Evaporative Cooling Chambers
Susanta K. Roy and D.S. Khuridiya
ECCs are large storage units made from local materials that keep vegetables and fruits at lower temperatures.
Evaporative cooling chambers (ECCs), also known as “zero energy cool chambers” (ZECCs), are simple and inexpensive systems that keep vegetables fresh without the use of electricity. These chambers can be made from locally available materials including bricks, sand, wood, dry grass, gunny/burlap sack, and twine.
Hot and dry regions worldwide
Open sourced technology, locally manufactured
Depends on the cost of local materials and ECC size
Solar-powered refrigerators, charcoal coolers, Naya Celler Storage, and the smaller, household-sized Zeer Pot
Goal 2: End hunger, achieve food security and improved nutrition and promote sustainable agriculture
Those who could benefit from improved vegetable storage and longer shelf life may include vegetable producers, wholesalers, retailers, and household consumers, particularly off-grid, rural communities dependent on subsistence farming. Produce spoilage causes disease and loss of income for needy farmers and venders who are forced to ‘rush sell’ most agricultural products, even though they are well aware of the negative impact flooding the market has on their profits. Even in towns and cities where erratic power supply is available, most of the urban poor cannot afford refrigerators.
Evaporative Cooling Chambers (ECCs) can be constructed from locally available materials such as bricks, sand, wood, dry grass, gunny/burlap sack, and twine. The chamber is constructed with two brick walls and the space in between the walls is filled with sand, which retains the water that is added. The ECCs should be constructed in a shaded area, under trees or a shed. For step-by-step instructions, see MIT D-Lab’s Evaporative Cooling Best Practices Guide.
Watch this video on building an ECC, published by the World Vegetable Center.
Materials to construct ECCs are obtained/purchased locally. Units are built on-site by end-users or local builders.
The holding volume, measured in liters
Length of time it takes to cool products, measured in hours
Time the products remain cold, measured in hours
Is there a way to control temperature?
Maximum internal temperature, measured in degrees Celsius
The materials used in construction
Does the product prevent insects from entering the chamber?
What is the medium for cooling?
Evaporative cooling chambers (ECCs) are double-walled storage containers that use evaporative cooling principles to reduce their internal temperature. Sand and water fills the space between the two brick walls. As the water evaporates outwards into the atmosphere, heat is removed from the inner wall, creating a cooling effect. Water can be added manually with a pitcher or via a gravity-fed dripper. ECCs have a larger capacity compared to household clay pot coolers and are designed for farmers, communities, or farming cooperatives.
The following diagram is provided by Practical Action:
ECCs designs are open-source. Technical support can be provided by the local manufacturer.
Detailed information regarding construction and use can be found in MIT D-Lab’s Evaporative Cooling Best Practices Guide.
Replacement components, such as bricks, sand, and straw, are available locally.
Approximately 3 years
If the evaporative cooling chambers are operated in hot and dry climates (greater than 25 °C and less than 40% humidity) they can be expected to provide a storage environment with humidity greater than 80% and temperature at least 8 °C lower than the maximum daily ambient temperature.
MIT D-Lab conducted testing in Mali, in partnership with the World Vegetable Center. They reported that with a brick ECC storage, shelf life was up to 10 days for hot peppers and eggplant, 8 days for tomatoes, and 7 days for Okra, compared to only 2-4 days without cooled storage.
Evaporative cooling chambers are constructed locally and generally not tested before use. MIT D-Lab has conducted research on the performance of the open-source design in Mali.
Possible contamination and spoilage of foods if not used properly.
Clay pot coolers, or Zeer pots, operate on the same principle and provide a smaller, household storage capacity.
Verploegen, E., Sanogo, O., Chagomoka, T. Evaluation of Low-Cost Vegetable Cooling and Storage Technologies in Mali. 2018. Copyright ©Massachusetts Institute of Technology.
Kumar, R., Chandra, S., Samsher, Singh, B., Kumar, R., Kumar, A.A., Zero energy cool chamber for food commodities: A need of eco-friendly storage facility for farmers: A review. Journal of Pharmacognosy and Phytochemistry, 2018; 7(5): 2293-2301
Ambuko, J., Wanjiru, F., Chemining’wa, G.N., Owino, W.O., Mwachoni, E., Preservation of Postharvest Quality of Leafy Amaranth (Amaranthus spp.) Vegetables Using Evaporative Cooling. Journal of Food Quality. Volume 2017. Article ID 5303156, 6 pages.
Basediya, A. I., Samuel, D. V. K., Veera, V., Evaporative cooling system for storage of fruits and vegetables – A review. Journal of Food Science and Technology. 2013 Jun, 50(3):429-442.
Odesola, I. F., Onyebuchi, O., A review of porous evaporative cooling for the preservation of fruits and vegetables. The Pacific Journal of Science and Technology. 2009 Nov, 10(2):935-941.
Roy, S.K., On-farm storage technology can save energy and raise farm income. 1989. Amity Science, Technology & Innovation Foundation. Amity University Uttar Pradesh, India.
Performance evaluation should include measurements of the internal temperature as a function of external humidity, external temperature, and the frequency and amount of water added. Additionally, measurement of the average number of days before produce spoils (shelf life) when using the evaporative cooling chamber, compared to alternative storage methods can be used to evaluate performance.
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