Solar Cabinet Dryer for Agricultural Produce

A significant fraction of harvested fruit and vegetables in India is lost between the farm and the market, and a major reason is drying: open sun drying — produce spread on the ground — is slow, invites dust, insects and animals, and one rain shower ruins the batch. Solar cabinet dryers solve the problem with simple physics: a black absorber plate converts sunlight to heat, the glazed cabinet traps it like a greenhouse, and warm air rising through stacked mesh trays carries moisture away from the produce. This project builds a working cabinet dryer as a student prototype — wooden cabinet with a glass door, three removable mesh trays, a finned black absorber collector at the base, a digital temperature display, and a fan for forced-convection mode — and pairs it with a real drying experiment: the student measures moisture loss over time for a produce batch and plots the drying curve.

1. The student prepares a produce batch (e.g. mango or banana slices of uniform thickness) and records the initial weight on the weighing sheet.
2. The trays are loaded in a single layer inside the cabinet, the door is closed, and the dryer is placed facing the sun with the collector exposed.
3. Sunlight heats the black absorber; the glazed cabinet traps the heat, and warm air rises naturally through the mesh trays, carrying moisture out through the top vent.
4. Every hour the student records chamber temperature, ambient temperature and the batch weight using the procedure's schedule.
5. Moisture content is computed on wet and dry basis from the weight data, and the drying curve (moisture vs time) is plotted — optionally repeated in fan-assisted mode for comparison.
6. The curves and efficiency discussion form the results chapter of the report, all from the student's own measurements.

Tech stack:

• Wooden drying cabinet with glazed glass door (fabricated)
• Black finned absorber collector plate
• Food-grade mesh drying trays (3)
• Digital temperature probe with display
• DC exhaust fan with solar/battery power option
• Drying-experiment procedure manual
• Moisture-content calculation and weighing templates
• Report, PPT and viva Q&A documents

• [Glazed drying cabinet] A wooden cabinet with a glass front door traps solar heat in the greenhouse effect while letting the student watch the produce; the door opens for loading and tray access.
• [Black absorber collector] A finned black absorber plate at the cabinet base converts incoming sunlight to heat; fins increase the heat-transfer area to the drying air.
• [Three removable mesh trays] Stainless/food-grade mesh trays hold sliced produce in a single layer so warm air passes through every slice, not just around the batch.
• [Temperature display and monitoring] A digital temperature probe shows the chamber temperature live; the experiment procedure uses it for hourly readings.
• [Fan-assisted forced convection mode] A small DC fan (solar-powered option) forces air through the collector and trays, so the student can compare natural vs forced convection drying rates.
• [Drying-experiment procedure] A documented procedure covers sample preparation, weighing schedule, moisture-content calculation and drying-curve plotting — the student produces real measured data.
• [Moisture-content calculation templates] Weighing sheets and the dry-basis/wet-basis moisture formulas are supplied so every number in the report is computed, not guessed.

• Working solar cabinet dryer (cabinet, collector, trays, display, fan)
• Drying-experiment procedure manual with weighing schedules
• Moisture-content calculation templates (wet-basis and dry-basis)
• Fabrication drawings and bill of materials
• Project report PDF (solar thermal principles, experiment design, results procedure)
• PPT presentation for final review
• Viva Q&A preparation document (greenhouse effect, drying kinetics, collector efficiency)

• Drying rate depends entirely on sunshine — cloudy days slow the process and the procedure says how to handle interrupted runs honestly.
• The expected chamber temperatures and drying times are typical ranges, not guarantees; the student's own measurements are the report's data.
• Batch capacity is a few kilograms — this is a lab demonstrator, not a farm-scale dryer.
• The wood cabinet must be kept dry when not in use; prolonged rain exposure warps it.
• Only non-toxic, food-safe materials touch the produce; the manual lists what to clean between batches.
• Night-time drying is not possible without the optional backup heater, which is listed as future scope.