本文分別以理論及實驗方法研究數種高效率熱交換器之熱液動性能，包含(1)裝置渦漩產生器之板鰭式熱交換器，(2)山形板式熱交換器，(3)交錯式鰭片熱交換器，(4)橢圓鰭管熱交換器與板鰭式熱交換器於除濕狀態下的鰭片熱效率，對空氣相對濕度由0 %至100 %做全範圍的研究。
渦漩產生器熱交換器是利用裝置於板鰭式熱交換器鰭片上之凸起物，使空氣流經渦漩產生器時產生縱向渦漩以增進熱傳的裝置。本文針對波浪形之渦漩產生器作理論的探討，配合實驗的部分以紅外線熱相儀系統做溫度量測，並以水洞做流場觀測，以印證數值結果。結果顯示裝置渦漩產生器之板鰭式熱交換器在最大的局部紐塞數增強可達120%，而平均的紐塞數可增加18.5%，使用渦漩產生器的熱交換面積縮減率可達到18~20 %。
山形板是經改良之板式熱交換器面板，面板上溝槽傾斜角β是影響熱液動性能的主要因數。本文同時以理論及實驗做熱傳量的探討，結果顯示β越大時流體除了順著溝槽方向流動較為明顯外，更伴隨著渦漩之產生，對增強熱傳較為有效，但是流動阻力也相對越大，於β=40°時，具有最佳的熱傳與阻力比(j/f)。
交錯式鰭片熱交換器是利用邊界層重複破壞，再重新生長的技巧以增強熱傳。本文的研究中顯示，鰭片熱效率會隨著流體速度增加而減少，使用傳統一維分析法則會低估熱效率值，而誤差會隨著速度之增加而增加。在第二排鰭片具有最大之熱效率，第三排鰭片及後面鰭片之熱效率則改變並不明顯。
橢圓鰭管熱交換器與板鰭式熱交換器應用在除濕時，針對空氣冷卻時是否有凝結水產生與否，鰭片之狀況可分為乾式、半乾濕式和全濕式三種情形。鰭片熱效率於全乾式時鰭片熱效率與空氣相對濕度無關，於全濕時鰭片熱效率隨著空氣相對濕度增加而略為下降，但是在半乾濕時鰭片熱效率隨著空氣相對濕度增加而快速下降。對於橢圓與板鰭式的鰭片熱效率在全濕的狀態下均比全乾的狀態下低了10~20％。橢圓鰭管與相對應的圓鰭管在熱效率的比較上，前者在乾鰭片的狀態下可增加4％，而全濕的狀態下則可高達8％。橢圓鰭管的熱效率會隨著半長短軸比之增加而增加，本文並與一維的扇形法對熱效率的計算做比較。最後本文對橢圓鰭片的熱效率與板鰭片熱效率，分別提出在全乾與全濕狀態下之近似公式。

The numerical and experimental method are used to study three dimension turbulent fluid flow and heat transfer of heat exchangers in this paper. Four types of heat exchangers are included in this study, they are: (1) Fin-and-tube heat exchangers by means of fins with embedded wave-type vortex generators, (2) chevron plates heat exchangers , (3) the rectangular offset strip fin type heat exchangers and (4) the elliptic finned tube heat exchangers.
Vortex generators are usually incorporated on a surface by means of an embossing, stamping, punching or attaching process. When a stream flows over vortex generators embedded surfaces, vortices are induced in that stream. The infrared thermovision system and water tunnel were used to assist the results of numerical method. The results indicate that both the heat transfer and the friction losses are significantly affected by the geometric parameters of the vortex generators. This study identifies a maximum improvement in the local heat transfer coefficient of 120 %, and an improvement of 18.5 % in the average heat transfer coefficient. Furthermore, the results indicate that it is possible to obtain a reduction in fin area of approximately 18-20 % if vortex generators embedded fins are used rather than plain fins, and that the magnitude of this reduction increases with higher Reynolds numbers.
