AIR DISTRIBUTOR FOR AN ALMOND STOCKPILE HEATED AND AMBIENT AIR DRYER (SHAD)

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

A portion of the material in this patent document may be subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all copyright rights whatsoever. The copyright owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. § 1.14.

BACKGROUND
1. Technical Field

The technology of this disclosure pertains generally to foodstuff drying and more particularly to drying piles of almonds.

2. Background Discussion

Almond conventional windrow drying is prone to pest and human pathogen infestation; it affects timely irrigation and involves harvesting steps, such as picking and sweeping, which generate significant and undesirable amounts of dust. Therefore, a prior stockpile heated and ambient air Dryer (the “Dryer”) was developed and its performance was evaluated in a previous study. The purpose of developing the Dryer was to facilitate early harvest, timely irrigation, and eliminate harvesting dust-generating steps. However, the Dryer did not properly distribute drying air to the stockpile, which resulted in a lack of drying uniformity through the stockpile layers. Additionally, the Coefficient of Performance (COP) of the Dryer equaled 1.33, which was above the limits of other commercially available dryers, suggesting that the drying air was not efficiently used to dehydrate almonds within the stockpile. These results indicated that an improvement in the distribution of the drying air through the almond stockpile was required, and there was a need to develop an air distributor that ensures uniform dispersion of the drying air through the almond stockpile.

Airflow and its distribution are described as the movement of air between regions of high to low pressure. Airflow is bound by three fundamental laws of physics, which include the conservation of: 1) mass, which states that the mass of air can neither be created nor destroyed; 2) energy, which states that the sum of all energy types (kinetic, potential, and internal) along the air stream are the same at every point; and 3) momentum, which states that air movement can only be compelled by an external force, or fan in the case of the Dryer. Further, airflow is mainly categorized as laminar or turbulent flow. The Navier-Stokes differential equations are governed by the mass, momentum, and energy conservation laws, as described above, and shown in Eq. 1, Eq. 2, and Eq. 3 below. The derivation of Navier-Stokes equations and definition of boundary conditions are described elsewhere, and are well known in the field of fluid dynamics.

$\begin{matrix} \frac{\partial p}{\partial t} + \nabla \cdot (ρ U) = 0 & (1) \end{matrix}$

$\begin{matrix} \frac{\partial ρ U}{\partial t} + \nabla \cdot (ρ U \times U) = \nabla \cdot {- p δ + μ [\nabla U + {(\nabla U)}^{T}]} + S_{M} & (2) \end{matrix}$

$\begin{matrix} \frac{\partial ρ h}{\partial t} + \nabla \cdot (ρ Uh) = \nabla \cdot (λ \nabla T) + S_{E} & (3) \end{matrix}$

where

- ρ=air density (kg/m³) where p is 1.204 kg/m³
- U=air velocity vector (m/s)
- μ=dynamic air viscosity (mPa·s). μ is 0.01825 mPa·s
- S_M=momentum source (kg/m²·s²)
- h=specific static enthalpy (J/kg).
- λ=air thermal conductivity (W/m·K). λ is 0.02514 W/m·K
- S_E=energy source (Kg/m·s³)

Air distribution systems are often used in dryers to deliver and uniformly distribute drying air (heated or ambient) to achieve consistent drying of food under similar thermal conditions. Also, the ventilation industry is another major application of air distribution technology, mainly adopted to optimize room heating and cooling. A typical air distributor, without limitation, typically consists of: 1) a plenum chamber, which generates a laminar flow of the inlet air, before splitting it into multiple outlets; and 2) outlets (air ducts, perforations, false floors), which are the exit points for drying air aimed to dehydrate foods.

BRIEF SUMMARY

A Stockpile Heated and Ambient air Dryer (SHAD) was developed as an alternative to conventional windrow drying of almonds. Previous experiments showed that the drying air supplied by the Dryer through the almond stockpile was unevenly distributed. Therefore, an embodiment of an air distributor was developed containing 12 outlets, arranged in 4 rows of 3 outlets each. This disclosure also describes steps taken to design the air distributor and optimize air delivery by combining a Computational Fluid Dynamics (CFD) simulation model with in-field airflow validation measurements.

In-field validation measurements indicated that the percentages of airflow distribution were found to be 4.1, 30.8, 44.9, and 20.2% for the outlets in rows 1 through 4. It is noted that almonds located in the region of row 1 (nearest the airflow inlet) would receive insufficient air to properly dry. Thus, an optimized 3-row air distributor configuration was developed and validated by sealing off the outlets in row 1 to yield an airflow distribution percentage of 31.3%, 44.4%, and 24.3% for outlets in rows 2 through 4. The 3-row air distributor configuration is preferred due to the typical almond stockpile roughly conical shape, where the middle and tallest section of the stockpile would receive the highest airflow. Ultimately, the developed air distributor significantly improved the air supply of the SHAD.

Further aspects of the technology described herein will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the technology without placing limitations thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

The technology described herein will be more fully understood by reference to the following drawings which are for illustrative purposes only:

FIG. 1A is a perspective view of one embodiment of a plenum according to the present disclosure that incorporates an internal flow divider.

FIG. 1B is uniform cuboid cross-section plenum.

FIG. 1C is a tapered plenum used to improve air distribution through multiple outlets.

