These blowers provide a constant volume of air even if the system pressure varies. Scribd will begin operating the SlideShare business on December 1, 2020 Regular maintenance of fans is important to maintain their performance levels. 3,600 rpm) and are often belt driven to facilitate speed changes. Some of the common blower choices in these ranges may include Regenerative Blowers, Rotary Lobe Positive Displacement Blowers, Multiple Stage Centrifugal Blowers, Rotary Vane Blowers. (Click once) Step 5. Their output and pressure are directly governed by the speed you run them at. The Toro 850 featured what the company called a "super quiet" motor. The air enters the fan wheel through the housing inlet, turns 90 degrees and is accelerated radially and exits the fan housing. A typical fan system consists consist of a fan, an electric motor, a drive system, ducts or piping, flow control devices, and air conditioning equipment (filters, cooling coils, heat exchangers, etc.). The air velocity can be measured with a pitot tube and a manometer, or a flow sensor (differential pressure instrument), or an accurate anemometer. Clipping is a handy way to collect important slides you want to go back to later. In single-stage blower, air does not take many turns, and hence it is more efficient. Understanding this relationship is essential to designing, sourcing, and operating a fan system and is the key to optimum fan selection. Learn more. This action causes a new system performance curve (SC2) where the required pressure is greater for any given air flow. Centrifugal fans increase the speed of an air stream with a rotating impeller. In multi-stage blowers, air is accelerated as it passes through each impeller. Summit Power International, No public clipboards found for this slide, Student at Pydah College of Engineering, Yanam Road, Patavala,Tallarevu (M), Kakinada-533461 (CC-6T). Difficulty in velocity measurement : Actual velocity measurement becomes a difficult task in fan performance assessment. In order to obtain correct operating figures it should be ensured that: Fan and its associated components are operating properly at its rated speed Operations are at stable condition i.e. DC Shunt Motor. There are four basic types: An electric blower is capable of clearing light snow from sidewalks and small driveways. APIdays Paris 2019 - Innovation @ scale, APIs as Digital Factories' New Machi... No public clipboards found for this slide. Types of leaf blowers There are plenty of different types of leaf blowers you will find in the market. If you need a blower with a significantly high pressure and flow, look for a high … 14 Positive displacement lobe blowers are typically use for smaller applications. Possible solutions include, amongst other replacing the fan, replacing the motor, or introducing a variable speed drive motor. DC shunt motor is used … The fan efficiency depends on the type of fan and impeller. See our Privacy Policy and User Agreement for details. Impeller design is the most significant factor for determining performance of a centrifugal pump. 6. introduction to fan and blower, types of fans and blower,various application, performance parameters. They are popular with industry because they are inexpensive, compact and light. Variation of process parameters during test s: If there is a large variation of process parameters measured during test periods, then the performance assessment becomes unreliable. If you continue browsing the site, you agree to the use of cookies on this website. The power of the drive motor (kW) can be measured by a load analyzer. Click here for the different types of snow blowers. \\ The centrifugal blower and the positive displacement blower are two main types of blowers, which are described next. Axial fans are also useful in ventilation applications that require the ability to generate reverse airflow. PSC (Permanent Split Capacitor) A common medium torque single phase motor with a run capacitor always in the circuit. They are especially suitable for applications prone to clogging, since they can produce enough pressure (typically up to 1.25 kg/cm2) to blow clogged materials free. In this figure, the fan’s operating point at “A” is flow (Q1) against pressure (P1). The air-fuel mixture enters the impeller at the center and after passing through the impeller and diffuser vanes goes out of the casing to the engine cylinder. 3.3 Inch Blower | Replaces: Dayton 1TDP7, 4C446, 6FHX8, 4C005 & Fasco A166, 7021-3469 If this is the case, then the velocity pressure can be measured in the center of the duct and corrected by multiplying it with a factor 0.9. One type fits all is not the right answer! The centrifugal blower and the positive displacement blower are two main types of blowers. The fan operates at a point where the system resistance curve and the fan curve intersects. Main Difference in Turbo Blowers • All single-stage centrifugal impellers normally operate in the 10-50,000 rpm range. The fan's actual operating point on this curve will depend on the system resistance. Now the fan’s mechanical and static efficiencies can be calculated using these equations. (Click once) We already discussed the fan performance curve earlier: a graph that shows the different pressures developed by the fan and the corresponding required power. Fan systems are essential to keep manufacturing