Numerical Simulation For Enhancing Convective Heat Transfer In The Core-flow

Technology of enhancing heat transfer, which can improve efficiency of heat exchanger and reduce equipment's weight and volume, is always attached importance to by scientists and engineers. After energy crisis in 1970s, technology of enhancing heat transfer is developed greatly. Some technologies of enhancing heat transfer have been applied widely, but there is a similar problem in these technologies, most of them are based on boundary theory, as a result, flow resistance's enhancement is faster than heat transfer's. We did researches on these problem and proposed new theory: heat transfer enhancement in the core flow.For comparison of the results, a standard advanced by Webb about heat transfer and fluid resistance is brought forward. The standard is simple and very convenient and has more specific physical meaning than other standards. It is applied widely in study of heat transfer at present.For comparisons of the three kinds of tubes, namely, smooth tube, tube with single row poles inserted and tube with two row poles inserted, the numerical simulations were done. The indicates that, when water is used as working fluid, core-field heat transfer enhancement can improved the temperature field, making the temperature field more uniform. Heat transfer coefficient increased obviously, but the flow resistance coefficient did not increase so fast. And the result also shows that core-field heat transfer enhancement in laminar flow is better than it used in turbulent flow.Finally, according to results of numerical simulation and comparison, we analyze some phenomena appearing in study with field synergy principle. It is proved that core-field heat transfer enhancement can reduce the field synergy angle. It is consistent with the heat transfer coefficient.