FIG. 1D is a bottom view of an assembled air distributor, previously shown as a plenum in FIG. 1A

FIG. 1E is a side view of the assembled air distributor, previously shown as a plenum in FIG. 1A, with the lateral outlet ports omitted for clarity.

FIG. 2A is a mechanical drawing of an end view of a plenum according to the present disclosure, with dimensions shown in meters.

FIG. 2B is a mechanical drawing of a side view of the plenum of FIG. 2A.

FIG. 2C is a mechanical drawing of a top view of the plenum of FIG. 2A.

FIG. 2D is a mechanical drawing of a cross sectional view of the side view of FIG. 2B taken midways through the plenum.

FIG. 3A is a mechanical drawing of an end view of a flow divider, with dimensions shown in meters.

FIG. 3B is a mechanical drawing of a side view of the flow divider of FIG. 3A, now showing a tapered top.

FIG. 3C is a mechanical drawing of a top view of the flow divider of FIG. 3A with a double side taper shown.

FIG. 3D is a mechanical drawing of a perspective view of the views of FIG. 3A, FIG. 3B, and FIG. 3C. Here, a triply tapered geometry is present, where a top side slopes from 0.300-0.200 m, and sides adjacent to the top together are sloped from 0.300-0.000 m in thickness.

FIG. 4A is a perspective line drawing of a constructed plenum shell.

FIG. 4B is a perspective line drawing of a constructed flow divider.

FIG. 4C is a perspective line drawing of an air distributor, comprising the plenum shell of FIG. 4A with the flow divider of FIG. 4B installed within, depicted as placed inside an A-frame structure.

FIG. 4D is a line drawing of the air distributor shown attached to the SHAD in an open outdoor space to measure the airflow in each outlet.

FIG. 4E is a perspective line drawing of a second pitot tube inserted into a pipe connected to the air distributor outlets to measure the airflow at each outlet.

FIG. 5A is a surface plot of the pressure distribution within the plenum with the flow divider

FIG. 5B is a surface plot of the pressure distribution within the plenum without the flow divider.

FIG. 5C is a graph of the in-field airflow measurement results (line graph) and corresponding B-values (bar graph) when all of the outlets are open.

FIG. 6 is a graph that shows a comparison between the airflow data obtained from the in-field airflow measurements and the CFD airflow data, when all the outlets are open.

FIG. 7A is a graph of air distributor in-field airflow measurement results (line graphs) and corresponding β-values (bar graphs) when outlets in Row 1 was sealed off.

FIG. 7B is a graph of air distributor in-field airflow measurement results (line graphs) and corresponding B-values (bar graphs) when outlets in Row 2 was sealed off.

FIG. 7C is a graph of air distributor in-field airflow measurement results (line graphs) and corresponding B-values (bar graphs) when outlets in Row 3 was sealed off.

FIG. 7D is a graph of air distributor in-field airflow measurement results (line graphs) and corresponding β-values (bar graphs) when outlets in Row 4 was sealed off.

FIG. 8A is a graph of a 4-row configuration air distributor that yielded B-values of 4.1, 30.8, 44.9, and 20.2% as tested with almonds.

FIG. 8B is a graph of the resulting 3-row configuration of the 4-row air distributor of FIG. 8A with Row 1 sealed off, with air distributor B-values of 31.3, 44.4, and 24.3% as tested with almonds.

FIG. 9 is a graph showing a comparison between the in-field measured airflows and the CFD-generated airflow data, based on the optimized air distributor design.

DETAILED DESCRIPTION
1. Introduction

Designing an optimized system to efficiently distribute the air from the SHAD to an almond stockpile is a complex, time-consuming, and costly process; however, Computational Fluid Dynamic (CFD) techniques can reduce these challenges. CFD generally comprises three main stages: 1) a pre-processing stage, which defines the system's geometry known as meshing, boundary conditions, and underlying mathematical equations; 2) a solving stage, where discretized equations are solved; and 3) a post-processing stage, which involve quantitative measurements and airflow results. Various experimental and numerical studies have leveraged CFD to analyze and improve air distribution in multiple outlet plenums for different applications and designs such as three-lateral dividing manifolds, fluidized bed equipment, and hydrogen reformer furnaces.

Currently, it does not appear that air distributors have been developed as an addition to foodstuff stockpile drying, including almonds. Therefore, an air distributor comprising of 12 outlets using both vertical and horizontal air distribution was manufactured from a CFD model, as an additional component of the SHAD. The air distributor is placed within a SHAD A-frame, beneath the almond stockpile. Thus, the main purpose of this study was to model, design, fabricate, validate, and optimize a multi-outlet air distributor for the SHAD. The effect on energy consumption, drying, and almond quality is described elsewhere.

The steps followed in this study are based on a development of the SHAD air distributor CFD model, its optimization to maximize air distribution through the almond stockpile, based on the typical almond stockpile shape, and its validation by performing in-field airflow measurements.

2. Materials and Methods
2.1 Air Distributor Design and CFD Modeling

The three-dimensional (3D) CFD model design and simulations of the SHAD air distributor were performed in SolidWorks 2019 Service Pack (SP) 3.0 and its CFD simulation tool (Dassault Systèmes SolidWorks Corp, Waltham, MA, USA) using the parts, assembly, and drawing environments as described below.

