Effects of Aspect Ratio, Drying Temperature and Drying Duration on the Performance of a Custom-Made Fluidized Bed Drying System

2018 ◽  
Author(s):  
Sammy Sadaka ◽  
Kaushik Luthra ◽  
Griffiths G. Atungulu
Keyword(s):  
Aspect Ratio ◽  
Fluidized Bed ◽  
Drying Temperature ◽  
Custom Made ◽  
Fluidized Bed Drying ◽  
Drying System

Evaluation of the Performance of a Custom-Made Fluidized Bed Drying System

2018 ◽  
Vol 34 (6) ◽  
pp. 1027-1037 ◽  
Author(s):  
Sammy S. Sadaka ◽  
Kaushik Luthra ◽  
Griffiths G. Atungulu
Keyword(s):  
Aspect Ratio ◽  
Moisture Content ◽  
Fluidized Bed ◽  
Initial Moisture Content ◽  
Small Scale ◽  
Drying Rate ◽  
Furnace Temperature ◽  
Fluidized Bed Dryer ◽  
Custom Made ◽  
Drying System

Abstract. Laboratory and farm-scale fluidized bed dryers are not available to purchase. Additionally, a deliberation is presently continuing regarding the beneficial and damaging effects of drying grain in a fluidized bed. Therefore, the goal of this research was to develop and test a custom-made small-scale fluidized bed dryer, suitable for moderate farms and capable of drying small and large size grains from high moisture content to a safe storage moisture content. The customary fluidized bed dryer was developed and constructed in the Rice Research and Extension Center, Stuttgart, Arkansas. The fluidized bed dryer was used to dry wheat from an initial moisture content of 23.3% db. The effects of the aspect ratio (bed height to bed diameter ratio) of 2, 3, and 4 m/m, the furnace temperature of no heat, 100°C, 150°C, and 200°C and drying duration of 10, 20, 30, 40, 50, and 60 min on the wheat moisture content, drying rate, and dryer efficiency were investigated. The lowest wheat moisture content of 16.3% db was observed at the lowest aspect ratio of 2 m/m, the highest furnace temperature of 200°C, and the longest drying duration of 60 min. Conversely, the highest wheat moisture content of 19.0% db was observed at the highest aspect ratio of 4 m/m, and the no heat condition. The drying rate of 0.47%/min was observed at the lowest aspect ratio of 2 m/m and the furnace temperature of 200°C after 10 min. The maximum dryer efficiency of 63.2% was achieved at the aspect ratio of 4 m/m, the furnace temperature of 200°C. Two empirical models were developed to predict the moisture content of wheat and the dryer efficiency as affected by the aspect ratio, the furnace temperature and the drying duration with the adjusted coefficient of determination of 0.91 and 0.88, respectively. Although, the developed fluidized bed dryer is a lab-scale system, the experimental results provided an exceptional indication to scale up the drying system to dry grains. Keywords: Dryer efficiency, Drying rate, Fluidized bed, Moisture content, Wheat-drying.

scholarly journals Challenges and Opportunities Associated with Drying Rough Rice in Fluidized Bed Dryers: A Review

2020 ◽  
Vol 63 (3) ◽  
pp. 583-595 ◽  
Author(s):  
Kaushik Luthra ◽  
Sammy S. Sadaka
Keyword(s):  
Developing Countries ◽  
Moisture Content ◽  
Fluidized Bed ◽  
Airflow Rate ◽  
List Type ◽  
Rice Quality ◽  
Drying Temperature ◽  
Rough Rice ◽  
Energy And Exergy ◽  
Fluidized Bed Drying

Highlights Fluidized bed drying of rice has several advantages that outweigh its disadvantages. Increasing the drying temperature above 60°C could reduce rice quality. Research related to energy and exergy efficiencies in fluidized bed dryers of rice is needed. Abstract. Rice (Oryza sativa L.) is a staple food for more than half the world’s population. World rice production reached approximately 740 million metric tons (MMT) in 2018 due to the ever-increasing demand driven by population and economic growth. Rice producers face challenges in meeting this demand, especially in developing countries where rice is prone to spoilage if the moisture content is not reduced to a safe level shortly after harvest. Rice producers, particularly in developing countries, typically use conventional drying methods, i.e., sun drying and natural air drying. These methods are time-consuming and environmentally dependent. On the other hand, fluidized bed drying, which is a well established technology, could provide rice producers with an effective drying technique that is quick, practical, affordable, and portable. Several innovative designs for fluidized bed dryers have been developed that could be installed on-farm or off-farm at a reasonable cost. Some studies have mentioned that the main advantage of fluidized bed drying is the increase in drying rate and the reduction of rice spoilage after harvest. Conversely, other studies have raised alarms regarding low rice quality, which is seen as a significant flaw of fluidized bed drying. Due to this lack of consensus, there is a great need to review this drying technology objectively. Therefore, this review article explores fluidized bed drying and details its advantages and disadvantages related to rice drying. It also sheds light on the effects of the operating parameters involved in fluidized bed drying, i.e., rice moisture content, drying temperature, airflow rate, air velocity, drying duration, and tempering duration, on dryer performance and rice quality. Several fluidized bed numerical models are also reviewed and evaluated. Additionally, this review explores the energy and exergy efficiencies of fluidized bed dryers and suggests opportunities for research associated with fluidized bed drying of rice. Keywords: Energy, Exergy, Fluidized bed drying, Fluidized bed modeling, Moisture content, Rice quality, Rough rice, Tempering.