The main parameter of chevron plate heat exchangers is the corrugation inclination angles β, three different (β= 20o, 40o, and 60o), relative to the main flow direction, are investigated in detail for the inlet water velocity ranging from 0.5 to 2.0 m/s. The heat flux was also recorded in both the hot and cold sides of the plate exchanger. It is shown that both the heat transfer coefficients and pressure drop are increased as the inclination angle is increased. For chevron plate with β = 40o gives the largest flow area goodness factor (j/f). The numerical predictions of the heat transfer coefficient agree with the experimental data within 6-20 %.
For the rectangular offset strip fin, the one-dimensional approximation underestimates the fin efficiency and the error is increased as the fluid velocity increases. The laminar model is valid up to Re 2000 based on the hydraulic diameter. A comparison of the numerical results with the available experimental data is also presented.
The air relative humidity over the full range from φ = 0 % to φ = 100 %. Were study for elliptic fin and plate-and-tube heat exchangers. The results indicate the fin efficiencies of elliptic fin increase as the axis ratio Ar is increased. For a given axis ratio Ar, the fin efficiency decreases as the fin height or Biot number is increased. The conventional 1-D sector method overestimates the fin efficiency resulting in increasing error as the axis ratio Ar is increased. In addition, using experimentally determined heat transfer coefficients, it is found that both the fully dry and wet elliptic fin efficiencies are up to 4% - 8% greater than the corresponding circular fin efficiencies having the same perimeter. This paper also presents the two-dimensional analysis for the efficiency of the in-lined and staggered fin for different values of Xt/Do ratio, heat transfer coefficient. It is shown that the fin efficiencies of the staggered fin are higher than the in-lined fins, and the fin efficiency is decreased as the Xt/Do ratio is increased. For a given Xt/Do ratio, the fin efficiency is decreased as the heat transfer coefficient is increased. The conventional 1-D sector method underestimates the in-lined fin efficiency by 1.5-4 % as compared to the 2-D analysis. The deviation of fin efficiency between the conventional 1-D sector method and the 2-D analysis is 0.5-2.5 % for the staggered arrangement.

1. Webb, R. L., Principles of Enhanced Heat Transfer, John Wiley & Sons, Inc., 1994.
2. Bergles, A. E., Heat Transfer Enhancement - The Encouragement and Accommodation of High Heat Fluxes, Experimental Heat Transfer, Fluid Mechanics and Thermodynamics, pp 1907-1919, 1997.
3. ESDU 93024, Engineering Science Data Unit, Vortex Generators for Control of Shock-Induces Separation Part 1: Introduction and Aerodynamics, 1993.
4. Edwards, F.J. and Alker, G.J.R., The Improvement of Forces Convection Surface Heat Transfer Using surfaces Protrusions in the Form of (A) cubes and (B) Vortex Generators, Proc. 5th Int. Heat transfer, Tokyo, Vol. 2, pp. 244-248, 1974.
5. Eibeck, P.A. and Eaton, J.K., Heat Transfer Effects of a Longitudinal Vortex Embedded in a Turbulent Boundary Layer, Journal of Heat Transfer, Vol. 109, pp. 37-57, 1987.
6. Gentry, M.C. and Jacobi, A.M., Heat Transfer Enhancement by Delta-Wing Vortex Generators on a Flat Plate: Vortex Interactions with the Boundary Layer, Experimental Thermal and Fluid Science, Vol. 14, pp. 231-242, 1997.
7. Fiebig, M., Guntermann T. and Mitra N.K., Numerical Analysis of Heat Transfer and Flow Loss in a Parallel Plate Heat Exchanger Element with Longitudinal Vortex Generators as Fins, Journal of Heat Transfer, Vol. 117, pp. 1064-1067, 1995.
8. Tiggelbeck, S.T., Mitra N.K., Fiebig M., Experimental Investigations of Heat Transfer Enhancement and Flow Losses in a Channel with Double Rows of Longitudinal Vortex Generators, International Journal of Heat and Mass Transfer, Vol. 36, pp. 2327-2337, 1993.
