Numerical predictions are presented for seven different two-dimensional turbulent "elliptic" flows. The solution procedure, which is embodied in the TEACH computer program, is described and numerical tests reported. The calculated properties of the seven flows are compared with experimental results and demonstrate that the procedure, with a two-equation turbulence model, provides adequate precision for many engineering applications. The two-equation model is shown, however, to be deficient in detail.

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The recent energy crisis and environmental burden are becoming increasingly urgent and drawing enormous attention to solar-energy utilization. Direct solar thermal power generation technologies, such as, thermoelectric, thermionic, magneto hydrodynamic, and alkali-metal thermoelectric methods, are among the most attractive ways to provide electric energy from solar heat. Direct solar thermal power generation has been an attractive electricity generation technology using a concentrator to gather solar radiation on a heat collector and then directly converting heat to electricity through a thermal electric conversion element. Compared with the traditional indirect solar thermal power technology utilizing a steam-turbine generator, the direct conversion technology can realize the thermal to electricity conversion without the conventional intermediate mechanical conversion process. The power system is, thus, easy to extend, stable to operate, reliable, and silent, making the method especially suitable for some small-scale distributed energy supply areas. Also, at some occasions that have high requirements on system stability, long service life, and noiselessness demand, such as military and deep-space exploration areas, direct solar thermal power generation has very attractive merit in practice. At present, the realistic conversion efficiency of direct solar thermal power technology is still not very high, mainly due to material restriction and inconvenient design. However, from the energy conversion aspect, there is no conventional intermediate mechanical conversion process in direct thermal power conversion, which therefore guarantees the enormous potential of thermal power efficiency when compared with traditional indirect solar thermal power technology [1].

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In the present paper, simulation for shell and tube heat exchanger investigated using CFD techniques. Numerical simulations of the turbulent, three-dimensional fluid flow and heat transfer are performed using Ansys Fluent 6.3. The effect of friction characteristics on the model of heat exchanger is discussed. A RNG κ-ε turbulence model with non-equilibrium wall function and 2nd order upwind is used. The present model is validated with the experimental literature and show a good agreement. The numerical results of the present study predict reasonably agree well with available correlations. Finally the present study model can be used to model a shell and tube heat exchanger with a satisfactory accuracy level in predictions.