This paper investigates the thermohydraulic performance and methane production of a Liquid recirculation Mesophilic Digester with Submerged solid waste (LMDS) under different mixing strategies. A combination of food waste and cow dung was used as a substrate in the co-digestion experiments. After 24 days of incubation, we reported a higher specific methane yield (301.84 Nm³ CH₄ t_vs^-1) when gentle mixing was adopted, compared to intense mixing (221.32 Nm³ CH₄ t_vs^-1). As for the unmixed co-digestion, it produced the lowest methane yield (112.88 Nm³ CH₄ t_vs^-1). Furthermore, the thermal study showed that the gentle mixing caused less heat loss from the LMDS (20.90 kW h) compared to the intense mixing (40.21 kW h). Moreover, CFD results showed that intense mixing caused a higher pumping energy consumption (through increasing pressure drop) without inducing a significant improvement in the mixing inside the LMDS. Additionally, the liquid flow fields, force distribution, and percolation of the submerged waste were qualitatively evaluated for the considered mixing strategies. Based on these findings, we presented several recommendations aimed at reducing thermal and hydraulic energy losses while guaranteeing optimal methane production in LMDS systems.

本文研究了在不同混合策略下，液体淹没式中温消化池与淹没固体废物（LMDS）的热工性能和甲烷产生。在共消化实验中，将食物垃圾和牛粪的混合物用作底物。温育后的24天，我们报道了较高的比甲烷产率（301.84牛顿米³ CH ₄吨_VS ^-1）时温和混合获得通过，相较于剧烈搅拌（221.32牛顿米³ CH ₄吨_VS ^-1）。至于未混合共消化，它产生的甲烷产量最低（112.88 Nm ³ CH ₄ t_与^-1）。此外，热学研究表明，与强力混合（40.21 kW h）相比，轻度混合导致LMDS产生的热量损失更少（20.90 kW h）。此外，CFD结果表明，剧烈混合会导致较高的泵送能耗（通过增加压降），而不会引起LMDS内部混合的明显改善。另外，针对所考虑的混合策略，定性评估了浸没废物的液体流场，力分布和渗滤。基于这些发现，我们提出了一些建议，旨在减少热能和水力损失，同时确保LMDS系统中甲烷的最佳生产。