CFD analysis of heat and flow in coach bus with different vents: the effect of size and position

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.

Numerical Investigation of Airflow Temperature and Velocity Distribution in a Cleanroom

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.

Comparative CFD Analysis of Double-Skin Façade Cavities Under Extreme Hot-Arid Conditions

Double-skin façades (DSFs) can moderate heat transfer and airflow between the outdoor environment and the building interior; however, their performance in hot-arid climates is highly dependent on cavity geometry, ventilation arrangement, and the interaction between the airflow and any active cooling surfaces. The objective of this study is to establish, under a single idealised extreme hot-arid design point, how sealed, ventilated and actively cooled double-skin façade cavities differ in their predicted temperature, velocity and turbulent kinetic energy fields, and which arrangements merit controlled follow-up study. The four configurations are treated as an idealised comparative case study rather than as validated building-performance predictions. This exploratory study uses computational fluid dynamics (CFD) to compare the aerothermal behaviour of four DSF cavity configurations under prescribed external air and outer-wall temperatures of 50 °C, an inner-wall temperature of 24 °C, and an external inlet velocity of 3.06 m/s. The configurations comprise a sealed 0.4 m cavity (M1), a wind-driven ventilated 0.4 m cavity (M2), the same ventilated cavity with six 25 mm cooling pipes at 10 °C (M3), and a concept-stage lateral-flow arrangement combining a 0.10 m cavity, a 0.025 m slit and four 80 mm cooling pipes at 10 °C (M4). The simulations employ the standard k-ε turbulence model with fixed thermal boundary conditions. Along the reported sampling lines, M1 exhibited a nearly uniform air temperature of approximately 45.7 °C, whereas M2 remained close to the imposed 50 °C external-air temperature. M3 produced lower temperatures in the immediate vicinity of the cooling pipes, but most of the sampled profile remained near ambient conditions. M4 exhibited a broader spanwise temperature range of approximately 26.9–50 °C, with local pipe-adjacent air temperatures approaching 24 °C and cooler regions developing along parts of the lateral flow path. The findings provide preliminary concept-screening evidence and support further controlled parametric analysis, higher-fidelity modelling, and experimental validation.

CFD analysis of thermal plume behavior under diagonal heat source orientation.

Confined fire environments in marine and industrial compartments present serious safety challenges due to rapid heat accumulation, restricted ventilation, and complex buoyancy-driven flow behavior. Accurate prediction of propagation of heat and development of plume is important for the effective and efficient design of thermal detection and mist-based fire suppression systems. In the present study, a 2D transient Computational Fluid Dynamics analysis has performed to investigate buoyancy-driven heat transfer generated by heat source of 0.5 m diameter maintained at 450 °C inside a closed container of dimensions 2.6 m × 2.6 m. The air was considered as the working fluid, and natural convection was modeled to capture plume rise, entrainment, and thermal stratification effects. The heat source was sequentially positioned at four diagonal locations: D1 (0.65 m, 0.65 m), D2 (1.95 m, 0.65 m), D3 (1.95 m, 1.95 m), and D4 (0.65 m, 1.95 m) to assess the influence of source orientation relative to enclosure (Container) boundaries. The numerical methodology incorporates mesh-independence verification, transient time-step control with Courant numbers maintained below 2, appropriate turbulence modeling, and strict mass conservation to ensure numerical accuracy. The simulation reveals the formation of strong buoyancy-driven thermal plumes with peak velocities in the range of 0.9-1.3 m/s. Lower heat source configurations produce tall vertical plumes, while upper source placements result in early plume impingement and the development of ceiling jets, significantly enhancing lateral heat transport. Temperature and density fields indicate localized high-temperature zones near the heat source, with air density reducing to approximately 0.5-0.7 kg/m3 within plume cores. Turbulent kinetic energy reaches peak values of the order of 10-2 m2/s2 along plume shear layers and ceiling interaction regions, reflecting intense mixing. Pressure and mass imbalance analyses confirm stable transient behavior, with mass imbalance remaining within ± 10-⁷ kg/s. The findings present design trends under idealized enclosed conditions, which may support future development of fire detection and suppression strategies for marine and industrial compartments after further validation under realistic operating conditions.

Impact of flow distribution on the combustion and emission performances in a high temperature rise combustor based on RQL