Volume is the quantity or velocity of air, gas, and/or other materials moving through the fan as measured in cubic feet per minute (CFM). As explained by Ted ,I am only showing you an example for calculation in both the units and I hope you doubt will be clear. Static efficiency is the product of the volume and pressure you need in your application divided by the product of the conversion constant and horsepower, as follows: You can use the maximum static efficiency to determine the horsepower you need in your application. Static efficiency is a ratio of the fan power output to the power supplied to the fan. by time will give you the power. In Sweden, ECiS AB (Energy Concept in Sweden) performed performance measurements of 767 fans in existing HVAC systems between the years 2005 and 2009. Static efficiency is efficiency in terms of the refinement of existing products, processes or capabilities. FEG . so 102 value comes in numerator instead of denomenator. Founders’ Message: Quality of Work, Quality of Life, Stainless Steel Fan for Protein Rendering. This figure can be used to determine the most efficient size and type of fan for a particular application. Horsepower is the measurement of energy in units of power. wg Pt = Total pressure, in. Generally, efficiency increases and fan size decreases as specific speed increases. 12 issues of the leading cement industry magazine, your choice of complimentary handbook, plus unlimited access to CemNet.com News, Articles and HD Videos. The fan is designed to produce a pressure difference, and hence force, to cause a flow through the fan.Factors which determine the performance of the fan include the number and shape of the blades. 1. Optimum fan efficiency 21 Witt&Sohn AG Oct-14 c. Use of diffusers Case study, fan selection for static pressure C: fan with diffuser Large distance to STALL Fan is operated at optimum efficiency Recommended selection 22 Witt&Sohn AG Oct-14 Optimum fan efficiency. re FAN EFFICIENCY FORMULA DERIVATION. 8.30 . Draft fan engineers are most familiar with this formula and use it frequently to rate a fan. Housed Centrifugal . Fig 2shows the pressures through a fan, each of which is described below: Inlet Pressure; is the static pressure on the inlet side of the fan. How does it impact your decisions and operations? Achieving static efficiency may not be consistent with achieving dynamic efficiency. Air Flow must be in m3/s, Pressure must be in Pascals, and … The fan shaft passes through the core shaft for mechanical reasons. Join the community and register for a free guest account to post a reply. On the contrary, dynamic efficiency takes into account the development of new products, processes, and capabilities. Fans use approximately 40% of all electricity in HVAC systems. In the same application, if you selected a less efficient fan with only 50% static efficiency, the calculation would indicate 63 HP, so you’d have to bump all the way up to a 75 HP motor to drive it. For example, if you have an industrial fan that can achieve 80% static efficiency and you’re trying to move 20,000 CFM through 10 inches WG of resistance, a 40 horsepower motor would get the job done. Technical; Useful Formulas; Useful Formulas. Fans and Blowers Bureau of Energy Efficiency Figure 5.1 Centrifugal Fan Figure 5.2 Axial Fan Centrifugal Fan: Types The major types of centrifugal fan are: radial, forward curved and backward curved (see Figure 5.3). P AHP = q dp inWG SG / 6356 (1). Controlling Fans with Variable Loads 9. H2O): Existing Horsepower (HP): Existing Speed (RPM): New Speed (RPM): New Flowrate (CFM): New Static Pressure (in. of Our most efficient wheel, a backward-curved fan, can achieve 77-80 percent static efficiency. 1m³/s = 3600m³/h. use the fan static efficiency calculation to determine what type of industrial fan is optimal for your application, connect with one of our application engineers, Industrial Fan Types and the Fan Static Efficiency Calculation, Choosing the Right Motor Speed for Your Industrial Fan. W.G). Total Pressure Versus Static Pressure. efficiency of the fan or the static efficiency of the fan. It is a measure of the total mechanical energy added to the air by the fan. Understanding Fan Static Efficiency Fan manufacturers typically provide static efficiency as the value of efficiency, while total efficiency includes the outlet velocity term. 6.8 13.4 6.87 . When calculating this, you will be able to determine the power that a fan requires theoretically, but you must be aware that the actual power that the fan requires (called brake horsepower) will always be greater than what you calculated simply because no fan can achieve perfect efficiency. Fan Drive Options 10. Both the formulas are used in SI units and in general the work done theory the amount of air handle by a fan against a pressure is called work done and dividing workdone Why Fan Static Efficiency Matters. The fan efficiency is the ratio between power transferred to airflow and the power used by the fan. This peak total efficiency is used to determine the FEG value. 