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Discover the revolutionary 2.500-year-old “Refrigerator” that preserved ICE in 50°C desert temperatures

Written by Valdemar Medeiros
Published 09/07/2024 às 19:02
Discover the revolutionary 2.500-year-old “Refrigerator” that preserved ICE in 50°C temperatures in the Sahara Desert
Photo: Dall-e

Ancient people developed a refrigerator that preserved ice in the desert. Known as “yakhchal”, this ingenious structure was more than 18 meters high and had underground chambers to store ice and food, using advanced thermal insulation and natural ventilation techniques.

The invention of refrigerators undoubtedly represented a true revolution in food preservation. However, long before that, the ancient Persians, ancestors of today's Iranians, had already developed their own refrigeration technology. The technology not only preserved food, but also played a key role: storing ice in the desert. Using ingenious engineering methods and taking advantage of the arid climate, the Persians were able to create structures that preserved ice year-round, transforming resource management in desert regions.

The working process of the refrigerator that preserved ice in the desert

The “ancestor” of the refrigerator was very different from the appliances we have in our homes today. Call of yakhchal, she was, in fact, a giant construction. The refrigerator preserved ice in the desert and was raised above the ground. It looked like a rounded clay dome, but it had a huge storage space below the surface. According to researchers, it would have been created 2,5 years ago.

A yakhchal was on average about 18 meters tall and had large underground storage spaces. Some ruins located indicate that the total capacity could reach six thousand cubic meters. The underground chambers of evaporative cooling systems worked through wind collectors and water from nearby springs brought by canals.

Water absorbs heat from the environment and evaporates, reducing the ambient temperature. The sensation inside the yakhchal would be similar to that of a refrigerated chamber, in this way, the refrigerator preserved ice in the desert.

Construction process of the Persian 'refrigerator'

The walls of the Persian “refrigerator” were built with a special type of mortar (a mixture of sand, clay and other elements, such as egg white and goat hair) that provided isolation and protection from the Sun. Remembering that these people inhabited large proportions of the desert and had to create forms of resist intense heat.

Discover the revolutionary 2.500-year-old “Refrigerator” that preserved ICE in 50°C desert temperatures
Photo: Wikipedia/Disclosure

The trenches underground were built to collect all the water from the melting ice. This volume was refrozen at night, when temperatures in the desert drop below freezing. This refrigerator preserved ice in the desert, but it also often preserved food for many years.

Typically, a wall was made in an east-west direction near the yakhchal and the water was channeled from the north side of the wall so that the shadow of the wall keeps the water cool to help it freeze faster. In some yakhchals, ice is also brought from nearby mountains for storage or to fuel the water freezing process.

The division process

Ice is created and stored actively and passively in these specially designed coolers. The specific design of the building allows cool air to enter from inlets at the base of the structure and descend to the lowest part of the yakhchal, at the same time, the tall, conical shape of the building guides any remaining heat upward and outward through from the openings at the top of the building, and through this active process the air inside the refrigerator remains colder than that outside.

Commonly the refrigerator preserved ice in the desert and had access to a Qanat (water channels or conduits), sometimes equipped with a system of Bâdgirs (ancient design of wind catchers or wind towers) that could easily bring temperatures inside the space to frigid levels, even on summer days.

Constructed of clay or mud bricks, in square or round shapes, Bâdgirs capture the slightest breeze through openings at the top and channel the cold air downwards, through vertically placed wooden slats, to the water or structure below. Alternatively, the Bâdgir can function as a chimney, expelling hot air upwards to draw cold air in from an opening in the base or a Qanat connected to it.

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Valdemar Medeiros

Journalist in training, specialist in creating content with a focus on SEO actions. Writes about the Automotive Industry, Renewable Energy and Science and Technology

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