SIMULATION OPTIMIZATION AND EXPERIMENTAL STUDY OF THE AIR DISTRIBUTION CHAMBER STRUCTURE OF STRAW-BASED NUTRIENT SEEDING-GROWING BOWL TRAY MICROWAVE–HOT-AIR COUPLING DRYERS

Li, Haiyuan; Hu, Yuhui; Qi, Lianxing; Yu, Haiming

doi:10.1590/1809-4430-Eng.Agric.v42n2e20210226/2022

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Scientific Paper • Eng. agríc. (Online) 42 (2) • 2022 • https://doi.org/10.1590/1809-4430-Eng.Agric.v42n2e20210226/2022 copy

SIMULATION OPTIMIZATION AND EXPERIMENTAL STUDY OF THE AIR DISTRIBUTION CHAMBER STRUCTURE OF STRAW-BASED NUTRIENT SEEDING-GROWING BOWL TRAY MICROWAVE–HOT-AIR COUPLING DRYERS

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

To improve the flow field structure of the air distribution chamber of the microwave–hot-air coupling dryer for a straw-based nutrient seeding-growing bowl tray and enhance the uniformity of the outlet gas velocity distribution, computational fluid dynamics software was used to simulate the flow field of the air distribution chamber based on the gas motion differential equation and the (RNG) k–ε turbulence model. Using the front panel height, upper apex angle, and side wall inclination angle as factors and the speed nonuniformity coefficient as the index, the results showed that when the air distribution chamber front panel height was 33 mm, the upper apex angle was 108°, the side wall inclination angle was 78°, the height of the two spoilers was 40 mm, the outlet airflow speed varied from 5.36 to 5.71 m/s, and the speed unevenness coefficient was reduced from 13.95% in the original model to 6.05%. The maximum deviation between the numerical simulation results and test data was less than 4%, which met the uniformity requirement of the outlet airflow speed of the dryer. The results provide theoretical support for the design and industrial production of microwave–hot-air coupling dryers.

KEYWORDS
air distribution chamber structure; CFD model; simulation optimization

Coding level	Cavity front plate height	Cavity top angle	Side wall inclination angle
Coding level	X₁(mm)	X₂(°)	X₃(°)
1.682	39	118	88
1	36	115	85
0	32	110	80
−1	28	105	75
−1.682	25	102	72

Test number	Test factor			Test index
Test number	X ₁	X ₂	X ₃	Speed unevenness factor M/%
1	−1	−1	−1	10.1
2	1	−1	−1	9.3
3	−1	1	−1	11.7
4	1	1	−1	11.2
5	−1	−1	1	12.2
6	1	−1	1	11.6
7	−1	1	1	12.9
8	1	1	1	12
9	−1.682	0	0	11.3
10	1.682	0	0	10.3
11	0	−1.682	0	10.3
12	0	1.682	0	12.2
13	0	0	−1.682	9.9
14	0	0	1.682	13.1
15	0	0	0	8.5
16	0	0	0	8.6
17	0	0	0	8.7
18	0	0	0	8.4
19	0	0	0	8.5
20	0	0	0	8.8
21	0	0	0	8.5
22	0	0	0	8.7
23	0	0	0	8.6

Variance source	Qualification index
Variance source	Sum of square	Degree of freedom	F	P
Model	58.74	9	397.74	<0.0001^ <0.01 (very significant)
X ₁	1.08	1	65.98	<0.0001^ <0.01 (very significant)
X ₂	4.80	1	292.43	<0.0001^ <0.01 (very significant)
X ₃	10.69	1	651.32	<0.0001^ <0.01 (very significant)
X ₁ X ₂	0.011	1	0.69	0.4226
X ₁ X ₃	1.250E−003	1	0.076	0.7869
X ₂ X ₃	0.55	1	33.59	<0.0001^ <0.01 (very significant)
$X_{1}^{2}$	10.81	1	658.48	<0.0001^ <0.01 (very significant)
$X_{2}^{2}$	14.29	1	870.92	<0.0001^ <0.01 (very significant)
$X_{2}^{3}$	17.08	1	1040.82	<0.0001^ <0.01 (very significant)
Residual	0.21	13
Misfit	0.084	5	0.017	0.4525
Error	0.13	8
Sum	58.96	22

Statistical item	Value	Statistical item	Value
Std. Dev.	0.13	R-Squared	0.9964
Mean	10.26	Adj R-Squared	0.9939
C.V./%	1.25	Pred R-Squared	0.9861
PRESS	0.82	Adeq Precision	52.31

Associação Brasileira de Engenharia Agrícola SBEA - Associação Brasileira de Engenharia Agrícola, Departamento de Engenharia e Ciências Exatas FCAV/UNESP, Prof. Paulo Donato Castellane, km 5, 14884.900 | Jaboticabal - SP, Tel./Fax: +55 16 3209 7619 - Jaboticabal - SP - Brazil
E-mail: revistasbea@sbea.org.br

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[1] *Corresponding author. College of Electrical and Information, Northeast Agricultural University, Harbin, China. E-mail: hmyu09@yeah.net