Journal of Scientific Research and Reports

Aims: This study experimentally investigated the drying behaviour, energy use, direct operating cost, direct combustion CO₂ emissions and copra quality of a nominal 500-coconut-capacity, biomass-fired, indirect-heat rotary-drum dryer, thereby establishing a biomass-only engineering baseline for subsequent solar-biomass hybridisation.

Study Design: The study comprised a descriptive experimental evaluation involving two production-scale biomass-only trials and a separate standardised 240-nut batch for detailed energy, cost and emission accounting.

Place and Duration of Study: The study was conducted at the Agricultural Research Station (Mannuthy) of the Kerala Agricultural University; the production-scale trials were conducted in October-November 2025.

Methodology: Two production-scale trials were monitored from initial kernel moisture contents of 52.1–53.4% (w.b.) to process-end moisture contents of 7.6–7.9% (w.b.). A separate standardised 240-nut batch containing approximately 45 kg wet kernel was used for energy, cost and emission accounting. The energy boundary comprised the chemical energy of biomass, based on an adopted calorific value of 19.0 MJ kg⁻¹, together with measured electrical energy consumption. Biomass consumption, electricity use, drying temperature, moisture removal, product yield and copra grading were recorded.

Results: The production-scale trials required 27.81–29.11 h at chamber temperatures of 56.4°–61.2°C and consumed 191–193 kg coconut shell, producing 60.2–64.8 kg copra. For the standardised batch, 167.3 kg shell supplied 883.0 kWh of chemical energy and, together with 21.72 kWh of electricity, resulted in a total external energy input of 904.7 kWh. Approximately 21.9–22.0 kg of water was removed, corresponding to a calorific-value-based SMER of 0.0242–0.0243 kg kWh⁻¹ and SEC of 41.1–41.3 kWh kg⁻¹ water removed. Furnace–heat-exchanger and drying-chamber efficiencies were 64.82% and 78.3%, respectively. Direct operating cost was ₹736.5 batch⁻¹, equivalent to approximately ₹31.9 kg⁻¹ dry copra, while gross direct combustion CO₂ emissions were approximately 276 kg batch⁻¹. The grading assessment indicated 85–86% MCG1 copra under the IS 6220:1971 framework.

Conclusion: The dryer demonstrated technically feasible biomass-only copra drying under the tested conditions and provides a traceable engineering baseline for subsequent solar-biomass hybridisation. Because only two production-scale trials were available and the energy-accounting batch was conducted separately, the results are interpreted descriptively and should not be considered statistically generalizable.