2.1.1 Parts Environment

The SHAD's air distributor components or ‘parts’ are the model building blocks, and an “assembly’ is comprised of one or multiple ‘parts’ (SolidWorks, 2015). First, the ‘sketch’ feature was used to develop 2D sketches for each ‘part’, which are then transformed into independent 3D models with the ‘features’ element. The air distributor ‘assembly’ consists of the combination of two ‘parts’, including the plenum and flow divider. The selected material for both ‘parts’ (plenum and flow divider) was ‘cast carbon steel’.

2.1.1.1 Plenum

The plenum is connected to the fan, with a goal to uniformly distribute the drying air through the outlets to the almond stockpile. The role of the plenum is to form a laminar airflow to achieve a similar pressure and temperature (T) along its length, prior to diffusing the drying air through the outlets. There are two main types of plenums: 1) extended, which contains a main large duct with multiple outlets along its cross-section; and 2) radial, which doesn't contain a main duct, but rather individual outlets are connected to the main air supply or fan. In this embodiment, an extended plenum of cuboid cross-sectional shape was used, since it allows for a higher airflow rate distribution with reduced airflow resistance through multiple outlets. There are three main shapes of outlets, including round, square, and rectangular. Round outlets were used in this embodiment, as this type offers the least resistance through the longitudinal air path, requiring less fan power, using the least amount of material, and producing lower frequency noise.

Refer now to FIG. 1A, which is a perspective view 100 of one embodiment of a plenum 102 according to the present disclosure. The plenum 102 has an air inlet duct 104 providing inlet air to the rectangular plenum body 106, which has an internal flow divider 108. Twelve outlets 110-1, 110-2, 110-3, 110-4, 110-5, 110-6, 110-7, 110-8, 110-9, 110-10, 110-11, and 110-12 are arranged in 4 rows with 3 on each side (right 112, top 114, and left 116) are placed on the plenum 102.

2.1.1.2 Flow Divider

Refer now to FIG. 1B, which is uniform cuboid cross-section plenum 118. Here, the plenum 118 air velocity profile reflects a pressure increase along the plenum's longitudinal path, therefore forcing the majority of the air through the outlets furthest to the air inlet 120, or fan, as indicated by increasing arrow lengths at outlets 122-1, 122-2, 122-3, and 122-4 progressing along the length of the plenum 102. This results in insufficient airflow distribution to the outlets closer to the air inlet (e.g. 122-1 has a lower output relative to that of 122-4).

Refer now to FIG. 1C, which is a tapered plenum 124 used to improve air distribution through multiple outlets 126-1, 126-2, 126-3, and 126-4. Here, the exerted velocity pressure generated by the air is inversely proportional to the area within the plenum 124. With this improved understanding, a three-sided tapered flow divider was placed inside the plenum 124 to gradually increase the pressure of the air through the plenum's longitudinal path. Hence, improving the air distribution through the outlets 126-1, 126-2, 126-3, and 126-4. One wall of the three-sided tapered flow divider is shown as plane 128.

2.1.2 Assembly Environment

Refer now to FIG. 1D, which is a bottom view 130 of an assembled air distributor, previously shown as a plenum 102 in FIG. 1A. The “Assembly” feature in the assembly environment was used for two purposes: 1) to combine the two “parts” into the air distributor “assembly” (the rectangular plenum 132 and flow divider 134, which appears triangular in this FIG. 1D); and 2) to conduct the CFD simulation (model and analysis) with the ‘flow simulation’ feature.

Refer now to FIG. 1E, which is a side view 136 of the assembled air distributor, previously shown as a plenum 102 in FIG. 1A, with the lateral outlet ports omitted for clarity. It is noted that the divider 134 tapers from the distal end 138, diminishing in height toward the air inlet 140.

Refer now collectively to FIG. 1D and FIG. 1E. The distance between the divider 134 and the rectangular plenum 132 walls (left 142, right 144, and top 146, as viewed from the air inlet 140) decreases lengthwise, modifying the air velocity pressure through the rectangular plenum 132.

2.1.2.1 CFD Simulation

The overall CFD simulation is categorized into internal and external analyses. The internal analysis includes airflow within the air distributor model, or the flow of the drying air into the inlet and out through the outlets. The external analysis relates to the airflow surrounding the CFD model was not considered in this application (SolidWorks, 2012), as the air distributor is fully surrounded by the almond stockpile. CFD analysis includes pre-processing, solving, and post-processing steps, as followed:

(a) Pre-processing. Model openings are closed, while performing an internal analysis using the ‘lid’ tool. Lids, which are protrusions that cover openings, allow defining the airflow boundary conditions (SolidWorks, 2011). In this study, 13 lids were placed on all the air distributor openings, or 12 outlets and 1 air inlet. The ‘check geometry tool’ was used to inspect for model leakages.

