Airflow distribution in an apple storage room

Airflow is important in plant factories as it is responsible for the air exchange inside the structure to create desired growing conditions for plants. A uniform airflow distribution enhances photosynthesis and the transpiration process of the plants. In this study, computational fluid dynamics (CFD) analysis was used to analyse the airflow distribution inside a commercial scale plant factory developed by MARDI. CFD plays an important role in designing and optimisation of control environment structure in the agriculture industry. Many studies have proved that the CFD technique is able to predict the internal climate of the plant factory in the designing stage before the actual plant was built. This study was conducted to analyse the airflow characteristics in a plant factory with different inlet and outlet locations. The study also analyses the effect of different inlet location to the overall temperature distribution inside the plant factory. Validation of the developed CFD model was carried out by comparing simulation results with experimental data. The validation result showed an acceptable percentage error between simulated and actual data. The validated CFD model was then used to analyse different inlet locations that can produce more uniform airflow and temperature distribution inside the plant factory. From the simulation results, it shows that the new inlet location was able to produce more uniform airflow and temperature distribution as compared to existing inlet location.

Numerical approximation of air flow, temperature distribution and thermal comfort in buildings

Quality and safety of perishable products such as fruits and vegetables during transportation is dependent on the air temperature, temperature fluctuation and air velocity distribution. In this study a full scale model of a refrigerated container was constructed in order to investigate experimentally the airflow patterns and temperature distribution within the refrigerated container. A numerical investigation is carried out using computational fluid dynamics (CFD) code, Fluent, in order to study the air velocity and temperature distribution using different configurations ( duct system) inside the refrigerated containers. The results showed that adding a duct system improves the air velocity and temperature distribution within the chilling room

Evaluation of thermal comfort conditions in a classroom equipped with radiant cooling systems and subjected to uniform convective environment

Cabinet dryers are the most popular devices for fruit drying. One of the drawback of this dryer can be non-uniformity in the desired end product moisture content. To surmount this problem, a new version of cabinet dryer with separate entrances for the trays was designed in this research. Some involving physical properties of fruit such as air flow resistance, kernel and bulk densities and porosity were measured. Several different three dimensional geometries of cabinet dryer with three fruit holding trays were studied theoretically using Computational Fluid Dynamics (CFD) technique. The most appropriate geometrical sketch with acceptable uniform air flow and temperature distribution in the cabinet dryer was selected and fabricated. Several experiments were conducted on the new pilot size dryer Lemon fruit with initial moisture content of 84 % (wb) was selected to be dried in the new dryer. The experimental results showed that the new cabinet dryer illustrated an even distribution of air velocity and temperature throughout the dryer. Comparing the experimental and predicted (extracted for the CFD analysis) data under different operating conditions ( air velocities of 1, 2 and 3 ms−1, initial product moisture content of 84 %(wb) and drying air temperature of 50 ◦C) revealed a very good correlation coefficient of 0.99 for air velocity in the drying chamber. In the next step, the new cabinet dryer was compared with the existing design Amanlou and Zomorodian (J Food Eng 101: 8–15, 2011) with air flow distribution uniformity among the trays, rate of drying in different trays, and electrical energy consumptions, It was revealed that the new design was superior to the existing design in all of these aspects.

