Ancient Yakhchal freezers that kept ice cold – even during the desert summer:
These ancient refrigerators (Yakhchal), created by Persian engineers, were used primarily to store ice for use in the summer, as well as food storage in the hot, dry desert climate of Iran.People harvested ice and snow as early as 1,000 BC and there is written evidence that the ancient Chinese, Jews, Greeks and Romans did so.
By 400 BCE, Persian engineers had mastered the technology to freeze the desert in the middle of summer. Ice was brought in enormous quantities from the nearby mountains during the winter, and stored in their freezers called Yakhchal, or ice-pits.
Toward the top, the structure consisted of a large mud-brick dome, often up to 60 feet high. Below are large underground spaces of up to 5000 cubic metres, with a deep storage space. The space often had access to a qanat, or wind catchers, and often contained a system of wind catchers that would ease the temperature inside the space to lower levels on hot summer days.
Yakhchal has thick mud brick walls up to two meters thick at the base, made of a special mortar called Saroj, which is made of sand, clay, egg white, lime, goat hair in specific proportions and is made of ash. which acts as an insulator. This mixture was supposed to be completely water impervious.
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The massive insulation and the constantly cooling water that spirals down it keep the winter ice frozen there throughout the summer. These ice houses, used in desert cities since ancient times, have a moat at the bottom to catch melt water from the snow and allow it to re-freeze during cold desert nights. The ice has broken and gone into caves deep in the ground. As more water drains into the ditch, the process is repeated.
Isfahan had many Yakhchal and some of them were for personal use. Fruit and large pieces of ice were carried by donkeys and sold everywhere, along with preserved sorbet and ice in shops. Ice could also be bought in the market or directly from the Yakhchal building. Yakhchal was the forerunner of modern thermal energy storage systems.
Some of these buildings were so well built that some of them are still standing today. One of the yakhchals that still stands today is in Kerman, the capital of Iran’s Kerman province. It is about eighteen meters high. But it is one of the rare surviving Yakhchals.
Over time they were replaced with modern electric refrigerators, freezers and air conditioners because of a number of different reasons such as accessibility, practicality and the many health risk issues. In addition, desert storms destroyed many khachchal buildings, especially those that were in the open in desert areas.
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