Abstract: In modern citrus production systems, postharvest preservation represents a critical phase that significantly influences commercial value and consumer acceptance. Extensive research has demonstrated that polyethylene (PE) film packaging effectively extends the shelf life of citrus fruits by establishing a modified atmosphere that reduces oxidative stress and moisture loss. However, conventional packaging methodologies face considerable challenges including low automation levels, inconsistent sealing performance, and inadequate packaging efficiency. These limitations often result in improper sealing that induces anaerobic respiration and accelerates fruit quality deterioration. To address these technical barriers, this study developed and validated an innovative dual-channel tubular PE film packaging machine specifically engineered for citrus fruits. The integrated mechanical system comprises several precisely coordinated subsystems: a vibration-assisted feeding mechanism ensuring proper fruit orientation, a servo-driven indexing conveyor maintaining precise fruit positioning, a dual-film unwinding system with active tension control, an adjustable mandrel-based bagging device, a thermomechanical sealing unit incorporating PID-controlled heating elements and pneumatic actuation, and a synchronized discharge conveyor system. The comprehensive mechanical design enables continuous operation while maintaining handling precision throughout the packaging process. Initial single-factor experiments identified the preliminary ranges for critical parameters, followed by a systematically designed L₉(3⁴) orthogonal array experiment to optimize the heat-sealing parameters. The experimental design evaluated three key factors—sealing temperature (Levels: 124℃, 130℃, 136℃), dwell time (Levels: 1.2s, 1.7s, 2.2s), and film thickness (Levels: 0.01mm, 0.02mm, 0.03mm)—across three statistically defined levels, while incorporating an empty column for error estimation. Throughout the experimental trials, the prototype demonstrated excellent operational stability with smooth citrus transportation and seamless coordination among all subsystems. The packaged products exhibited consistent quality, effectively meeting all design specifications and functional requirements. The final packaged citrus products are presented in Figure 25, demonstrating the machine's packaging capability. The experimental results, as summarized in Table 6, revealed outstanding performance metrics: the prototype achieved a mean packaging success rate of 97.1%, a premium quality rate of 90.3%, and sustained operational efficiency of 45 fruits per minute. According to the national standard "GB/T 24709-2009" for packaging machinery, the minimum required success rate is 95%. Our prototype exceeds this requirement by 2.1 percentage points, demonstrating its superior reliability. Comparative analysis with mainstream large-scale pillow packaging machines—including the Xinkeli KL-350X, Bichuan CY-450X, and HMD-350X models, which typically achieve success rates between 93% and 95%—further highlights our machine's competitive advantage. Moreover, when compared with large-scale vertical form-fill-seal machines such as the Bichuan L-320 and IMA Jupiter-35 models, which achieve approximately 94% success rates, our design demonstrates not only higher packaging reliability but also a more compact footprint. These comparative advantages confirm that the dual-channel configuration offers enhanced suitability for citrus packaging applications. Further comparison with small-scale packaging machines, demonstrates that our prototype maintains significantly higher packaging efficiency compared to conventional equipment of similar dimensions. The successful integration of precision mechanical automation with optimized thermal parameters represents a substantial advancement in citrus packaging technology. The research outcomes provide valuable insights for designing specialized packaging equipment for delicate horticultural products, with particular relevance to the citrus industry. The systematic optimization methodology and mechanical design principles established in this study offer a replicable framework for developing efficient packaging solutions for various fresh produce items, contributing significantly to the advancement of postharvest management technologies in the fruit industry. The comprehensive experimental validation confirms that the dual-channel tubular PE film packaging machine effectively addresses the limitations of conventional packaging methods through enhanced automation, improved sealing consistency, and superior operational efficiency. The prototype's performance not only meets but exceeds industry standards while offering practical advantages in terms of space utilization and operational reliability, positioning it as an ideal solution for modern citrus packaging requirements.