Development and Promotion of the Reversible Airflow Flatbed Dryer in the Philippines

Abstract

A flatbed dryer with a reversible airflow was introduced in the Philippines through a collaborative project between Nong Lam University of Vietnam and the Philippine Rice Research Institute (PhilRice). In this design, airflow is reversed at some point during the drying period to achieve uniform drying without mixing the grain. An 8-ton capacity dryer was constructed at PhilRice Central Experiment Station in Nueva Ecija to evaluate its performance and adaptability under Philippine conditions. Appropriate and locally available materials were used in the construction of the pilot unit. Nine (9) additional dryers were then constructed at PhilRice stations (Nueva Ecija, Isabela, Negros, Agusan, Central Mindanao University, and Midsayap) that served as pilot units for technology promotion in their respective areas of coverage. Performance of the dryer was evaluated in terms of the following parameters: (1) drying; (2) quality of dried grains; and (3) economic analysis of using the dryer. The performance evaluation was conducted in three drying batches of newly harvested rice seeds. Paddy dried with the reversible airflow flatbed dryer at full load capacity has a uniform moisture content with one percent (1%) moisture gradient at different layers of the grain mass along the depth and across the drying bin. The drying rate was 1% moisture reduction per hour. The drying cost of using the reversible dryer is PhP0.74 per kg which is lower than the prevailing mechanical drying cost of PhP1.13 per kg. It has a payback period of 2.5 years and break-even point of 53.0 batches/year. To date, eight (8) privately-owned units have already been constructed and fully operational in the provinces of Nueva Ecija, Quirino, and Bukidnon, with PhilRice receiving inquiries from interested individuals here and abroad regarding the technology.

Development and verification of a simulation model for paddy drying with different flatbed dryers

“…The modeling and verification were developed for optimizing the management of the different types of FBDs that were recently adopted in Southeast Asia and are described in Phan et al (1995), Gummert (2013), and Tado et al (2015). These FBDs (Figure 1(a)) consist of three main components: (1) a furnace to generate heat, (2) a blower to generate drying air with the required airflow rate and static pressure, and (3) a drying chamber.…”

“…This dryer type is widely used for paddy drying in Southeast Asian countries as they are fixed with the desired scales, have relatively low investment and cost, and low management capacity requirement (Phan et al, 1995;Gummert, 2013). Design layouts, performance, and adaptation of FBDs to different conditions are presented in many publications, such as RKB (2017), Gummert (2013), Phan et al (1995), and Tado et al (2015). The grain bulk is contained in a rectangular bed, on an elevated perforated floor, which is on top of a plenum chamber.…”

Deep‐bed drying kinetics and thermodynamic parameters of high‐moisture parboiled paddy (ASD‐16) in a reversible airflow fixed bed dryer

“…Despite being time-consuming and energy-intensive (Jimoh et al, 2023), convective hot air drying is widely employed in paddy drying due to its simple construction arrangement. Due to the higher performance, less investment, and maintenance cost, the RAFBD are being used by the paddy processing communities in South Asian countries (Tado et al, 2015;Wincy et al, 2022Wincy et al, , 2023. In an FBD, the energy efficiency of the dryer and quality of dried grain are influenced by various factors, including the drying temperature, humidity, depth of the paddy layer, and airflow rate.…”

Best practices for paddy drying: case studies in Vietnam, Cambodia, Philippines, and Myanmar

“…Many different drying technologies were developed and adapted in SEA's various regions and countries. For instance, more than 45% of the paddy in the Mekong River Delta of Vietnam (MRD) is dried by mechanical dryers as reported by Nguyen-Van-Hung, Nguyen-Le-Hung, Truong-Quang-Truong, and Phan-Hieu-Hien (2013), compared to 5-10% in Cambodia (Meas, 2012) and the Philippines (Tado et al, 2015) while just less than 5% in Myanmar (adapted from Myo, 2013;Ricestat, 2018). Paddy drying technologies with better performance than sun drying have been adapted in SEA, particularly in Vietnam, Cambodia, Myanmar, and the Philippines since the 1990s (RKB, 2016a).…”

“…Specific technologies for paddy drying are presented in many related publications. FBD use in SEA is referred to by RKB (2016a), Gummert (2013), Phan-Hieu-Hien, Truong-Vinh, andNguyen-Quang-Loc (1995), and Tado et al (2015). The RCD was introduced for paddy drying in some recent studies, such as Kocsis, Keppler, Herdovics, Fenyvesi, and Farkas (2011), Olaniyan andAlabi (2014), andNguyen-Van-Hung et al (2016).…”