Fabrication and Testing of a Low-Cost Evaporative Cooling System for Vegetable Preservation in Market Stalls in Gombe State

Fresh vegetable spoilage at market level represents a critical source of post-harvest loss in the North East agricultural economy of Nigeria, where the absence of cold chain infrastructure results in estimated daily losses of 30 to 50 percent of produce for market traders in hot semi-arid conditions. This study presents the fabrication and performance testing of a charcoal-based evaporative cooler designed for in-situ vegetable preservation at market stalls in Gombe State. The cooling unit was constructed using a double-walled wooden frame, with the interlayer filled with moistened activated charcoal granules, and burlap fabric covering the outer surface to promote evaporative cooling. Performance tests were conducted in an open market environment in Gombe metropolis over two-week periods in both the dry and early wet seasons. Internal temperature, relative humidity, and the shelf life of selected vegetables including tomatoes, carrots, and leafy greens were monitored daily. The cooler maintained internal temperatures 9 to 14 degrees Celsius below ambient during peak daytime heat, with internal relative humidity between 85 and 95 percent, conditions favourable for vegetable preservation. Shelf life of tomatoes extended from an average of 2 days to 6 days compared to ambient storage. Total material cost per unit was 4,800 naira, making it accessible for low-income traders. Keywords: evaporative cooler, vegetable preservation, post-harvest loss, market stalls, Gombe State.