NBIRT Solar Dryer Research Published in Elsevier Journal

NBIRT Solar Dryer Research Published in Elsevier Journal

Digital twin lets rural solar dryers be tested virtually before they are built

The team comprising Dr Richik Ghoshthakur, Research Scientist, NBIRT, along with Prof. Srinivasan Balachandran from Visva-Bharati and Mr Anupam Baral from Geetanjali Solar, guided by NBIRT President Prof. S.P. GonChaudhuri, published a study in Sustainable Energy Technologies and Assessments (Elsevier). The study presents a physics-assisted digital twin of NBIRT’s solar dryer, developed and validated with self-help groups (SHGs) in rural Tripura.

The technology

The forced-convection solar dryer is built for community-scale agro-processing. A flat-plate solar collector heats the air, and a small PV panel drives the blower that moves it into a closed drying cabinet. The product dries on trays away from dust, insects and direct sunlight, which protects its quality. The system runs entirely on solar energy, with no grid electricity or fuel. SHGs in Tripura now use it to process turmeric.

Why a digital twin

Rural energy systems are often installed on assumptions. How the system performs in local weather, with real loads, becomes clear only after the investment is made. A digital twin changes this. It is a virtual replica of a specific, working unit, calibrated on data measured in the field. A conventional simulation describes how a system should behave in theory. A digital twin captures how this dryer actually behaves at real sites, and it can be updated as new field data come in. Performance, sizing, and economics can therefore be tested virtually before deploying a new unit.

The research

The NBIRT team combined physics-based heat and moisture modelling with machine learning calibrated on field data collected at SHG sites. The twin was validated on sites it had not seen during training. This demanding test reflects real deployment conditions far better than the random-split testing common in the literature. The twin simulates complete drying runs, predicts drying time, and flags periods when the cabinet may get too hot for the product.

Key findings

• Payback period of about 2.8 years

• Benefit-cost ratio of about 2.2

• No grid electricity or fuel required

• Code and data openly available to support replication

Impact

The twin gives SHGs, NGOs, government agencies and financing institutions a practical tool to plan drying operations and assess investment before deployment. It strengthens the case for scaling solar drying across Tripura and the wider Northeast. The same approach can extend to other decentralised renewable energy interventions that NBIRT works on, including mini-grids, solar pumping, energy storage and cold storage.

Acknowledgements

The work was supported by the SEED Division, Department of Science and Technology (DST), Govt. of India, under the SUNIL Programme. NBIRT gratefully acknowledges the SHG members in Tripura who operated the dryers and supported data collection.