tailieunhanh - Computational Fluid Mechanics and Heat Transfer Third Edition_4

Tham khảo tài liệu 'computational fluid mechanics and heat transfer third edition_4', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | a Single shell-pass single tube-pass exchanger b One shell-pass two tube-pass exchanger 1. Stationary head-channel 14. Expansion joint 26. Lantern ring 2. Stationary head-bonnet 15. Floating tube sheet 27. Tie rods and spacers 3. Stationary head-flange- 16. Floating head cover 28. Transverse baffles channel or bonnet 17. Floating head flange or support plates 4. Channel cover 18. Floating head 29. Impingement plate 5. Stationary head nozzle backing device 30. Longitudinal baffle 6. Stationary tube sheet 19. Split shear ring 31. Pass partition 7. Tubes 20. Slip-on backing 32. Vent connection 8. Shell flange 33. Drain connection 9. Shell cover 21. Floating head cover- 34. Instrument connection 10. Shell flange- external 35. Support saddle stationary head end 22. Floating tube sheet 36. Lifting lug 11. Shell flange- skirt 37. Support bracket rear head end 23. Packing box 38. Weir 12. Shell nozzle 24. Packing 39. Liquid level 13. Shell cover flange 25. Packing gland connection Figure Four typical heat exchanger configurations continued on next page . Drawings courtesy of the Tubular Exchanger Manufacturers Association. 106 Evaluation of the mean temperature difference in a heat exchanger 107 d One split shell-pass two tube-pass kettle type of exchanger Figure Continued Our problem then reduces to finding the appropriate mean temperature difference that will make this equation true. Let us do this for the simple parallel and counterflow configurations as sketched in Fig. . The temperature of both streams is plotted in Fig. for both singlepass arrangements the parallel and counterflow configurations as a function of the length of travel or area passed over . Notice that in the parallel-flow configuration temperatures tend to change more rapidly with position and less length is required. But the counterflow arrangement achieves generally more complete heat exchange from one flow to the other. Figure shows another variation on the single-pass .