Description
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 OVERVIEW OF FAN
A fan is a machine used to create flow within a fluid, typically a gas such as air. The fan consists of a rotating arrangement of vanes or blades which act on the fluid. The rotating assembly of blades and hub is known as an impeller, a rotor, or a runner. Usually, it is contained within some form of housing or case (Cory, 2010). This may direct the airflow or increase safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors and internal combustion engines. Fans produce flows with high volume and low pressure (although higher than ambient pressure), as opposed to compressors which produce high pressures at a comparatively low volume. A fan blade will often rotate when exposed to a fluid stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan (Cory, 2010).
An electric fan allowing selection of oscillating angles and including an oscillating angle limitation switch to limit an oscillating angle of the electric fan.
Electric fans generally include a fan driven by a motor to provide air currents for cooling purposes. Although air conditioners are widely used, electric fans are still an option in view of costs and energy conservation in many families, offices, public areas, and industries requiring dissipation of heat (Cory, 2010).
2.2 HISTORICAL BACKGROUND OF THE PROJECT
The punkah fan was used in India about 500 BCE. It was a handheld fan made from bamboo strips or other plant fibre that could be rotated or fanned to move air. During British rule, the word came to be used by Anglo-Indians to mean a large swinging flat fan, fixed to the ceiling, and pulled by a servant, called the punkawallah.
For purposes of air conditioning, the Han Dynasty craftsman and engineer Ding Huan (fl. 180 CE) invented a manually operated rotary fan with seven wheels that measured 3 m (10 ft) in diameter; in the 8th century, during the Tang Dynasty (618–907), the Chinese applied hydraulic power to rotate the fan wheels for air conditioning, while the rotary fan became even more common during the Song Dynasty (960–1279) (Wallop, 2009).
In the 17th century, the experiments of scientists like Otto von Guericke, Robert Hooke and Robert Boyle, established the basic principles of vacuum and airflow. The English architect Sir Christopher Wren applied an early ventilation system in the Houses of Parliament that used bellows to circulate air. Wren’s design would be the catalyst for much later improvement and innovation (Wallop, 2009).
The first rotary fan used in Europe was for mine ventilation during the 16th century, as illustrated by Georg Agricola (1494–1555).
John Theophilus Desaguliers, a British engineer, demonstrated a successful use of a fan system to draw out stagnant air from coal mines in 1727 and soon afterwards he installed a similar apparatus in Parliament. Good ventilation was particularly important in coal mines to reduce casualties from asphyxiation. The civil engineer John Smeaton, and later John Buddle installed reciprocating air pumps in the mines in the North of England. However, this arrangement was not ideal as the machinery was liable to breaking down.
Steam
With the advent of practical steam power, fans could finally be used for ventilation. David Boswell Reid, a Scottish physician, installed four steam powered fans in the ceiling of St George’s Hospital in Liverpool, so that the pressure produced by the fans would force the incoming air upward and through vents in the ceiling. In 1849 a 6 m radius steam driven fan, designed by William Brunton, was made operational in the Gelly Gaer Colliery of South Wales. The model was exhibited at the Great Exhibition of 1851. Improvements in the technology were made by James Nasmyth, Frenchman Theophile Guibal and J. R. Waddle.
Electrical
Between the years 1882 and 1886, New Orleans, LA resident Schuyler Skaats Wheeler invented a fan powered by electricity. It was commercially marketed by the American firm Crocker & Curtis Electric Motor Company. In 1882, Philip Diehl introduced the electric ceiling fan. During this intense period of innovation, fans powered by alcohol, oil, or kerosene were common around the turn of the 20th century (Wallop, 2009).
In 1909, KDK pioneered the invention of mass-produced electric fans for home use. In the 1920s, industrial advances allowed steel fans to be mass-produced in different shapes, bringing fan prices down and allowing more homeowners to afford them. In the 1930s, the first art deco fan (the “swan fan”) was designed. By the 1950s, fans were manufactured in colors that were bright and eye catching.