Heat abatement (e.g., soakers, fans) effectively reduces the negative physiological and production effects of heat stress, but no previous studies have documented effective interventions for the reduced lying times observed in response to hot weather. Although likely adaptive for heat dissipation, the reduction in motivated lying behavior may be an animal welfare concern. We evaluated the effect of air speed from fans with variable frequency drives on the heat stress responses of cows in a naturally ventilated freestall barn. Eight groups of lactating Holsteins (16 cows/group) were exposed to 3 treatments in a replicated crossover design: control (fans off, 0.4 ± 0.2 m/s, measured 0.5 m above the stall surface to represent cow resting height) vs. 60% (1.7 ± 0.5 m/s; ≥ 1 m/s in all stalls) and 100% (2.4 ± 0.8 m/s) fan power. Each treatment was applied for 3 d of acclimation and 4 d of data collection. The effects of treatment on daily maximum vaginal temperature (VT) and lying time (LT; both measured with data loggers), respiration rate (RR; recorded from video), unshaved scapular skin temperature (ST), milk yield (MY), and dry matter intake (DMI) were analyzed using linear mixed models. All models included the fixed effect of treatment and a repeated term for treatment day within group of cows, with group as the subject. The models for LT, VT, and RR also included a fixed effect for same-day Temperature Humidity Index (THI; recorded in the pens with data loggers) and the THI × treatment interaction. The models for DMI and MY, using data from the latter 3 d of each treatment period, also included a fixed effect for the previous day's THI and the -1 d THI × treatment interaction. Lying time differed among treatments (100% vs. 60% fan power vs. control: 14.2 vs. 13.9 vs. 13.2 h/d, respectively, SEM = 0.15 h/d), but both fan treatments prevented the reduction in LT observed in the control treatment as THI increased. Relative to the control, both fan treatments effectively reduced ST, RR, and VT and increasing DMI and MY. In the control, average values were elevated for both RR (68.7 ± 1.5 breaths/min, mean ± SEM, greater than a common benchmark of 60 breaths/min) and VT (39.3 ± 0.05°C) but remained in the normal range in both fan treatments (54.2 vs. 50.7 breaths/min in the 60% vs. 100% fan power treatments; 39.0°C in both fan treatments). Both fan treatments resulted in greater overall MY (42.6 vs. 43.0 ± 0.4 kg/d in the 60% vs. 100% fan power treatments) relative to the control (41.0 kg/d) and similarly avoided the reduction in MY when -1 d THI increased. Compared with natural ventilation alone, fans delivering air speeds of at least 1 m/s at cow resting height were effective not only for reducing thermoregulatory responses, but also for maintaining lying time, DMI, and milk yield in heat stress conditions. This is the first study to demonstrate an intervention to improve animal welfare by maintaining lying times during periods of heat stress.

Computational fluid dynamics (CFD) have been playing an increasingly important role in designing the agriculture control environment structure in the past few years. Plant factory is a fully enclose control environment agriculture structure developed to create optimum growing conditions for the crops. Previous studies have proven that the CFD technique was able to analyse and predict the internal climate of the plant factory in the designing stage before the actual plant was built. This study was conducted to analyse the changes in airflow characteristics and temperature distribution in a shipping container size plant factory with different inlet and outlet locations. Uniformity of airflow and temperature distribution was important in plant factories as it is responsible to create optimum and uniform growing conditions for crops. The CFD model was validated by comparing simulation and experimental data of existing plant factory inlet and outlet location. The validation result shows an acceptable percentage error between simulated and measured data. Two alternative design of the inlet and outlet location was simulated to improve the uniformity of airflow and temperature distribution. The validated CFD model was then used to simulate the alternative design. Finally, the location of the inlet and the outlet that produce the most uniform airflow and temperature distribution inside the plant factory was identified.

Highlights Airflow uniformity was determined using CFD simulations and uniformity index. The uniformity of airflow for the different duct and fan designs in the covered outdoor pile was determined. Regions with poor airflow were identified for each duct and fan design. Grain pile design that gave the highest uniformity index and the least region of poor airflow was identified. ABSTRACT. Adequate and uniform airflow within covered outdoor piles is critical for preserving grain quality during storage. Poor airflow uniformity can lead to uneven moisture distribution, temperature gradients, and localized hotspots within the grain mass, creating an environment conducive to the growth of molds, fungi, and insect infestations. Consequently, such compromised storage conditions can lead to significant economic losses for grain elevators and impact the availability and affordability of grain-based products in the market. However, despite considerable literature addressing airflow uniformity in permanent storage structures, aeration system designs for covered outdoor piles have not generally included in-depth analyses affecting airflow distribution. This study aimed to investigate the airflow uniformity in covered outdoor piles using computational fluid dynamics (CFD) simulations. A rectangular grain pile, commonly used in Kansas, was modeled using ANSYS Fluent. Various configurations of covered outdoor piles were evaluated regarding airflow velocity and uniformity. The velocity magnitude, vector plots, and contour plots of velocity were used to visualize the air velocity in the different regions of the grain pile. The uniformity index was used to determine the degree of uniformity. Results showed which configuration has better uniformity and less incidence of poor air velocities in the grain mass. By determining the airflow distribution within the grain mass, we can identify potential areas for improvement in the design of covered outdoor piles. Keywords: Airflow, CFD, Grain pile, Storage, Uniformity.

