Comparative Analysis of Drying Rate and Moisture Content Reduction in Cassava Peel Using Direct and Indirect Solar Drying Methods

¹ Chemical Engineering Department, Engineering Faculty, Universitas Muhammadiyah Jakarta, 10510 Jakarta, Indonesia
² Master Program of Chemical Engineering Department, Engineering Faculty, Universitas Muhammadiyah Jakarta, 10510 Jakarta, Indonesia
³ Faculty of Chemical & Process Engineering Technology, Universiti Malaysia Pahang AlSultan Abdullah, Lebuh Persiaran Tun Khalil Yaakob, 26300 Kuantan, Pahang, Malaysia

^* Corresponding author: yustinah@umj.ac.id

Abstract

Cassava peel, an abundant agro-industrial by-product, holds significant potential as a feedstock for biochar production. However, appropriate pre-treatment through drying is essential to improve energy efficiency during carbonization. This study aims to evaluate and compare the drying performance of direct and indirect solar drying methods in terms of drying rate and moisture content reduction. Cassava peel samples weighing 500 grams each were prepared through manual washing and draining without mechanical assistance. Drying tests were conducted over a 10-hour period at 2-hour intervals using both direct and indirect solar drying methods. Moisture content was measured gravimetrically based on mass loss over time, while the drying rate was calculated as the change in sample mass per unit surface area per unit time (kg/m²•h). The results showed that direct solar drying achieved a significantly higher drying rate, with a mean of 0.0990 kg/m²•h and a standard deviation of 0.0337. In contrast, indirect solar drying yielded a lower mean drying rate of 0.0256 kg/m²•h with a standard deviation of 0.0088, highlighting the impact of solar intensity on the drying process. Moisture content in the direct drying method decreased from 70% to 36% within 10 hours, while the indirect method only reduced it to 60% over the same period. These findings suggest that direct solar drying not only accelerates moisture removal but also exhibits greater drying dynamics, especially during the initial hours. The nearly fourfold increase in drying rate further underscores the effectiveness of direct exposure to sunlight in enhancing drying performance.