Window and central air conditioning in the 1960s caused many companies to discontinue production of fans. But in the 1970s, with an increasing awareness of the cost of electricity and the amount of energy used to heat and cool homes, Victorian-style ceiling fans became popular again as both decorative and energy efficient units.
In 1998, Walter K. Boyd invented the HVLS ceiling fan. It was a slow moving fan with an eight foot diameter. Due to its size, the fan moved a large column of air and continuously mixed fresh air with the stale air inside. They are used in many industrial and agricultural settings, because of their energy efficiency (Wallop, 2009).
2.3 REVIEW OF DIFFERENT TYPES OF FANS
Ceiling fan with lamp
Revolving blade fans are made in a wide range of designs. They are used on the floor, table, desk, or hung from the ceiling. They can also be built into a window, wall, roof, chimney, etc. Most electronic systems such as computers include fans to cool circuits inside, and in appliances such as hair dryers and portable space heaters and mounted/installed wall heaters. They are also used for moving air in air-conditioning systems, and in automotive engines, where they are driven by belts or by direct motor. Fans used for comfort create a wind chill by increasing the heat transfer coefficient, but do not lower temperatures directly. Fans used to cool electrical equipment or in engines or other machines do cool the equipment directly by forcing hot air into the cooler environment outside the machine. There are three main types of fans used for moving air, axial, centrifugal (also called radial) and cross flow (also called tangential). The American Society of Mechanical Engineers Performance Testing Code 11 (PTC) provides standard procedures for conducting and reporting tests on fans, including those of the centrifugal, axial, and mixed flows (Wallop, 2009).
Axial-flow fans
Axial-flow fans have blades that force air to move parallel to the shaft about which the blades rotate. This type of fan is used in a wide variety of applications, ranging from small cooling fans for electronics to the giant fans used in wind tunnels. Axial flow fans are applied in air conditioning and industrial process applications. Standard axial flow fans have diameters from 300–400 mm or 1800 to 2000 mm and work under pressures up to 800 Pa. Examples of axial fans are:
- Table fan: Basic elements of a typical table fan include the fan blade, base, armature and lead wires, motor, blade guard, motor housing, oscillator gearbox, and oscillator shaft. The oscillator is a mechanism that moves the fan from side to side. The axle comes out on both ends of the motor, one end of the axle is attached to the blade and the other is attached to the oscillator gearbox. The motor case joins to the gearbox to contain the rotor and stator. The oscillator shaft combines to the weighted base and the gearbox. A motor housing covers the oscillator mechanism. The blade guard joins to the motor case for safety.
- Ceiling fan: A fan suspended from the ceiling of a room is a ceiling fan. Ceiling fans can be found in both residential and industrial/commercial settings.
- In automobiles, a mechanical fan provides engine cooling and prevents the engine from overheating by blowing or sucking air through a coolant-filled radiator. It can be driven with a belt and pulley off the engine’s crankshaft or an electric fan switched on or off by a thermostatic switch.
- Computer cooling fan for cooling electrical components
- Variable-pitch fan: A variable-pitch fan is used where precise control of static pressure within supply ducts is required. The blades are arranged to rotate upon a control-pitch hub. The fan wheel will spin at a constant speed. As the hub moves toward the rotor, the blades increase their angle of attack and an increase in flow results (Robert, 2012).
Centrifugal fan
Often called a “squirrel cage” (because of its similarity in appearance to exercise wheels for pet rodents) or “scroll fan”, the centrifugal fan has a moving component (called an impeller) that consists of a central shaft about which a set of blades, or ribs, are positioned. Centrifugal fans blow air at right angles to the intake of the fan, and spin the air outwards to the outlet (by deflection and centrifugal force). The impeller rotates, causing air to enter the fan near the shaft and move perpendicularly from the shaft to the opening in the scroll-shaped fan casing. A centrifugal fan produces more pressure for a given air volume, and is used where this is desirable such as in leaf blowers, blow dryers, air mattress inflators, inflatable structures, climate control, and various industrial purposes. They are typically quieter than comparable axial fans (Robert, 2012).