Airflow simulation was performed with the ‘wizard’ tool, which defines the air distribution model and its parameters, including the model's name, unit system (i.e., International System of Units), analysis type (i.e., Internal), and fluid type (i.e., Air). The final SolidWorks Flow Simulation Design Tree (SFSDT) was created under the ‘configuration manager’ tab. SFSDT provides specifics of the model, data, and a platform to visualize results (SolidWorks, 2012). The ‘Boundary condition’ feature under the SFSDT was used to specify the flow conditions at each opening. The inlet airflow rate of 1.2 m³/s, equal to the airflow provided by the fan, was selected as the inlet boundary condition. Then, the static atmospheric pressure (i.e., 101,325 Pa) was selected for the 12 outlets to simulate an open environment model (SolidWorks, 2012). The goal of this study was to obtain the CFD model airflow data for each outlet. Therefore, the ‘volume flow rate’ feature was selected as the surface goal for each of the 12 outlets, under the ‘goals’ icon in the SFSDT.

(b) Solving stage. The solving stage (‘run’) is controlled by SolidWorks and requires no user input. After the 3D model mesh has been automatically generated, the Navier-Stokes equations for the model are solved.

(c) Post processing. Surface plots were generated to visualize the results. Surface plots showing the velocity pressure distribution within the plenum with and without the divider were developed to visualize the effect of the divider. Also, outlet airflow data was obtained by selecting the ‘Results’ icon, then ‘Goal Plots’ feature under the SFSDT.

2.1.3 Example

Refer now to FIG. 2A, FIG. 2B, FIG. 2C, and FIG. 2D. FIG. 2A is an end view 200 of a plenum 202 according to this disclosure. FIG. 2B is a side view 204 of the plenum 202 of FIG. 2A, now showing the air inlet 206. FIG. 2C is a top view 208 of the plenum 202 of FIG. 2A. Finally, FIG. 2D is a cross sectional view 210 of the side view 204 of FIG. 2B taken midways through the plenum 202.

Refer now to FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D, which all depict views of a flow divider according to this disclosure. FIG. 3A is an end view 300 of a flow divider 302. FIG. 3B is a side view 304 of the flow divider 302 of FIG. 3A, now showing a tapered top 306. FIG. 3C is a top view 308 of the flow divider 302 of FIG. 3A with a double side taper 310 shown, both of which are adjacent to the tapered top 306. Finally, FIG. 3D is perspective view 312 of the views of FIG. 3A, FIG. 3B, and FIG. 3C. Note that in FIG. 3D, there is a doubly tapered geometry present, where one side slopes from 0.300-0.200 m, and another two sides are sloped from 0.300-0.000 m in thickness. The double side taper 310 and adjacent tapered top 306 combine to form a triply tapered flow divider 302.

In the figure sets of FIG. 2A, FIG. 2B, FIG. 2C, and FIG. 2D, and FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D, example dimensions are shown, which were based on fixed and variable parameters.

Fixed parameters were selected based on space available, applicability, and design feasibility, including: 1) the overall (including outlets) air distributor length of 3 m long to dry typically sized stockpiles, and a width of 0.5 m, based on the available space within the SHAD A-frame; 2) outlet dimensions, which were 0.1 m diameter, 0.1 m length, and 0.6 m spacing from each other, sufficient to cover the length of the plenum.

Variable parameters were optimized to provide the lowest deviation between the outlets' air delivery by applying the “parametric” tool, included the: 1) outlet angle of inclination (θ); 2) longitudinal distance from both ends of the divider (y); and 3) vertical distance from the front end of the divider (x). The air distributor with θ=45°, y=3.0 m, and x=0.2 m showed the lowest standard deviation of airflow between outlets, as seen in Table 1.

2.2 Air Distributor Fabrication

Refer now to FIG. 4A, FIG. 4B, FIG. 4C, FIG. 4D, and FIG. 4E.

FIG. 4A is a perspective line drawing of a constructed plenum shell 400. FIG. 4B is a perspective line drawing of a constructed flow divider 402. FIG. 4C is a perspective line drawing of an air distributor 404, comprising the plenum shell 400 of FIG. 4A with the flow divider 402 of FIG. 4B installed, depicted as placed inside an A-frame 406 structure to provide spacing from the air distributor 404 and foodstuff (not shown here) placed over and around the A-frame 406. There is generally no contact between air distributor 404 and the A-frame 406.

The air distributor 404 components, comprising the plenum shell 400 and a flow divider 402, were built at the Biological and Agricultural Engineering (BAE) fabrication shop at the University of California (UC) Davis campus. Both ‘parts’ were fabricated from 18 gage carbon steel metal sheets.

2.3 In-Field Airflow Measurements

In FIG. 4D, the air distributor 404 is shown attached to the SHAD 408 without no A-frame contact (the A-frame is not shown in this view) and in an open outdoor space to measure the airflow in each outlet. The SHAD 408 consisted of a 1.49 KW (2 hp) propane-heated vane axial fan with a 457.2 mm diameter outlet (Sukup Manufacturing Co, Sheffield, IA, USA). The propane-heated fan was powered by a 12 KW (16 hp) generator (Model 100297, Champion Global power equipment, Santa Fe Springs, CA, USA). Two straight 304 stainless steel ducts 410 of dimension 152.4 mm diameter, 1.5 m length, and one 152.4 mm diameter high temperature rigid 304 stainless steel hose were used to connect the outlet of the SHAD's 408 fan to the inlet of the assembled plenum 404.

One pitot tube 412 (a DS 300 flow sensor, Dwyer Instrument Inc, Michigan City, IN, USA) was inserted in a 0.15 m pipe connecting the outlet of the fan to the air distributor, 2.2 m away from the fan to measure inlet airflow under approximate laminar flow.