processes working Fans and blowers are differentiated by the method used to move the air, and by the system pressure they must operate against. If you wish to opt out, please close your SlideShare account. The trainer notes for each slide provide more detailed information, but it is up to the trainer to decide if and how much of this information is presented also. Axial fans move the air stream along the axis of the fan. A sootblower is a device for removing the soot that is deposited on the internal furnace tubes of a boiler during combustion to prevent plugging of the gas passes and maintain boiler efficiency.. Types of soot blowers: Wall Blowers also known as IRs (Insertable Rotating) Long Retractable Soot Blower (LRSB) or IK (Insertable Kinetic) Air Heater Blower. Types of Impellers in Centrifugal Pumps. The result is that the air flow of the fan reduces, and thus the fan efficiency. Positive displacement compressors cab be further divided into Reciprocating and rotary compressors. 5. Clipping is a handy way to collect important slides you want to go back to later. Centrifugal fans or blowers use one of seven types of wheels that are enclosed in a scroll shaped housing. One who speaks out, typically to expose corruption or dangers to the public or environment. Free PPT and PDF Download for COMPRESSOR: Compressors, fans, and blowers are devices which are designed in such a way that they deliver gas at a pressure which is more than the genuinely existing pressure.The features like a rise in pressure, working pressure, mechanical design and specific speed become the basis for the classification and differentiation. In a mixed flow fan the air flows in … Various types of soot blowers such a wall blowers, long retractable blowers and air heater blowers are used for cleaning. See our User Agreement and Privacy Policy. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. The impeller of a centrifugal pump can be of three basic types: Centrifugal blowers look more like centrifugal pumps than fans. • The method for achieving these speeds is the main difference in the various types of high-speed turbo blowers. Types of Blowers: Blowers can also be classified as Centrifugal and Positive displacement blowers. Additional materials that can be used for the training session are available on under “Energy Equipment” and include: Textbook chapter on this energy equipment that forms the basis of this PowerPoint presentation but has more detailed information Quiz – ten multiple choice questions that trainees can answer after the training session Workshop exercise – a practical calculation related to this equipment Option checklist – a list of the most important options to improve energy efficiency of this equipment Company case studies – participants of past courses have given the feedback that they would like to hear about options implemented at companies for each energy equipment. Major types are: centrifugal blower and positive-displacement blower. The manufacturers normally provide these fan performance curves. If your property appears unreasonably big to be carrying a long cord around, you may do well to purchase a gas-powered blower. Steam is normally used as a medium for blowing away the soot. For a given volume of air, the fan in a system with narrow ducts and multiple short radius elbows is going to have to work harder to overcome a greater system resistance than it would in a system with larger ducts and a minimum number of long radius turns. Lathe tools Fan specification data should be collected from the original equipment manufacturer (OEM) and kept on record. Whistleblowing. In existing systems, the system resistance can be measured. Fan efficiency is the ratio between the power transferred to the air stream and the power delivered by the motor to the fan. This characteristic is useful when a space may require contaminated air to be exhausted or fresh air to be supplied. To determine what volume the fan will produce, it is therefore necessary to know the system resistance characteristics. (Click once) Step 3. This system curve can then be plotted on the fan curve to show the fan's actual operating point at "A" where the two curves (N1 and SC1) intersect. The system resistance changes Marginally by the formation of the coatings / erosion of the lining in the ducts Drastically, in some cases, due to the change of equipment, duct modifications Hence, the system resistance has to be periodically checked, more so when modifications are introduced and action taken accordingly to reduce the system resistance, for efficient operation of the fan. Snow blowers were born out of necessity in Canada, where it snows for the most part of the year. You can change your ad preferences anytime. As the flow rate increases, the efficiency increases to certain height (“peak efficiency”) and then decreases with further increasing flow rate. A single-stage blower whirls the auger at a very high speed to cut and throw the snow. Now customize the name of a clipboard to store your clips. There exist two main fan types. You can change your ad preferences anytime. Avoid resonance problems as normal operating speed is maintained Can operate from a no-flow to a full-flow condition without stall problems Disadvantages: Applicable to some axial fan types only Fouling problems if contaminants accumulate in the mechanical actuator