The high cost of power has made industries look into equipment to reduce power consumption. Cooling Towers, heat exchanger, humidification and ventilator are areas where a major saving is possible at reasonable cost in the industries
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The pioneering works of Aerotech have resulted in 20% plus power saving and recovering the cost of fan in short time.

Cast aluminum fans are consuming more power due to low efficiency and heavy weight. The fans operate at duty point all throughout 24 hours using excess power, which can be saved by using Aerotech aerodynamic design energy efficient FRP hollow axial flow fans.

Aerotech has designed and developed structurally strong FRP hollow fans which are light-in-weight with help of USA based NACA* computerized software, having more lift and low drag airfoil shape, Engineered twist, optimized camber to increase the fan efficiency which means resultant low operating cost.

Aerotech method of Axial Flow Fan design is based on data obtained from the combination of the blade element theory, model fan tests in a wind tunnel, and tests of full scale fans in the field. The data are plotted as curves for fans of standard theory form, making the actual operation in designing the fan very short and simple. For the analysis or design of special blade which is not conforming to the standards, the modified blade element theory is used, with airfoil section characteristics, which give resultant powers and efficiencies checking the standard model data.

APPLICATION OF AXIAL FLOW FANS

The axial flow fans are widely used for providing the required airflow for the heat & mass transfer operations in various industrial equipment and processes. These includes cooling tower for air conditioning & ventilation, humidifiers in textile mills, air–heat exchangers for various chemical processes, ventilation & exhaust as in mining industry etc. all the major industries use large number of axial flow fans operation, such as:

Cooling Towers
Heat Exchangers
Humidifiers
Ventilation
Industrial Air Circulator
Man Cooler
All type of Industrial Axial Flow Fan

ENERGY EFFICIENT FRP AXIAL FLOW FAN

Fiber Reinforced Plastics (FRP) providing the desired non-corrosive quality to the fan blades, resulting in the operation of the fans even in the chemical environment. Lightweight FRP fan also ensures a low moment of inertia, minimum wear & stress on motor, bearing and drive system. Hollow FRP blades is less weightier than aluminum fan assembly, easy to Carry and non-possibility of damage to fan & drive during sudden stops due to light weight. Composite structural design can be tailor made by using various glass fibers (Glass cloth & woven roving mat and roving) in right direction while moulding the fan blades with Epoxy resin thus imparting the desired mechanical strength by improving its industrial stability and enhanced mechanical properties. Aerotech design of the fan blades ensure more airflow, lower noise level & less power consumption means high efficiency. The AERODYNAMICALLY designed fan impeller of the fans, fabricated by composite material can be excellent alternative to ensure enhanced efficiency & appropriate energy saving apart from wide gamut of critical advantages.

ADVANTAGE OF FRP AXIAL FLOW FANS

The FRP fans offer certain critical advantages as mentioned here under:

1.Optimal aerodynamic design of fan impellers to provide higher efficiency for any specific    application.
2.Reduction in overall weight of the fan, thereby extending the life of mechanical drive system
3.Requires lower drive motor rating and light duty bearing system.
4.Lower power consumption resulting in appreciable energy savings.
5.FRP fan fabricated compression moulding/resin transfer moulding technique would have    uniform dimensions and consistent quality.
6.Lower flow noise and mechanical noise level compared to conventional metallic fans.
7.Longer life of the fan due to improved mechanical strength.

FRP HOLLOW FAN BLADES.

The basic purpose of a “fan” is to move a mass of gas or vapor at the desired velocity. For achieving this objective there is a slight increase in the gas pressure across the fan rotor or impeller. However main aim remains to move air or gas without any appreciable increase in its pressure. The total pressure developed by the fan is of the order of a few millimeter of water gauge. A “blower” which is also referred to as “fan” in some literature deliver the gas or air with the appreciable race in pressure to overcome some kind of resistance in the flow. Some applications develop pressure of the order or 1000 mm W.G. or more. An axial flow fan stage in its simplest form consists of a rotor made up of number of blades fitted to the hub. When it is rotated by an electric motor or any other drive, a flow is established through the rotor. The actions of the rotor causes an increase in the stagnation pressure of air or gas across it. A cylindrical casing encloses the rotor. It receives the flow through a

P HOLLOW BLADE AERODYNAMIC DESIGN.

As mentioned previously the choice of correct twist and of special airfoil sections to reduce compressibility losses are of major importance in modern fan blades design. However other considerations still remain to be studied with care if the efficiency of the blade is to be kept at its maximum under severe operating conditions.

CENTRIFUGAL AND AERODYNAMIC TWISTING

In variable-pitch fan as described later the blades are turned in the hub about their longitudinal or pitch-change axis. Clearly the mechanism provided to produce this pitch change must be capable of exerting sufficient force to overcome any mechanical or aerodynamic opposing force set up by the blades themselves. It will be useful then to see exactly what these force are.
The “mechanical force” involved is known as Centrifugal Twisting Moment (C.T.M)which as its name implies is closely allied to the normal centrifugal force acting on the blades when the fan is rotating about the shaft . It is turning couple brought about by the fact that the blade section are inclined at an angle to the fan of rotation and results in the natural tendency for any fan blade, when rotating turned about its longitudinal axis towards zero pitch so that the blades section are turned in to the fan blade rotation .

THRUST AND TORQUE FORCES.

The main factor that determines the force developed by an aerofoil section is the angle at which it is inclined to the relative airflow, i.e. the angle of attack in order, therefore, for the fan blade section to develop the requisite aerodynamic force for propulsion, each section along the blade must be inclined at the appropriate angle of attack to the relative airflow direction pertaining to the section hence knowing angle of attack is a simple mater to indicate the force developed as shown in figure 1) from which it will be noted that the total blade angle of attack and the helix angle