In FIG. 4E, a line drawing is shown of a second pitot tube 414 (PAFS-1010 flow sensors, Dwyer Instrument Inc, Michigan City, IN, USA) inserted into a 0.1 m pipe 416 connected to the air distributor 404 outlets, 2.4 m away from the output of each outlet, to measure the airflow per outlet. A pressure sensor (Series MS Magnesense, Dwyer Instruments Inc, Michigan City, IN, USA) was connected to each of the pitot tubes to record the static and total pressure at 5 s intervals. The difference between total and static pressures yields the velocity pressure (P_v). Airflow (Q) was calculated in m³/s using Eq.4 and 5.

$\begin{matrix} V = \sqrt{\frac{2 P_{v}}{ρ}} & (4) \end{matrix}$

$Q = AV$

where,

- V=Velocity of airflow (m/s).
- A=Pipe area (m²) where A=0.018, and 0.008 m²for the inlet pipe and each of the outlets, respectively.
- ρ=Air density (kg/m³).
- An average heated drying T of 55.37° C. and ambient drying T of 16.69° C. measured by an embedded T sensor (HX94C, Omega Engineering Inc, Norwalk, CT, USA) were used to calculate the density of air p, as stated in Eq. 6.

$\begin{matrix} ρ = \frac{P \times m}{n \times R \times T} & (6) \end{matrix}$

where,

- P=Atmospheric pressure (101,325 Pa)
- m=Air molar mass (0.02896 kg/mol)
- n=Number of moles (taken as 1 to match units of molar mass)
- R=Gas constant (8.3145 J/Kmol)

Percentage airflow distribution (B) was calculated using Eq.7, reflecting the airflow per outlet, or group of outlets, in relation to the inlet airflow.

$\begin{matrix} β = \frac{Q_{i}}{Q} \times 1 0 0 & (7) \end{matrix}$

where,

- i=Outlet number
- β=Flow ratio for the i^thoutlet
- Q_i=Air flow rate of the i^thoutlet (m³/s)
- Q=Inlet airflow (m³/s)

2.4 CFD Air Distributor Model Validation

The CFD model validation was performed by comparing the in-field airflow measurements with CFD model simulation data. The percentage Root Mean Square Error (% Error) was used to determine the variation between the in-field and CFD outlet airflow data, as shown in Eq. 8.

$\begin{matrix} % Error = \frac{\sqrt{\sum_{i = 1}^{N_{i}} \frac{{(M_{i} - S_{i})}^{2}}{N_{i}}}}{\frac{1}{N_{i}} \sum_{i = 1}^{N_{i}} M_{i}} \times 100 & (8) \end{matrix}$

where;

- i=Outlet number
- N_i=Total number of outlets (12)
- S_i=Predicted CFD airflow for the i^thoutlet
- M_i=Measured in-field airflow for the i-th outlet

2.5 Air Distribution Optimization

Air distribution optimization was conducted to determine the optimum air distributor configuration to properly distribute air through the natural shape of an almond stockpile. Optimization was performed by evaluating the changes in air distribution through subsequent sealing of outlets in Rows 1 through 4 with 152.4 mm diameter wingnut expansion plugs (McMaster-Carr Supply co, Santa Fe Springs, CA). Outlets in a sealed row that generate the lowest standard deviation (SD) of airflow, as calculated in Eq. 9, in relationship to the open outlets are selected to optimize the air distributor.

$\begin{matrix} S D = \sqrt{\frac{Σ Q_{i}^{2} - \frac{{(Σ Q_{i})}^{2}}{n}}{n - 1}} & (9) \end{matrix}$

where

- n=Total number of open outlets (n=9)
- Q_i=Air flow rate of the i^thoutlet (m³/s)

In-field measurements for the optimized air distributor and its comparison with the CFD design were also performed. An optimized air distributor should uniformly distribute the air through the outlets, based on a defined total airflow requirement. Most air distribution systems, such as building ventilation units, parallel flow heat exchangers, tray dryers, and bin dryers, aim at outputting the same amount of air through every outlet. An optimized SHAD air distributor needs to consider the cone shape of the almond stockpile. Due to the almond stockpile shape, it is desired that most of the airflow be delivered to the outlets in the middle region (Rows 2 and 3) of the stockpile, as this is the region that holds the most almonds.

3. Results and Discussion
3.1 Role of the Divider

Refer now to FIG. 5A and FIG. 5B. These figures show the surface plots that reflect the pressure distribution within the plenum with (FIG. 5A) and without the flow divider (FIG. 5B). The addition of the flow divider modifies the pressure distribution in the plenum and forces input air to the outlets accordingly.

3.2 In-Field Airflow Measurements

Refer now to FIG. 5C, which shows the in-field airflow measurement results (line graph) and corresponding B-values (bar graph) when all of the outlets are open. In the subsequent discussion, each Outlet is previously described in FIG. 1A sequentially as elements 110-1, 110-2, 110-3, 110-4, 110-5, 110-6, 110-7, 110-8, 110-9, 110-10, 110-11, and 110-12, Row 1 (Outlets 1, 2, and 3) yielded the lowest β-value of 4.1%. A low average β-value for Outlets in Row 1 corresponds to lower velocity pressure within the plenum, due to the largest distance between the divider and the Outlets. A decrease in the lateral distance between the divider and outlets leads to an increase in the B-value. Thus, the B-value for Outlets in Row 2 (Outlets 4, 5, and 6), Row 3 (Outlets 7, 8, and 9), and Row 4 (Outlets 10, 11, and 12) were 30.8, 44.9, and 20.2%, where the middle section of the air distributor (Row 2 and Row 3) outputs most of the air. Future work will explore an air distributor design with and increased overall length for larger stockpiles.

