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Experimental study on pressure drop and heat transfer of turbulent flow in tube in tube helical heat exchanger / Monisha Mridha Mandal in Industrial & engineering chemistry research, Vol. 48 N° 20 (Octobre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 20 (Octobre 2009) . - pp. 9318–9324 Titre : Experimental study on pressure drop and heat transfer of turbulent flow in tube in tube helical heat exchanger Type de document : texte imprimé Auteurs : Monisha Mridha Mandal, Auteur ; K. D. P. Nigam, Auteur Année de publication : 2010 Article en page(s) : pp. 9318–9324 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Turbulent  flow  Heat  transfer  Fluid  flow  Reynolds  numbers Résumé : In the present study, experiments were conducted for the first time in tube in tube helical heat exchanger at the pilot plant scale to investigate the fluid flow and heat transfer under turbulent flow conditions. The experiments were carried out with hot compressed air in the inner tube and cooling water in the outer tube in the countercurrent mode of operation. The flow rate of compressed air flowing in the inner tube was varied for Reynolds numbers from 14 000 to 86 000. The pressure of compressed air was varied from 10 to 30 kgf/cm2. The friction factor and Nusselt number values for compressed air flowing in the inner tube were calculated for elevated pressure and compared with the experimental data reported in the literature at ambient conditions. Most of the works reported in the literature on heat transfer in coiled tubes have been carried out considering wall boundary conditions of either constant heat flux or constant wall temperature. In the present work, heat transfer calculations were based on physically realistic condition of fluid to fluid heat transfer. The inner tube Nusselt number of compressed air in the present study was found to be slightly higher than the data reported in the literature for ambient conditions while the friction factor values are within the range reported in the literature for ambient conditions. The friction factor as well as Nusselt number calculated for cooling water flowing in the outer tube was higher than the existing literature data. On the basis of the experimental results, new correlations for friction factor and Nusselt number in the inner as well as outer tubes have been developed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002393 [article] Experimental study on pressure drop and heat transfer of turbulent flow in tube in tube helical heat exchanger [texte imprimé] / Monisha Mridha Mandal, Auteur ; K. D. P. Nigam, Auteur . - 2010 . - pp. 9318–9324. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 20 (Octobre 2009) . - pp. 9318–9324 Mots-clés : Turbulent  flow  Heat  transfer  Fluid  flow  Reynolds  numbers Résumé : In the present study, experiments were conducted for the first time in tube in tube helical heat exchanger at the pilot plant scale to investigate the fluid flow and heat transfer under turbulent flow conditions. The experiments were carried out with hot compressed air in the inner tube and cooling water in the outer tube in the countercurrent mode of operation. The flow rate of compressed air flowing in the inner tube was varied for Reynolds numbers from 14 000 to 86 000. The pressure of compressed air was varied from 10 to 30 kgf/cm2. The friction factor and Nusselt number values for compressed air flowing in the inner tube were calculated for elevated pressure and compared with the experimental data reported in the literature at ambient conditions. Most of the works reported in the literature on heat transfer in coiled tubes have been carried out considering wall boundary conditions of either constant heat flux or constant wall temperature. In the present work, heat transfer calculations were based on physically realistic condition of fluid to fluid heat transfer. The inner tube Nusselt number of compressed air in the present study was found to be slightly higher than the data reported in the literature for ambient conditions while the friction factor values are within the range reported in the literature for ambient conditions. The friction factor as well as Nusselt number calculated for cooling water flowing in the outer tube was higher than the existing literature data. On the basis of the experimental results, new correlations for friction factor and Nusselt number in the inner as well as outer tubes have been developed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002393

Liquid – liquid mixing in coiled flow inverter / Monisha Mridha Mandal in Industrial & engineering chemistry research, Vol. 50 N° 23 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 13230-13235 Titre : Liquid – liquid mixing in coiled flow inverter Type de document : texte imprimé Auteurs : Monisha Mridha Mandal, Auteur ; Palka Aggarwal, Auteur ; K. D. P. Nigam, Auteur Année de publication : 2012 Article en page(s) : pp. 13230-13235 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Mixing Résumé : The mixing of liquids is a common operation in process industries such as refineries and chemical and pharmaceutical industries, etc. However, the problem of mixing of different liquids has not been rigorously characterized. Therefore, the objective of this paper is to investigate liquid―liquid mixing in a novel coiled flow inverter (CFI). The device works on the principle of flow inversion which is achieved by bending a coiled tube to 90° at equidistant length. In the present study, velocity field and scalar concentration distribution of liquids were characterized. The mixing performances and pressure drop in CFI was investigated and compared with that of a straight, coiled tube and helical element mixer (HEM) for a liquid flow range of 98 ≤ Re ≤ 1020. CFI exhibits significant mixing of two liquids with negligible change in pressure drop as compared to a coiled tube as well as a HEM. The present study reveals that CFI is an efficient device for the mixing of two liquids in process industries. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25267478 [article] Liquid – liquid mixing in coiled flow inverter [texte imprimé] / Monisha Mridha Mandal, Auteur ; Palka Aggarwal, Auteur ; K. D. P. Nigam, Auteur . - 2012 . - pp. 13230-13235. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 13230-13235 Mots-clés : Mixing Résumé : The mixing of liquids is a common operation in process industries such as refineries and chemical and pharmaceutical industries, etc. However, the problem of mixing of different liquids has not been rigorously characterized. Therefore, the objective of this paper is to investigate liquid―liquid mixing in a novel coiled flow inverter (CFI). The device works on the principle of flow inversion which is achieved by bending a coiled tube to 90° at equidistant length. In the present study, velocity field and scalar concentration distribution of liquids were characterized. The mixing performances and pressure drop in CFI was investigated and compared with that of a straight, coiled tube and helical element mixer (HEM) for a liquid flow range of 98 ≤ Re ≤ 1020. CFI exhibits significant mixing of two liquids with negligible change in pressure drop as compared to a coiled tube as well as a HEM. The present study reveals that CFI is an efficient device for the mixing of two liquids in process industries. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25267478