Mathematical modeling and performance investigation of mixed-mode and indirect solar dryers for natural rubber sheet drying

Published Date
Energy for Sustainable Development
October 2016, Vol.34:44–53, doi:10.1016/j.esd.2016.07.003

• Author 

• Racha Dejchanchaiwong ^a,b
• Auk Arkasuwan ^a,c
• Anil Kumar ^a,c
• Perapong Tekasakul ^a,c,,

• aEnergy Technology Research Center, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
• bDepartment of Chemical Engineering, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
• cDepartment of Mechanical Engineering, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand

Received 13 July 2015. Revised 19 July 2016. Accepted 19 July 2016. Available online 14 September 2016. 

Highlights

• Performance of mixed-mode and indirect solar rubber drying system is evaluated.
• •
  Combined Page and two-term (Hii et al.) model is best to describe drying behavior.
• •
  Performance of the mixed-mode dryer is superior to the indirect solar dryer.

Abstract

Smallholder rubber producers typically dry rubber in the open air, a process that takes about seven days, allowing the rubber to deteriorate and thus decreasing the price obtained by the producers. Solar dryers decrease the drying time by 2–3 days, thereby yielding a higher quality product. In this study, performances of mixed-mode and indirect solar drying systems have been investigated for 30 natural rubber sheets. Drying efficiency of the mixed-mode dyer is 15.4% which is higher than the indirect solar dryer (13.3%). The moisture contents of rubber sheets are reduced from 32.3 to 2.0% and 29.4 to 8.0% on a wet basis for mixed-mode and indirect solar drying, respectively, in 4 days. Hii et al. model is the combination of the Page and Two-term drying model. This model is found to best describe the natural rubber sheet drying behavior in both mixed-mode and indirect solar dryers. Coefficient of determination and root mean square error for mixed-mode and indirect solar drying of natural rubber are 0.998 & 0.0096 and 0.996 & 0.0109, respectively. Performance of the mixed-mode dryer is superior to the indirect solar dryer. Therefore, mixed-mode solar dryers are recommended for natural rubber sheet drying to smallholders.

Keywords

Rubber drying

Solar dryer

Mixed-mode dryer

Air-dried sheet

Mathematical model

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• ⁎ 
  Corresponding author at: Energy Technology Research Center, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.

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