Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.)

Combined infrared and hot-air drying method has been identified to be able to improve both energy efficiency and quality of dried agricultural crops. However, being a novel drying technique, studies on its application to the drying of industrial crops such as sweet potato are still limited. Pa...

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Main Author:	Onwude, Daniel Iroemeha Chikwendu
Format:	Thesis
Language:	English
Published:	2018
Subjects:	Sweet potatoes - Drying Infrared heating
Online Access:	http://psasir.upm.edu.my/id/eprint/71431/1/FK%202018%2096%20IR.pdf
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spelling	my-upm-ir.714312019-11-20T08:49:11Z Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.) 2018-07 Onwude, Daniel Iroemeha Chikwendu Combined infrared and hot-air drying method has been identified to be able to improve both energy efficiency and quality of dried agricultural crops. However, being a novel drying technique, studies on its application to the drying of industrial crops such as sweet potato are still limited. Particularly, the drying conditions, combination strategies and modelling studies are not properly investigated. This research investigated the potential of combined infrared and hot-air in drying of sweet potato (Ipomoea batatas L.) slices. The combined computer vision (CV) and laser-light backscattering imaging was adopted to monitor the shrinkage and quality attributes. The specific energy consumption (SEC), colour and microstructural changes of sweet potato (Ipomoea batatas L.) based on experimental set-up of different combined IR and HAD strategies (Simultaneous IR and HAD, two-stage HAD + IR, two-stage IR + HAD, intermittent IR and HAD) were investigated. Mathematical models based on Lambert’s equation of electromagnetics for single-phase and multiphase change during the combined IR and HAD of sweet potato were developed and evaluated, using finite element methods in both COMSOL and MATLAB software. The combined IR and HAD resulted in 69.34 – 85.59% reduction in the SEC of HAD. The specific energy consumption during simultaneous IR and HAD, two-stage HAD+IR, two-stage IR+HAD, and intermittent IR and HAD varied between 174.10- 310.93 MJ/kg, 95.80-177.48 MJ/kg, 56.30-68.36 MJ/kg, 99.61-149.18 MJ/kg, respectively. The intermittent IR and HAD was demonstrated to be the most suitable combination strategy based on the combined effect of total drying time, shrinkage, SEC and total colour change. The moisture and temperature distribution results of the single-phase model for simultaneous and intermittent IR and HAD of sweet potato agreed well with experimental drying data. The multiphase simulations results indicated that the model could adequately describe the underling drying mechanism of combined IR and HAD. The water and vapour fluxes due to gas diffusion and gas pressure resulted to increased drying efficiency of combined IR and HAD. The understanding of these phenomenon could be used to improve food quality and increase energy efficiency. The automation and optimization ability could also be increased. Sweet potatoes - Drying Infrared heating 2018-07 Thesis http://psasir.upm.edu.my/id/eprint/71431/ http://psasir.upm.edu.my/id/eprint/71431/1/FK%202018%2096%20IR.pdf text en public doctoral Universiti Putra Malaysia Sweet potatoes - Drying Infrared heating
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English
topic	Sweet potatoes - Drying Infrared heating
spellingShingle	Sweet potatoes - Drying Infrared heating Onwude, Daniel Iroemeha Chikwendu Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.)
description	Combined infrared and hot-air drying method has been identified to be able to improve both energy efficiency and quality of dried agricultural crops. However, being a novel drying technique, studies on its application to the drying of industrial crops such as sweet potato are still limited. Particularly, the drying conditions, combination strategies and modelling studies are not properly investigated. This research investigated the potential of combined infrared and hot-air in drying of sweet potato (Ipomoea batatas L.) slices. The combined computer vision (CV) and laser-light backscattering imaging was adopted to monitor the shrinkage and quality attributes. The specific energy consumption (SEC), colour and microstructural changes of sweet potato (Ipomoea batatas L.) based on experimental set-up of different combined IR and HAD strategies (Simultaneous IR and HAD, two-stage HAD + IR, two-stage IR + HAD, intermittent IR and HAD) were investigated. Mathematical models based on Lambert’s equation of electromagnetics for single-phase and multiphase change during the combined IR and HAD of sweet potato were developed and evaluated, using finite element methods in both COMSOL and MATLAB software. The combined IR and HAD resulted in 69.34 – 85.59% reduction in the SEC of HAD. The specific energy consumption during simultaneous IR and HAD, two-stage HAD+IR, two-stage IR+HAD, and intermittent IR and HAD varied between 174.10- 310.93 MJ/kg, 95.80-177.48 MJ/kg, 56.30-68.36 MJ/kg, 99.61-149.18 MJ/kg, respectively. The intermittent IR and HAD was demonstrated to be the most suitable combination strategy based on the combined effect of total drying time, shrinkage, SEC and total colour change. The moisture and temperature distribution results of the single-phase model for simultaneous and intermittent IR and HAD of sweet potato agreed well with experimental drying data. The multiphase simulations results indicated that the model could adequately describe the underling drying mechanism of combined IR and HAD. The water and vapour fluxes due to gas diffusion and gas pressure resulted to increased drying efficiency of combined IR and HAD. The understanding of these phenomenon could be used to improve food quality and increase energy efficiency. The automation and optimization ability could also be increased.
format	Thesis
qualification_level	Doctorate
author	Onwude, Daniel Iroemeha Chikwendu
author_facet	Onwude, Daniel Iroemeha Chikwendu
author_sort	Onwude, Daniel Iroemeha Chikwendu
title	Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.)
title_short	Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.)
title_full	Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.)
title_fullStr	Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.)
title_full_unstemmed	Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.)
title_sort	mathematical modelling of combined infrared and hot air drying of sliced sweet potato (ipomoea batatas l.)
granting_institution	Universiti Putra Malaysia
publishDate	2018
url	http://psasir.upm.edu.my/id/eprint/71431/1/FK%202018%2096%20IR.pdf
_version_	1747813001103147008

Mathematical modelling of combined infrared and hot air drying of sliced sweet potato (Ipomoea batatas L.)

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