that controls the blades Operating at low loads for long periods reduces the power factor and motor efficiency, thus loosing efficiency advantages and risking low power factor charge from the utility, Variable Speed Drive (VSD): reducing the speed of the fan to meet reduced flow requirements Mechanical VSDs: hydraulic clutches, fluid couplings, and adjustable belts and pulleys Electrical VSDs: eddy current clutches, wound-rotor motor controllers, and variable frequency drives (VFDs: change motor’s rotational speed by adjusting electrical frequency of power supplied) (Click once) Advantages: Most improved and efficient flow control Allow fan speed adjustments over a continuous range Disadvantages: Mechanical VSDs have fouling problems Investment costs can be a barrier, Variable frequency drives (VFDs) VFDs are the most commonly used type of electrical VSD used Change motor’s rotational speed by adjusting electrical frequency of power supplied (Click once) Advantages for VFDs specifically: Effective and easy flow control Improve fan operating efficiency over a wide range of operating conditions Can be retrofitted to existing motors Compactness No fouling problems Reduce energy losses and costs by lowering overall system flow, Multiple speed drive (Click once) Advantages Efficient control of flow Suitable if only two fixed speeds are required Disadvantages Need to jump from speed to speed Investment costs can be a barrier, Disc throttle: a sliding throttle that changes the width of the impeller that is exposed to the air stream (Click once) Advantages: Simple design Disadvantages: Feasible in some applications only, Operate fans in parallel: two or more fans in parallel instead of one large one (Click once) Advantages: High efficiencies across wide variations in system demand Redundancy to mitigate the risk of downtime because of failure or unexpected maintenance Two smaller fans are less expensive and offer better performance than one relatively large one Can be equipped with other flow controls to increase flexibility and reliability Disadvantages: Should only be used when the fans can operate in a low resistance almost in a free delivery condition, Operate fans in series: using multiple fans in a push-pull arrangement (Click once) Advantages: Lower average duct pressure Lower noise generation Lower structural and electrical support requirements Suited for systems with long ducts, large pressure drops across system components, or high resistances Disadvantages: Not suited for low resistance systems. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Centrifugal blowers are quiet and reliable and are made to operate in a variety of environments and applications. 1. The system resistance curve and the fan curve were explained earlier. For example, if the speed is increased by 10%, then the air flow also increases by 10% (Click once) When the speed is increased then the pressure SP increases much more, as shown in the graph and formula. In systems that have been designed, but not built, the system resistance must be calculated. PRESENTED Centrifugal blowers use high-speed impellers or blades to impart velocity to air or other gases. Now customize the name of a clipboard to store your clips. Centrifugal fans are categorized by their blade shapes. Scribd is the world's largest social reading and publishing site. (Click once) Speed control with VSDs reduces the flow by reducing the speed and therefore the power consumption. Looks like you’ve clipped this slide to already. Centrifugal blowers typically operate against pressures of 0.35 to 0.70 kg/cm2, but can achieve higher pressures. 2)Positive Displacement Blower:- Provides constant volume of air. The calculated or expected system curve in this figure has higher flow rates for a given flow rate than the actual system curve. Here are some basic definitions and guidelines to consider for selecting the right centrifugal blower for your system's needs. This figure compares the fan curves of fans in series in fans in parallel (Click once) The fan curve of two fans in series starts high but drops rapidly. Axial fans move an air stream along the axis of the fan. There are three main types of blowers; positive displacement lobe, centrifugal and high efficiency. Customer Code: Creating a Company Customers Love, Be A Great Product Leader (Amplify, Oct 2019), Trillion Dollar Coach Book (Bill Campbell). Looks like you’ve clipped this slide to already. As of this date, Scribd will manage your SlideShare account and any content you may have on SlideShare, and Scribd's General Terms of Use and Privacy Policy will apply. In these cases, the percentage of fan loading with respect to flow or pressure can not be estimated satisfactorily. The relationship between the fan speed on one hand, and the air flow, pressure and power requirements is described by fan laws. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The point at which maximum efficiency is obtained is called the peak efficiency or “Best Efficiency Point” (BEP). The main types are corded electric, battery-operated and gasoline powered machines. Types of blades used in centrifugal fans are. A two-stage blower uses an additional auger for throwing snow out of the path. Normally it is closer to the rated capacity of the fan at a particular designed speed and system resistance. In practice certain difficulties have to be faced when assessing the fan and blower performance, some of which are explained below: Non-availability of fan specification data : Fan specification data (see Worksheet 1) are essential to assess the fan performance. ducted HVAC installations Can quickly accelerate to rated speed (because of their low rotating mass) and generate flow in reverse direction, which is useful in many ventilation applications Create sufficient pressure to overcome duct losses and are relatively space efficient, which is useful for exhaust applications Disadvantages: Relatively expensive Moderate airflow noise Relatively low energy efficiency (65%), Vane-axial fan (Figure 13) Advantages: Suited for medium- to high-pressure applications (up to 500 mmWC), such as induced draft service for a boiler exhaust Can quickly accelerate to rated speech (because of their low rotating mass) and generate flow in reverse directions, which is useful in many ventilation applications Suited for direct connection to motor shafts Most energy efficient (up to 85% if equipped with airfoil fans and small clearances) Disadvantages: Relatively expensive compared to propeller fans, Blowers can achieve much higher pressures than fans, as high as 1.20 kg/cm2. The term “system resistance” is used when referring to the static pressure. Improper calibration of the pitot tube, manometer, anemometer & measuring instruments : All instruments and other power measuring instruments should be calibrated correctly to avoid an incorrect assessment of fans and blowers. Therefore a long extension cord is your most likely need to get the range you are looking for, especially if you have a large yard or property. (Click once) The second method to reduce air flow is by reducing the speed from N1 to N2, keeping the damper fully open. If you continue browsing the site, you agree to the use of cookies on this website. High Speed Blowers. A. Centrifugal Fans:- • Rotating impeller increases air velocity. As of this date, Scribd will manage your SlideShare account and any content you may have on SlideShare, and Scribd's General Terms of Use and Privacy Policy will apply. A common problem is that companies purchase oversized fans for their service requirements. Consequently, oversized fans not only cost more to purchase and to operate, they create avoidable system performance problems. It is not intended for … Before the fan efficiency can be calculated, a number of operating parameters must be measured, including air velocity, pressure head, temperature of air stream on the fan side and electrical motor kW input. (Click once) The speed is directly correlated with the air flow. The impeller is typically gear-driven and rotates as fast as 15,000 rpm. TO THE TRAINER This PowerPoint presentation can be used to train people about the basics of fans and blowers. Blowers can be multi- or variable speed units. At a 50% of full air flow, the power consumption has reduced to about 25% of full load power. Types of Compressors: Positive Displacement and Roto-Dynamic Compressors. These are described next. Thus, reducing the fan speed is a much more efficient method to decrease airflow since less power is required. These types are characterized by the path of the airflow through the fan. ... A common device of this type is the gear pump, which consists of a pair of … • Depending on types of flow, fans are categorized as, • Major blower types are, 1)Centrifugal Blower:- Similar to centrifugal fan but can achieve high pressure. Pumps.ppt - Free download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides online. Assessment should not be carried out by applying correction factors to compensate for this. These fans are able to produce high pressures, which makes them suitable for harsh operating conditions, such as systems with high temperatures, moist or dirty air streams, and material handling. For example, let’s compare the use of outlet vanes and speed control (Click once) Outlet vanes reduce the flow of air but not the fan speed, and therefore not the power consumption. Most of the industries do not keep these data systematically or have none of these data available at all. M.TECH (HPE) In single-stage blower, air does not take many turns, and hence it is more efficient. In many applications, air flow and pressure (or vacuum) level requirements may determine what type of blower should be used. This figure shows how some types of flow control are more effective in reducing power consumption than others. The system resistance varies with the square of the volume of air flowing through the system. In other words, the efficiency gain in a High Resistance System is minimal. Learn more. Centrifugal fans are typically used … Generally, all types of machinery are provided with supports for rotating shafts, the supporting device is known as a bearing.In other words, a bearing is a machine element that constrains relative motions and used to reduce the friction between moving parts.. Ramdeobaba College of Engineering & Management ,NAGPUR In other words, the efficiency gain is significant. Positive Displacement Positive displacement blowers have rotors, which "trap" air and push it through housing. In centrifugal blowers, fan affinity laws dictate that a percent reduction in speed will produce a like reduction in flow. Propeller fan (Figure 11) Advantages: Generate high