Cross-flow fan
Cross-section of cross-flow fan, from the 1893 patent. The rotation is clock-wise. The stream guide F is usually not present in modern implementations.
Cross-flow fan
The cross-flow or tangential fan, sometimes known as a tubular fan, was patented in 1893 by Paul Mortier, and is used extensively in the HVAC industry. The fan is usually long in relation to the diameter, so the flow approximately remains two-dimensional away from the ends. The CFF uses an impeller with forward curved blades, placed in a housing consisting of a rear wall and vortex wall. Unlike radial machines, the main flow moves transversely across the impeller, passing the blading twice. The flow within a cross-flow fan may be broken up into three distinct regions: a vortex region near the fan discharge, called an eccentric vortex, the through-flow region, and a paddling region directly opposite. Both the vortex and paddling regions are dissipative, and as a result, only a portion of the impeller imparts usable work on the flow. The cross-flow fan, or transverse fan, is thus a two-stage partial admission machine. The popularity of the crossflow fan in the HVAC industry comes from its compactness, shape, quiet operation, and ability to provide high pressure coefficient. Effectively a rectangular fan in terms of inlet and outlet geometry, the diameter readily scales to fit the available space, and the length is adjustable to meet flow rate requirements for the particular application. Common household tower fans are also cross-flow fans (Robert, 2012).
Much of the early work focused on developing the cross-flow fan for both high and low-flow-rate conditions, and resulted in numerous patents. Key contributions were made by Coester, Ilberg and Sadeh, Porter and Markland, and Eck.
One phenomenon particular to the cross-flow fan is that, as the blades rotate, the local air incidence angle changes. The result is that in certain positions the blades act as compressors (pressure increase), while at other azimuthal locations the blades act as turbines (pressure decrease).
Uncommon types of fan
Bellows
Bellows are also used to move air, although not generally considered fans. A hand-operated bellows is essentially a bag with a nozzle and handles, which can be filled with air by one movement, and the air expelled by another. Typically it would comprise two rigid flat surfaces hinged at one end, where a nozzle is fitted, and with handles at the other. The sides of the surfaces are joined by a flexible and air-proof material such as leather; the surfaces and joining material comprise a bag sealed everywhere but at the nozzle. (The joining material typically has a characteristic pleated construction that is so common that similar expanding fabric arrangements not used for moving air, such as on a folding camera, are called bellows.) Separating the handles expands the bag, which fills with air; squeezing them together expels the air. A simple valve (e.g., a flap) may be fitted so that air enters without having to come from the nozzle, which may be close to a fire. Bellows produce a directed pressurized stream of air; the airflow volume is typically low with moderate pressure. They are an older technology, used mainly to produce a strong and directed airflow unlike non-electric bladed mechanical fans, before the introduction of electricity.
- A single-acting bellows will only produce airflow during the exhaust stroke.
- A double-acting bellows is a pair of bellows capable of blowing out air from one while inhaling air into the other, but airflow still temporarily ceases when the stroke direction is reversed.
- Combining multiple bellows at third-cycle or quarter-cycle arrangements on a crank arm allows for nearly continuous airflow from several bellows at once; each is in a different phase of inhaling and exhausting during the cycle.
Convective
Differences in air temperature will affect the density of air and can be used to induce air circulation through the mere act of heating or cooling an air mass. This effect is so subtle and works at such low air pressures that it does not appear to fit the definition of a fan technology. However, prior to the development of electricity, convective airflow was the primary method of inducing airflow in living spaces. Old fashioned oil and coal furnaces were not electric and operated simply on the principle of convection to move the warm air. Very large volume air ducts were sloped upwards away from the top of the furnace towards floor and wall registers above the furnace. Cool air was returned through similar large ducts leading to the bottom of the furnace. Older houses from before electrification often had open duct grilles leading from the ceiling of a lower level to the floor of an upper level, to allow convective airflow to slowly rise up the building from one floor to the next. Outhouses commonly rely on a simple enclosed air channel in a corner of the structure to exhaust offensive odors. Exposed to sunlight, the channel is warmed and a slow convective air current is vented out the top of the building, while fresh air enters the pit through the seat hole.
