Plant Factory Airflow Distribution Analysis with Different Inlet Configuration

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.

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.

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

Airflow plays a crucial role in plant growth because it supplies CO2, O2, and energy to plants in a plant factory with artificial light (PFAL). Therefore, understanding how various factors affect airflow in and around a plant canopy is essential. In this study, we developed a computational fluid dynamics (CFD) model with realistic plant structures created using structure-from-motion imaging to investigate airflow in and around a plant canopy. The averages of the absolute percentage errors of simulated air velocity in three conditions were 6.7%, 10.1%, 12.7%, respectively. The simulated and measured air velocities agreed well, confirming the accuracy of the developed CFD model. The effects of inflow velocities and plant canopy structures on the airflow in and around the plant canopy were analysed using the validated CFD model. The inflow velocities significantly decreased stagnant zones (from 62.4% to 7.2%) and increased the airflow uniformity in and around the plant canopy. A staggered layout of the plant canopy slightly decreased stagnant zones (from 16.4% to 13.2%) and increased the airflow uniformity. The airflow in and around the plant canopy was further inhibited by a large plant structure. This CFD model provided a basis for improving the airflow status in and around a plant canopy in a PFAL.

An investigation of airflow distributions with booster fan for a large opening mine through field study and CFD modeling

CFD modeling of MPS coal mill with moisture evaporation

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.

Effects of inlet and exhaust locations and emitted gas density on indoor air contaminant concentrations

This critical review delves into the impact of Computational Fluid Dynamics (CFD) modeling techniques, specifically 2D, 2.5D, and 3D simulations, on the performance and vortex dynamics of Darrieus turbines. The central aim is to dissect the disparities apparent in numerical outcomes derived from these simulation methodologies when assessing the power coefficient (Cp) within a defined velocity ratio (λ) range. The examination delves into the prevalent turbulence models shaping Cp values, and offers insightful visual aids to expound upon their influence. Furthermore, the review underscores the predominant rationale behind the adoption of 2D CFD modeling, attributed to its computationally efficient nature vis-à-vis the more intricate 2.5D or 3D approaches, particularly when gauging the turbine’s performance within the designated λ realm. Moreover, the study meticulously curates a compendium of findings from an expansive collection of over 250 published articles. These findings encapsulate the evolution of pivotal parameters, including Cp, moment coefficient (Cm), lift coefficient (Cl), and drag coefficient (Cd), as well as the intricate portrayal of velocity contours, pressure distributions, vorticity patterns, turbulent kinetic energy dynamics, streamlines, and Q-criterion analyses of vorticity. An additional focal point of the review revolves around the discernment of executing 2D parametric investigations to optimize Darrieus turbine efficacy. This practice persists despite the emergence of turbulent flow structures induced by geometric modifications. Notably, the limitations inherent to the 2D methodology are vividly exemplified through compelling CFD contour representations interspersed throughout the review. Vitally, the review underscores that gauging the accuracy and validation of CFD models based solely on the comparison of Cp values against experimental data falls short. Instead, the validation of CFD models rests on time-averaged Cp values, thereby underscoring the need to account for the intricate vortex patterns in the turbine’s wake—a facet that diverges significantly between 2D and 3D simulations. In a bid to showcase the extant disparities in CFD modeling of Darrieus turbine behavior and facilitate the selection of the most judicious CFD modeling approach, the review diligently presents and appraises outcomes from diverse research endeavors published across esteemed scientific journals.

A CFD model for the frictional resistance prediction of antifouling coatings

Analysis of climate uniformity in indoor plant factory system with computational fluid dynamics (CFD)

A “credible” computational fluid dynamics (CFD) model has the potential to provide a meaningful evaluation of safety in medical devices. One major challenge in establishing “model credibility” is to determine the required degree of similarity between the model and experimental results for the model to be considered sufficiently validated. This study proposes a “threshold-based” validation approach that provides a well-defined acceptance criteria, which is a function of how close the simulation and experimental results are to the safety threshold, for establishing the model validity. The validation criteria developed following the threshold approach is not only a function of Comparison Error, E (which is the difference between experiments and simulations) but also takes in to account the risk to patient safety because of E. The method is applicable for scenarios in which a safety threshold can be clearly defined (e.g., the viscous shear-stress threshold for hemolysis in blood contacting devices). The applicability of the new validation approach was tested on the FDA nozzle geometry. The context of use (COU) was to evaluate if the instantaneous viscous shear stress in the nozzle geometry at Reynolds numbers (Re) of 3500 and 6500 was below the commonly accepted threshold for hemolysis. The CFD results (“S”) of velocity and viscous shear stress were compared with inter-laboratory experimental measurements (“D”). The uncertainties in the CFD and experimental results due to input parameter uncertainties were quantified following the ASME V&V 20 standard. The CFD models for both Re = 3500 and 6500 could not be sufficiently validated by performing a direct comparison between CFD and experimental results using the Student’s t-test. However, following the threshold-based approach, a Student’s t-test comparing |S-D| and |Threshold-S| showed that relative to the threshold, the CFD and experimental datasets for Re = 3500 were statistically similar and the model could be considered sufficiently validated for the COU. However, for Re = 6500, at certain locations where the shear stress is close the hemolysis threshold, the CFD model could not be considered sufficiently validated for the COU. Our analysis showed that the model could be sufficiently validated either by reducing the uncertainties in experiments, simulations, and the threshold or by increasing the sample size for the experiments and simulations. The threshold approach can be applied to all types of computational models and provides an objective way of determining model credibility and for evaluating medical devices.

Hydrodynamics and scale-up of liquid–solid circulating fluidized beds: Similitude method vs. CFD

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.

The aim of this study is to investigate the use of computational fluid dynamics (CFD) in evaluating the thermal performance of a parallel/counterparallel flow heat exchanger used as part of a fluid warmer to treat hypothermia. The developed CFD model was validated in a parametric study using previously collected experimental data. The effects of heat exchanger length and inlet mass flow rate were considered. To more accurately represent the thermodynamic average temperature profile, the current CFD analysis evaluated outlet temperatures in terms of mean bulk temperature as opposed to the centerpoint temperature probe used in the experimental study. Despite this difference, the CFD results were found to agree well with the experimental values. As such, the CFD simulations are not only applicable to future design considerations but elicit further understanding of the thermal and hydrodynamic characteristics within the heat exchanger. Using the validated CFD model, thermal hydraulic entrance lengths ...