ORIGINAL PAPER
Development and performance evaluation of a hybrid solar dryer using
pumpkin fruit. Part 2. Analysis of the drying process and the operation of the equipment used
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1
Post-harvest Engineering Research Department, Nigerian Stored Products Research Institute, Kano Zonal Office, Nigeria
2
Department of Agricultural and Environmental Engineering, Bayero University, Kano, Nigeria
3
Perishable Crop Research Department, Nigerian Stored Products Research Institute, Kano Zonal Office, Nigeria
4
Research Outreach Department, Nigerian Stored Products Research Institute, Kano Zonal Office, Nigeria
Submission date: 2025-12-15
Final revision date: 2026-01-28
Acceptance date: 2026-02-04
Online publication date: 2026-02-11
KEYWORDS
TOPICS
ABSTRACT
This second part of our work presents the results of analyses of the process of drying pumpkin fruit slices at 50, 55, and 60 °C and slice thicknesses of 3, 5, and 7 mm. The dryer exhibited distinct heating phases under no-load and loaded conditions, with product load slowing the temperature rise. Drying temperature and slice thickness significantly affected drying rate and drying efficiency (p<0.05). The highest drying rate (12–14 kg/h) occurred within the first 2 hours, especially for 3 mm slices at 60 °C. The rate then declined to 2–3 kg/h between 2 and 5 hours and fell below 1 kg/h after 5 hours. Drying efficiency ranged from 42–58% at 50 °C, 47–72% at 55 °C, and increased markedly to 43–94% at 60 °C, with the 3 mm slices at 60 °C achieving the highest efficiency. Energy analysis showed a chamber efficiency of 32.2%. Product quality parameters, including shrinkage, rehydration ratio, proximate composition, microbial load, and colour, varied significantly with drying conditions. Economic analysis indicated a positive net benefit and a payback period of 1 year and 5 months. Overall, the hybrid dryer demonstrated high drying performance, improved energy use, acceptable product quality, and strong economic viability.
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