Ho-Ming Yeh This email address is being protected from spambots. You need JavaScript enabled to view it.1

1Energy and Opto-Electronic Materials Research Center, Department of Chemical and Materials Engineering, Tamkang University, Tamsui, Taiwan 251, R.O.C.


Received: December 4, 2013
Accepted: May 12, 2014
Publication Date: June 1, 2014

Download Citation: ||https://doi.org/10.6180/jase.2014.17.2.08  


The effect of pass number on the collector efficiency in downward-type multi-pass solar air heaters has been investigated theoretically. The application of multi-pass operation to solar air heaters actually has two conflict effects. One is the desirable effect of increasing fluid velocity to decrease the heat transfer resistance. The other is the undesirable effect of increasing the hydraulic dissipated power. It is found that considerable improvement in collector efficiency is obtainable if the operation is carried out with multi-pass operation, while the undesirable effect is still small and may be ignored. The enhancement increases with increasing pass number, especially for operating at lower air flow rate with higher inlet air temperature.

Keywords: Solar Air Heater, Collector Efficiency, Multipass, Downward Type


  1. [1] Garg, H. P. and Adhikari, R. S., “Performance Evaluation of a Single Solar Air Heater with n-Subcollectors Connected in Different Combinations,” International Journal of Energy Research, Vol. 23, pp. 403414 (1999). doi: 10.1002/(SICI)1099-114X(199904)23:5 3.0.CO;2-F
  2. [2] Belusko, M., Saman, W. and Bruno, F., “Performance of Jet Impingement in Unglazed Air Collectors,” Solar Energy, Vol. 82, pp. 389398 (2008). doi: 10.1016/j. solener.2007.10.005
  3. [3] Duffie, J. A. and Beckman, W. A., Solar Engineering of Thermal Processes, Wiley, New York (1991).
  4. [4] Koyuncu, T., “Performance of Various Design of Solar Air Heaters for Crop Drying Applications,” Renewable Energy, Vol. 31, pp. 10731088 (2006). doi: 10. 1016/j.renene.2005.05.017
  5. [5] Liu, C. H. and Sparrow, E. M., “Convective-Radiative Interaction a Parallel Plate Channelapplication to AirOperated Solar Collectors,” International Journal of Heat and Mass Transfer, Vol. 23, pp. 11371146 (1980). doi: 10.1016/0017-9310(80)90178-7
  6. [6] Yeh, H. M. and Ting, Y. C., “Effects of Free Convection on Collector Efficiencies of Solar Air Heaters,” Applied Energy, Vol. 22, No. 2, pp. 145155 (1986). doi: doi:10.1016/0306-2619(86)90078-4
  7. [7] Forson, F. K., Nazha, M. A. A. and Rajakaruna, H., “Experimental and Simulation Studies on a Single Pass, Double Duct Solar Air Heater,” Energy Conversion and Management, Vol. 44, pp. 12091227 (2003). doi: 10.1016/S0196-8904(02)00139-5
  8. [8] Naphon, P., “On the Performance and Entropy Generation of the Double-Pass Solar Air Heater with Longitudinal Fins,” Renewable Energy, Vol. 30, pp. 1345 1357 (2005). doi: 10.1016/j.renene.2004.10.014
  9. [9] Yeh, H. M., Ho, C. D. and Lin, C. Y., “Effect of Collector Aspect Ratio on the Collector Efficiency of Upward Type Baffled Solar Air Heaters,” Energy Conversation and Management, Vol. 41, No. 9, pp. 971 981 (2000). doi: 10.1016/S0196-8904(99)00148-X
  10. [10] Goldstein, L. and Sparrow, E. M., “Experiments on Transfer Characteristics of a Corrugated Fin and Tube Heat-Exchanger Configuration,” ASME Journal of Heat Transfer, Vol. 98, pp. 2634 (1976). doi: 10. 1115/1.3450464
  11. [11] Gao, W. F., Lin, W. X. and Lu, E. R., “Numerical Study on Natural Convection Inside the Channel between the Flat-Plate Cover and Sine-Wave Absorber of a CrossCorrugated Solar Air-Heater,” Energy Conversation Management, Vol. 41, pp. 145151 (2000). doi: 10. 1016/S0196-8904(99)00098-9
  12. [12] Gao, W., Lin, W., Liu, T. and Xia, C., “Analytical and Experimental Studies on the Thermal Performance of Cross-Corrugated and Flat-Plate Solar Air Heaters,” Applied Energy, Vol. 84, pp. 425441 (2007). doi: 10.1016/j.apenergy.2006.02.005
  13. [13] Chaube, A., Sahoo, P. K. and Solanki, S. C., “Analysis of Heat Transfer Augmentation and Flow Characteristics Due to Rib Roughness over Absorber,” Renewable Energy, Vol. 31, pp. 317331 (2006). doi: 10.1016/ j.renene.2005.01.012
  14. [14] Kays, W. M. and Crawford, M. E., Convective Heatand-Mass Transfer, McGraw-Hill, New York (1980). doi: 10.1016/0017-9310(67)90130-5
  15. [15] McAdams, W. H., Heat Transmission, Third ed., McGraw-Hill, New York (1954). doi: 10.1126/science. 120.3128.984
  16. [16] Klein, S. A., “Calculation of Flat-Plate Loss Coefficients,” Solar Energy, Vol. 17, No. 1, pp. 7980 (1975). doi: 10.1016/0038-092X(75)90020-1
  17. [17] Hottel, H. C. and Woertz, B. B., “Performance of Flat-Plate Solar-Heat Collector,” Transactions of the ASME, Vol. 64, pp. 91104 (1942).