Enhancing piston-type fertilizer injection pump performance through check valve optimization

Piston-type injection pumps are critical components for fertilizer delivery in drip fertigation systems. The volumetric efficiency and metering accuracy of the pump, key determinants of fertilization uniformity, depend mainly on the structural parameters of its check valves. While the dosing uniformity of piston-type fertilizer injection pumps is significantly superior to that of other types of injection devices, the understanding of their underlying hydrodynamic mechanisms remains inadequate. This study developed a high-fidelity three-dimensional transient Computational Fluid Dynamics (CFD) model, incorporating a dynamic mesh method and the Renormalization Group k-ε turbulence model, to investigate the unsteady internal flow dynamics of a piston-type injection pump. A quadratic regression orthogonal design was employed to systematically optimize three key valve parameters—valve core diameter, core stroke, and seat diameter—with the goal of enhancing volumetric efficiency of the pump. Numerical predictions were in good agreement with experimental data, with a maximum relative error of 4.11% for the time-averaged flow rate. Transient flow analysis revealed that valve closure lag during the suction-discharge transition induced backflow, limiting the volumetric efficiency of the baseline pump to 72.16% under rated conditions. Sensitivity analysis ranked valve core diameter as the most influential parameter affecting volumetric efficiency, followed by core stroke and seat diameter. Optimization yielded an optimal configuration (core diameter: 11.4 mm; core stroke: 8.3 mm; seat diameter: 17.7 mm), which improved the volumetric efficiency by 11.32–11.85 %age points over an operating pressure range of 0.3–0.5 MPa at a rated drive frequency of 50 Hz. The findings provide critical insights and a theoretical basis for the design of high-performance piston-type injection pumps for precision agriculture, underpinning precise fertilization and refined nutrient management in drip irrigation systems.