Study of solar heated biogas fermentation system with a phase change thermal storage device

A new technique of solar heating biogas fermentation system integrated with a phase change thermal storage device is introduced for improving the low efficiency of the traditional biogas fermentation devices during winter. For a designed solar heated biogas system, its performance of anaerobic fermentation process under the different natural cooling conditions has been assessed by varying the thicknesses of insulation materials. And the optimum relative proportion between the heat supplied by solar and that stored in phase change heat storage device has been also investigated. The preliminary results based on the numerical simulations performed with meteorological data from Anhui Province, China show that the proposed PCM device with 3 m3 paraffin wax as phase change material (PCM) and 20 m2 solar collector areas can satisfy the heat required by producing 5 m3 biogas per day corresponding to a solar fraction (f) of 0.8 in winter. It indicates that the proposed solar heating system could be a promising approach for promoting biogas technology applications in cold rural regions of China.