9. Deb, P., Biswas, G. and Mitra, N.K., Heat Transfer and Flow Structure in Laminar and Turbulent flows in a Rectangular Channel with Longitudinal Vortices, International Journal of Heat and Mass Transfer, Vol. 38, pp. 2427-2444, 1995.
10. Biswas, G., Torii, K., Fujii, D. and Nishino, K., Numerical and Experimental Determination of Flow Structure and Heat Transfer Effects of Longitudinal Vortices in Channel flow, International Journal of Heat and Mass Transfer, Vol. 39, pp. 3441-3451, 1996.
11. Lau, S., Experimental Study of the Turbulent Flow in a Channel with Periodically Arranged Longitudinal Vortex Generators, Experimental Thermal and Fluid Science, Vol. 11, pp. 255-261, 1995.
12. Biswas, G., Mitra, N.K. and Fiebig, M., Heat Transfer Enhancement in Fin-Tube Heat Exchangers by Winglet Type Vortex Generators, International Journal of Heat and Mass Transfer, Vol. 37, pp. 283-291, 1994.
13. Fiebig, M., Valencia, A. and Mitra, N.K., Wing-Type Vortex Generators for Fin-and-Tube Heat Exchangers, Experimental Thermal and Fluid Science, Vol. 7, pp. 287-295, 1993.
14. Valencia, A., Fiebig, M. and Mitra, N.K., Heat Transfer Enhancement by Longitudinal Vortices in a Fin-and-Tube Heat Exchangers Element with Flat Tubes, Journal of Heat Transfer, Vol. 118, pp. 209-211, 1996.
15. Fiebig, M., Valencia, A. and Mitra, N.K., Local Heat Transfer and Flow Losses in Fin-and-Tube Heat Exchangers with Vortex Generators: A Comparison of Round and Flat Tubes, Experimental Thermal and Fluid Science, Vol. 8 pp. 35-45, 1994.
16. Chen, Y., Fiebig, M. and Mitra, N.K., Conjugate Heat Transfer of a Finned Tube with a Punched Longitudinal Vortex Generator in Form of a Delta Winglet-Parametric Investigations of the Winglet, International Journal of Heat and Mass Transfer, Vol. 41, pp. 3961-3978, 1998.
17. Chen, Y., Fiebig, M. and Mitra, N.K., Heat Transfer Enhancement of a Finned Tube with Punched Longitudinal Vortex Generator In-Line, International Journal of Heat and Mass Transfer, Vol. 41, pp. 4151-4166, 1998.
18. Chen, Y., Fiebig, M. and Mitra, N.K., Heat Transfer Enhancement of Finned Tube with Staggered Punched Longitudinal Vortex Generator, International Journal of Heat and Mass Transfer, Vol. 43, pp. 417-435, 2000.
19. Wang, C.C., Lo, J., Lin, Y.T. and Liu, M.S., Flow Visualization of Wavy-Type Vortex Generator Having Inline Fin-Tube Arrangement, International Journal of Heat and Mass Transfer, Vol. 45, pp.1933-1944, 2001.
20. Shah, R. K. and Focke, W. W., Plate Heat Exchangers and Their Design Theory, Heat Transfer Equipment Design, edited by R. K. Shah, E. C. Subbarao and R. A. Mashelkar, Hemisphere Publishing Co., Washington, DC, pp. 227-254, 1998.
21. Focke, W. W., Zacharirades, J. and Olivier, I., The Effects of the Corrugation Inclination Angle on the Thermal-Hydraulic Performance of Plate Heat Exchanger, International Journal of Heat and Mass Transfer, Vol. 28, pp. 1469-1479, 1985.
22. Focke, W. W. and Knibbe, P. G., Flow Visualization in Parallel-Plate Ducts with Corrugated Walls, Journal of Fluid Mechanics, Vol. 165, pp. 73-77, 1986.
23. Heavner, R. L., Kumar, H. and Wannizrachi, A. S., Performance of an Industrial Plate Heat Exchanger：Effect of Chevron Angle, AICHE, Symp Ser., Vol. 89, pp. 65-70, 1993.
