Journal of Applied Science and Engineering

Published by Tamkang University Press

1.30

Impact Factor

2.10

CiteScore

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: March 3, 2011
Accepted: August 16, 2011
Publication Date: June 1, 2012

Download Citation: ||https://doi.org/10.6180/jase.2012.15.2.06  


ABSTRACT


The influence of internal recycle on the collector efficiency in upward-type solar air heaters has been investigated theoretically. The equations for predicting the outlet air temperature and the collector efficiency were derived from the energy balances on the absorbing plate and flow air. Considerable improvement in collector efficiency is obtainable if the operation is carried out with an internal recycle, where the desirable effect of increase in fluid velocity leading to improved heat transfer, overcomes the undesirable effect of decrease in driving force (temperature difference) of heat transfer due to remixing. The enhancement in collector efficiency based on the device of same size without recycle, increases with increasing reflux ratio, especially for operating at lower air flow rate with higher inlet air temperature and radiation incident. It is found that more than 150% of improvement in collector efficiency is obtained by recycle operation. Further, the performance in a upward-type solar air heater operated with internal recycle overcomes that in the same-size device operated with external recycle.


Keywords: Solar Air Heater, Upward Type, Flat-Plate, Collector Efficiency, Internal Recycle


REFERENCES


  1. [1] Duffie, J. A. and Backman. W. A., “Solar Engineering of Thermal Processes,” 2nd ed. New York: Wiley (1991).
  2. [2] Whillier, A., “Plastic Covers for Solar Collectors,” Sol Energy, Vol. 7, pp. 148154 (1963).
  3. [3] Tan, H. M. and Charters W. S., “Experimental Investigation of Force-Convective Heat Transfer for FullyDeveloped Turbulent Flow in a Rectangular Duct with Asymmetric Heating,” Sol Energy, Vol. 13, pp. 121 125 (1970).
  4. [4] Close, D. J. and Dunkle, R. V., “Behaviour of Absorbent Energy Storage Beds,” Sol Energy, Vol. 18, pp. 287292 (1976).
  5. [5] Seluck, M. K., Solar Air Heaters and Their Applications, In: Sayigh AAM, editor, New York: Academic Press (1977).
  6. [6] Gary, H. P. and Adhikari, R. S., “Performance Evaluation of a Single Solar Air Heater with N-Subcollectors Connected in Different Combinations,” International Energy Research, Vol. 23, pp. 403414 (1999).
  7. [7] Belusko, M., Saman, W. and Bruno, F., “Performance of Jet Impingement in Unglazed Air Collectors,” Sol Energy, Vol. 82, pp. 389398 (2008).
  8. [8] Yeh, H. M. and Ting, T. C., “Effects of Free Convection on Collector Efficiencies of Solar Air Heaters,” App. Energy, Vol. 22, pp. 145155 (1986).
  9. [9] Tonui, J. K. and Tripanagnostopoulos, Y., “Improved PV/T Solar Collectors with Heat Extraction by Force or Natural Air Circulation,” Renew Energy, Vol. 32, pp. 623637 (2007).
  10. [10] Mohamad, A. A., “High Efficiency Solar Air Heater,” Sol Energy, Vol. 60, pp. 7176 (1997).
  11. [11] Yeh, H. M., “Theory of Baffle Solar Air Heaters,” Energy, Vol. 17, pp. 692702 (1992).
  12. [12] Gao, W. F., Lin, W. X. and Liu, E. R., “Numerical Study on Natural Convection Inside the Channel between the Flat Plate Cover and Sine-Wave Absorber of a Cross-Corrugated Solar Air-Heater,” Energy Conv. Manag., Vol. 41, pp. 145151 (2000).
  13. [13] Yeh, H. M. and Ho, C. D., “Solar Air Heaters with External Recycle,” App. Thermal Eng., Vol. 29, pp. 16941701 (2009).
  14. [14] Yeh, H. M. and Ho, C. D., “Effect of External Recycle on the Performances of Flate-Plate Solar Air Heaters with Internal Fins Attached,” Renew Energy, Vol. 34, pp. 13401347 (2009).
  15. [15] Yeh, H. M. and Ho, C. D., “Effect of External Recycle on Upward-Type Solar Air Heaters,” J. Taiwan Inst. Chem. Engrs., Vol. 41, pp. 9295 (2009).
  16. [16] Kay, W. H. and Crawford, M. E., Convective Heatand Mass-Transfer, 2nd ed., New York, McGraw-Hill (1980).
  17. [17] McAdams, W. H., Heat Transmission, 3rd ed., New York, McGraw-Hill (1954).
  18. [18] Klein, S. A., “Calculation of Flat-Plate Loss Coefficients,” Sol Energy, Vol. 17, pp. 7980 (1975).
  19. [19] Hottel, H. C. and Woertz, B. B., “Performance of FlatPlate Solar-Heat Collector,” Trans. ASME, Vol. 64, pp. 91104 (1942).


    



 

2.1
2023CiteScore
 
 
69th percentile
Powered by  Scopus

SCImago Journal & Country Rank

Enter your name and email below to receive latest published articles in Journal of Applied Science and Engineering.