Documents disponibles écrits par cet auteur

Heat conduction through eccentric annuli / Manoj Kumar Moharana in Journal of heat transfer, Vol 134 N° 9 (Septembre 2012) 

Public ISBD [article]  in Journal of heat transfer > Vol 134 N° 9 (Septembre 2012) . - 09 p. Titre : Heat conduction through eccentric annuli : an appraisal of analytical, semi-analytical, and approximate techniques Type de document : texte imprimé Auteurs : Manoj Kumar Moharana, Auteur ; Prasanta Kumar Das, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : heat transfer Langues : Anglais (eng) Mots-clés : eccentric  annulus;  boundary  collocation  method;  sector  method;  perturbation  expansion;  shape  factor;  crossover  perimeter;  critical  perimeter;  heat  conduction Index. décimale : 536 Chaleur. Thermodynamique Résumé : The problem of conduction heat transfer through an eccentric annulus with the inner surface kept at a constant temperature and the outer surface subjected to convective condition is solved by three different techniques. A perturbation analysis yields an analytical expression for temperature profile for small values of eccentricity. The two dimensional conduction problem has also been solved by a two dimensional semi-analytical technique in which the condition at the outer periphery is matched by a collocation technique. Finally, a one dimensional approximate technique namely sector method has been used to solve the same problem. The sector method does not require any numerical technique yet yields remarkable accuracy. Next, the heat flow through an eccentric insulation surrounding a circular cylinder was considered. It has been demonstrated that the sector method is effective also in determining the geometry of the critical insulation in this case over a wide range of radius ratio and Biot number. Finally, both all the three methods, i.e., the perturbation technique, the boundary collocation method and the sector method have been applied to determine the geometry of the critical as well as crossover perimeter of insulation around a circular cylinder when the insulation is provided eccentrically. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000009 [...] [article] Heat conduction through eccentric annuli : an appraisal of analytical, semi-analytical, and approximate techniques [texte imprimé] / Manoj Kumar Moharana, Auteur ; Prasanta Kumar Das, Auteur . - 2012 . - 09 p. heat transfer Langues : Anglais (eng) in Journal of heat transfer > Vol 134 N° 9 (Septembre 2012) . - 09 p. Mots-clés : eccentric  annulus;  boundary  collocation  method;  sector  method;  perturbation  expansion;  shape  factor;  crossover  perimeter;  critical  perimeter;  heat  conduction Index. décimale : 536 Chaleur. Thermodynamique Résumé : The problem of conduction heat transfer through an eccentric annulus with the inner surface kept at a constant temperature and the outer surface subjected to convective condition is solved by three different techniques. A perturbation analysis yields an analytical expression for temperature profile for small values of eccentricity. The two dimensional conduction problem has also been solved by a two dimensional semi-analytical technique in which the condition at the outer periphery is matched by a collocation technique. Finally, a one dimensional approximate technique namely sector method has been used to solve the same problem. The sector method does not require any numerical technique yet yields remarkable accuracy. Next, the heat flow through an eccentric insulation surrounding a circular cylinder was considered. It has been demonstrated that the sector method is effective also in determining the geometry of the critical insulation in this case over a wide range of radius ratio and Biot number. Finally, both all the three methods, i.e., the perturbation technique, the boundary collocation method and the sector method have been applied to determine the geometry of the critical as well as crossover perimeter of insulation around a circular cylinder when the insulation is provided eccentrically. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000009 [...]

Optimum Nusselt number for simultaneously developing internal flow under conjugate conditions in a square microchannel / Manoj Kumar Moharana in Journal of heat transfer, Vol. 134 N° 7 (Juillet 2012) 

Public ISBD [article]  in Journal of heat transfer > Vol. 134 N° 7 (Juillet 2012) . - 10 p. Titre : Optimum Nusselt number for simultaneously developing internal flow under conjugate conditions in a square microchannel Type de document : texte imprimé Auteurs : Manoj Kumar Moharana, Auteur ; Piyush Kumar Singh, Auteur ; Sameer Khandekar, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : heat transfer Langues : Anglais (eng) Mots-clés : microchannel;  axial  heat  conduction;  conjugate  heat  transfer;  thermally  developing  flow;  optimum  Nusselt  number Index. décimale : 536 Chaleur. Thermodynamique Résumé : A numerical study has been carried out to understand and highlight the effects of axial wall conduction in a conjugate heat transfer situation involving simultaneously developing laminar flow and heat transfer in a square microchannel with constant flux boundary condition imposed on bottom of the substrate wall. All the remaining walls of the substrate exposed to the surroundings are kept adiabatic. Simulations have been carried out for a wide range of substrate wall to fluid conductivity ratio (ksf ~ 0.17–703), substrate thickness to channel depth (deltasf ~ 1–24), and flow rate (Re ~ 100–1000). These parametric variations cover the typical range of applications encountered in microfluids/microscale heat transfer domains. The results show that the conductivity ratio, ksf is the key factor in affecting the extent of axial conduction on the heat transport characteristics at the fluid–solid interface. Higher ksf leads to severe axial back conduction, thus decreasing the average Nusselt number ([overline Nu]). Very low ksf leads to a situation which is qualitatively similar to the case of zero-thickness substrate with constant heat flux applied to only one side, all the three remaining sides being kept adiabatic; this again leads to lower the average Nusselt number ([overline Nu]). Between these two asymptotic limits of ksf, it is shown that, all other parameters remaining the same (deltasf and Re), there exists an optimum value of ksf which maximizes the average Nusselt number ([overline Nu]). Such a phenomenon also exists for the case of circular microtubes. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000007 [...] [article] Optimum Nusselt number for simultaneously developing internal flow under conjugate conditions in a square microchannel [texte imprimé] / Manoj Kumar Moharana, Auteur ; Piyush Kumar Singh, Auteur ; Sameer Khandekar, Auteur . - 2012 . - 10 p. heat transfer Langues : Anglais (eng) in Journal of heat transfer > Vol. 134 N° 7 (Juillet 2012) . - 10 p. Mots-clés : microchannel;  axial  heat  conduction;  conjugate  heat  transfer;  thermally  developing  flow;  optimum  Nusselt  number Index. décimale : 536 Chaleur. Thermodynamique Résumé : A numerical study has been carried out to understand and highlight the effects of axial wall conduction in a conjugate heat transfer situation involving simultaneously developing laminar flow and heat transfer in a square microchannel with constant flux boundary condition imposed on bottom of the substrate wall. All the remaining walls of the substrate exposed to the surroundings are kept adiabatic. Simulations have been carried out for a wide range of substrate wall to fluid conductivity ratio (ksf ~ 0.17–703), substrate thickness to channel depth (deltasf ~ 1–24), and flow rate (Re ~ 100–1000). These parametric variations cover the typical range of applications encountered in microfluids/microscale heat transfer domains. The results show that the conductivity ratio, ksf is the key factor in affecting the extent of axial conduction on the heat transport characteristics at the fluid–solid interface. Higher ksf leads to severe axial back conduction, thus decreasing the average Nusselt number ([overline Nu]). Very low ksf leads to a situation which is qualitatively similar to the case of zero-thickness substrate with constant heat flux applied to only one side, all the three remaining sides being kept adiabatic; this again leads to lower the average Nusselt number ([overline Nu]). Between these two asymptotic limits of ksf, it is shown that, all other parameters remaining the same (deltasf and Re), there exists an optimum value of ksf which maximizes the average Nusselt number ([overline Nu]). Such a phenomenon also exists for the case of circular microtubes. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000007 [...]