24. Bond, M. P., Plate Heat Exchanger for Effective Heat Transfer, The Chemical Engineer, Vol. 367, pp. 162-166, 1981.
25. Ding, J. and Manglik, R. M., Analytical Solutions for Laminar Fully Developed Flows in Double-Sine Shaped Ducts, International Journal of Heat and Mass Transfer, Vol. 39, pp. 269-277, 1986.
26. Manglik, R. M. and Ding, J., Laminar Flow Heat Transfer to Viscous Power-Law Fluids in Double-Sine Ducts, International Journal of Heat and Mass Transfer, Vol. 40, pp. 1379-1390, 1997.
27. Fischer, L. and Martin, H., Friction Factors for Fully Developed Laminar Flow in Ducts Confined by Corrugated Parallel Walls, International Journal of Heat and Mass Transfer, Vol. 40, pp. 635-639, 1997.
28. Wieting, A. R., Empirical Correlations for Heat Transfer and Flow Friction Characteristics of Rectangular Offset-Fin Plate-Fin Heat Exchangers, Journal of. Heat Transfer, Vol. 97, pp 488-490, 1975.
29. Kays and London, Compact Heat Exchanger, 3rd ed., pp. 243 New York, McGraw-Hill, 1984.
30. Mochizuki, S., Yagi, Y. and Yang, W. J., Transport phenomena in stacks of interrupted parallel-plate surfaces. Experimental Heat Transfer, Vol. 1, pp. 127-140, 1987..
31. Mochizuki, S., Yagi, Y. and Yang, W.J., Flow pattern and turbulence intensity in stacks of interrupted parallel-plate surface. Experimental Thermal Fluid Sci., Vol. 1, pp. 51-57, 1988.
32. Joshi, H. M., and Webb, R. L., Heat Transfer and Friction in the Offset Strip-Fin Heat Exchanger. International Journal of Heat and Mass Transfer, Vol. 30, pp. 69-84, 1987.
33. Manglik, R. M., and Bergles, A. E., Heat Transfer and Pressure Drop Correlation for the Rectangular Offset Strip Fin Compact Heat Exchanger, Experimental Thermal Fluid Sci., Vol. 10, pp. 171-180, 1995.
34. Xi, G. N. and Suzuki, K., A Flow Visualization Experiment on the Instability of Wakes of Plates for Performance Study of Compact Heat Exchangers, Proc. 2nd Int. Symp. Heat Transfer, Beijing, Vol. 2, p. 638-643, 1988.
35. Xi, G. N., Hagiwara, Y. and Suzuki, K., Flow Instability and Augmented Heat Transfer on Fin Arrays, Journal of Enhanced Heat Transfer, Vol. 2, pp. 23-32, 1991.
36. Suzuki, K., Xi, G. N., Inaoka, K. and Hagiwara, Y., Mechanism of Heat Transfer Enhancement due to Self-Sustained Oscillation for an In-Line Fin Array, International Journal of Heat and Mass Transfer, Vol. 97, pp. 83-96, 1994.
37. Mercier, P. and Tochon, P., Analysis of Turbulent Flow and Heat Transfer in Compact Heat Exchanger by Pseudo Direct Numerical Simulation., Compact Heat Exchangers for the Process Industries, ed. R. K. Shah, Begell House Inc., New York, p. 223-230, 1997.
38. Mizuno, M., Morioka, M., Hori, M. and Kudo, K., Heat Transfer and Flow Characteristics of Offset Fins in Low Reynolds Number Region ASME, HTD-Vol. 317-1, pp. 425-432, New York, 1995.
39. Toossi,R., Asheghi, M, and Hou, K. S., Effect of Fluid Properties on Heat Transfer in Channels with Offset Strip Fins, Experimental Heat Transfer, Vol. 7, pp. 189-202, 1994.
40. Xi, G. N., and Shah, R. K., Numerical Analysis of Offset Strip Fin Heat Transfer and Flow Friction Characteristics, Proceedings of Int. conference on computational heat and mass transfer, pp. 75-87, Northern Cyprus, 1999.
