DOI: 10.1615/ICHMT.2014.IntSympConvHeatMassTransf
ISBN Print: 978-1-56700-356-7
ISSN Online: 2642-3499
ISSN Flash Drive: 2642-3502
CONVECTIVE HEAT TRANSFER ENHANCEMENT: MECHANISM, TECHNIQUES AND PERFORMANCE EVALUATION
ABSTRAKT
In this keynote lecture the existing mechanisms for enhancing single phase convective heat transfer are reviewed and the fundamental mechanism, that is, reducing the intersection angle between fluid velocity and temperature gradient, is presented in detail. This basic idea is called field synergy principle (FSP). A great number examples are provided to demonstrate the validity of the FSP. Some typical convective heat transfer phenomena are analyzed and found that their characteristics can be well understood by the FSP. An effective way for improving convective heat transfer performance of an existing heat transfer structure is to reveal the locations with bad synergy (i.e., large local synergy angle) and improve it by changing local structure of the surface. Examples of new enhanced surfaces are provided which are developed under the guidance of the FSP. Then the thermo-hydraulic performance comparisons of the enhanced structures compared with the reference one are discussed under three constraints: identical pumping power, identical pressure drop and identical flow rate. All the three constraints can be unified in a picture with log ( fe/fo) and log ( Nue/Nuo) as abscissa and ordinate, respectively. An enhanced technique can be expressed in this plot and under what constraint it enhances heat transfer can be clearly identified.