CFD Letters 15, Issue 2 (2023) 71-86 71 CFD Letters Journal homepage: https://semarakilmu.com.my/journals/index.php/CFD_Letters/index ISSN: 2180-1363 Hydrodynamics Investigations of Kaffir Lime Leaves Drying in a Swirling Solar Drying Chamber with Inclined Slotted Angle Air Distributor Muhammad Amirul Azwan Azmi 1 , Amir Abdul Razak 1,* , Muhammad Amir Syahiran Muhammad Tarminzi 1 , Ahmad Fadzil Sharol 1 , Ahmmad Shukrie Md Yudin 1 , Zafri Azran Abdul Majid 2 1 Energy Sustainability Focus Group (ESFG), Faculty of Mechanical and Automotive Engineering Technology, Universiti Malaysia Pahang, Pekan, Pahang, Malaysia 2 Kuliyyah of Allied Health Sciences, International Islamic University of Malaysia, Kuantan, Pahang, Malaysia ARTICLE INFO ABSTRACT Article history: Received 20 July 2022 Received in revised form 20 August 2022 Accepted 21 September 2022 Available online 1 February 2023 The present work aims to investigate the behavior of drying kaffir lime leaves in a swirling solar drying chamber (S-SDC) fitted with an inclined slotted angle air distributor. A distributor plated with inclined slotted angle was located at the air inlet at the bottom of the chamber. Experimental and numerical methods have been applied to analyze the efficiency of developed S-SDC assisted solar drying system based on the moisture content (MC), moisture content ratio (MR) and drying rate (DR) were examined. The experimental results showed that the S-SDC can reduce the moisture content of kaffir lime leaves more rapidly than a conventional solar drying chamber (CSDC). The S-SDC gave a higher DR and decreased drying time compared to that of C- SDC. The results also indicated that operation at higher air velocities resulted in a greater DR, especially at the beginning stage of the drying process. For the S-SDC, the reduced of MC, MR and DR at a high air velocity (v = 2.0 m/s) was better than at low air velocities (v = 0.5 and 1.0 m/s). Drying chamber efficiency is also observed at a higher air velocity of 2 m/s for both SSDC and CSDC. In addition, obtained experimental findings are in line with numerical results. The outcomes of this study present the potential of using the S-SDC compared to the C-SDC to be used in drying crops. Keywords: Hydrodynamics; Swirl flow; Drying chamber; Swirling Solar Drying Chamber (SSDC) 1. Introduction In agricultural sector, the solar energy is used to dry crops since it is practical, can cut the cost of heat source since the heat can freely available and it do not harm the environment [1]. Solar heating system is built to improve the traditional drying method. Solar dryer, which uses the heating system can produce better quality products and it also can increase yield of the products since less waste are produced [2]. Rabha and Muthukumar [3] had stated that solar dryer is an efficient device that can be used to replace direct open sun drying. The main purpose of the drying process is to make sure that the products can be stored in a longer period by reducing the moisture content inside the product to the safe storage level [3]. However, this process consumes a lot of time and is energy * Corresponding author. E-mail address: amirrazak@ump.edu.my (Amir Abdul Razak) https://doi.org/10.37934/cfdl.15.2.7186