Yacht scarf
A yach-chāl ( Persian يخچال) is a traditional refrigerator that was mainly used in Persia since the 5th century. As early as 500 BC The Persians built the first underground and aboveground cold rooms, which achieved a cooling function through complex ventilation systems.
In these underground, dome-like buildings (up to 5000 m³ volume) ice was stored, they were also used to keep food fresh. The more than 2 m thick walls of the dome prevented the heat from penetrating the interior. The ice was fetched from nearby mountains during the winter months and stored in order to be used for traditional Persian ice cream during the summer months.
functionality
First, very large basins with a depth of around 40 to 50 cm were dug into the ground. Then the water from a qanat or a stream was led into the basin. Ice formed during the night and was transported from the basin and stored in the cold store.
A very high brick or mud wall was built on the south side of the pool in order to prevent direct sunlight on the pool during the day. The bottom of the water basin remained much cooler than the neighboring area in order to accelerate the ice formation process. Often two more walls were also built on the western and eastern sides, so that the pool was shielded from direct rays at sunrise and sunset.
A special mortar ( sārudsch ), a mixture of sand , clay , lime , ash , and goat hair, etc., was used for the construction, which in a certain mixing ratio was heat-repellent.
The Yach-chāl, which were built on the edge of deserts , had a huge dome-like part above ground and a large and very deep (up to 15 m) storage space below ground.
The cold rooms themselves have different sizes. One of the largest of them is in Meybod . Its double-shell dome is made of raw brick. In order to achieve an optimum in terms of economy and statics, the outer shell of the conical dome became thinner from bottom to top. This construction resulted in a weight reduction, material savings and also a deeper shift of the center of gravity. The Meyboder dome is 15 m high. The outer shell has a thickness of 240 cm at the bottom and 20 cm at the top (thickness of a brick). So the dome reaches a stepped outer wall, which was helpful for the repair and the annual maintenance of this giant building.
Most of the time, as in Meybod, there was an approximately 12 m high, 40 m long and up to 2 m (at the lower edge) thick shadow throwing wall north of the dome. To the north of this wall was the water basin. Most of the yach-chāl also have a wind catcher for lowering and regulating temperatures .
The “ice store” was once connected to the water basin through a sluice-like opening, through which the chunks of ice landed for storage in the store, which was then bricked up again after the “harvest”. On the opposite side, it also had an entrance that was usually lockable, through which a narrow staircase led deep down, which was used to transport the ice.