Thermodynamic analysis of a solar-driven supercritical water gasification-oxidation system for ammonia production and heat supply from chicken manure

Faced with the dual challenges of energy shortage and environmental pollution, researchers are turning to extracting clean energy from waste resources. The coupled system of solar energy and supercritical water gasification offers a novel solution to these issues. In this study, a solar-driven supercritical water gasification-oxidation system for ammonia production and heat supply from chicken manure was simulated. Additionally, the effects of temperature of supercritical water gasification, chicken manure slurry concentration, water-dry matter ratio, and pressure of supercritical water gasification and oxidation on the system's products, efficiency, and device exergy losses were examined. Under typical working conditions (the temperature of supercritical water gasification: 750 degrees C, chicken manure slurry concentration: 50 wt%, water-dry matter ratio: 5, the pressure of supercritical water gasification and oxidation: 25 MPa), and the system had a treatment capacity of 5 t/h of dry chicken manure. The system yielded 2604.04 kg/h of NH3 and 23763.9 kg/h of heating steam. It demonstrated an energy efficiency of 68.38% and an exergy efficiency of 46.85%. The total exergy losses of the system amounted to 34704.73kw, with the solar collector accounting for the largest share at 49.6%. The temperature of supercritical water gasification and water-dry matter ratio significantly impacted the system efficiency. Conversely, chicken manure slurry concentration and the pressure of supercritical water gasification and oxidation exerted minimal influence. The solar collector and gasification reactor emerged as the primary contributors to exergy losses in the entire system. Notably, the lower temperatures of supercritical water gasification, chicken manure slurry concentrations, pressures of supercritical water gasification and oxidation, and water-dry matter ratios can reduce exergy losses in both the solar collector and the gasification reactor.