airflow rates at low pressures Not combined with extensive ductwork (because the generate little pressure) Inexpensive because of their simple construction Achieve maximum efficiency, near-free delivery, and are often used in rooftop ventilation applications Can generate flow in reverse direction, which is helpful in ventilation applications Disadvantages: Relative low energy efficiency Comparatively noisy, Tube-axial fan, essentially a propeller fan placed inside a cylinder (Figure 12) Advantages: Higher pressures and better operating efficiencies than propeller fans Suited for medium-pressure, high airflow rate applications, e.g. Such blowers use high speed blades or impellers to impart velocity to air or other gases. They are mostly driven by electric motor. Oversized fans generate excess flow energy, resulting in high airflow noise and increased stress on the fan and the system. In a High Resistance System the operating point is only slightly higher than that of a single fan. Take the duct diameter (or the circumference from which the diameter can be estimated). Centrifugal fans increase the speed of an air stream with a rotating impeller. The power of the airflow is the product of the pressure and the flow, corrected for unit consistency. At a 50% of full air flow, the power consumption is still close to 100% of full load power. However, there are some other types that are good to be aware of. Typically a system resistance curve (see Figure) is generated with for various flow rates on the x-axis and the associated resistance on the y-axis. These machines are offered in a variety of styles, right from handheld units to backpack units as well as wheeled models for heavy duty debris cleaning. In multi-stage blowers, air is accelerated as it passes through each impeller. They turn much slower than centrifugal blowers (e.g. In the figure, if the system resistance is increased then the operating point moves from A to B. This is why fans in series are not suited for low resistance systems (Click once) For fans in parallel we see exactly the opposite. But in a Low Resistance System the operating point of two fans in parallel is relatively high. Read here to know about various types of air compressors used and get a clear inside view of each type of compressor with the attached pictures. Roots air-blower type supercharger. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. This section briefly describes about different types of fans and blowers. Either an electric or a single-stage snow blower can easily clear light to medium snowfalls; it is equipped with an auger which lifts and throws the snow out of the chute. The fan would operate at "C" to provide the same Q2 air flow, but at a lower pressure P3. Nominal Blower Efficiency (percent) The speed increases as the reaches the ends of the blades and is then converted to pressure. But at the operating point in a Low Resistance System, the flow is low and practically the same as that of a single fan. BY They can be single or multi-stage units. For example, if the speed is increased by 10%, then the power requirement increases by 33%. FANS AND BLOWERS. The first step is to calculate the air or gas density using the given equation (Click once) Step 2. The fan will now operate at "B" to provide the reduced air flow Q2 against higher pressure P2. They will not operate at their best efficiency point (BEP) and in extreme cases these fans may operate in an unstable manner because of the point of operation on the fan airflow-pressure curve. The impeller is typically gear-driven and rotates as fast as 15,000 rpm. The use of a “systems approach” in the fan selection process will result in a quieter, more efficient, and more reliable system. The parameter used by ASME to define fans, blowers and compressors is____ a) Fan ration b) Specific ratio c) Blade ratio d) Twist factor 2. a) Propeller b) … If you continue browsing the site, you agree to the use of cookies on this website. This is why fans in parallel are suited for low resistance systems. See our User Agreement and Privacy Policy. The addition of extra amount of air-fuel mixture into the cylinder increases the mean effective pressure of the engine. Fans and Blowers Difference between fans, blowers and compressors Fan types Centrifugal Fan: Types Axial Flow Fan: Types Fan Types and Efficiencies System ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on - id: 3bfc09-MjMwO 5. The calculation of fan efficiency is explained in 5 steps. The system resistance is the sum of static pressure losses in the system. They offer a number of blade orientations such as radial, forward curved and backward curved. See our Privacy Policy and User Agreement for details. Calculate the average air velocity by taking number of velocity pressure readings across the cross-section of the duct using the given equation, where Cp is the pitot tube constant of 0.85 or as given by the manufacturer, and  p is the average differential pressure. Today, you’ll find various snow blowers that differ in style and offer different features. The blower ran only on corded electricity. TheGreen,aswellastheConnersvilleblower,isalmostexact- lylike the Root blower.As is shown in the drawing the impellers of the Green b.lowar are different in design andtwo rollers are This is due to the system resistance. (Point at the peak of one of the curves) The