Effects of solar two-stage heating on temperature rising for biogas fermentation

Temperature is the key factor to restrict efficiency of gas production in biogas fermentation especially in winter. Improving and stabilizing the biogas fermentation temperature are the technical problems for low cost system of small and medium-sized methane project. In order to solve the problems, the experiments of two-stage solar heating technology were conducted in rural ecological campus biogas system. The results showed that the two-stage solar heating system could achieve good heating effects: 1) The temperature of biogas fermentation system in greenhouse averagely increased 11℃ or 4.8℃ than that ouside in a sunny day or cloudy day; 2) The temperature of biogas fermentation system heat collection chamber increased 11.8℃averagely than that ouside the collector in a sunny day, and 4.6℃ in a cloudy day; 3) The average temperature of liquid materials in the two-stage solar heating biogas ferment tank was 10±0.5℃, which was (6±1.0)℃ higher than that without heating.