67 . The average total efficiency of all the fans was only 33% (Figure 1). If the diameter does not change the fans must be geometrically similar. ASHRAE Rocky Mountain Chapter “Things are not always as they seem; the first appearance deceives many.” - Phaedrus (Roman Poet) ASHRAE Rocky Mountain Chapter . Above and below the optimum range of operation the flow across the fan becomes noisier and the efficiency of the fan system decreases. This type of arrangement is called a two spool engine; one "spool" for the fan, one "spool" for the core. 1.7 . Brake Horse Power - BHP. You can include thi… It allows you to determine how much horsepower you need to achieve maximum static efficiency in your application based on volume, pressure. Static efficiency uses static pressure, which does not include the kinetic energy, to calculate the effi- ciency. The best forecast is that the target static efficiency for non-ducted fans will be 62% at the fan shaft, and the target total efficiency for ducted fans will be 68% at the fan shaft. Fan performance is often represented in the form of fan curves. ie. WG). Existing Static Pressure (in. Next Page >> ATEX Fans >> Conversion Factors. You can use the maximum static efficiency to determine the horsepower you need in your application. wg BHP = Fan power input, hp . FANS AND BLOWERS Bureau of Energy Efficiency 87 6.1 Introduction This section describes the method of testing a fan installed on site in order to determine the performance of the fan in conjunction with the system to which it is connected. Static pressure indicates how much resistance the airflow needs to move through as measured in inches of water gauge (in. FLOW RATE 1 m3/s 1 m3/hr x 2118.9 x 0.58858 2118.9 CFM 0.5884 CFM VELOCITY 1 m/s x 32.8083 x 196.85 32.8083 ft / s 196.85 FPM PRESSURE 1 N/m2 x 0.00402264 x 0.00029530 … For example, if you have an industrial fan that can achieve 80% static efficiency and you’re trying to move 20,000 CFM through 10 inches WG of resistance, a 40 horsepower motor would get the job done. Fan total efficiency is calculated using total pressure. 3.8 . Fan total pressure is the total pressure (static pressure plus velocity pressure) at the fan outlet minus the total pressure at the fan inlet. Fan efficiency metrics tend to be defined in terms of total pressure. pressure differential, respectively) effectively raise the power input allowed at lower flows and pressures. Multiple-Fan Arrangements 11. ‘fan static pressure’ (p sf) has been used to determine fan gas power in the efficiency equation for fan static efficiency; and (b) ‘fan total pressure’ (p f) has been used to determine fan gas power in the efficiency equation for total efficiency. In the same application, if you selected a … FORMULA EQUIVALENT FPS UNITS LENGTH 1 m x 3.2802 3.2802 ft MASS 1 kg x 2.2046 2.2046 lbs TEMPERATURE 0o C 1.8 x oC +32 32o F FORCE 1 N x 0.22481 0.22481 lbs. Fan static and total efficiency (Figure 1) can be plotted along with the fan pressure curves. FEG Curve :Pressure Vs Airflow – Total Fan Efficiency. 6.1 . CAN ANYBODY SHARE THE HOW TO DERIVE FAN EFFICIENCY FORMULA. Radial fans are industrial workhorses because of their high static … The curves are based on a specific set of conditions which typically include speed, volume, efficiency, static pressure and power required to drive the fan at the given set of conditions. Despite all the textbooks and handbooks, which describe the proper procedure for selection of fans, practice shows that fans in existing HVAC systems have very low total efficiency. ANSI/ASHRAE/IES 90.1-2013 requires fans have a fan-efficiency grade (FEG), as defined in AMCA 205, Energy Efficiency Classification for Fans, of 67 or higher. Where: CFM = Fan flow rate, ft3/min Ps = Static pressure, in. You can also use the fan static efficiency calculation to determine what type of industrial fan is optimal for your application. Using the formula given by Ted as Watt = m3/sec x pressure (pa). It indicates how much energy the motor will provide and how much energy the fan will consume given application-specific factors. Brake horse power - the actual power a fan requires … Static Efficiency - Fan efficiency based on static pressure and fan brake horsepower at the same density. It can be found by multiplying the Mechanical efficiency by the ratio of the fan static pres-sure to the fan total pressure. The fan efficiency is in general independent of the air density and can be expressed as: μ f = dp q / P (2) where. The factor of 102 is used to convert mmWC into pascals because the formula for the static fan efficiency in SI units is;-Static Fan Efficiency = Volume (m3/s) * Pressure gain (Pa) / Power input (W) * 100. Fig 2: FEG Curve. Note that the flow and pressure constants in the FEP formula (250 cfm and 0.4-in. When you’re ready to start your project or update your maintenance program, reach out, and connect with one of our application engineers to discuss the details of your project. Figure 8. 7.11 BHP 90 . The flow is axial at entry and exit. Example of the way an array of measurements ... formula team ... of fan and radiator that will achieve appropriate cooling. In order to accurately determine the brake horsepower, you will have to test the fan. Assuming 100% efficiency AHP is the power required to move a given air volume against a given pressure. Air Horse Power - AHP. 56 . (Velocity pressure excluded). Diagram of a pitot-static tube in a duct with air flow..... 18 Figure 9. An axial fan is a type of fan that causes gas to flow through it in an axial direction, parallel to the shaft about which the blades rotate. 