3.3 CFD Air Distributor Model Validation

Refer now to FIG. 6, which is a graph 600 that shows a comparison between the airflow data obtained from the in-field airflow measurements and the CFD airflow data, when all the outlets are open. The mean % Error was equal to 31.21%. Even though high, the discrepancy between the CFD model outputs and the in-field measurements can be attributed to: iteration and grid convergence, discrepancies between the physical properties of the fabricated air distributor in comparison to the digital CFD model, placement of the divider within the plenum, and high variability of in-field measurements. The highest % Error was observed in the airflow outputs for Row 1 (Outlets 1, 2, and 3). In addition, Row 1 outlets also produced the least amount of airflow. Therefore, there was a need to optimize the design and explore the effect on air distribution with a 3-row, instead of a 4-row air distributor.

CFD modeling studies by others have yielded a wide range of error rates, partly based on model complexity, and environmental conditions that cannot be entirely included in the CFD design and simulation. On the low end (<10% Error):

- a. a % Error between 2.3 and 5.9% was found when simulating the temperature and airflow distribution of a solar biomass dryer;
- b. a % Error of less than 3% was predicted in the air ventilation and thermal comfort of an atrium space;
- c. a % Error of between 4.7 and 8.23% was found when the air velocity of a fluidized bed dryer was simulated; and finally,
- d. a % Error of 8.9% and 7.5% was predicted of the air temperature and velocities for the aeration of an indoor plant factory system, respectively.

Higher errors rates include:

- a. predictions of the velocity and temperature of a ship's cabin air distributor with a % Error of 20.3% and 5.7%, respectively,
- b. predictions of air velocity distribution and ventilation effectiveness of wind towers with a % Error of 1.58 to 24.3%; and
- c. predictions of a % Error of 4.4% and 23.1% at the center and periphery, respectively, for airflow distribution within a maize silo with different grain mass configurations.

3.4 Air Distributor Optimization

Refer now to FIG. 7A, FIG. 7B, FIG. 7C, and FIG. 7D, which show the air distributor in-field airflow measurement results (line graphs) and corresponding B-values (bar graphs) when outlets in Row 1 (FIG. 7A), Row 2 (FIG. 7B), Row 3 (FIG. 7C), and Row 4 (FIG. 7D) were subsequently sealed off. Sealing off outlets in Row 1 yielded the lowest airflow standard deviations on the open outlets (0.03 m³/s), in comparison to sealing off Row 2 (0.06 m³/s), Row 3 (0.04 m³/s), and Row 4 (0.06 m³/s).

Refer now to FIG. 8A and FIG. 8B. In FIG. 8A, a 3-row configuration air distributor yielded B-values of 4.1, 30.8, 44.9, and 20.2%, When Row 1 was sealed off, the 3-row configuration air distributor yielded B-values of 31.3, 44.4, and 24.3%, as seen in FIG. 8B. FIG. 8A and FIG. 8B both show results of in-field experimental tests with almonds.

3.5 Optimized Model Validation

Refer now to FIG. 9, which shows a comparison 900 between the in-field measured airflows and the CFD-generated airflow data, based on the optimized air distributor design. The % Error of the 3-row optimized design was equal to 14.72%, which is within an acceptable range in relation to other studies and lower than the 4-row design. In addition, the 3-row optimized air distributor delivers air to the almond stockpile in relationship to its natural shape. Optimized air distribution to the stockpile can be achieved by sealing off a selected group of outlets, or through modifying the placement of the air distributor within the SHAD's A-frame. More specifically, the air distributor can be placed towards the entrance of the SHAD's A-frame so that the outlets in Row 2, Row 3, and Row 4 are underneath the tallest section of the stockpile (the center).

4. Experimental Results

In-field airflow measurements from the 12-outlet air distributor yielded β-values equal to 4.1, 30.8, 44.9, and 20.2% of the air distributed to outlets in Rows 1, 2, 3, and 4, respectively, as previously seen in FIG. 8A. This leads to a low air distribution for almonds in the Row 1 region. Therefore, a 3-row optimized air distributor, which was obtained by sealing outlets in Row 1, leads to B-values of 31.3, 44.4, and 24.3% for outlets in Rows 2, 3, and 4, respectively, as seen previously in FIG. 8B.

The majority of almonds are in the middle of the stockpile, due to its cone shape. Therefore, it is ideal that most of the air is distributed in the middle section of the stockpile. Accordingly, the 3-row air distributor configuration is desired, since the middle and tallest region of the stockpile, which contains the majority of the almonds, will receive the most airflow. Air distributor optimization showed that the % Error between the in-field airflow measurements and CFD airflow data was 31.21% and 14.72% for the initial (4-row configuration) and optimized (3-row configuration with outlets in row 1 sealed off) models, respectively. Comparison with other studies showed that the % Error of the 4-configuration model is beyond limits, but the optimized 3-configuration model is within acceptable limits. The optimized 3-row air distributor configuration yielded desirable B-values, and can enhance the SHAD's air distribution.

