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The effect of drainage on condensation heat transfer / Z. L. Aidoun

Public ISBD Titre : The effect of drainage on condensation heat transfer Type de document : texte imprimé Auteurs : Z. L. Aidoun, Auteur ; A. A. Nicol, Directeur de thèse Editeur : Ecosse : University of Strathclyde Année de publication : 1984 Importance : 255 f. Présentation : ill. Format : 30 cm. Note générale : Thèse de Doctorat : Génie Mécanique : Ecosse, University of Strathclyde : 1984 Annexe f. 257 - 365 . Bibliogr. f. 366 - 375 Langues : Anglais (eng) Mots-clés : Heat  transfer Condenser  tube Water  issuing Drainage  patterns Index. décimale : D003884 Résumé : The experimental and theoretical investigation of the effect of condensate inundation on the heat transfer coefficient of a quiescent vapour condensing on a horizontal condenser tube is reported. Simulated condensation studies have been made using water issuing through a row of small holes drilled along the top of a 28 mm 0.D. copper tube. Adjacent holes were close enough to ensure that a continuous film formed over the whole surface. The drainage mechanism from this tube and also from a second tube, located below, was studied by analysing individual frames on a film taken with a high speed camera. Drainage patterns were studied for a range of water flowrates and the number of drainage sites, drop sizes and frequencies were determined. Additional tests were made with freon 113, water-Teepol and water-Glycerol mixtures to investigate the effets of surface tension and viscosity on the drainage patterns. Drainage behaviour was shown to be markedly dependent on surface tension but relatively insensitive to viscosity. Experiments under real actual condensation conditions have also been carried out on a row of 3 tubes 19.05 mm 0D, 16.53 mm ID and 300 mm length located in a glass condenser to allow for visual observation. In these experiments condensate drainage was increased by recycling part of the condensate collected at the bottom of the condenser through a fourth tube located above the test row and drilled with small holes along the top. The range of mass flowrates recycled was 0 - 70.56 g/s. The pressures and velocities used were respectively 0.20 - 0.66 bar and 0.321 - 1.389 m/s. Average values of overall heat transfer coefficient were obtained in the range 1.653 - 4.061 kW/m²K. Values of steamside heat transfer coefficient were also obtained in the range 4 - 16 kW/m²K. The results were compared with existing correlations, the Nusselt theory for drainage and with a theoretical analysis developed in this thesis based on thin film considerations. The experimental and theoretical results show that for condensation with inundation the heat transfer coefficient decreases with increasing film Reynolds Number. The influence of the cooling water on the heat transfer coefficient is also shown to be appreciable. The effect of drainage on condensation heat transfer [texte imprimé] / Z. L. Aidoun, Auteur ; A. A. Nicol, Directeur de thèse . - Ecosse : University of Strathclyde, 1984 . - 255 f. : ill. ; 30 cm. Thèse de Doctorat : Génie Mécanique : Ecosse, University of Strathclyde : 1984 Annexe f. 257 - 365 . Bibliogr. f. 366 - 375 Langues : Anglais (eng) Mots-clés : Heat  transfer Condenser  tube Water  issuing Drainage  patterns Index. décimale : D003884 Résumé : The experimental and theoretical investigation of the effect of condensate inundation on the heat transfer coefficient of a quiescent vapour condensing on a horizontal condenser tube is reported. Simulated condensation studies have been made using water issuing through a row of small holes drilled along the top of a 28 mm 0.D. copper tube. Adjacent holes were close enough to ensure that a continuous film formed over the whole surface. The drainage mechanism from this tube and also from a second tube, located below, was studied by analysing individual frames on a film taken with a high speed camera. Drainage patterns were studied for a range of water flowrates and the number of drainage sites, drop sizes and frequencies were determined. Additional tests were made with freon 113, water-Teepol and water-Glycerol mixtures to investigate the effets of surface tension and viscosity on the drainage patterns. Drainage behaviour was shown to be markedly dependent on surface tension but relatively insensitive to viscosity. Experiments under real actual condensation conditions have also been carried out on a row of 3 tubes 19.05 mm 0D, 16.53 mm ID and 300 mm length located in a glass condenser to allow for visual observation. In these experiments condensate drainage was increased by recycling part of the condensate collected at the bottom of the condenser through a fourth tube located above the test row and drilled with small holes along the top. The range of mass flowrates recycled was 0 - 70.56 g/s. The pressures and velocities used were respectively 0.20 - 0.66 bar and 0.321 - 1.389 m/s. Average values of overall heat transfer coefficient were obtained in the range 1.653 - 4.061 kW/m²K. Values of steamside heat transfer coefficient were also obtained in the range 4 - 16 kW/m²K. The results were compared with existing correlations, the Nusselt theory for drainage and with a theoretical analysis developed in this thesis based on thin film considerations. The experimental and theoretical results show that for condensation with inundation the heat transfer coefficient decreases with increasing film Reynolds Number. The influence of the cooling water on the heat transfer coefficient is also shown to be appreciable.

Exemplaires

Code-barres	Cote	Support	Localisation	Section	Disponibilité	Spécialité	Etat_Exemplaire
D003884	D003884	Papier	Bibliothèque centrale	Thèse de Doctorat	Disponible	Genie_mecanique	Consultation sur place

Discharge phenomena on thin wires in atmospheric air / Mabrouk Boumagouda

Public ISBD Titre : Discharge phenomena on thin wires in atmospheric air Type de document : texte imprimé Auteurs : Mabrouk Boumagouda, Auteur ; Aked, Directeur de thèse Editeur : Ecosse : University of Strathclyde Année de publication : 1986 Importance : 56 f. Présentation : ill. Format : 30 cm. Note générale : Mémoire de Master : Electrotechnique : Ecosse, University of Strathclyde : 1986 Bibliogr. f. 58 - 60 . Annexe [56] f Langues : Anglais (eng) Mots-clés : Corona  discharges Thin  wires dc  voltages Pulse  discharge Index. décimale : Ms01386 Résumé : The work presented in this thesis was undertaken to investigate the phenomena of corona discharges on thin wires under atmospheric conditions. The first chapter presents a theoretical review which includes the previous experimental work on the subject. This is followed by descriptions of the apparatus, measuring techniques and the experimental procedure. The investigation was divided into three phases. In the first phase, with negative and positive dc voltages applied, the onset corona voltage was recorded along with the glow corona threshold voltage. Current pulse discharge and mean current values were measured and current-voltage characteristics were established. The effects of gap length, wire radius and voltage polarity on corona discharge were examined. A calculation of the electric field is also presented. All the results are compared to those of previous studies. In the next stage, involving impulse voltages of 5/5000 µs waveshape, the 50% corona voltage, V50c was studied and compared to the dc onset voltage. The last stage was concerned with applying higher voltage impulses of different waveshapes, to the wire. The 50% and the minimum breakdown voltage versus gap -length characteristics were studied. Comparisons were made between the results obtained using 1/50 µs and 1/2000 µs waveforms. The effects of gap length, and voltage polarity on the breakdown voltages were examined. Discharge phenomena on thin wires in atmospheric air [texte imprimé] / Mabrouk Boumagouda, Auteur ; Aked, Directeur de thèse . - Ecosse : University of Strathclyde, 1986 . - 56 f. : ill. ; 30 cm. Mémoire de Master : Electrotechnique : Ecosse, University of Strathclyde : 1986 Bibliogr. f. 58 - 60 . Annexe [56] f Langues : Anglais (eng) Mots-clés : Corona  discharges Thin  wires dc  voltages Pulse  discharge Index. décimale : Ms01386 Résumé : The work presented in this thesis was undertaken to investigate the phenomena of corona discharges on thin wires under atmospheric conditions. The first chapter presents a theoretical review which includes the previous experimental work on the subject. This is followed by descriptions of the apparatus, measuring techniques and the experimental procedure. The investigation was divided into three phases. In the first phase, with negative and positive dc voltages applied, the onset corona voltage was recorded along with the glow corona threshold voltage. Current pulse discharge and mean current values were measured and current-voltage characteristics were established. The effects of gap length, wire radius and voltage polarity on corona discharge were examined. A calculation of the electric field is also presented. All the results are compared to those of previous studies. In the next stage, involving impulse voltages of 5/5000 µs waveshape, the 50% corona voltage, V50c was studied and compared to the dc onset voltage. The last stage was concerned with applying higher voltage impulses of different waveshapes, to the wire. The 50% and the minimum breakdown voltage versus gap -length characteristics were studied. Comparisons were made between the results obtained using 1/50 µs and 1/2000 µs waveforms. The effects of gap length, and voltage polarity on the breakdown voltages were examined.

Exemplaires

Code-barres	Cote	Support	Localisation	Section	Disponibilité	Spécialité	Etat_Exemplaire
Ms01386	Ms01386	Papier	Bibliothèque centrale	Mémoire de Master	Disponible