Big ceiling fans
Big ceiling fans are often abbreviated to HVLS fans (HVLS Fan- High volume low speed fan).
Technically, Big ceiling fans are usually ceiling fans, although some are pole mounted, which are large industrial ceiling fans with large wingspan – the ceiling diameter is usually 3-7.3 m. Big ceiling fans move slowly and distribute large amounts of air at low rotational speeds hence the name “large flow, low speed”.
Typical applications for Big ceiling fans fall into two categories: Industrial and Commercial. Big ceiling fans were originally designed for large spaces such as barns, factories, warehouses, factories. Big ceiling fans are also used in commercial spaces where air conditioners are more common, but increased air movement from ceiling fans can effectively increase user comfort or prevent prevent stratification. Typical commercial applications include shopping centers, churches, office buildings, airport terminals, fitness centers and schools.
An important concern for many commercial spaces, such as schools and libraries, is sound sensitivity and quiet operation. In contrast, industrial spaces have median dBAs of 85 or higher and prioritize air movement (effective in combating thermal stress) in silent operation.
Principle of operation of big ceiling fans
Big ceiling fans operate on the principle of cool air movement breaking the moisture-saturated boundary around the body and increasing the evaporation rate to create a cooling effect. Big ceiling fans create an air column as they rotate. This column of air moves down and along the floor. This horizontal airflow is related to the diameter of the fan and, to a lesser extent, the fan speed.
In ideal conditions, a fan with a diameter of 2.4 m creates a deep airflow of about 0.910 m. A 7.3 m diameter fan creates a 2.7 m deep airflow, high enough to submerge a person standing on the floor or a cow, its original development purpose.
Commercial big ceiling fans differ from residential ceiling fans in regards to diameter, rotational speed and performance. While some fans use modern propellers to move the air, other methods are being used to make it more efficient like using airplanes.
Benefits of big ceiling fans
Air movement can have a significant effect on human thermal comfort. Cold winds in cold conditions are considered unfavorable, but air movement in neutral to warm environments is considered beneficial. This is because usually in conditions with an air temperature above 74 ° F, the body needs heat loss to maintain a constant internal temperature.
Unlike air conditioner, cool room, cooling fan. Ceiling fans increase air velocity at the user level, enabling more efficient heat removal, cooling of occupants, instead of space. The increased air velocity increases the rate of convection heat loss and evaporation from the body, thus making occupants feel cooler without changing the dry bulb temperature of the air.
Hot air is less dense than cold air, causing the hot air to naturally rise to the ceiling through a process called convection. In still air, the layers have a constant temperature, the coldest at the bottom and the warmest at the top. This is called stratification. The most effective and effective way of mixing air in a stratified space is to push hot air down to occupancy. This allows complete mixing of air in the space while reducing both heat loss through walls and roofs, and energy consumption of buildings. To avoid causing a draft, the fan should be slowed so that the air flow at the occupancy level does not exceed 40 feet per minute (12 m / min).