5. Conclusion

From the description herein, it will be appreciated that the present disclosure encompasses multiple implementations of the technology which include, but are not limited to, the following:

An air distribution apparatus, comprising: (a) a plenum having an open first end and a closed second end, a substantially uniform cross-section between the first end and the second end, an inlet port at the first end, and a plurality of outlet ports between the first end and the second end; (b) a flow divider having first and second ends and a taper between the first and second ends, wherein the first end is smaller than the second end; (c) the flow divider positioned in the plenum with the first end of the flow divider in proximity to the first end of the plenum and the second of the flow divider positioned in proximity to the second end of the plenum.

An air distribution apparatus, comprising: (a) a plenum; and (b) a flow divider; (c) the plenum comprising a chamber of substantially uniform cross section with an open first end and a closed second end; (d) an inlet port at the first end of the plenum; (e) the plenum having a plurality of outlet ports; (f) the flow divider having a first end and a second end; (g) the flow divider positioned in the plenum with the first end of the flow divider in proximity to the first end of the plenum and the second of the flow divider positioned in proximity to the second end of the plenum; (h) the flow divider being tapered between its first and second ends wherein the first end is smaller than the second end.

An air distribution apparatus, comprising: (a) a plenum, the plenum comprising a chamber of substantially uniform rectangular cross-section with an open first end and a closed second end, an inlet port at the first end, and a plurality of outlet ports; (b) the plenum having at least three rows of at least three outlet ports per row, each row spaced apart at substantially a uniform distance between rows; (c) wherein in each row, at least one output port is positioned on a first sidewall of the plenum, at least one output port is positioned on a second sidewall of the plenum, and at least one output port is positioned on a third sidewall of the plenum; (f) the flow divider having a first end and a second end, the flow divider positioned in the plenum with the first end of the flow divider in proximity to the first end of the plenum and the second of the flow divider positioned in proximity to the second end of the plenum; (h) the flow divider being tapered between its first and second ends wherein the first end is smaller than the second end.

The apparatus of preceding implementation, wherein the flow divider divides airflow from the inlet port to maximize distribution of airflow to outlet ports positioned in an area approximately midpoint between the first and second ends of the plenum.

The apparatus of any preceding implementation, wherein airflow to the output ports has a profile with a bell-curve shape.

The apparatus of any preceding implementation, wherein the flow divider balances airflow from the inlet port to the outlet ports.

The apparatus of any preceding implementation, wherein airflow to the output ports has a substantially uniform flow profile.

The apparatus of any preceding implementation, wherein the flow divider has a compound taper that increases in width and height from the first end toward the second end.

An air distribution apparatus, comprising: (a) a plenum having an open first end and a closed second end, a substantially uniform cross-section between the first end and the second end, an inlet port at the first end, and a plurality of outlet ports between the first end and the second end; (b) a flow divider having first and second ends and a taper between the first and second ends, wherein the flow divider first end is smaller than the flow divider second end; (c) the flow divider positioned in the plenum with the flow divider first end in proximity to the first end of the plenum and the flow divider second end positioned in proximity to the second end of the plenum.

The apparatus of any preceding implementation, wherein the flow divider divides airflow from the inlet port to maximize distribution of airflow to outlet ports positioned in an area approximately midpoint between the first and second ends of the plenum.

The apparatus of any preceding implementation, wherein the flow divider has a compound taper that increases in width and height from the flow divider first end toward the flow divider second end.

The apparatus of any preceding implementation, further comprising: (a) the plenum having four rows of three outlet ports per row, each row spaced apart at a substantially uniform distance between rows; (b) wherein the flow divider divides airflow between the inlet port and the outlet ports.

The apparatus of any preceding implementation, wherein the flow divider maximizes distribution of airflow to outlet ports positioned in an area approximately midpoint between the first and second ends of the plenum.

The apparatus of any preceding implementation, wherein the flow divider has a compound taper that increases in width and height from the first end toward the second end.

The apparatus of any preceding implementation, wherein the flow divider has a triply-compounded taper that increases in width and height from the first end toward the second end, with each taper facing at least one outlet port.

The apparatus of any preceding implementation, wherein each taper faces toward a group of four outlet ports.

An air distribution apparatus, comprising: (a) a plenum; and (b) a flow divider; (c) the plenum comprising a chamber of substantially uniform cross section with an open first end and a closed second end; (d) an inlet port coupled to the first end of the plenum; (e) the plenum having a plurality of outlet ports; (f) the flow divider having a first end and a second end; (g) the flow divider positioned in the plenum with the first end of the flow divider in proximity to the first end of the plenum and the second of the flow divider positioned in proximity to the second end of the plenum; (h) the flow divider being tapered between its first and second ends wherein the first end is smaller than the second end.

An air distribution apparatus, comprising: (a) a plenum, the plenum comprising a chamber of substantially uniform rectangular cross-section with an open first end and a closed second end, an inlet port at the first end, and a plurality of outlet ports; (b) the plenum having at least three rows of at least three outlet ports per row, each row spaced apart at substantially a uniform distance between rows; (c) wherein in each row, at least one output port is positioned on a first sidewall of the plenum, at least one output port is positioned on a second sidewall of the plenum, and at least one output port is positioned on a third sidewall of the plenum; (f) a flow divider having a first end and a second end, the flow divider positioned in the plenum with a first end of the flow divider in proximity to the open first end of the plenum and a second end of the flow divider positioned in proximity to the closed second end of the plenum; (h) the flow divider being tapered between its first end and second end wherein the first end is smaller than the second end.

