A novel concept for convective heat transfer enhancement
01 Jul 1998-International Journal of Heat and Mass Transfer (Pergamon)-Vol. 41, Iss: 14, pp 2221-2225
TL;DR: In this paper, an analog between convection and conduction with heat sources is made to have a further understanding of the mechanism of convective heat transfer, and three ways to raise the strength of heat sources/convection terms, and consequently to enhance the heat transfer are presented.
Abstract: An analog between convection and conduction with heat sources is made to have a further understanding of the mechanism of convective heat transfer. There are three ways to raise the strength of heat sources/convection terms, and consequently to enhance the heat transfer: (a) increasing Reynolds and/or Prandtl number, (b) increasing the fullness of dimensionless velocity and/or temperature profiles, (c) increasing the included angle between the dimensionless velocity and temperature gradient vectors. Some approaches of heat transfer enhancement are suggested based on such a novel concept of heat transfer enhancement.
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TL;DR: In this paper, the concept of field synergy (coordination) principle is briefly introduced and then its numerical verification is presented, with focusing being paid on the application for developing new type of enhanced techniques.
Abstract: In this paper the concept of field synergy (coordination) principle is briefly introduced first, and then its numerical verification is presented. A dimensionless number, field synergy number Fc, is defined as an indication of the synergy degree between velocity and temperature field for the entire flow and heat transfer domain. It is found that for the ideal case, this number should equal one, and for most of the engineering heat transfer cases, its value is far from being equal to one, showing a large room for the heat transfer enhancement study. Then the applications of the principle are discussed, with focusing being paid on the application for developing new type of enhanced techniques. Three examples are provided to demonstrate the importance and feasibility of the field synergy principle.
406 citations
Cites background from "A novel concept for convective heat..."
...[5,6] is then reviewed and its applications in the development of enhanced heat transfer surfaces are presented....
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TL;DR: In this paper, the concept of enhancing parabolic convective heat transfer by reducing the intersection angle between velocity and temperature gradient is reviewed and extended to elliptic fluid flow and heat transfer situation.
Abstract: The concept of enhancing parabolic convective heat transfer by reducing the intersection angle between velocity and temperature gradient is reviewed and extended to elliptic fluid flow and heat transfer situation. Five examples of elliptic flow are provided to show the validity of the new concept (field synergy principle). Two further examples are supplemented to demonstrate the importance of the concept in the design of the enhanced surfaces.
310 citations
Cites background from "A novel concept for convective heat..."
...In this paper, the new concept ‘‘field synergy principle’’ proposed firstly in [6,7] is extended from parabolic flow to elliptic flow....
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...Guos’ proposal [6,7] will be briefly reviewed here....
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...In 1998, Guo and his co-workers proposed a novel concept for enhancing convective heat transfer of parabolic flow [6,7], the reduction of the intersection angle between velocity and temperature gradient can effectively enhance convective heat transfer....
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...Thus either for parabolic flow or for elliptic flows, the idea proposed in [6,7] is all valid....
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TL;DR: In this paper, the authors reveal the inherent relation between the filed synergy principle and the three existing mechanisms for enhancing single phase convective heat transfer, i.e., decreasing of thermal boundary layer, increasing of flow interruption and increasing of velocity gradient near a solid wall, all lead to the reduction of intersection angle between velocity and temperature gradient.
Abstract: Numerical simulations were conducted to reveal the inherent relation between the filed synergy principle and the three existing mechanisms for enhancing single phase convective heat transfer. It is found that the three mechanisms, i.e., the decreasing of thermal boundary layer, the increasing of flow interruption and the increasing of velocity gradient near a solid wall, all lead to the reduction of intersection angle between velocity and temperature gradient. It is also revealed that at low flow speed, the fin attached a tube not only increases heat transfer surface but also greatly improves the synergy between the velocity and the temperature gradient.
280 citations
Cites background from "A novel concept for convective heat..."
...In 1998 Guo and his co-workers proposed a novel concept of enhancing convective heat transfer based on the parabolic fluid flow situation [11,12]....
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TL;DR: In this article, a review of the performance of compact heat exchangers (CHEs) is presented, including well-established devices, some relative newcomers to the market and also designs still being tested in the laboratory.
Abstract: This paper gives a review on performances of compact heat exchangers (CHEs), including well-established devices, some relative newcomers to the market and also designs still being tested in the laboratory. The structures of the CHEs are briefly introduced, and their heat transfer enhancement mechanisms, as well as their advantages and limitations, are summarized. Then, different heat transfer enhancement technologies in CHEs are compared and their thermo-hydraulic performances are analyzed on the basis of available correlations for heat transfer and friction factor developed by various investigators quoted in the open literature. Finally, the technologies that may fit the specifications for a new generation of solar receiver, which is a critical component of the Concentrated Solar Power (CSP) system, are proposed. It is concluded, among others in the review, that solar receivers based upon CHE technology have been rarely reported, and therefore, more work is needed in this field for a comprehensive understanding and to improve the uses of new energy sources and contribute to sustainability.
239 citations
Cites background from "A novel concept for convective heat..."
...[49] Guo ZY, Li DY, Wang BX....
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...eat transfer enhancement at relatively lower pressure drop from he point of the field synergy principle proposed by Guo [49,50]....
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TL;DR: The emergence and development of constructal theory, which has been a new discipline branch to research sorts of structures in nature and engineering, are reviewed in this paper, where various shapes and structures of the matters in nature are generated from the tendency to obtain optimal performance.
Abstract: The emergence and development of constructal theory, which has been a new discipline branch to research sorts of structures in nature and engineering, are reviewed. The core of the constructal theory is that various shapes and structures of the matters in nature are generated from the tendency to obtain optimal performance. Constructal theory and its application are summarized, from disciplines such as heat, mechanism, fluid flow, electricity, magnetism and chemistry, to life and non-life systems in nature.
203 citations
References
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Book•
01 Jan 1955
TL;DR: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part, denoted as turbulence as discussed by the authors, and the actual flow is very different from that of the Poiseuille flow.
Abstract: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part. These actual flows show a special characteristic, denoted as turbulence. The character of a turbulent flow is most easily understood the case of the pipe flow. Consider the flow through a straight pipe of circular cross section and with a smooth wall. For laminar flow each fluid particle moves with uniform velocity along a rectilinear path. Because of viscosity, the velocity of the particles near the wall is smaller than that of the particles at the center. i% order to maintain the motion, a pressure decrease is required which, for laminar flow, is proportional to the first power of the mean flow velocity. Actually, however, one ob~erves that, for larger Reynolds numbers, the pressure drop increases almost with the square of the velocity and is very much larger then that given by the Hagen Poiseuille law. One may conclude that the actual flow is very different from that of the Poiseuille flow.
17,321 citations
Book•
01 Mar 1994
TL;DR: In this article, the authors evaluated two-phase heat exchangers for single-phase flows and showed that they can achieve state-of-the-art performance in terms of heat transfer.
Abstract: Heat Transfer Fundamentals Performance Evaluation for Single-Phase Flows Performance Evaluation Criteria for Two-Phase Heat Exchangers Plate-and-Fin Extended Surfaces Externally Finned Tubes Insert Devices for Single-Phase Flow Internally Finned Tubes and Annuli Integral Roughness Fouling on Enhanced Surfaces Pool Boiling Vapor Space Condensation Convective Vaporization Convective Condensation Enhancement Using Electric Fields Simultaneous Heat and Mass Transfer Additives for Gases and Liquids Problem Supplement Index.
1,296 citations