Electrostatic
An electrostatic fluid accelerator propels airflow by inducing motion in airborne charged particles. A high voltage electric field (commonly 25,000 to 50,000 volts) formed between exposed charged anode and cathode surfaces is capable of inducing airflow through a principle referred to as ionic wind. The airflow pressure is typically very low but the air volume can be large. However, a sufficiently high voltage potential can also cause the formation of ozone and nitrogen oxides, which are reactive and irritating to mucous membranes.
Fan drive methods
Building heating and cooling systems commonly use a squirrel cage fan driven by belt from a separate electric motor.
Internal combustion engines sometimes drive an engine cooling fan directly, or may use a separate electric motor.
Large electric motors may have a cooling fan either on the back or inside the case.
Standalone fans are usually powered by electric motors, often attached directly to the motor’s output with no gears or belts. The motor is either hidden in the fan’s center hub or extends behind it. For big industrial fans, three-phase asynchronous motors are commonly used, placed near the fan and driving it through a belt and pulleys. Smaller fans are often powered by shaded pole AC motors, or brushed or brushless DC motors. AC-powered fans usually use mains voltage, while DC-powered fans use low voltage, typically 24, 12, or 5 V. Cooling fans for computer equipment always use brushless DC motors, which generate much less electromagnetic interference than other types. In machines with a rotating part, the fan is often connected to it rather than being powered separately. This is commonly seen in motor vehicles with internal combustion engines, where the fan is connected to the drive shaft directly or through a belt and pulleys. A common configuration is a dual-shaft motor, where one end of the shaft drives a mechanism, while the other has a fan mounted on it to cool the motor itself. Window air conditioners commonly use a dual-shaft fan to operate separate blowers for the interior and exterior parts of the device. Where electrical power or rotating parts are not available, fans may be drive by other methods. High-pressure gases such as steam can be used to drive a small turbine, and high-pressure liquids can be used to drive a pelton wheel, which can provide the rotational drive for a fan. Large, slow-moving energy sources such as a flowing river can also power a fan using a water wheel and a train of gears or pulleys (Robert, 2012).
2.4 COMPONENTS OF ELECTRIC FAN
The basic elements of a table fan include the base, stand, fan blade, blade guard, motor, motor housing, gearbox, oscillating link and shaft.
1.1 Blade
Blades (also known as paddles or wings) usually made from wood, plywood, iron, aluminum. The blades are designed such that they can supply proper and smooth air delivery. Its main function is to take air from back side and throw air to front side at constant speed. Blades are mounted on motor shaft with the help of a key.
1.2 Motor
Standalone fans are usually powered by an electric motors, often attached directly to the motor’s output, with no gears or belts. The motor is either hidden in the fan’s center hub or extends behind it. For big industrial fans, three-phase asynchronous motors are commonly used, placed near the fan and driving it through a belt and pulleys. Smaller fans are often powered by shaded pole AC motors, or brushed or brushless DC motors. AC- powered fans usually use mains voltage, while DC-powered fans use low voltage.
1.3 Bearing
The main work of the bearing is to convert rotary (mechanical) motion of shaft (inner end) into stationary or static (outer end) energy of guard. Its inner end is connected with motor shaft and outer end with guard. A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts (Wedel et al., 2014). The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts (Wedel et al., 2014).
1.4 Regulator
In automatic control, a regulator is a device which has the function of maintaining a designated characteristic. It performs the activity of managing or maintaining a range of values in a machine. The measurable property of a device is managed closely by specified conditions or an advance set value; or it can be a variable according to a predetermined arrangement scheme. It can be used generally to connote any set of various controls or devices for regulating or controlling items or objects.
A voltage regulator is an electronic circuit that provides a stable DC voltage independent of the load current, temperature and AC line voltage variations. A voltage regulator may use a simple feed-forward design or may include negative feedback. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages (Wedel et al., 2014).
Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements.
