Documents disponibles écrits par cet auteur

Cost and entropy generation minimization of a cross-flow plate fin heat exchanger using multi-objective genetic algorithm / Pouria Ahmadi in Journal of heat transfer, Vol. 133 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 2 (Fevrier 2011) . - pp. [021801/1-10] Titre : Cost and entropy generation minimization of a cross-flow plate fin heat exchanger using multi-objective genetic algorithm Type de document : texte imprimé Auteurs : Pouria Ahmadi, Auteur ; Hassan Hajabdollahi, Auteur ; Ibrahim Dincer, Auteur Année de publication : 2011 Article en page(s) : pp. [021801/1-10] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  exchanger  Heat  transfer  Number  of  generation  units  Cost  Optimization  Genetic  algorithm Index. décimale : 536 Chaleur. Thermodynamique Résumé : In the present work, a thermal modeling is conducted for optimal design of compact heat exchangers in order to minimize cost and entropy generation. In this regard, an epsilon−NTU method is applied for estimation of the heat exchanger pressure drop, as well as effectiveness. Fin pitch, fin height, fin offset length, cold stream flow length, no-flow length, and hot stream flow length are considered as six decision variables. Fast and elitist nondominated sorting genetic algorithm (i.e., nondominated sorting genetic algorithm II) is applied to minimize the entropy generation units and the total annual cost (sum of initial investment and operating and maintenance costs) simultaneously. The results for Pareto-optimal front clearly reveal the conflict between two objective functions, the number of entropy generation units and the total annual cost. It reveals that any geometrical changes, which decrease the number of entropy generation units, lead to an increase in the total annual cost and vice versa. Moreover, for prediction of the optimal design of the plate fin heat exchanger, an equation for the number of entropy generation units versus the total annual cost is derived for the Pareto curve. In addition, optimization of heat exchangers based on considering exergy destruction revealed that irreversibilities, such as pressure drop and high temperature difference between cold and hot streams, play a key issue in exergy destruction. Thus, more efficient heat exchanger leads to have a heat exchanger with higher total cost rate. Finally, the sensitivity analysis of change in the optimum number of entropy generation units and the total annual cost with change in the decision variables of the plate fin heat exchanger is also performed, and the results are reported. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Cost and entropy generation minimization of a cross-flow plate fin heat exchanger using multi-objective genetic algorithm [texte imprimé] / Pouria Ahmadi, Auteur ; Hassan Hajabdollahi, Auteur ; Ibrahim Dincer, Auteur . - 2011 . - pp. [021801/1-10]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 2 (Fevrier 2011) . - pp. [021801/1-10] Mots-clés : Heat  exchanger  Heat  transfer  Number  of  generation  units  Cost  Optimization  Genetic  algorithm Index. décimale : 536 Chaleur. Thermodynamique Résumé : In the present work, a thermal modeling is conducted for optimal design of compact heat exchangers in order to minimize cost and entropy generation. In this regard, an epsilon−NTU method is applied for estimation of the heat exchanger pressure drop, as well as effectiveness. Fin pitch, fin height, fin offset length, cold stream flow length, no-flow length, and hot stream flow length are considered as six decision variables. Fast and elitist nondominated sorting genetic algorithm (i.e., nondominated sorting genetic algorithm II) is applied to minimize the entropy generation units and the total annual cost (sum of initial investment and operating and maintenance costs) simultaneously. The results for Pareto-optimal front clearly reveal the conflict between two objective functions, the number of entropy generation units and the total annual cost. It reveals that any geometrical changes, which decrease the number of entropy generation units, lead to an increase in the total annual cost and vice versa. Moreover, for prediction of the optimal design of the plate fin heat exchanger, an equation for the number of entropy generation units versus the total annual cost is derived for the Pareto curve. In addition, optimization of heat exchangers based on considering exergy destruction revealed that irreversibilities, such as pressure drop and high temperature difference between cold and hot streams, play a key issue in exergy destruction. Thus, more efficient heat exchanger leads to have a heat exchanger with higher total cost rate. Finally, the sensitivity analysis of change in the optimum number of entropy generation units and the total annual cost with change in the decision variables of the plate fin heat exchanger is also performed, and the results are reported. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Laminar boundary layer development around a circular cylinder / A. Alper Ozalp in Journal of heat transfer, Vol. 132 N° 12 (Décembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 12 (Décembre 2010) . - pp. [121703-1/17] Titre : Laminar boundary layer development around a circular cylinder : fluid flow and heat-mass transfer characteristics Type de document : texte imprimé Auteurs : A. Alper Ozalp, Auteur ; Ibrahim Dincer, Auteur Année de publication : 2010 Article en page(s) : pp. [121703-1/17] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  transfer  Fluid  flow  Mass  transfer  Confined  flow  Friction  coefficient  Moisture  diffusivity  Moisure  transfer  Coefficient  Drying Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper presents a comprehensive computational work on the hydrodynamic, thermal, and mass transfer characteristics of a circular cylinder, subjected to confined flow at the cylinder Reynolds number of Red=40. As the two-dimensional, steady and incompressible momentum and energy equations are solved using ANSYS-CFX (version 11.0), the moisture distributions are computed by a new alternating direction implicit method based software. The significant results, highlighting the influence of blockage (beta=0.200–0.800) on the flow and heat transfer mechanism and clarifying the combined roles of beta and moisture diffusivity (D=1×10−8–1×10−5 m2/s) on the mass transfer behavior, are obtained for practical applications. It is shown that the blockage augments the friction coefficients (Cf) and Nusselt numbers (Nu) on the complete cylinder surface, where the average Nu are evaluated as Nuave=3.66, 4.05, 4.97, and 6.51 for beta=0.200, 0.333, 0.571, and 0.800. Moreover, the blockage shifts separation (thetas) and maximum Cf locations (thetaCf−max) downstream to the positions of thetas=54.10, 50.20, 41.98, and 37.30 deg and thetaCf−max=51.5, 53.4, 74.9, and 85.4 deg. The highest blockage of beta=0.800 encourages the downstream backward velocity values, which as a consequence disturbs the boundary layer and weakens the fluid-solid contact. The center and average moisture contents differ significantly at the beginning of drying process, but in the last 5% of the drying period they vary only by 1.6%. Additionally, higher blockage augments mass transfer coefficients (hm) on the overall cylinder surface; however, the growing rate of back face mass transfer coefficients (hm−bf) is dominant to that of the front face values (hm−ff), with the interpreting ratios of [overline h]m−bf/[overline h]m=0.50 and 0.57 and [overline h]m−ff/[overline h]m=1.50 and 1.43 for beta=0.200 and 0.800. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Laminar boundary layer development around a circular cylinder : fluid flow and heat-mass transfer characteristics [texte imprimé] / A. Alper Ozalp, Auteur ; Ibrahim Dincer, Auteur . - 2010 . - pp. [121703-1/17]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 12 (Décembre 2010) . - pp. [121703-1/17] Mots-clés : Heat  transfer  Fluid  flow  Mass  transfer  Confined  flow  Friction  coefficient  Moisture  diffusivity  Moisure  transfer  Coefficient  Drying Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper presents a comprehensive computational work on the hydrodynamic, thermal, and mass transfer characteristics of a circular cylinder, subjected to confined flow at the cylinder Reynolds number of Red=40. As the two-dimensional, steady and incompressible momentum and energy equations are solved using ANSYS-CFX (version 11.0), the moisture distributions are computed by a new alternating direction implicit method based software. The significant results, highlighting the influence of blockage (beta=0.200–0.800) on the flow and heat transfer mechanism and clarifying the combined roles of beta and moisture diffusivity (D=1×10−8–1×10−5 m2/s) on the mass transfer behavior, are obtained for practical applications. It is shown that the blockage augments the friction coefficients (Cf) and Nusselt numbers (Nu) on the complete cylinder surface, where the average Nu are evaluated as Nuave=3.66, 4.05, 4.97, and 6.51 for beta=0.200, 0.333, 0.571, and 0.800. Moreover, the blockage shifts separation (thetas) and maximum Cf locations (thetaCf−max) downstream to the positions of thetas=54.10, 50.20, 41.98, and 37.30 deg and thetaCf−max=51.5, 53.4, 74.9, and 85.4 deg. The highest blockage of beta=0.800 encourages the downstream backward velocity values, which as a consequence disturbs the boundary layer and weakens the fluid-solid contact. The center and average moisture contents differ significantly at the beginning of drying process, but in the last 5% of the drying period they vary only by 1.6%. Additionally, higher blockage augments mass transfer coefficients (hm) on the overall cylinder surface; however, the growing rate of back face mass transfer coefficients (hm−bf) is dominant to that of the front face values (hm−ff), with the interpreting ratios of [overline h]m−bf/[overline h]m=0.50 and 0.57 and [overline h]m−ff/[overline h]m=1.50 and 1.43 for beta=0.200 and 0.800. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle / Hakan Caliskan in International journal of refrigeration, Vol. 34 N° 4 (Juin 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 980-990 Titre : Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle Titre original : Evaluation de la performance thermodynamique d'un nouveau cycle de refroidissement : le cycle de Maisotsenko Type de document : texte imprimé Auteurs : Hakan Caliskan, Auteur ; Arif Hepbasli, Auteur ; Ibrahim Dincer, Auteur Année de publication : 2011 Article en page(s) : pp. 980-990 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Energy  Exergy  Cooling  Air  cooler  Evaporative  system  Maisotsenko  cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study presents energy and exergy analyses and sustainability assessment of the novel evaporative air cooling system based on Maisotsenko cycle which allows the product fluid to be cooled in to a dew point temperature of the incoming air. In the energy analysis, Maisotsenko cycle’s wet-bulb and dew point effectiveness, COP and primary energy ratio rates are calculated. Exergy analysis of the system is then carried out for six reference temperatures ranging from 0 °C to 23.88 °C as the incoming air (surrounding) temperature. The specific flow exergy, exergy input, exergy output, exergy destruction, exergy loss, exergy efficiency, exergetic COP, primary exergy ratio and entropy generation rates are determined for various cases. Furthermore, sustainability assessment is obtained using sustainability index method. As a result, maximum exergy efficiency is found to be 19.14% for a reference temperature of 23.88 °C where the optimum operation takes place. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000363 [article] Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle = Evaluation de la performance thermodynamique d'un nouveau cycle de refroidissement : le cycle de Maisotsenko [texte imprimé] / Hakan Caliskan, Auteur ; Arif Hepbasli, Auteur ; Ibrahim Dincer, Auteur . - 2011 . - pp. 980-990. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 980-990 Mots-clés : Energy  Exergy  Cooling  Air  cooler  Evaporative  system  Maisotsenko  cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study presents energy and exergy analyses and sustainability assessment of the novel evaporative air cooling system based on Maisotsenko cycle which allows the product fluid to be cooled in to a dew point temperature of the incoming air. In the energy analysis, Maisotsenko cycle’s wet-bulb and dew point effectiveness, COP and primary energy ratio rates are calculated. Exergy analysis of the system is then carried out for six reference temperatures ranging from 0 °C to 23.88 °C as the incoming air (surrounding) temperature. The specific flow exergy, exergy input, exergy output, exergy destruction, exergy loss, exergy efficiency, exergetic COP, primary exergy ratio and entropy generation rates are determined for various cases. Furthermore, sustainability assessment is obtained using sustainability index method. As a result, maximum exergy efficiency is found to be 19.14% for a reference temperature of 23.88 °C where the optimum operation takes place. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000363

Thermoeconomic optimization of a shell and tube condenser using both genetic algorithm and particle swarm / Hassan Hajabdollahi in International journal of refrigeration, Vol. 34 N° 4 (Juin 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1066-1076 Titre : Thermoeconomic optimization of a shell and tube condenser using both genetic algorithm and particle swarm Titre original : Optimisation thermoéconomique d'un condenseur multitubulaire à l'aide d'un algorithme évolutif Type de document : texte imprimé Auteurs : Hassan Hajabdollahi, Auteur ; Pouria Ahmadi, Auteur ; Ibrahim Dincer, Auteur Année de publication : 2011 Article en page(s) : pp. 1066-1076 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Shell-and-tube  condenser  Refrigeration  Optimization  Effectiveness  Cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a thermoeconomic optimization of a shell and tube condenser, based on two new optimization methods, namely genetic and particle swarm (PS) algorithms. The procedure is selected to find the optimal total cost including investment and operation cost of the condenser. Initial cost includes condenser surface area and operational cost includes pump output power to overcome the pressure loss. Design parameters are tube number, number of tube pass, inlet and outlet tube diameters, tube pitch ratio and tube arrangements (30, 45, 60 and 90°). Therefore, shell diameter should be selected less than 7 m, tube length should be less than 15 m, and ratio of diameter to tube length should be in the range of 1/12 to 1/3. In addition, it is found that GA provides better results for computer CPU running time, compared to PS algorithm. Finally, a sensitivity analysis of design parameters at the optimal point is conducted. Results show that an increase in the tube number leads to decrease in the objective function first then it leads to a considerable increment in objective function. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000600 [article] Thermoeconomic optimization of a shell and tube condenser using both genetic algorithm and particle swarm = Optimisation thermoéconomique d'un condenseur multitubulaire à l'aide d'un algorithme évolutif [texte imprimé] / Hassan Hajabdollahi, Auteur ; Pouria Ahmadi, Auteur ; Ibrahim Dincer, Auteur . - 2011 . - pp. 1066-1076. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1066-1076 Mots-clés : Shell-and-tube  condenser  Refrigeration  Optimization  Effectiveness  Cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a thermoeconomic optimization of a shell and tube condenser, based on two new optimization methods, namely genetic and particle swarm (PS) algorithms. The procedure is selected to find the optimal total cost including investment and operation cost of the condenser. Initial cost includes condenser surface area and operational cost includes pump output power to overcome the pressure loss. Design parameters are tube number, number of tube pass, inlet and outlet tube diameters, tube pitch ratio and tube arrangements (30, 45, 60 and 90°). Therefore, shell diameter should be selected less than 7 m, tube length should be less than 15 m, and ratio of diameter to tube length should be in the range of 1/12 to 1/3. In addition, it is found that GA provides better results for computer CPU running time, compared to PS algorithm. Finally, a sensitivity analysis of design parameters at the optimal point is conducted. Results show that an increase in the tube number leads to decrease in the objective function first then it leads to a considerable increment in objective function. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000600