1 cfm = 1.7m³/h. Some advanced engines have additional spools for sections of the compressor which provides for even higher compressor efficiency. At this point the ratio of the output power of the fan (Volume flow (m 3 /s) x Static Pressure development (Pa) and the electrical power input (W) is at its greatest and the sound pressure being produced by the fan will be at its quietest. Because it is based only on a fan’s impeller diameter and a single point of operation at peak total efficiency, FEG alone fails to provide a true indication of a fan’s actual power consumption. 60” 49” 54” 54” 54” Impeller Dia . The factor of 102 is used to convert mmWC into pascals because the formula for the static fan efficiency in SI units is;-, Static Fan Efficiency =  Volume (m3/s) * Pressure gain (Pa) /  Power input (W) * 100, But, if the pressure is measured in mmWC instead of Pascals and Power is expressed in kW, the formula can be derived as follows;-, Therefore 1Pa = 1/9.81 = 0.102 mmWC  (or, divide mmWC by 0.102 to get Pa), So, Static Fan Efficiency =  [Volume (m3/s) * Pressure gain (mmWC) / 0.102] /  [Power input (kW) * 1000] * 100, or  Static Fan Efficiency = [Volume (m3/s) * Pressure gain (mmWC)]  /  [Power input (kW) * 1000 * 0.102] *100, or  Static Fan Efficiency = [Volume (m3/s) * Pressure gain (mmWC)] *100 /  [Power input (kW) * 102], efficiency = m3/s X 0.102 mmwc *100/( motor kw x motoe eff.). Fig 1: FEG Formula . They are most useful for determining the impact of extrapolating from a known fan performance to a desired performance. 4.4 . For more information on fan static efficiency, check out these additional articles: We welcome comments and questions via our LinkedIn Page, and you can always Contact Us or Request a Quote for more details. This is the useful work required from the fan. AHP can be expressed as. psF = fan static pressure, Pa pdF = fan dynamic/velocity pressure, Pa pd = system dynamic/velocity pressure, Pa V = velocity of air, m/sec PWL = sound power level Formulae 1 to 4 can be applied to any fan provided the diameter does not change. For a given point of operation (CFM and pressure) an FEG63 fan could consume less power than an FEG75 fan simply because it is selected closer to its peak efficiency point. Page (7) ‘Static efficiency’ means the energy efficiency of a fan, based upon measurement of the ‘fan static pressure’ (p sf). Second, as communicated earlier, the FEG value is based on the peak efficiency of the fan. 1 mmWG = 9.81Pascals Notice that the 72-inch fan has the highest static efficiency which is the proper metric for nonducted applications. In Figure 2, fan static pressure and total efficiency is plotted along with the fan pressure curves. I TRIED A LOT BUT HOW 102 IS COMING IN DENOMINATOR ? 1litre/s = 3.6m³/h. efficiency = m3/s X 0.102 mmwc *100/( motor kw x motoe eff.) Positive static pressure is created as a fan moves air through a system. Using the formula, you’ll find that this fan will require about 19.7 horsepower, indicating a 20 horsepower motor, to reach the full performance potential of the volume to static pressure ratio. Using the formula given in books using mmH2O as pressure, Kw = (m3/sec x Pressure mmH2O)  /102  = 16 x 500 /102 = 78.4 Kw, 2. 1.0 $ Cost . Only a minor share of the fans had … Use of diffusers Case study, final overview with cost c A No. WG. 90 . The higher the volume relative to static pressure, the more likely it is that you can select a high-efficiency fan. Fan static efficiency is the measure of the airstream’s potential, or optimal energy consumption, as determined by the ratio of power output to the power supplied. Industrial Fans or Packers Fans: Which are Louder? The peak total efficiency occurs at the top of the “bell” shaped efficiency curve. 75 . Fan BHP = (cfm x static press "w.c.) / (6356 x fan efficiency) Fam Motor HP = fan bhp / motor efficiency Following are values from a propeller fan manufacturer's catalog for a particular fan: Static press. Water): Static Fan Efficiency (%): Brake Horsepower (HP): Air Density: Barometric Pressure (in Hg): Temperature … The conversion constant for static efficiency is 6343. P AHP = Air Horse Power (hp). Know the answer to this question? You are getting confusions for change in unit from mmH2O to Pascal. This equation can also be used for calculating hydrodynamic horsepower in a ducted flow. H2O): New Horsepower (HP): FAN APPLICATION FORMULAS Fan Brake Horsepower: Flowrate (CFM): Static Pressure at Discharge (in. Static efficiency is calculated using only static pressure. In both the cases the power is same , I dont think there is any confusions now. A test section that has the capability of interfacing with both the wind tunnel in the Thermal Science Lab and a radiator will be used to facilitate the necessary experiments. Static Pressure - Sum of all the system resis-tances against which the fan must work, expressed in inches of H2O. This should also include the velocity pressure on the inlet side (if known) that is constant and in-line with the fan. The fan efficiency formula is in SI units. where . But, if the pressure is measured in mmWC instead of Pascals and Power is expressed in kW, the formula can be derived as follows;- 1 mmWC = 9.81Pa. 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