peak efficiency is also called the Best Efficiency Point (BEP) The peak efficiency ranges for different types of centrifugal and axial fans are given in the Table. This type makes up the majority of HVAC motors (condenser fans motors, blower motors compressors) CSCR – (Capacitor Start, Capacitor Run) Which of the following axial fan types is most efficient? An increment in MEP makes the engine produce more power. Power to the compressor/blower is transmitted from engine via the belt drive. Although the fans are typically designed to generate flow in one direction, they can operate in the reverse direction too. There are five main areas for energy conservation for fans which we will discuss on the next slides. (Click once) Step 1. Training Session on Energy Equipment Fans & Blowers Presentation from the “ Energy Efficiency Guide for Industry in Asia” © UNEP 2006 Electrical Equipment Fans & Blowers. Because of this, they are most often used in applications that are not prone to clogging. Two methods can be used to reduce air flow from Q1 to Q2: (Click once) The first method is to restrict the air flow by partially closing a damper in the system. curved blowers are the most common type of air blower because they propel the most air volume in relation to blower size and speed. Filename.ppt The Right Blower? Th… 1. steady temperature, densities, system resistance etc. Centrifugal Fan Blade Types. Need to find the right fit for each project Blower that provides the most efficient system Best value to Owner . The centrifugal blower and the positive displacement blower are two main types of blowers. Fan characteristics can be represented in form of fan curve(s). Centrifugal fans use a rotating impeller to move air first radially outwards by centrifugal action, and then tangentially away from the blade tips. ABHISHEK T MENDHE If you continue browsing the site, you agree to the use of cookies on this website. the operating point, the flow is much higher than that of a single fan. The system resistance has a major role in determining the performance and efficiency of a fan. Next, calculate the volume of air/gas in the duct by using the given formula, Step 4. FAN & BLOWER TYPES There are two primary types of fans: • Centrifugal fans, and • Axial fans. Bearing employs to support, guide and restrain moving the element. The snow blower industry began in 1884 and quickly boomed at the turn of the century. In most cases the location of duct makes it difficult to take measurements and in other cases it becomes impossible to traverse the duct in both directions. A properly designed impeller optimizes flow while minimizing turbulence and maximizing efficiency.. SOOT BLOWERS AND THEIR IMPORTANCE IN POWER PLANT A soot blower is a system for removing the soot that is deposited on the furnace tube of a boiler during Combustion. At the point where the fan curve meets the High Resistance System curve, i.e. For example, a 10% speed increase results in a 21% pressure increase (Click once) When the speed is increased then the power kW increases most, as shown in the graph and formula. Important considerations when selecting a fan are: Noise Rotational speed Air stream characteristics Temperature range Variations in operating conditions Space constraints and system layout Purchase costs, operating costs (determined by efficiency and maintenance), and operating life But as a general rule it is important to know that to effectively improve the performance of fan systems, designers and operators must understand how other system components function as well. Presentedby~LisaA.Wines Definition of Whistle-Blowing One who reveals wrong-doing within an organization to the public or to those in positions of authority. Maintenance activities include: Periodic inspection of all system components Bearing lubrication and replacement Belt tightening and replacement Motor repair or replacement Fan cleaning, Pulley change: reduces the motor / drive pulley size (Click once) Advantages: Permanent speed decrease Real energy reduction ( Explain the figure : a 2 inch reduction in pulley, from 8 inch to 6 inch, results in 12 kW savings) Disadvantages: Fan must be able to handle capacity change Fan must be driven by V-belt system or motor, Dampers: reduce the amount of flow and increases the upstream pressure, which reduces fan output (Click once) Advantages: Inexpensive Easy to install Disadvantages: Provide a limited amount of adjustment Reduce the flow but not the energy consumption Higher operating and maintenance costs, Inlet Guide vanes: Inlet guide vanes: create swirls in the fan direction thereby lessening the angle between incoming air and fan blades, and thus lowering fan load, pressure and airflow (Click once) Advantages: Improve fan efficiency because both fan load and delivered airflow are reduced Cost effective at airflows between 80-100% of full flow Disadvantages: Less efficient at airflows lower than 80% of full flow, Variable-pitch fans Change the angle between incoming airflow and the blade by tilting the fan blades, thereby reducing both the motor load and airflow (Click once) Advantages: Can keep fan efficiency high over a range of operating conditions. Filename.ppt Typical Blower Efficiencies . The “systems approach” requires knowing the interaction between fans, the equipment that supports fan operation, and the components that are served by fans. They are also used to produce negative pressures for industrial vacuum systems. about Fan Blades and Blowers details are there. Gardner Denver’s IQ blower package is perfect for these small or medium applications. Chapter 3.5: Fans and Blowers Part – I: Objective type questions and answers 1. Straight steel plate paddle wheel; Forward multi-vane multi-blade; Backward turbo-vane; The different blades can be characterized as shown in the capacity diagram below: Mixed flow fans. Scribd will begin operating the SlideShare business on December 1, 2020 This kW multiplied by motor efficiency gives the shaft power to the fan. The way these fans work can be compared to a propeller on an airplane: the fan blades generate an aerodynamic lift that pressurizes the air. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. Different types of snow blower Electric and Single-stage blowers. Backward-Inclined and Backward-Curved Air Blowers A backward-inclined blower, operating at roughly twice the speed of a forward-curved air blower, has flat blades that slant away from the direction of travel. The motor is a 12-amp, 120 volt design. It is earlier described that the fan efficiency increases as the flow increases to certain point and thereafter it decreases. Centrifugal blowers look more like centrifugal pumps than fans. Deviation from the BEP will result in increased loss and inefficiency. Axial fans are frequently used in exhaust applications where airborne particulate size is small, such as dust streams, smoke, and steam. One characteristic is that airflow tends to drop drastically as system pressure increases, which can be a disadvantage in material conveying systems that depend on a steady air volume. Like fans, blowers use blades in various designs such as backward curved, forward curved and radial. The fan curve of two fans in parallel does not start high but drops much slower. Blower Type . Radial fans, with flat blades Advantages: Suitable for high static pressures (up to 1400 mmWC) and high temperatures Simple design allows custom build units for special applications Can operate at low air flows without vibration problems High durability Efficiencies up to 75% Have large running clearances, which is useful for airborne-solids (dust, wood chips and metal scraps) handling services Disadvantages: Only suitable for low-medium airflow rates, Forward curved fans, with forward curved blades Advantages: Can move large air volumes against relatively low pressure Relative small size Low noise level (due to low speed) and well suited for residential heating, ventilation, and air conditioning (HVAC) applications Disadvantages: Only suitable for clean service applications but not for high pressure and harsh services Fan output is difficult to adjust accurately Driver must be selected carefully to avoid motor overload because power curve increases steadily with airflow Relatively low energy efficiency (55-65%), Backward inclined fan, with blades that tilt away from the direction of rotation: flat, curved, and airfoil Advantages: Can operate with changing static pressure (as this does not overload the motor) Suitable when system behavior at high air flow is uncertain Suitable for forced-draft services Flat bladed fans are more robust Curved blades fans are more efficient (exceeding 85%) Thin air-foil blades fans are most efficient Disadvantages: Not suitable for dirty air streams (as fan shape promotes accumulation of dust) Airfoil blades fans are less stable because of staff as they rely on the lift created by each blade Thin airfoil blades fans subject to erosion. These are described next. Centrifugal Type Supercharger. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. More than 200 examples are available from 44 companies in the cement, steel, chemicals, ceramics and pulp & paper sectors, We will first explain the fan components and go through some important theory about system and fan characteristics, Most manufacturing plants use fans and blowers for ventilation and for industrial processes that need an air flow. If you wish to opt out, please close your SlideShare account. The system resistance is a function of the configuration of ducts, pickups, elbows and the pressure drops across equipment, for example bag filter or cyclone. It has medium starting torque and a nearly constant speed. The fan curve is a performance curve for the particular fan under a specific set of conditions, usually including: fan volume, system static pressure, fan speed, and brake horsepower required to drive the fan under the stated conditions. Like fans, centrifugal blowers offer a number of blade orientations, including backward curved, forward curved, and radial. One who discloses information about misconduct in their workplace that they feel violates the law or endangers the welfare of others. It consists of an impeller which rotates at a very high speed, about 10,000 r.p.m. Centrifugal fans used a rotating impeller to move the air stream. • Air speed is converted to pressure. The information on the slides is the minimum information that should be explained. In this way, adding a compressor to the engine makes it more efficient. Centrifugal fans used a rotating impeller to move the air stream. Axial fans move the air stream along the axis of the fan.

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