The present work intended to investigate thermal and thermohydraulic efficiencies of two different models of recyclic double pass packed bed solar air heaters experimentally. Model-I consists of single air pass through two glass covers as well as double air pass caused due to recycle of the air exiting from the packed bed duct formed between the absorber plate and the glass cover through another duct integrated between the absorber and back plates to inlet of the packed bed duct. On the other hand, model-II consists of only double air pass originated due to recycle operation constituted between the similar solar air heater elements as that of model-I. Twelve numbers of wire mesh screens to form 95% bed porosity were used. Both solar air heater models were tested under the range of packed bed Reynolds number from 300 to 1500 for air mass flow rate and recycle ratio of 0.01 kg/s to 0.025 kg/s and 0.3 to 1.8, respectively. Results revealed that thermal performance of model-I is found to be 15% higher than that of model-II. The optimum value of the recycle ratio for model-I and model-II are obtained as 0.9 and 1.2, respectively, at a mass flow rate of 0.025 kg/s that yields the best thermohydraulic efficiency of 77% and 67%, respectively. Moreover, optimum solution for recycle ratio and air mass flow rate during off sun shine hours are also obtained and presented in the current work.
Double Duct Packed Bed Solar Air Heater Under Combined Single and Recyclic Double Air Pass
Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING: INCLUDING WIND ENERGY AND BUILDING ENERGY CONSERVATION. Manuscript received May 21, 2015; final manuscript received November 6, 2015; published online December 22, 2015. Assoc. Editor: Werner Platzer.
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Singh, S., and Dhiman, P. (December 22, 2015). "Double Duct Packed Bed Solar Air Heater Under Combined Single and Recyclic Double Air Pass." ASME. J. Sol. Energy Eng. February 2016; 138(1): 011009. https://doi.org/10.1115/1.4032142
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