Drying of stingless bees pot-pollen using a multi-angle swirling fluidised bed dryer with pulsed flow /
Luqman Bin Abdul Halim
Drying of stingless bees pot-pollen using a multi-angle swirling fluidised bed dryer with pulsed flow / Luqman Bin Abdul Halim - xvii, 182 pages : illustration ; 30 cm. + 1 CD-ROM.
Faculty of Mechanical and Automotive Engineering Technology
Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang - 2025
Includes bibliographical references
A Swirling Fluidised Bed Dryer (SFBD) is a promising method for drying heat-sensitive materials, such as Stingless Bees Pot-Pollen (SBPP), a valuable nutritional product. However, limitations in temperature and energy consumption restrict its drying performance. This study addresses these by investigating Multi-Angle Swirling Distributors (MASD) and pulsed airflow to enhance moisture removal and improve fluidization. Previous SFBD research were limited to Single-Angle Swirling Distributor (SASD). Meanwhile, pulsed flow research mainly focused on conventional fluidised beds, with minimal research on the effect of pulsation frequency, fp and duty cycle ratio, DCp, particularly for SFBDs. The objectives of the current study are to evaluate the drying performance of MASD, the effect of adding pulsed flow, flow dynamics, and the suitable drying model, alongside drying time and specific energy consumption (SEC). A laboratory-scale SFBD was used to conduct drying experiments using 6767 SASD, 6745 MASD, and 6730 MASD with continuous flow at a superficial air velocity of 3.0 m/s. Similar drying experiments were carried out with pulsed flow at varying fp (1, 3, 5 Hz) and different DCp (25%, 50%, 75%). In each experiment, 25 g of SBPP was dried for 60 min in SFBD, weighed every 5 minutes, conducted in triplicate. The results then converted into moisture content (MC) and moisture ratio (MR) values for further analysis. Additionally, the SBPP particles movement inside the drying chamber was captured at a high frame rate, alongside a Computational Fluid Dynamics (CFD) simulation using ANSYS Fluent software. A suitable drying model was determined based on regression analysis using IBM SPSS software. Then, this model was used to predict the time taken to reach 8% MC and SEC values. It was found that the 6730 MASD is the most effective distributor for the drying of SBPP, with an effective moisture diffusivity, Deff value of 2.457 10–6 m2/s. The average drying rate of the 6730 MASD is 12.6% higher than that of the 6767 SASD. The 6767 SASD has the lowest average drying rate of 0.01196 kg/kg·min, followed by the 6745 MASD at 0.01263 kg/kg·min, and the 6730 MASD at 0.01345 kg/kg·min (p<0.05). In the pulsed flow study, the effect of DCp on drying performance is more prominent compared to the fp effect. An increase in DCp leads to improved drying performance. Meanwhile, operating at the fp of 1 Hz results in better drying performance compared to 3 Hz and 5 Hz. Consequently, the best pulsed flow drying performance is at the fp of 1 Hz and the DCp of 75% using the 6730 MASD, with a Deff value of 1.710 10–6 m2/s. In bed dynamics analysis, the “dead zone”, an area with low velocity, is largest in 6767 SASD, followed by 6745 MASD. The 6730 MASD has minimal dead zone. In pulsed flow, an increase in DCp results in more active swirling inside the drying chamber. The response of SBPP particles is frequency-dependent, with particle movement exhibiting a greater delay as fp increases. The logarithmic model is determined as the best model to describe SBPP drying in the SFBD with the MASD and pulsed flow (R2 = 0.9993). The predicted shortest times taken to reach 8% MC are 27.29, 35.98, and 41.08 min, corresponding to the 6730 MASD with continuous flow, the 6745 MASD with continuous flow, and the 6730 MASD at 75% DCp and 1 Hz fp, respectively. In terms of SEC, the lowest values obtained are 5.683 × 104, 6.853 × 104, and 7.601 × 104 kJ/kg, corresponding to the 6730 MASD with continuous flow, the 6730 MASD at 75% DCp and 1 Hz fp, and the 6745 MASD at 50% DCp and 1 Hz fp, respectively. In conclusion, the MASDs reduced “dead zone” which enhanced drying performance, with the best drying performance and SEC achieved using the 6730 MASD. The SFBD could be scaled up for real applications. Future works should explore different materials, in-depth analysis on the bed flow dynamics, and combined continuous and pulsed flow.