41. McQuiston, F. C. and Parker, J. D., Heating, Ventilating and Air Conditioning Analysis and Desig, New York: John Wiley, pp 604-613, 1994.
42. ARI Standard 410-72, Forced-Circulation Air-Cooling and Air-Heating Coils, Air-Conditioning & Refrigeration Institute, Arlington, VA. 1972.
43. Threlkeld, J. L., Thermal Environment Engineering, 2nd Ed. New York: Prentice-Hall, 1970.
44. McQuiston, F. C., Fin Efficiency with Combined Heat and Mass Transfer, ASHRAE Transaction, Vol. 71, pp 350-355, 1975.
45. Coney, J. E. R., Kazeminejad, H. and Sheppard, C. G. W., Dehumidification of air on a Vertical Rectangular Fin: A Numerical Study, Proc. Instn. Mech. Engrs., Vol. 203, pp 141-146, 1989.
46. Coney, J. E. R., Sheppard, C. G. W. and Shafei, E. A. M., Fin Performance with Dehumidification from Humid Air: A numerical Investigation, International Journal of Heat & Fluid Flow, Vol. 10, pp 224-231, 1989, 1989.
47. Kazeminejad, H., (1996) Analysis of One-Dimensional Fin Assembly Heat Transfer with Dehumidification. International Journal of Heat & Mass Transfer, Vol. 38, pp. 455-462.
48. Chen, L. T., Two-Dimensional Fin Efficiency with Combined Heat and Mass Transfer between Water-Wetted Fin Surface and Moving Moist Air Stream, International Journal of Heat & Fluid Flow., Vol. 12, pp 71-76, 1991.
49. Elmahdy, A. H. and Biggs, R. C., Efficiency of Extended Surfaces with Simultaneous Heat and Mass Transfer, ASHRAE transactions, Vol.89, pp. 135-143, 1983.
50. Hong, K. T. and Webb, R. L., Calculation of Fin Efficiency for Wet and Dry Fins, HVAC & R Research, Vol. 2, pp. 27-41, 1995.
51. Wang, C. C., Hsieh, Y. C. and Lin, Y. T., Performance of Plate Finned Tube Heat Exchangers under Dehumidifying Conditions, Journal of Heat Transfer, Vol. 119, pp 109-117, 1997.
52. Rosario, L. and Rahman M. M., Analysis of Heat Transfer in a Partially Wet Radial Fin Assembly During Dehumidification, International Journal of Heat and Fluid Flow, Vol. 20, pp 642-648, 1999.
53. Liang, S. Y., Wong, T. N. and Nathan, M. M., Comparison of One-Dimensional and Two-Dimension Models for Wet Surface Fin Efficiency of a Plate-Fin-Tube Heat Exchanger, Applied Thermal Engineering., Vol. 20, pp 941-962, 2000.
54. Wu, G. and Bong, T. Y., Overall Efficiency of a Straight Fin with Combined Heat and Mass Transfer, ASHRAE Transactions Part 1, Vol. 100, pp 367-374, 1995.
55. Salah, El-Din, Performance Analysis of Partially-Wet Fin Assembly, Applied Thermal Engineering, Vol. 18, pp 337-349, 1998.
56. Rosario, L. and Rahman, M. M., Analysis of heat transfer in a partially wet radial fin assembly during dehumidification, International Journal of Heat and Fluid Flow, Vol. 20, pp. 642-648, 1999.
57. Besendnjak, D. and Poredos, A., Efficiency of Cooled Extended Surfaces, International Journal of Refrigeration, Vol. 21, pp 372-380, 1998.
58. Brauer, H., Compact heat exchangers, Chem. and Process Engineering, Vol. 45, pp 451-460, 1964.
59. Jang, J. Y., and Yang, J. Y., Experimental and Numerical Analysis of the Thermal-Hydraulic Characteristics of Elliptic Finned-Tube Heat Exchangers, Heat Transfer EngineerIng, Vol. 19, No. 4, pp 55-67, 1998.