Effect of Fluidized Bed Drying Temperature on Various Quality Attributes of Paddy

2004 ◽  
Vol 22 (7) ◽  
pp. 1731-1754 ◽  
Author(s):  
Supawan Tirawanichakul ◽  
Somkiat Prachayawarakorn ◽  
Warunee Varanyanond ◽  
Patcharee Tungtrakul ◽  
Somchart Soponronnarit
Keyword(s):  
Fluidized Bed ◽  
Quality Attributes ◽  
Drying Temperature ◽  
Fluidized Bed Drying

Energy and Exergy Efficiencies of Fluidized and Fixed Bed Rice Drying

2021 ◽  
Vol 64 (6) ◽  
pp. 1943-1954
Author(s):  
Kaushik Luthra ◽  
Sammy Sadaka
Keyword(s):  
Fluidized Bed ◽  
Fixed Bed ◽  
Ambient Air ◽  
Exergy Efficiency ◽  
Energy Utilization ◽  
Rough Rice ◽  
Energy And Exergy ◽  
Fluidized Bed Drying ◽  
Drying System ◽  
Rice Drying

HighlightsFluidized bed drying of rough riceat 40°C with or without ambient air dehumidification worked best based on the energy and exergy utilization.The dryer lost exergy in the exit air, which was the primary cause of thermal inefficiency; recirculation of the exit air could improve the exergy efficiency.Ambient air dehumidification did not reduce the dryer’s energy utilization and exergy efficiency for rough rice.Abstract. Fluidized bed drying of rough rice in the U.S. has not been used to its full potential due to a lack of research to address rice quality impacts and energy consumption. Little research has been done to analyze the energy and exergy of fluidized bed drying of rough rice. Thermal analysis allows using the drying air’s energy better and improving the drying system’s thermal efficiency. In this study, energy utilization and energy utilization ratio were calculated using the first law of thermodynamics, while exergy loss and exergy efficiency were determined using the second law. Drying air temperature (40°C, 45°C, or 50°C), drying bed condition (fluidized or fixed), drying duration (30, 45, or 60 min), and ambient air dehumidification (yes or no) were the tested factors. A lab-scale drying system designed in a previous study was used. Three replicates were performed to minimize any bias or human errors. All factors significantly affected the energy and exergy of the drying process, except dehumidification and replication. The minimum and maximum energy utilization values were 0.01 and 0.55 kJ s-1 for fixed bed drying at 40°C for 30 min with dehumidification and fluidized bed drying at 50°C for 60 min without dehumidification, respectively. The minimum and maximum exergy efficiency values were 13.46% and 49.14% for fixed bed drying at 45°C for 45 min with dehumidification and fluidized bed drying at 40°C for 60 min with dehumidification, respectively. The primary cause of thermal inefficiency was attributed to the energy and exergy losses in the exit air, while the secondary source was the exergy and energy losses from the drying chamber and inlet air pipes. Costly solutions could be recirculation of the exit air and better insulation of the drying chamber and inlet pipes. However, using the optimal drying conditions for the energy and exergy utilization of the drying air is suggested. This study found that fluidized bed drying was better than fixed bed drying overall. At the primary drying stage, fluidized bed drying had a higher exergy efficiency, energy utilization, and energy utilization ratio than fixed bed drying. At 40°C, fluidized bed drying with or without ambient air dehumidification worked best based on the energy and exergy utilization of the drying system. Keywords: Dehumidification, Energy, Exergy, Fixed bed, Fluidized bed, Rice drying.

Effects of fluidized bed drying temperature and tempering time on quality of waxy rice

2009 ◽  
Vol 95 (3) ◽  
pp. 517-524 ◽  
Author(s):  
Petcharat Jaiboon ◽  
Somkiat Prachayawarakorn ◽  
Sakamon Devahastin ◽  
Somchart Soponronnarit
Keyword(s):  
Fluidized Bed ◽  
Drying Temperature ◽  
Waxy Rice ◽  
Fluidized Bed Drying ◽  
Tempering Time
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