Design and Optimization of Multi-Stream Plate-Fin Heat Exchangers Using Optimum Fins and Variable Physical Properties

Document Type : Research Article


1 School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, I.R. IRAN

2 Petro Hitech Co., Tehran, I.R. IRAN


Although several methods have been proposed in design of multi-stream heat exchangers, but they often apply for constant physical properties. In this research, a new method is presented using the variation of physical properties with temperature as well as optimum pressure drops. Having indicated the dependency of specific heat capacity, viscosity, density and thermal conductivity on temperature variation, a set of temperature correction factors is defined for each stream. Calculating the correction factors for all streams will lead in finding an optimum DTmin in targeting stage as well as a reliable design based on effective pressure drops, which will guarantee the accuracy of results. Moreover, the optimum pressure drops are used by the optimum selection of fins for each stream in which the total annual cost of exchanger is minimized using genetic algorithm. Having applied the temperature correction factors in design of a multi-stream heat exchanger as case study, the results showed a 27.3% and 13.5% reduction in exchanger volume and total annual cost, respectively, compared to those calculated based on constant physical properties. Also, by optimization of fin types using the genetic algorithm, the results showed a 4.28% and 4.92% reduction in volume and total annual cost, respectively.


Main Subjects

[1] Feldman A., Marvillet C. and Lebouche M., Nucleate and Convective Boiling in Plate Fin Heat Exchangers, International Journal of Heat and Mass Transfer, 43, p. 3433 (2000).
[2]. قاسم زاده، ژاله؛ پنجه­شاهی، محمدحسن؛ تخمین خواص فیزیکی سیالات برای استفاده در الگوریتم سطح شبکه مبدل­های حرارتی، نشریه مهندسی شیمی دانشکده فنی دانشگاه تهران، شماره30، ص 898 (1376).
[3] Ghannadi M.M., Omidkhah M.R., Hojjati M.R., Area Targeting of HEX for Shiraz Refinery Atmospheric Distillation Unit with Variable Physical Properties of Crude Oil Consideration, The 6th International Chemical Engineering Congress & Exhibition, Kish Island, Iran, (2009).
[4] Hojjati M.R., Omidkhah M.R., Panjeshahi M.H., Heat Exchanger Network Design with Pressure Drop Consideration Using Mathematical Programming, Iranian Journal of Chemistry and Chemical Engineering, 26(1), p. 1 (2007).
[5] Moosavi E., Omidkhah M.R., Hojjati M.R., MINLP Synthesis of Heat Exchanger Networks with Variable Physical Properties of Fluids, 12th Chemical Engineering Conference, Sahand University, Tabriz, Iran, (2008).
[6] Fakharzadeh H.R., Omidkhah M.R., Hojjati M.R., Optimization of Steam Network in Shiraz Refinery Utility Systems using Variable Physical Properties, The 6th International Chemical Engineering Congress & Exhibition, Kish Island, Iran, (2009).
[7]. فلاحی حمیدرضا؛ "بهینه­سازی افت فشار درانتگراسیون فرایند"، پایان نامه دکتری، دانشکده مهندسی شیمی دانشگاه تهران، (1378).
[8] Kays W.M., London A.L., “Compact Heat Exchangers”, 3rd Edition .McGraw-Hill, New York, (1984).
[9] Sheik Ismail L., Ranganayakulu C., Shah Ramesh K., Numerical Study of Flow Patterns of Compact Plate Fin Heat Exchangers and Generation of Design Data for Offset and Wavy Fins, International Journal of Heat and Mass Transfer, 52, p.3972 (2009).
[10] Peng H., Ling X., Optimal Design Approach for the Plate Fin Heat Exchangers Using Neural Networks Cooperated with Genetic Algorithms, Applied Thermal Engineering, 28, p. 642 (2008).
[11] Picon-Nunez M., Polley G.T., Medina-Flores M., Thermal Design of Multistream Heat Exchangers, Applied Thermal Engineering, 22, p. 1643 (2002).