The apparatus of any preceding implementation, wherein the flow divider has a compound taper that increases in width and height from the flow divider first end toward the flow divider second end.

The apparatus of any preceding implementation, wherein the flow divider has a compound taper that increases in width and height from the first end toward the second end.

The apparatus of any preceding implementation, wherein the flow divider has three tapers, each of which cause an increase in width and height from the first end toward the second end, with each taper facing at least one outlet port.

The apparatus of any preceding implementation, wherein each taper faces toward a group of four outlet ports.

The apparatus of any preceding implementation, wherein each taper faces toward one of the sidewalls selected from a group of sidewalls comprising: the first sidewall, the second sidewall, and the third sidewall.

As used herein, the term “implementation” is intended to include, without limitation, embodiments, examples, or other forms of practicing the technology described herein.

As used herein, the singular terms “a,” “an,” and “the” may include plural referents unless the context clearly dictates otherwise. Reference to an object in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.”

Phrasing constructs, such as “A, B and/or C”, within the present disclosure describe where either A, B, or C can be present, or any combination of items A, B and C. Phrasing constructs indicating, such as “at least one of” followed by listing a group of elements, indicates that at least one of these groups of elements is present, which includes any possible combination of the listed elements as applicable.

References in this disclosure referring to “an embodiment”, “at least one embodiment” or similar embodiment wording indicates that a particular feature, structure, or characteristic described in connection with a described embodiment is included in at least one embodiment of the present disclosure. Thus, these various embodiment phrases are not necessarily all referring to the same embodiment, or to a specific embodiment which differs from all the other embodiments being described. The embodiment phrasing should be construed to mean that the particular features, structures, or characteristics of a given embodiment may be combined in any suitable manner in one or more embodiments of the disclosed apparatus, system, or method.

As used herein, the term “set” refers to a collection of one or more objects. Thus, for example, a set of objects can include a single object or multiple objects.

Relational terms such as first and second, top and bottom, upper and lower, left and right, and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, apparatus, or system, that comprises, has, includes, or contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, apparatus, or system. An element proceeded by “comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, apparatus, or system, that comprises, has, includes, contains the element.

As used herein, the terms “approximately”, “approximate”, “substantially”, “substantial”, “essentially”, and “about”, or any other version thereof, are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. When used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ±10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, “substantially” aligned can refer to a range of angular variation of less than or equal to ±10°, such as less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3º, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°

Additionally, amounts, ratios, and other numerical values may sometimes be presented herein in a range format. It is to be understood that such range format is used for convenience and brevity and should be understood flexibly to include numerical values explicitly specified as limits of a range, but also to include all individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly specified. For example, a ratio in the range of about 1 to about 200 should be understood to include the explicitly recited limits of about 1 and about 200, but also to include individual ratios such as about 2, about 3, and about 4, and sub-ranges such as about 10 to about 50, about 20 to about 100, and so forth.

The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed.

Benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of the technology described herein or any or all the claims.

In addition, in the foregoing disclosure various features may be grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Inventive subject matter can lie in less than all features of a single disclosed embodiment.

The abstract of the disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

It will be appreciated that the practice of some jurisdictions may require deletion of one or more portions of the disclosure after the application is filed. Accordingly, the reader should consult the application as filed for the original content of the disclosure. Any deletion of content of the disclosure should not be construed as a disclaimer, forfeiture, or dedication to the public of any subject matter of the application as originally filed.

All text in a drawing figure is hereby incorporated into the disclosure and is to be treated as part of the written description of the drawing figure.

The following claims are hereby incorporated into the disclosure, with each claim standing on its own as a separately claimed subject matter.

Although the description herein contains many details, these should not be construed as limiting the scope of the disclosure, but as merely providing illustrations of some of the presently preferred embodiments. Therefore, it will be appreciated that the scope of the disclosure fully encompasses other embodiments which may become obvious to those skilled in the art.

All structural and functional equivalents to the elements of the disclosed embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed as a “means plus function” element unless the element is expressly recited using the phrase “means for”. No claim element herein is to be construed as a “step plus function” element unless the element is expressly recited using the phrase “step for”.

TABLE 1

Air distributor variable parameters. The cross indicates

rejected values while the checkmark indicates acceptance

values used in the final design.

Outlet angle of inclination
30
45
60
70
90

(θ in degrees)
x
✓
x
x
x

Divider Height
0.17
0.18
0.19
0.2
0.21
0.22

(x in m)
x
x
x
✓
x
x

Divider Length
2.5
2.6
2.7
2.8
2.9
3.0

(y in m)
x
x
x
x
x
✓

AIR DISTRIBUTOR FOR AN ALMOND STOCKPILE HEATED AND AMBIENT AIR DRYER (SHAD)

Information

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CPC

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Abstract

Description

Claims

CROSS-REFERENCE TO RELATED APPLICATIONS

Provisional Applications (1)