A New Application of A Proven Concept
Although MacroAir has been producing hvls air circulating fans for more than 10 years, the application is somewhat new and unknown.
Nothing feels better on a hot day than a gentle breeze. Moving air breaks up the moisture-saturated boundary layer surrounding the body, accelerating evaporation to produce a cooling effect. People have been aware of this for thousands of years – long before the advent of modern physics. It was logical then, that with the advent of the electric motor, fans would be one of the first things to be mechanized.
At some point however, engineers became so focused on using speed to increase fan displacement – the cubic feet of air per minute (CFM) moved through the fan – that some important physics-based issues were overlooked: High velocity air movement – wind – is both unpleasant and disruptive.
Air speed beyond four or five miles per hour usually offers little, if any, additional cooling benefit. In very hot, low humidity conditions, very slow moving air actually cools best.
Small high-speed fans create a pressure differential that is essential for many applications, but where slow movement of free air is the objective, pressure differential is not important.
Displacement, the amount of air actually moved through the fan, is of no real significance. It’s the down-stream effects that are important. A turbulent, high velocity air jet dissipates very quickly.
A large column of air “travels” farther than a small one. The friction between moving and stationary air occurs at the periphery of the moving column. The perimeter of a column varies directly with the diameter. And while the cross-sectional area varies with the square of the diameter, the large column has proportionately less periphery, and therefore, less “drag.” The air column from a 3 foot diameter fan has more than 6 times as much “friction interface” per cubic foot as the air column from a 20 foot fan.
When the down column of air off a MacroAir hvls air circulating fan reaches the floor the air turns in the horizontal direction away from the column in all directions. The air flowing outward is called the “horizontal floor jet”. The height of the floor jet is determined by the diameter of the column of air. The larger the hvls air circulating fan, the larger the column and the higher the floor jet. Because of this far-reaching effect and the “horizontal floor jet” created by large low-speed fans smaller high-speed fans of equivalent displacement are incapable of producing the same effect.
The power to drive a fan increases roughly with the cube of the average air speed through the air circulating fan. A commercial fan delivering air at 20 mph requires about 64 times as much power as one the same size delivering air at 5 mph! This, combined with the “effectiveness” means that when free air movement for cooling people is the objective, very large low speed commercial fans are enormously more efficient and effective than small high-speed fans.
MacroAir Technologies, and its design, development, and production teams took the long overdue step of scaling-up the air circulating fan for use in large industrial, commercial and agricultural/farm buildings.
Then, we took it a step further and added some modern technology, including aluminum extruded airfoils, to both ceiling mount and vertical mount fans (which directs a large mass of air into areas not accessible to overhead fans.) This airfoil (blade) design, a shape reminiscent of a helicopter blade, has physical properties that maximize its ability to capture and direct large air volume.
For ten years MacroAir has developed hvls air circulating fan products with quality, equipment life and service in mind. Simple customer- friendly components that can last a lifetime and can be replaced easily over time make this simply the best air movement system available.
