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

Numerical Analysis of Outlet Number Effects on Temperature Distribution in a Briquette Oven Using CFD

The performance of briquette drying systems is strongly influenced by airflow distribution and thermal uniformity within the drying chamber, which are governed by outlet configuration and internal flow patterns. However, limited studies have systematically quantified the effect of exhaust outlet arrangements on the coupled heat transfer and fluid flow behavior in industrial-scale briquette ovens. This study aims to numerically investigate the influence of single-, double-, and four-outlet configurations on airflow characteristics, temperature distribution, and overall thermal performance of a briquette drying oven. A three-dimensional geometric model representing the combustion chamber, drying chamber, and briquette racks was developed and analyzed using Computational Fluid Dynamics (CFD). Steady-state simulations were performed in ANSYS Fluent employing the standard k–ε turbulence model, with air properties, inlet velocity (9.97 m/s), and thermal boundary conditions defined based on operational data. The results reveal that outlet configuration significantly affects flow recirculation intensity and temperature uniformity across the briquette racks. The four-outlet configuration produced the most homogeneous airflow distribution and reduced thermal gradients, thereby enhancing convective heat transfer effectiveness compared to single- and double-outlet designs. Conversely, the single-outlet case exhibited pronounced recirculation zones and localized temperature variations, potentially leading to uneven drying. These findings demonstrate that optimizing outlet arrangement is a critical design parameter for improving drying efficiency and energy utilization in briquette oven systems, providing a validated numerical framework for future thermal system optimization.

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.

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

To address uneven air supply among multiple needle tubes during the drying of high-density forage bales, this study investigated the airflow characteristics and structural optimization of the upper and lower air distribution chambers of a needle-type forage dryer. A three-dimensional CFD model was established, and airflow performance was evaluated using the velocity non-uniformity coefficient M and the inlet-to-outlet total pressure drop Δp. Response surface methodology was used to optimize the key structural parameters. For the upper chamber, installation of a T-shaped baffle and optimization of the cavity height Hc, diffuser angle α, and top-plate opening area ratio Ra yielded an optimal combination of Hc = 133.29 mm, α = 12.51°, and Ra = 1.12, reducing M from 11.2264% to 3.3886%. For the lower chamber, a strip-perforated airflow equalizing plate with Hb = 74.82 mm, D = 23.79 mm, and W = 25.03 mm reduced M from 9.8772% to 1.5484%, with Δp of approximately 130 Pa. Mesh-refinement and turbulence-model sensitivity analyses supported the robustness of the numerical predictions. Repeated outlet-velocity measurements yielded mean absolute relative errors of 3.09%–4.58%. Smoke visualization and grayscale analysis further indicated that the optimized structures enhanced airflow diffusion and redistribution. The results provide guidance for air distribution chamber design in needle-type forage dryers.

Investigation of Thermal Performance of Solar Air Heater with parabolic Absorber Shapes Using Experimentation & ANSYS Simulations

The increasing global demand for clean and sustainable energy has accelerated research on high-performance solar thermal systems. Among these, Solar Air Heaters (SAHs) offer a simple and cost-effective solution; however, their thermal efficiency is strongly influenced by absorber plate geometry. This study investigates the thermal performance of a Solar Air Heater employing parabolic absorber plates with four different configurations: regular inward, regular outward, zigzag inward, and zigzag outward. The performance evaluation was carried out through both experimental investigations and Computational Fluid Dynamics (CFD) simulations using ANSYS Workbench R15.0. The analysis considered inlet and outlet air temperatures, solar irradiance, heat transfer rate, Reynolds number, Nusselt number, and thermal efficiency under operating conditions from 11:00 AM to 3:00 PM. Experimental results demonstrate that the parabolic zigzag (outward) configuration provides the best thermal performance throughout the day due to enhanced airflow turbulence, improved heat transfer, and greater solar energy absorption. At peak solar irradiance (1350 W/m² at 2:00 PM), this configuration achieved the highest experimental thermal efficiency of 28.70%, a heat transfer rate of 75 W/m², and a CFD-predicted efficiency of 31.10%. The CFD results closely agreed with the experimental observations, confirming the reliability of the numerical model with only minor deviations. Comparative analysis further revealed that outward configurations consistently outperform inward configurations, while zigzag profiles provide superior heat transfer characteristics compared to regular profiles. Overall, the parabolic zigzag (outward) absorber geometry proved to be the most effective design for enhancing thermal efficiency and solar energy utilization in solar air heaters. The findings provide valuable guidance for the optimization of absorber plate geometries and support the development of efficient, sustainable, and large-scale solar thermal energy systems.

Numerical Investigation of Airflow Temperature and Velocity Distribution in a Cleanroom

Investigating the effect of various baffle geometries on solar air heater thermal behavior: A numerical approach

This study employs Computational Fluid Dynamics (CFD) simulations to evaluate the thermo‐hydraulic performance of a solar air heater (SAH) equipped with a sinusoidal absorber plate and either arc‐ or sinusoidal baffles. The novelty lies in combining a sinusoidal absorber surface with different baffle geometries and systematically evaluating baffle pitch‐to‐height ratios ( P / e  = 8, 10, and 12) over a Reynolds number range of 5000–20,000. Using a grid‐independent and experimentally validated numerical model, results revealed that the baffles substantially enhanced convective heat transfer by promoting flow separation, vortex formation, and boundary‐layer disruption. Among the configurations, the arc‐shaped baffle provided the highest heat‐transfer enhancement. As the Reynolds number increased from 5000 to 20,000, the arc baffle's heat transfer coefficient increased from approximately 18 to 34 W/(m 2 ·K), and the average Nusselt number rose from 38 to 72. Furthermore, at low Reynolds numbers, the arc‐shaped baffle improved thermal performance by up to 22% compared with the sinusoidal baffle. Because this heat‐transfer improvement was accompanied by a higher pressure drop, thermo‐hydraulic optimization was essential. The pitch‐ratio analysis demonstrated that P / e  = 10 provided the best compromise between heat transfer enhancement and flow resistance, while P / e  = 8 delivered the highest overall thermal performance. These findings confirm that optimized baffle geometry and spacing significantly improve SAH performance, providing useful guidance for the design of more efficient solar thermal air‐heating systems.