tailieunhanh - Computational Fluid Mechanics and Heat Transfer Third Edition_10

Tham khảo tài liệu 'computational fluid mechanics and heat transfer third edition_10', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 7. Forced convection in a variety of configurations The bed was soft enough to suit I soon found that there came such a draught of cold air over me from the sill of the window that this plan would never do at all especially as another current from the rckely door met the one from the window and both together formed a series of small whirlwinds in the immediate vicinity of the spot where I had thought to spend the night. Moby Dick H. Melville 1851 Introduction Consider for a moment the fluid flow pattern within a shell-and-tube heat exchanger such as that shown in Fig. . The shell-pass flow moves up and down across the tube bundle from one baffle to the next. The flow around each pipe is determined by the complexities of the one before it and the direction of the mean flow relative to each pipe can vary. Yet the problem of determining the heat transfer in this situation however difficult it appears to be is a task that must be undertaken. The flow within the tubes of the exchanger is somewhat more tractable but it too brings with it several problems that do not arise in the flow of fluids over a flat surface. Heat exchangers thus present a kind of microcosm of internal and external forced convection problems. Other such problems arise everywhere that energy is delivered controlled utilized or produced. They arise in the complex flow of water through nuclear heating elements or in the liquid heating tubes of a solar collector in the flow of a cryogenic liquid coolant in certain digital computers or in the circulation of refrigerant in the spacesuit of a lunar astronaut. We dealt with the simple configuration of flow over a flat surface in 341 342 Forced convection in a variety of configurations Chapter 6. This situation has considerable importance in its own right and it also reveals a number of analytical methods that apply to other configurations. Now we wish to undertake a sequence of progressively harder problems of forced convection heat .