71 / 2025-04-15 17:40:22

Mitigating Methane and Ammonia Emissions in Pig Houses: A CFD Study on Funnel-Shaped Versus Traditional Manure Pits Under Different Ventilation Strategies and Seasons

Emission mitigation,Funnel-shaped manure pit,Pig house,Pit ventilation,Seasonal variations

5.减污降碳与废弃物利用 > （2）温室气体减排策略与技术

Compared to pig houses equipped with traditional rectangular manure pits, those with funnel-shaped pits may help mitigate greenhouse gas and ammonia (NH₃) emissions. However, the effects of this novel pit system on methane (CH₄) and NH₃ emissions remain unclear in commercial pig houses in China, particularly under precision-controlled air supply systems across different seasons and pit ventilation strategies. This study employed CFD simulations to investigate CH₄ and NH₃ emissions in an experimental pig house containing 30 full-scale pens, comparing traditional and funnel-shaped manure pits. Emission rates and gas concentrations in the animal-occupied zone were used as key indicators. The results showed that the pig house with traditional manure pits exhibited significantly higher gas emissions and in-zone concentrations compared to the one with funnel-shaped pits. While pit ventilation increased the total emissions of both CH₄ and NH₃, it notably reduced gas concentrations in the animal-occupied zone—especially when combined with the funnel-shaped pit design. Under the same ventilation mode, summertime emissions of CH₄ and NH₃ were higher than those in winter, likely due to increased ventilation rates, but this seasonal comparison was based on simulations assuming identical surface concentrations of manure. The reduced gas-emitting surface area in funnel-shaped pits, compared to the larger area in traditional pits, contributed to lower emissions of both gases. When pit ventilation was combined with air purification systems, further reductions in NH₃ emissions were achieved.