60. Shah, R. K., Heat Exchanger Basic Design Methods, Low Reynolds Number Flow Heat Exchanger, edit by S. Kakac, R. K. Shah and A. E. Bergles, Hemisphere, New York, pp. 21-72, 1983.
61. Rocha, L. A. O., Saboya, F. E. M. and Vargas, J. V. C., A Comparative Study of Elliptical and Circular Sections in One- and Two-Row Tubes and Plate Fin Heat Exchangers, International Journal of Heat and Fluid Flow, Vol. 18, pp 247-252, 1997.
62. Saboya, S. M. and Saboya, F. E. M., Experiments on Elliptic Sections in One- and Two-Row Arrangements of Plate Fin and Tube Heat Exchangers, Experimental Thermal and Fluid Science, Vol. 24, pp 67-75, 2001.
63. Sparrow, E. M. and Lin, S. H., Heat-Transfer Characteristics of Polygonal and Plate Fins, International Journal of Heat and Mass Transfer, Vol. 7, pp 951-953, 1964.
64. Le Feuvre, R. F., Laminar and Turbulent Forced Convection Processes Through in-line Tube Banks, HTS/74/5, Mechanical Engineering Department, Imperial College, London, 1973.
65. Wung, T. S. and Chen, C. J., Finite Analytic Solution of Convective Heat Transfer for Tube Arrays in Crossflow—I. Flow field analysis, Journal of Heat Transfer, Vol. 111, pp 633-640, 1989, 1989.
66. Wung, T. S. and Chen, C. J., Finite Analytic Solution of Convective Heat Transfer for Tube Arrays in Crossflow—II. Heat Transfer Analysis, Journal of Heat Transfer, Vol. 111, pp 641-648, 1989.
67. Chen, H. T. and Liou, J. T., Optimum Dimensions of the Continuous Plate Fin for Various Tube Arrays, Numerical Heat Transfer, Part A, Vol. 34, pp 151-168, 1998.
68. Jang, J. Y., Lai, J. T. and Liu, L. C., The Thermal –Hydraulic Characteristics of Staggered Circular Finned-Tube Heat Exchangers undr Dry and Dehumidifying Conditions, International Journal of Heat and Mass Transfer, Vol. 41, pp. 3321-3337, 1998.
69. Launder, B. E. and Spalding, A. D., Mathematical Models of Turbulence, pp. 90-100, Academic, London, 1972.
70. Chen, Y. S., Kim, S. W., Computation of Turbulent Flows Using an Extended Turbulence Closure Model, NASA CR-179204, Oct, 1987.
71. Wang, T. S., Chen, Y. S., Unified Navier-Stokes flowfield and performance analysis of liquid rocket engines, AIAA Journal, Vol. 9, No. 5, pp. 678-685, 1993.
72. Liakopoulos, A., Explicit Representations of the Complete Velocity Profile in a Turbulent Boundary Layer. AIAA Journal, Vol. 22, pp. 844-846, 1984.
73. Thompson, J. F., Thames, F. C. and Mastin, C.W., Automatic Numerical Generation of Boby-Fitted Curvilinear Coordinate System for Fields Containing any Number of Arbitrary Two-Dimensional Bodies, Journal of Computational Physics, Vol. 15, pp. 299-310, 1974.
74. Thompson, J. F., Warsi, Z. U. A. and Mastin, C.W., Numerical Grid Generation Foundations and Applications, North Holland, 1985.
75. STAR CD V.3.10B, Simulation of Turbulent Flow in Arbitrary Regions, Computational Dynamics Limited, UK, 2001.
76. UNIC V.3.1, UNIC General Purpose CFD Design Tool, Engineering Sciences, Inc. Alabama, US, 2001.
77. Moffat, R. J., Describing the Uncertainties in Experimental Results, Experimental Thermal and Fluid Science, Vol. 1, pp. 3-17, 1998.
78. Jacobi, A. M. and Shah, R. K., Heat Transfer Surface Enhancement through the Use of Longitudinal Vortices: A Review of Recent Progress. Experimental Thermal and Fluid Science, Vol. 11, pp. 295-309, 1995.