Numerical Simulation and Optimization of Airflow Distribution Characteristics in the Air Distribution Chamber of a Needle-type Forage Dryer

Influence of Structural Parameters on Airflow Uniformity and Optimisation of a Tower-type Air-assisted Sprayer Based on Computational Fluid Dynamics

In air-assisted orchard spraying, airflow characteristics strongly determine spray performance. This study designed a tower-shaped fan for grape canopies and investigated its aerodynamic behaviour. A three-dimensional computational fluid dynamics (CFD) model of the internal flow field was established to quantify the effects of shroud taper, upper and lower guide-vane angles, inlet diameter, and inlet position on outlet air-velocity uniformity. Single-factor simulations confirmed that all selected structural parameters significantly affect the outlet air velocity’s coefficient of variation (CV). Based on these results, central composite design was applied for multi-parameter optimisation. A second-order regression model was developed to describe the relationship between guide-vane angles, shroud taper, inlet position, inlet diameter, and air-velocity CV response. Analysis of variance showed that the influence of the factors decreased in the following order: guide-vane angle > inlet position > inlet diameter > shroud taper. Numerical optimisation identified the optimal configuration as a guide-vane angle of 118.37°, shroud taper of 23.84°, inlet position of 29.35 mm, and inlet diameter of 493.92 mm. Under these conditions, the predicted air-velocity CV decreased to 12.07%. A field validation experiment was conducted using representative measurement points selected from the simulated velocity distribution. The maximum relative error between measured and simulated values was below 6%, indicating strong agreement. These results confirm the reliability of the CFD model and demonstrate its effectiveness for structural optimisation of orchard air-assisted spraying equipment.

Optimization Analysis of Thermal Distribution in a Confined Balcony Space Under Air-Conditioning Outdoor Unit Operation Using Taguchi-Based CFD Simulation

This study analyzes the thermal behavior and airflow characteristics within a confined balcony space under typical hot and humid climatic conditions in Ho Chi Minh City. A computational fluid dynamics (CFD) model was developed and numerically assessed through mesh-independence and convergence analyses, incorporating an external air domain to ensure realistic boundary conditions. The Taguchi method, combined with analysis of variance (ANOVA), was employed to evaluate the influence of four key factors: number of outdoor units, installation position, ventilation opening ratio, and ambient wind velocity. The results indicate that the number of outdoor units is the dominant factor affecting the average balcony temperature, contributing the largest variation. Ambient wind velocity has a moderate influence, while installation position and ventilation opening ratio exhibit relatively minor effects. The consistency between Taguchi and ANOVA analyses confirms the reliability of the findings. Based on the signal-to-noise (S/N) ratio analysis using the “smaller-thebetter” criterion, the optimal configuration was identified as A1-B2-C1-D1. A verification simulation showed that the model converged and achieved an average temperature of 304.24 K, significantly lower than in the initial simulation cases. The findings highlight the importance of controlling internal heat sources and optimizing airflow pathways to improve thermal conditions in confined balcony spaces. This study provides practical insights into the design and installation of airconditioning systems in urban residential buildings.

Optimization of Hot Air Inlet Position in a Biomass-Fueled Rotary Drum Dryer Using CFD Simulation and Experimental Validation

This study evaluates the impact of hot air inlet positioning on heat transfer efficiency within a biomass-fueled rotary drum dryer system using Computational Fluid Dynamics (CFD) simulation combined with experimental validation. Three inlet configurations - at the drum head, at one-third of the drum length, and at the center of the drum - were compared based on velocity distribution, temperature fields, and energy loss characteristics. Simulation results using ANSYS Fluent indicate that the head-inlet configuration leads to non-uniform thermal distribution and high exhaust velocities $(\approx 3 mathrm{m} / \mathrm{s})$. Conversely, the internal-inlet configuration optimizes airflow circulation with lower velocities $(\approx \mathbf{1} \mathrm{m} / \mathrm{s})$, enhancing heat transfer efficiency to the material bed and minimizing energy loss to the environment. Experimental drying of agricultural products within a temperature range of 60-80°C confirmed the accuracy of the simulation model, with deviations in final temperature and moisture content below 5%. The results demonstrate that the internal-inlet configuration shortens drying time and improves product uniformity. This research confirms the critical role of CFD simulation in designing and optimizing renewable energy drying systems, particularly for decentralized small-scale production.

The Effect of Inlet and Outlet Pattern on a Parabolic Dome Solar Collector

This research aims to investigate the effects of air inlet and outlet patterns on parabolic-dome solar collectors. A three-dimensional transient computational fluid dynamics (CFD) simulation in ANSYS Fluent was used to analyze sixteen different inlet-outlet patterns and compare their effects on air behavior, outlet air temperature, and thermal efficiency. Simulation results show that most patterns led to recirculating air, resulting in hot spots and reduced heat transfer efficiency. Conversely, pattern 3-2 exhibited the most uniform air distribution. This 3-2 pattern also had an outlet air temperature and average thermal efficiency of about 42.75°C and 41.97%, respectively. Furthermore, the numerical model was validated using statistical indicators R², MRD, and RMSE, which showed that the model results were highly consistent with the experimental results (R² = 0.9942, MRD = -0.031°C, and RMSE = 3.656°C). These observations underscore the critical role of the inlet-outlet pattern in optimizing airflow and improving heat transfer efficiency. Therefore, this study presents an effective design for air inlet-outlet patterns that improves the efficiency of parabolic dome solar collectors through an optimized air channel design.

Numerical Investigation of Airflow Temperature and Velocity Distribution in a Cleanroom

CFD-Based Simulation and Optimization of Summer Environmental Conditions in Laying Hen Houses

To address uneven temperature and relative humidity distributions, localized heat accumulation, and insufficient air velocity in an enclosed stacked-cage laying hen house, a three-dimensional computational fluid dynamics (CFD) model of the laying hen house was developed using field-measured structural and environmental data, and a porous-media model was established for the cage zone. Model validation showed that the normalized mean square error (NMSE) values for temperature, relative humidity, and air velocity were all below 0.25, confirming the reliability of the CFD model. Through visualization analysis of the contour maps, the problems of uneven airflow distribution in the original ventilation system and significant heat accumulation at the fan end were identified. On this basis, numerical simulations were conducted for six air-inlet configurations by varying two key parameters: air-inlet spacing and air-inlet number. The simulation results showed that, compared with the original model, the configuration with an air-inlet spacing of 1.14 m and a total of 32 air inlets on the two gable walls improved the uniformity of temperature, air velocity, and relative humidity by 18.00%, 10.54%, and 18.38%, respectively, while reducing the mean effective temperature index (ETI) in the cage zone by 0.5 °C. This configuration effectively alleviated localized heat accumulation and improved air-velocity uniformity. These findings provide a theoretical basis and technical support for the structural optimization and environmental regulation of enclosed stacked-cage laying hen houses.