[article] 
inRevue internationale du froid > vol 34, issue 1 (janvier 2011) . - pp. 113-128

Titre :	Heat and mass transfer characteristics of a constrained thin-film ammonia–water bubble absorber
Titre original :	Absorbeur à bulles à ammoniac-eau aux pellicules minces limitées : caractéristiques du transfert de chaleur et de masse
Type de document :	texte imprimé
Année de publication :	2012
Article en page(s) :	pp. 113-128
Langues :	Anglais (eng) Français (fre)
Catégories :	621.5 : Technique pneumatique, du vide, des basses températures
Mots-clés :	Absorbeur; Microcanal; Bulle; Ammoniac; Eau
Index. décimale :	621.56 Technique des basses températures : réfrigération, pompe à chaleur
Résumé :	A study of absorption of ammonia vapour bubbles into a constrained thin-film of ammonia–water solution is presented. A large-aspect-ratio microchannel constrains the thickness of the weak solution film and ammonia vapour bubbles are injected from a porous wall. A counter flowing coolant in a minichannel removes the generated heat of absorption. Experiments and a simple one-dimensional numerical model are used to characterize the absorber performance at a nominal system pressure of 6.2 bar absolute. Effect of varying the mass flow rate of the weak solution, vapour flow rate, solution inlet temperature, and coolant inlet temperature on absorption heat and mass transfer rates and exit subcooling are discussed. Two absorber channel geometries, each of 600 ?m nominal depth, are considered: 1) a smooth-wall channel, and 2) a stepped-wall channel that has 2-mm deep trenches across the width of a channel wall. Results indicate that the reduction in coolant inlet temperature significantly enhances the mass transfer rates in both absorber geometries. While the stepped-wall geometry exhibits higher mass transfer rates at lower coolant inlet temperatures of 30 °C and 40 °C, the smooth-wall channel shows higher mass transfer rates at the highest coolant inlet temperature of 58 °C. Both absorption limited and residence time limited conditions are observed with variation of weak solution flow rate at fixed vapour flow rates.

[article] Heat and mass transfer characteristics of a constrained thin-film ammonia–water bubble absorber = Absorbeur à bulles à ammoniac-eau aux pellicules minces limitées : caractéristiques du transfert de chaleur et de masse [texte imprimé] . - 2012 . - pp. 113-128.
Langues : Anglais (eng) Français (fre)
in Revue internationale du froid > vol 34, issue 1 (janvier 2011) . - pp. 113-128

Catégories :	621.5 : Technique pneumatique, du vide, des basses températures
Mots-clés :	Absorbeur; Microcanal; Bulle; Ammoniac; Eau
Index. décimale :	621.56 Technique des basses températures : réfrigération, pompe à chaleur
Résumé :	A study of absorption of ammonia vapour bubbles into a constrained thin-film of ammonia–water solution is presented. A large-aspect-ratio microchannel constrains the thickness of the weak solution film and ammonia vapour bubbles are injected from a porous wall. A counter flowing coolant in a minichannel removes the generated heat of absorption. Experiments and a simple one-dimensional numerical model are used to characterize the absorber performance at a nominal system pressure of 6.2 bar absolute. Effect of varying the mass flow rate of the weak solution, vapour flow rate, solution inlet temperature, and coolant inlet temperature on absorption heat and mass transfer rates and exit subcooling are discussed. Two absorber channel geometries, each of 600 ?m nominal depth, are considered: 1) a smooth-wall channel, and 2) a stepped-wall channel that has 2-mm deep trenches across the width of a channel wall. Results indicate that the reduction in coolant inlet temperature significantly enhances the mass transfer rates in both absorber geometries. While the stepped-wall geometry exhibits higher mass transfer rates at lower coolant inlet temperatures of 30 °C and 40 °C, the smooth-wall channel shows higher mass transfer rates at the highest coolant inlet temperature of 58 °C. Both absorption limited and residence time limited conditions are observed with variation of weak solution flow rate at fixed vapour flow rates.