THE0010333 (Local)
Faculty of Mechanical and Automotive Engineering Technology--Dissertations
Universities and colleges--Dissertations
Theses--Dissertations
Drying of stingless bees pot-pollen using a multi-angle swirling fluidised bed dryer with pulsed flow / Luqman Bin Abdul Halim - xvii, 182 pages : illustration ; 30 cm. + 1 CD-ROM.
Faculty of Mechanical and Automotive Engineering Technology
Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang - 2025
Includes bibliographical references
A Swirling Fluidised Bed Dryer (SFBD) is a promising method for drying heat-sensitive materials, such as Stingless Bees Pot-Pollen (SBPP), a valuable nutritional product. However, limitations in temperature and energy consumption restrict its drying performance. This study addresses these by investigating Multi-Angle Swirling Distributors (MASD) and pulsed airflow to enhance moisture removal and improve fluidization. Previous SFBD research were limited to Single-Angle Swirling Distributor (SASD). Meanwhile, pulsed flow research mainly focused on conventional fluidised beds, with minimal research on the effect of pulsation frequency, fp and duty cycle ratio, DCp, particularly for SFBDs. The objectives of the current study are to evaluate the drying performance of MASD, the effect of adding pulsed flow, flow dynamics, and the suitable drying model, alongside drying time and specific energy consumption (SEC). A laboratory-scale SFBD was used to conduct drying experiments using 6767 SASD, 6745 MASD, and 6730 MASD with continuous flow at a superficial air velocity of 3.0 m/s. Similar drying experiments were carried out with pulsed flow at varying fp (1, 3, 5 Hz) and different DCp (25%, 50%, 75%). In each experiment, 25 g of SBPP was dried for 60 min in SFBD, weighed every 5 minutes, conducted in triplicate. The results then converted into moisture content (MC) and moisture ratio (MR) values for further analysis. Additionally, the SBPP particles movement inside the drying chamber was captured at a high frame rate, alongside a Computational Fluid Dynamics (CFD) simulation using ANSYS Fluent software. A suitable drying model was determined based on regression analysis using IBM SPSS software. Then, this model was used to predict the time taken to reach 8% MC and SEC values. It was found that the 6730 MASD is the most effective distributor for the drying of SBPP, with an effective moisture diffusivity, Deff value of 2.457 10–6 m2/s. The average drying rate of the 6730 MASD is 12.6% higher than that of the 6767 SASD. The 6767 SASD has the lowest average drying rate of 0.01196 kg/kg·min, followed by the 6745 MASD at 0.01263 kg/kg·min, and the 6730 MASD at 0.01345 kg/kg·min (p<0.05). In the pulsed flow study, the effect of DCp on drying performance is more prominent compared to the fp effect. An increase in DCp leads to improved drying performance. Meanwhile, operating at the fp of 1 Hz results in better drying performance compared to 3 Hz and 5 Hz. Consequently, the best pulsed flow drying performance is at the fp of 1 Hz and the DCp of 75% using the 6730 MASD, with a Deff value of 1.710 10–6 m2/s. In bed dynamics analysis, the “dead zone”, an area with low velocity, is largest in 6767 SASD, followed by 6745 MASD. The 6730 MASD has minimal dead zone. In pulsed flow, an increase in DCp results in more active swirling inside the drying chamber. The response of SBPP particles is frequency-dependent, with particle movement exhibiting a greater delay as fp increases. The logarithmic model is determined as the best model to describe SBPP drying in the SFBD with the MASD and pulsed flow (R2 = 0.9993). The predicted shortest times taken to reach 8% MC are 27.29, 35.98, and 41.08 min, corresponding to the 6730 MASD with continuous flow, the 6745 MASD with continuous flow, and the 6730 MASD at 75% DCp and 1 Hz fp, respectively. In terms of SEC, the lowest values obtained are 5.683 × 104, 6.853 × 104, and 7.601 × 104 kJ/kg, corresponding to the 6730 MASD with continuous flow, the 6730 MASD at 75% DCp and 1 Hz fp, and the 6745 MASD at 50% DCp and 1 Hz fp, respectively. In conclusion, the MASDs reduced “dead zone” which enhanced drying performance, with the best drying performance and SEC achieved using the 6730 MASD. The SFBD could be scaled up for real applications. Future works should explore different materials, in-depth analysis on the bed flow dynamics, and combined continuous and pulsed flow.
THE0010333 (Local)
Faculty of Mechanical and Automotive Engineering Technology--Dissertations
Universities and colleges--Dissertations
Theses--Dissertations