Practical and numerical analysis of solar-assisted anaerobic digestion system for cold regions

Over the past few decades, researchers have been contemplating various approaches to substitute the dependence on clean fuels for energy generation. In this context, the utilization of anaerobic digestion of waste emerges as a promising solution to mitigate environmental pollution and enhance energy production efficiency. Consequently, the present study was undertaken to develop a greenhouse-enclosed anaerobic digestion system aimed at elevating the temperature of rural biogas digestion. To achieve this objective, Gambit, a software tool, was employed to generate the desired geometric mesh, utilizing irregular techniques and tetrahedral elements. In order to determine the most suitable ratio of tank covering for optimal heat absorption, four different models were designed for this system: 1) uncovered tank; 2) fitted cover; 3) cover walls positioned at a distance of 0.5 m from the tank and its walls; 4) cover placed at a distance of 1 m from the tank body. The results demonstrated that the optimal distance in this design was 0.5 m, as it provided the highest temperature increase from 10 °C to 36.15 °C. This approach holds potential for being adapted in other regions and countries. It can be concluded that by constructing and developing similar devices, a big step can be taken toward waste management and sustainable development as well as energy management in the areas of Iran, and this approach could be localized for other countries.