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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-483-0

ISBN Online: 978-1-56700-482-3

4th Thermal and Fluids Engineering Conference
April, 14–17, 2019 , Las Vegas, NV, USA

OPTIMIZATION OF TURBULENT HEAT TRANSFER BASED ON EXERGY DESTRUCTION MINIMIZATION PRINCIPLE

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DOI: 10.1615/TFEC2019.fnd.028400

摘要

Heat exchange tubes are widely used in electricity, chemical, metallurgy, refrigeration and other industries. It is an important fundamental research to construct the optimal flow field in the tube so that the overall thermal hydraulic performance can be improved. The optimization approach based on the second law of thermodynamics has attracted worldwide attention in recent years. In this paper, the exergy destruction is chosen to represent the irreversibility of heat transfer and fluid flow process. The convective heat transfer theoretical maximum can be enhanced when the exergy destruction is minimized with a constant pump power consumption. Based on exergy destruction minimization principle, governing equations of optimized flow field are derived with variational method in laminar and turbulent flow respectively. The optimal flow field can be constructed by solving the governing equations. Besides, the multiple regions optimization strategy is applied to allow moderate disturbance in core flow region, which limits the increase of flow resistance. From the numerical results, the longitudinal flow pattern is found in turbulent flow. The fluid is fully mixed and the temperature field tends to be uniform in the transverse plane, which leads to a significant increase of heat transfer coefficient. In addition, it is also found that the disturbance existing near the tube wall destroys the thermal boundary layer, which is conducive to heat transfer enhancement. This basic research will promote the development of heat transfer techniques.