per second maximum), boiling in a vessel or a tube was observed up to 140 kg/cm{sup 2}. The populations of bubble-generating seeds (sites) were counted, and a correlation established giving their number per unit of surface area as a function of the thermal flux and the pressure. The diameter of the bubbles breaking of from the wall was studied up to 140 kg/cm{sup 2}: three types of bubble have been shown to exist: - those in equilibrium, their diameter following the formula of Fritz and Ende, - bubbles found by boiling, the diameters of which decrease rapidly with the pressure (1/100 mm to 140 kg/cm{sup 2}), - the coalescences which appear in saturated liquid above 15 W/cm{sup 2}, their proportion being independent of the pressure. Strioscopic observations were made of the movements of the thermal film associated with the generation of the seeds, at the initiation and condensation of the bubbles, the mechanisms responsible for the highly efficient heat transfer could thus be defined. 2 - Pressure Losses In Two-Phase Flow: A physical model of the continuous variation of the free space content in a boiling channel has been proposed by means of which the pressure losses can be calculated without invoking a break in the coefficient of friction when free boiling begins. Agreement between theory and experiment is satisfactory. The various forms which total pressure loss in a boiling tube may present as a function of flow rate have been studied. Special features are observed at very low and very high speeds. 3 - Burn-Out: Under steady operating conditions, it is shown that in a uniformly heated channel the burn-out flux as a function of output rate is generally independent of the length. When burn-out is a result of output oscillation, the conditions of burnout are compared with those obtained under steady conditions. The burn-out flux following uniform 'stopped' heating has been studied in a channel containing still water. The flux shows a maximum as a function of unsaturation. The influence of the geometry and the nature of the metal was investigated. 4 - Output Oscillations: Using a low pressure (8 atm) loop, the influence of various parameters on the periods of output oscillations in a boiling channel on the thresholds at which they appear, was studied. Some new aspects of this complex phenomena were observed and are reported. (authors) [French] On indique les principaux resultats obtenus a Grenoble depuis quatre ans dans le domaine des mecanismes de l'ebullition et des phenomenes connexes dans les reacteurs nucleaires. 1 - OBSERVATION DE L'EBULLITION: Par photographie et cinematographie ultrarapide (8000 images par seconde maximum) on a observe l'ebullition en vase ou en canal jusqu'a 140 kg/cm{sup 2}. On a denombre les populations de germes (sites) generateurs de bulles et obtenu une correlation donnant leur nombre par unite de surface en fonction du flux thermique et de la pression. Le diametre des bulles se detachant de la paroi a ete etudie jusqu'a 140 kg/cm{sup 2}. On a mis en evidence trois types de bulles: - Les bulles en equilibre dont le diametre suit la formule de Fritz et Ende, - Les bulles d'ebullition dont le diametre diminue rapidement avec la pression (1/100 mm a 140 kg/cm{sup 2}), - Les coalescences apparaissant en liquide sature au-dessus de 15 W/cm{sup 2} et dont la proportion est independante de la pression. Par visualisation en strioscopie on observe les mouvements du film thermique associes a l'amorcage des germes, au depart et a la condensation des bulles; les mecanismes responsables de l'excellent transfert de chaleur ont pu ainsi etre precises. 2 - PERTES DE PRESSION EN ECOULEMENT DIPHASE: On a etabli un modele de variation continue du taux de vide dans un canal bouillant permettant de calculer les pertes de pression sans discontinuite du coefficient de frottement au debut de l'ebullition franche. La comparaison avec l'experience est satisfaisante. On a etudie les diverses formes que peut presenter la perte de pression totale dans un canal bouillant en fonction du debit. Des singularites sont observees aux vitesses tres faibles et tres fortes. 3 - CALEFACTION (burn out): En regime etabli, on montre que dans un canal a chauffage uniforme le flux de calefaction en fonction du titre de sortie est en general independant de la longueur. Lorsque la calefaction est la consequence d'oscillation de debit, on compare les conditions de calefaction a celles obtenues en regime etabli. On a etudie le flux de calefaction a la suite d'un chauffage uniforme 'en echelon' dans un canal contenant de l'eau sans mouvement. Le flux comporte un maximum en fonction de la sous saturation. On a examine l'influence de la geometrie et de la nature du metal. 4 - OSCILLATIONS DE DEBIT: Sur une boucle a faible pression (8 atm) on a cherche l'influence de divers parametres sur les seuils d'apparition et sur les periodes d'oscillations de debit dans un canal bouillant. On enumere quelques aspects nouveaux de ce phenomene complexe observes a cette occasion. (auteurs)}
place = {France}
year = {1964}
month = {Jul}
}
title = {Some fundamental aspects of boiling in nuclear reactors; Quelques aspects fondamentaux de l'ebullition dans les reacteurs nucleaires}
author = {Mondin, H, Lavigne, P, and Semeria, R}