1.5 Motor Body
It is housing of electric motor and is mounted on the stand of fan. Its main function is to prevent the dust, smoke and other impurities entering into motor. It includes motor, motor shaft, oscillating mechanism, etc. It`s another function is to reduce the losses of electromagnetic flux (EMF) and to give safety to human. In machines with a rotating part, the fan is often connected to it rather than being powered separately. This is commonly seen in motor vehicles with internal combustion engines, large cooling systems, locomotives, and winnowing machines, where the fan is connected to the drive shaft or through a belt and pulleys. Another common configuration is a dual-shaft motor, where one end of the shaft drives a mechanism, while the other has a fan mounted on it to cool the motor itself.
Window air conditioners commonly use a dual-shaft fan to operate separate blowers for the interior and exterior parts of the device. Where electrical power or rotating parts are not readily available, fans may be driven by other methods. High-pressure gases such as steam can be used to drive a small turbine, and high- pressure liquids can be used to drive a pelt on wheel, either which can provide the rotational drive for a fan.
Large, slow-moving energy sources such as a flowing river can also power a fan using a water wheel and a series of step-down gears or pulleys to increase the rotational speed to that which is required for efficient fan operation (Wedel et al., 2014).
Oscillating Mechanism
A standing fan with oscillating mechanism includes a clutch member for adjusting the angle of oscillation according to user’s need. When the motor is actuated, the rotating torque induced by the motor and the transmission mechanism is smaller than the rotational resistance of the clutch member such that the motor may drive the fan to oscillate. Further, when the user applies an external rotational force greater than the rotational resistance of the clutch member, the user can swing the fan to any angle as desired without rotating or shifting other members except the fan and the fan suspension tube. In this manner, undesired damage of the mechanism or motor due to inappropriately applied external force can be avoided efficiently (Sanghani, 2016).
2.6. OVERVIEW OF SPARK PLUG
Spark plug is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air mixture by an electric spark, while containing combustion pressure within the engine (Denton, 2013). A spark plug has a metal threaded shell, electrically isolated from a central electrode by a ceramic insulator. The central electrode, which may contain a resistor, is connected by a heavily insulated wire to the output terminal of an ignition coil or magneto. The spark plug’s metal shell is screwed into the engine’s cylinder head and thus electrically grounded. The central electrode protrudes through the porcelain insulator into the combustion chamber, forming one or more spark gaps between the inner end of the central electrode and usually one or more protuberances or structures attached to the inner end of the threaded shell and designated the side, earth, or ground electrode(s) (Denton, 2013).
Spark plugs may also be used for other purposes; in Saab Direct Ignition when they are not firing, spark plugs are used to measure ionization in the cylinders – this ionic current measurement is used to replace the ordinary cam phase sensor, knock sensor and misfire measurement function (Lagana et al., 2018). Spark plugs may also be used in other applications such as furnaces wherein a combustible fuel/air mixture must be ignited. In this case, they are sometimes referred to as flame igniters.
2.7 REVIEW OF RELATED STUDIES
Diy (2014) proposed “copper coil” ice-chest air cooler. The ac is a combination of the standard ice-chest air cooler and a copper coil fan cooler. The ac was built with fountain pump, electric fan, and copper wire.
FT technology (2014) proposed “how to turn your fan into an air conditioner ac”. In his design a table fan was converted into air conditioner water stored in a plastic bottle and copper wire.
Crazy bd hacker (2016) proposed “How to make air conditioner at home using Plastic Bottle”. In his design he used table fan, condenser, plastic bottle, and ice.
American tech (2019) proposed “How to make an amazing air cooler for summer”. On his youtube page he modified the fan using 24V DC Motor, 500F Super capacitors and 775 DC motor 12V.
Fkteck (2021) proposed “Convert Standing Fan To Air Condition AC With Spark Plug And Condenser”. In his study on youtube, plastic bottles, table fan, condenser and spark plug were used. The result of work proved satisfactory. The problem with the design was that the condenser was not able to cover the fan air space and also, water drops from the condenser after an hour on use.
