Abstract
The flow and heat transfer of air-cooled heat exchangers play important roles in the performance of indirect dry cooling systems in power plants, so it is of benefit to the design and operation of a typical indirect dry cooling system to optimize the thermo-flow characteristics of air-cooled heat exchangers. The entransy dissipation method is applied to the performance optimization of air-cooled heat exchangers in this paper. Two irreversible heat transfer processes in air-cooled heat exchangers, the heat transfer between circulating water and cooling air and the mixing of circulating water, are taken into account and analyzed by means of the entransy dissipation method. The total entransy dissipation rate, which connects the geometrical parameters of air-cooled heat exchanger sectors and the heat capacity rates of the fluids to the heat flow rate in every sector, is obtained. Based on the mathematical relation and the conditional extremum method, an optimization equation group is derived, by which the air-cooled heat exchanger with known air-side parameters is optimized, showing that the entransy dissipation based optimization approach can contribute to the distribution optimization of circulating water in air-cooled heat exchangers of a typical indirect dry cooling system.
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References
Kroger D G. Air-Cooled Heat Exchangers and Cooling Towers: Thermal-Flow Performance Evaluation and Design. Pragati Maidan: Penwell Corporation, 2004
Wu X P, Yang L J, Du X Z, et al. Flow and heat transfer characteristics of indirect dry cooling system with horizontal heat exchanger A-frames at ambient winds. Int J Therm Sci, 2014, 79: 161–175
Yang L J, Wu X P, Du X Z, et al. Dimensional characteristics of wind effects on the performance of indirect dry cooling system with vertically arranged heat exchanger bundles. Int J Heat Mass Tran, 2013, 67: 853–866
Yang L J, Chen L, Du X Z, et al. Effects of ambient winds on the thermo-flow performances of indirect dry cooling system in a power plant. Int J Therm Sci, 2013, 64: 178–187
Su M D, Tang G F, Fu S. Numerical simulation of fluid flow and thermal performance of a dry-cooling tower under cross wind condition. J Wind Eng Ind Aerod, 1999, 79: 289–306
Wei Q D, Zhang B Y, Liu K Q, et al. A study of the unfavorable effects of wind on the cooling efficiency of dry cooling towers. J Wind Eng Ind Aerod, 1995, 54: 633–643
Al-Waked R, Behnia M. The performance of natural draft dry cooling towers under crosswind: CFD study. Int J Energ Res, 2004, 28: 147–161
Zhai Z, Fu S. Improving cooling efficiency of dry-cooling towers under cross-wind conditions by using wind-break methods. Appl Therm Eng, 2006, 26: 1008–1017
Goodarzi M. A proposed stack configuration for dry cooling tower to improve cooling efficiency under crosswind. J Wind Eng Ind Aerod, 2010, 98: 858–863
Goodarzi M, Ramezanpour R. Alternative geometry for cylindrical natural draft cooling tower with higher cooling efficiency under crosswind condition. Energ Convers Manage, 2014, 77: 243–249
Guo Z Y, Zhu H Y, Liang X G. Entransy-a physical quantity describing heat transfer ability. Int J Heat Mass Tran, 2007, 50: 2545–2556
Chen Q, Ren J X, Meng J A. Field synergy equation for turbulent heat transfer and its application. Int J Heat Mass Tran, 2007, 50: 5334–5339
Chen Q, Zhu H Y, Pan N, et al. An alternative criterion in heat transfer optimization. P Roy Soc Lond A Mat, 2011, 467: 1012–1028
Cheng X T, Liang X G. Entransy flux of thermal radiation and its application to enclosures with opaque surfaces. Int J Heat Mass Tran, 2011, 54: 269–278
Chen L, Chen Q, Li Z, et al. Optimization for a heat exchanger couple based on the minimum thermal resistance principle. Int J Heat Mass Tran, 2009, 52: 4778–4784
Chen Q, Xu Y C. An entransy dissipation-based optimization principle for building central chilled water systems. Energy, 2012, 37: 571–579
Xu Y C, Chen Q. An entransy dissipation-based method for global optimization of district heating networks. Energ Buildings, 2012, 48: 50–60
Xu Y C, Chen Q. Minimization of mass for heat exchanger networks in spacecrafts based on the entransy dissipation theory. Int J Heat Mass Tran, 2012, 55: 5148–5156
Yuan F, Chen Q. A global optimization method for evaporative cooling systems based on the entransy theory. Energy, 2012, 42: 181–191
Wang W H, Cheng X T, Liang X G, Entransy dissipation, entransy-dissipation-based thermal resistance and optimization of one-stream hybrid thermal network. Sci China Tech Sci, 2013, 56: 529–536
Liu X B, Guo Z Y. Anovel method for heat exchanger analysis (in Chinese). Acta Phys Sin, 2009, 58: 4766–4771
Cheng X T, Zhang Q Z, Liang X G. Analyses of entransy dissipation, entropy generation and entransy-dissipation-based thermal resistance on heat exchanger optimization. Appl Therm Eng, 2012, 38: 31–39
Wu X Z, Zhao J N. Approximate formulas of number of transfer unit of U shaped fin-tube heat exchangers (in Chinese). J Harbin Inst Tech, 2012, 44: 71–74
Yang L J, Jia S N, Pu Y D, et al. Numerical study on flow and heat transfer characteristics of finned tube bundles for air-cooled heat exchangers of indirect dry cooling systems in power plants (in Chinese). P CSEE, 2012, 32: 50–57
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Sun, J., Yuan, K., Yang, L. et al. Distribution optimization of circulating water in air-cooled heat exchangers for a typical indirect dry cooling system on the basis of entransy dissipation. Sci. China Technol. Sci. 58, 617–629 (2015). https://doi.org/10.1007/s11431-014-5762-3
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DOI: https://doi.org/10.1007/s11431-014-5762-3