Development and Experimental Study of a Diesel-Fired Heat Exchanger for Turmeric Drying in Pakistan

Abstract

 Turmeric is an important spice crop in Pakistan, where post-harvest drying is essential to 
extend shelf life and maintain quality. Traditional open-sun and conventional hot-air drying methods 
are inefficient, weather-dependent, and often compromise product quality. To address these 
limitations, this study aimed to design, develop, and evaluate a cost-effective, diesel-fired heat 
exchanger integrated into a turmeric dryer. The primary objective was to assess its thermodynamic 
performance and operational economics for both uncrushed and crushed rhizomes, while the 
secondary objective was to validate experimental findings through Computational Fluid Dynamics 
(CFD) simulations. CFD analysis was employed to model airflow and heat transfer within the heat 
exchanger, providing insights into temperature distribution and aiding design optimization. 
Experimental results showed that the heat exchanger achieved a maximum air temperature of 
96.8 °C with 1.6% relative humidity. For uncrushed turmeric, moisture content decreased from 80% 
to 9.67% in 30 hours, with a total moisture removal of 465.6 kg and a maximum dryer efficiency of 
56.6%. The drying cost was PKR 55 per kilogram. Crushed turmeric reached 9.94% moisture in 
8 hours at a cost of PKR 16 per kilogram. CFD predictions of outlet temperature closely matched 
experimental data, confirming model reliability, although non-uniform temperature zones were 
identified for future design improvements. These findings demonstrate that the developed system 
offers a practical, energy-efficient solution for turmeric drying in Pakistan.