CFD modeling of MPS coal mill with moisture evaporation

HighlightsCFD simulation was done for studying airflow uniformity during drying of aquatic feed in a belt dryer.The simulation predicted the airflow distribution in different feed layers of the dryer well.The fan frequency affected the moisture diffusivity and overall drying uniformity.The fan frequency of 30 Hz resulted in the best drying process.Abstract. Drying is an essential process in the production of aquatic feed products. Belt dryer is widely used in drying aquatic feed. The uniformity of airflow distribution inside the belt dryer affects the quality of dried products, the dryer efficiency, and energy consumption. Fan frequency was one of the critical factors affecting air distribution inside the dryer. However, the internal airflow distribution inside the belt dryer was not fully investigated, and air velocities were challenging to test accurately. The airflow distribution inside a belt dryer at four different fan frequencies (25, 30, 35, and 40 Hz) was studied with computational fluid dynamics (CFD) simulation and experimental verification. A finite volume method was employed to simulate airflow distribution inside the dryer. The porous medium model was added to improve result accuracy. The results showed that the simulated value of air velocity was consistent with the experimental value. The maximum gap between observed and simulated values was 7.24%, and the minimum was less than 0.1%. The air velocity on the feed layer ranged from 0.34 to 1.10 m s-1 with a standard deviation of up to 0.17 m s-1. When the fan frequency was 30 Hz, air velocity uniformity on the feed layer surfaces could reach the best results. Keywords: Airflow distribution, Belt dryer, CFD, Fan frequency, Porous media.

Apples are preserved in cold storage within standard size crates to avoid injury during handling and are stacked in a specific manner to promote adequate air circulation. This research builds an air flow and heat transfer model of a cold room (5.75 m × 3.83 m × 3.75 m) with apple filled crates (0.55 m × 0.37 m × 0.3 m) modeled as a porous media and uses CFD simulation to study how alternate stacking impacts airflow distribution and product temperature. The conventional arrangement of crates, termed CS1, was simulated, and the resulting temperature distribution data were used to validate the model with published experimental data, a root mean square error of 1.13 °C indicates good match. The model is extended to examine temperature distribution for two additional arrangements of crates (CS2 and CS3) with changed orientations and spacing, in accordance with a specific strategy. CS3, featuring larger spacing along the z-direction, showed higher average air velocity compared to CS2 and CS1 by 7.4% and 3.7% respectively. CS3 also improved cooling rate by 25.2% and increased the number of chilled crates by 20% within 40 h, along with a reduced temperature heterogeneity (3.59 °C). The model could predict hot spots in various stacking configurations, aiding in optimal arrangement.

Effect of Attic Insulation Thickness and Solar Gain in a Mild Climate

Ventilation shaft can be used in apartment units to provide cross ventilation by creating a pressure difference between the room’s windward opening and outlet at the roof. The previous research about ventilation shaft has shown its potential in providing good natural ventilation in high-rise apartment building. This paper examines the influence of ventilation shaft aperture configuration on its ability to generate air movement and uniform flow distribution. The experiment is carried out using computational fluid dynamics with RNG k-e calculation method. Ventilation shaft system with a uniform aperture can produce very high air velocity only at the top floor while ventilation shaft system with internal aperture size increased from the upper floor to the lower floor can produce better air flow distribution

CFD design and testing of an air flow distribution device for microwave infrared hot-air rolling-bed dryer

Maintaining optimal environmental conditions in radiopharmaceutical facilities is essential for operational efficiency, product quality, and regulatory compliance. This study focuses on assessing ventilation systems within the test chamber as a case study to address these critical needs. Using COMSOL Multiphysics, a detailed simulation framework was developed to model airflow and heat transfer dynamics in the chamber. The simulation results were compared with experimental measurements, including inlet velocity, temperature, and heat flux, producing air temperature and velocity profiles consistent with analytical global models. The study compared mixing and displacement ventilation strategies within the test chamber, finding that displacement ventilation was more efficient, providing better control over thermal conditions while minimising temperature variations. In contrast, mixing ventilation, although effective, demonstrated less uniformity in temperature distribution. Additionally, the impact of warm air inlet jets on airflow patterns and temperature distribution was investigated, utilising the Nonisothermal Turbulent Flow, k-ω model interface. Employing the k-ω turbulent model allowed for a comprehensive analysis of complex fluid dynamics, offering valuable insights into airflow patterns and their implications for operational efficiency and compliance. The findings provide facility managers and engineers with a robust methodology for assessing ventilation systems in radiopharmaceutical settings, guiding the design and optimisation of strategies that enhance operational efficiency, ensure regulatory compliance, and protect the integrity of radiopharmaceutical products.