Fixed-ratio exhaust air recirculation in grain dryers often compromises either energy efficiency (by under-recycling) or product safety (by over-recycling and condensation risk). This study proposes a dynamic, sensor-thresholded recirculation strategy that adapts – in real time – to exhaust air conditions, enabling safe waste-heat recovery without manual intervention. A 40×40×40 cm deep-bed corn dryer was retrofitted with LM35 (T), HIH3610 (RH), and load-cell sensors, interfaced via USB-4711A to a LabVIEW-based controller. Recirculation was activated only when exhaust RH 80%), ensuring condensation-free operation. Experiments (2×3×3, n=3) evaluated energy, drying time, and exergy efficiency at T = 50–70°C and Q = 0.19–0.33 kg·m⁻²·s⁻¹. Although absolute energy savings were modest (5.8%, p > 0.05), the system consistently delayed recirculation onset until the final 10–23% of drying time (Table 2), confirming a thermodynamically conservative yet intelligent control policy. Peak exergy efficiency (12.3%) was achieved at Q=0.26 kg·m⁻²·s⁻¹, T=70°C. Sensitivity analysis revealed that >8% energy savings (statistically detectable) are feasible under cooler, low-flow conditions (T ≤ 55°C, Q ≤ 0.25). This work establishes a low-cost, scalable automation framework where responsive actuation replaces fixed ratios, a critical advancement for sustainable post-harvest systems in variable-humidity regions. Future integration of desiccant pre-treatment could unlock earlier-stage recirculation and amplify gains.
Tabasizadeh et al. (Fri,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: