{
    "title": "Evaporative Refrigerator (Solar Powered)",
    "inventor_name": "Emily Cummins",
    "publication_year": 2009,
    "device_name": "Portable Evaporative Refrigerator",
    "goal": "Provide refrigeration without electricity for food and medical supplies in low-resource settings.",
    "problem_addressed": "Lack of reliable electricity and affordable refrigeration in developing regions, leading to food spoilage and difficulty transporting temperature-sensitive medicines.",
    "concept_summary": "A double-cylinder container where the gap between an inner metal cylinder and an outer shell is packed with a water-holding medium (sand, wool, soil). Sunlight heats the wet medium, causing water to evaporate and remove heat, thereby cooling the inner chamber to around 6  deg C without any external power.",
    "detailed_description": "The inner cylinder (metal) holds the items to be cooled. The outer cylinder can be made from wood, plastic, or any readily available material. The annular space between the cylinders is filled with a porous medium (sand, wool, soil) that is soaked with water. When placed in sunlight, the water in the medium evaporates, using the latent heat of vaporisation to draw heat away from the inner cylinder. The resulting temperature drop keeps perishables cool for days. The device is portable, inexpensive, and can be built from household or locally sourced materials. Field trials were conducted in Namibia for about five months, where the fridge maintained temperatures near 6  deg C and kept food and medicine fresh.",
    "category": "Thermal Systems",
    "principles": [
        "Evaporative cooling",
        "Latent heat of vaporisation",
        "Passive heat transfer",
        "Solar thermal heating"
    ],
    "scientific_domains": [
        "Thermodynamics",
        "Heat Transfer",
        "Sustainable Engineering",
        "Materials Science"
    ],
    "mechanisms_of_action": [
        "Evaporation of water from a moist medium",
        "Heat removal from inner chamber via latent heat",
        "Solar heating of wet medium to drive evaporation"
    ],
    "materials": [
        "Metal (inner cylinder)",
        "Wood or plastic (outer cylinder)",
        "Sand",
        "Sheep wool",
        "Soil",
        "Water"
    ],
    "energy_sources": [
        "Solar energy (provides heat for evaporation)"
    ],
    "inputs": [
        "Sunlight",
        "Water",
        "Moist medium (sand, wool, soil)"
    ],
    "outputs": [
        "Cool interior temperature (~6  deg C)",
        "Refrigerated storage space"
    ],
    "claimed_performance": "Keeps perishable goods cool for days at a temperature of around 6  deg C without any electricity.",
    "experimental_evidence": "Field testing in Namibia for nearly five months demonstrated that the fridge maintained low temperatures and kept food/medicine fresh for several days.",
    "replication_status": "Demonstrated in Namibia; used by local communities; no large-scale commercial production reported.",
    "keywords": [
        "evaporative cooling",
        "solar refrigerator",
        "passive cooling",
        "low-cost refrigeration",
        "sustainable design",
        "third world technology"
    ],
    "related_technologies": [
        "Earthen pot cooler",
        "Solar thermal cooling",
        "Passive refrigeration"
    ],
    "controversy_level": "low",
    "confidence_score": 0.9,
    "practicability_score": 0.8,
    "fringe_score": 0.2,
    "evidence_strength": 0.6,
    "risk_score": 0.1,
    "trl_estimate": 5,
    "source_urls": [
        "http://www.dailymail.co.uk/sciencetech/article-1108343/Amazing-solar-powered-fridge-invented-British-student-potting-shed-helps-poverty-stricken-Africans.html",
        "http://www.capitalistchicks.com/?q=node/410",
        "http://www.treehugger.com/files/2009/01/student-invents-solar-fridge.php",
        "http://www.emilycummins.co.uk",
        "http://www.emilycummins.co.uk/#/fridgeproblem/4521158226"
    ],
    "organizations": [
        "Make Your Mark",
        "International Traditional Development Group (ITDG)",
        "Women's Association for Earthenware Manufacturing"
    ],
    "applications": [
        "Food preservation in off-grid villages",
        "Transport and storage of temperature-sensitive medicines",
        "Emergency relief cooling"
    ],
    "limitations": [
        "Performance drops in high humidity environments",
        "Requires regular water replenishment",
        "Limited temperature reduction (~=6  deg C)",
        "Durability of outer shell depends on material choice"
    ],
    "open_questions": [
        "How does long-term exposure to sunlight affect material durability?",
        "Can the design be scaled to larger refrigeration units?",
        "What is the optimal moisture-holding medium for different climates?",
        "How does the system perform under continuous heavy load (e.g., large quantities of food)?"
    ],
    "red_flags": [],
    "evidence_quotes": [
        "The fridge comprises two cylinders - one inside the other. The inner cylinder is made from metal but the outer cylinder can be made from anything to hand, including wood and plastic.",
        "When the fridge is placed in a warm environment, the sun's energy causes the water to evaporate from the medium. As the water/medium mix is held against the inner cylinder, heat is removed in the form of energy. Due to heat transfer the inner cylinder becomes cooler.",
        "She spent nearly 5 months in Namibia testing her refrigerator. It kept perishable goods cool for days at a temperature of around 6  deg C without using any power.",
        "The outer cylinder and the inner cylinder is an open compartment where any medium capable of holding water can be placed. The medium would usually be sand, wool or soil and is packed into the gap and then water is added."
    ]
}