abstractNote = {The main results obtained at Grenoble during the last four years in the field of boiling mechanisms and related phenomena in nuclear reactors are reported. 1 - Observation Of Boiling: By the use of photography and ultrafast cinematography (8000 frames per second maximum), boiling in a vessel or a tube was observed up to 140 kg/cm{sup 2}. The populations of bubble-generating seeds (sites) were counted, and a correlation established giving their number per unit of surface area as a function of the thermal flux and the pressure. The diameter of the bubbles breaking of from the wall was studied up to 140 kg/cm{sup 2}: three types of bubble have been shown to exist: - those in equilibrium, their diameter following the formula of Fritz and Ende, - bubbles found by boiling, the diameters of which decrease rapidly with the pressure (1/100 mm to 140 kg/cm{sup 2}), - the coalescences which appear in saturated liquid above 15 W/cm{sup 2}, their proportion being independent of the pressure. Strioscopic observations were made of the movements of the thermal film associated with the generation of the seeds, at the initiation and condensation of the bubbles, the mechanisms responsible for the highly efficient heat transfer could thus be defined. 2 - Pressure Losses In Two-Phase Flow: A physical model of the continuous variation of the free space content in a boiling channel has been proposed by means of which the pressure losses can be calculated without invoking a break in the coefficient of friction when free boiling begins. Agreement between theory and experiment is satisfactory. The various forms which total pressure loss in a boiling tube may present as a function of flow rate have been studied. Special features are observed at very low and very high speeds. 3 - Burn-Out: Under steady operating conditions, it is shown that in a uniformly heated channel the burn-out flux as a function of output rate is generally independent of the length. When burn-out is a result of output oscillation, the conditions of burnout are compared with those obtained under steady conditions. The burn-out flux following uniform 'stopped' heating has been studied in a channel containing still water. The flux shows a maximum as a function of unsaturation. The influence of the geometry and the nature of the metal was investigated. 4 - Output Oscillations: Using a low pressure (8 atm) loop, the influence of various parameters on the periods of output oscillations in a boiling channel on the thresholds at which they appear, was studied. Some new aspects of this complex phenomena were observed and are reported. (authors) [French] On indique les principaux resultats obtenus a Grenoble depuis quatre ans dans le domaine des mecanismes de l'ebullition et des phenomenes connexes dans les reacteurs nucleaires. 1 - OBSERVATION DE L'EBULLITION: Par photographie et cinematographie ultrarapide (8000 images par seconde maximum) on a observe l'ebullition en vase ou en canal jusqu'a 140 kg/cm{sup 2}. On a denombre les populations de germes (sites) generateurs de bulles et obtenu une correlation donnant leur nombre par unite de surface en fonction du flux thermique et de la pression. Le diametre des bulles se detachant de la paroi a ete etudie jusqu'a 140 kg/cm{sup 2}. On a mis en evidence trois types de bulles: - Les bulles en equilibre dont le diametre suit la formule de Fritz et Ende, - Les bulles d'ebullition dont le diametre diminue rapidement avec la pression (1/100 mm a 140 kg/cm{sup 2}), - Les coalescences apparaissant en liquide sature au-dessus de 15 W/cm{sup 2} et dont la proportion est independante de la pression. Par visualisation en strioscopie on observe les mouvements du film thermique associes a l'amorcage des germes, au depart et a la condensation des bulles; les mecanismes responsables de l'excellent transfert de chaleur ont pu ainsi etre precises. 2 - PERTES DE PRESSION EN ECOULEMENT DIPHASE: On a etabli un modele de variation continue du taux de vide dans un canal bouillant permettant de calculer les pertes de pression sans discontinuite du coefficient de frottement au debut de l'ebullition franche. La comparaison avec l'experience est satisfaisante. On a etudie les diverses formes que peut presenter la perte de pression totale dans un canal bouillant en fonction du debit. Des singularites sont observees aux vitesses tres faibles et tres fortes. 3 - CALEFACTION (burn out): En regime etabli, on montre que dans un canal a chauffage uniforme le flux de calefaction en fonction du titre de sortie est en general independant de la longueur. Lorsque la calefaction est la consequence d'oscillation de debit, on compare les conditions de calefaction a celles obtenues en regime etabli. On a etudie le flux de calefaction a la suite d'un chauffage uniforme 'en echelon' dans un canal contenant de l'eau sans mouvement. Le flux comporte un maximum en fonction de la sous saturation. On a examine l'influence de la geometrie et de la nature du metal. 4 - OSCILLATIONS DE DEBIT: Sur une boucle a faible pression (8 atm) on a cherche l'influence de divers parametres sur les seuils d'apparition et sur les periodes d'oscillations de debit dans un canal bouillant. On enumere quelques aspects nouveaux de ce phenomene complexe observes a cette occasion. (auteurs)}
place = {France}
year = {1964}
month = {Jul}
}