Performance improvement of a double-pass solar air heater with fins and baffles under recycling operation

The performance of a solar air heater featured with double-pass as well as fins and baffles design was investigated for the effect of recycling operation via both experimental and theoretical approaches. The experimental results deviate by 1.5–23% from the theoretical predictions. The performance of solar air heaters with different designs are compared, including the single-pass, double-pass with recycle, fined double-pass with recycle, and fined plus baffled double-pass with recycle. The double-pass device introduced in this study was proposed for aiming to strengthen the convective heat transfer coefficient and enlarge the heat transfer area. Based on both theoretical and experimental results, the collector efficiency of the fined plus baffled double-pass with recycle design is much higher than the other designs under different reflux ratios and mass flow rates. The optimal reflux ratio for the fined plus baffled double-pass design is about 0.5 while considering both the collector efficiency and the pumping power requirement. An economic consideration in terms of the heat transfer efficiency and power consumption increment for double-pass operation is delineated.

[1]  W. Beckman,et al.  Solar Engineering of Thermal Processes , 1985 .

[2]  Chii-Dong Ho,et al.  Improvement in device performance of multi-pass flat-plate solar air heaters with external recycle , 2005 .

[3]  S. Klein,et al.  Calculation of the monthly-average transmittance-absorptance product , 1979 .

[4]  V. Lazarova,et al.  Holdup and Liquid Circulation Velocity in a Rectangular Air-Lift Bioreactor , 1999 .

[5]  B. N. Prasad,et al.  Investigation for the optimal thermohydraulic performance of artificially roughened solar air heaters , 2000 .

[6]  H. P. Garg,et al.  Theory of multiple-pass solar air heaters , 1985 .

[7]  E. Sparrow,et al.  Convective-radiative interaction in a parallel plate channel - Application to air-operated solar collectors , 1980 .

[8]  N. E. Wijeysundera,et al.  Thermal performance study of two-pass solar air heaters , 1982 .

[9]  Austin Whillier,et al.  Plastic covers for solar collectors , 1963 .

[10]  M. K. Selcuk.  Solar air heaters and their applications , 1977 .

[11]  James O. Wilkes,et al.  Fluid Mechanics for Chemical Engineers , 1998 .

[12]  Ho-Ming Yeh,et al.  An analytical study of heat and mass transfer through a parallel-plate channel with recycle , 1998 .

[13]  Chii-Dong Ho,et al.  Heat-transfer enhancement in double-pass flat-plate solar air heaters with recycle , 2005 .

[14]  Chii-Dong Ho,et al.  An analytical study of heat-transfer efficiency in laminar counterflow concentric circular tubes with external refluxes , 2003 .

[15]  D. Yogi Goswami,et al.  Principles of Solar Engineering , 1978 .

[16]  Frank P. Incropera,et al.  Fundamentals of Heat and Mass Transfer , 1981 .

[17]  J. Whitelaw,et al.  Convective heat and mass transfer , 1966 .

[18]  W. Charters,et al.  An experimental investigation of forced-convective heat transfer for fully-developed turbulent flow in a rectangular duct with asymmetric heating , 1970 .

[19]  C. Bennett,et al.  Momentum, Heat, and Mass Transfer , 1962 .

[20]  Tao Liu,et al.  Analytical and experimental studies on the thermal performance of cross-corrugated and flat-plate solar air heaters , 2007 .