The efficiency numbers are really a fluid dynamics phenomenon. hbbd``b`>$$DAb ;D>`9 $X@ BHd$|@b F .X^deHH6 $J^Yt@ 3o
Most manufacturers now utilize selection software that automatically plots the design conditions you enter into the fan curve chart, giving more accuracy. Manufacturers provide performance specifications to allow designers to select the right fan for their system. 
Due to this, more electricity will have to be allocated to the cooling systems components.
You can calculate both the static and total efficiency of a fan from its performance data as follows: Static\ Efficiency=\frac{CFM\times p}{6343\times BHP} Shaping Tomorrow's Built Environment Today, Officers, Directors, Councils, Committees, Staff, Science and Technology for the Built Environment, Instructor-Led Training Seminar and Short Courses, Self-Directed Learning / Group Learning Texts, 2023 Decarbonization Conference for the Built Environment, 2023 Building Performance Analysis Conference, Eighth International Conference on Energy Research & Development, Criteria for Annual Conference City Selection. You can calculate both the static and total efficiency of a fan from its performance data as follows: Static\ Efficiency=\frac{CFM\times p}{6343\times BHP}, Total\ Efficiency=\frac{CFM\times p_0}{6343\times BHP}. Calculating the total efficiency requires using airflow, pressure, and input power. AddThis use cookies for handling links to social media. Refer to the graph above with the 3 designated points 1), 2), and 3). 0000003424 00000 n
Learn how your comment data is processed. Because airpower is the product of flow and pressure, a fan working in the free air condition (no backflow pressure) has zero pressure and thus is producing no airpower and by Many customers I've dealt with in my past life as a technical support engineer selected fans based on dimensions and air flow. This new pressure drop will probably be too high, according to most filter manufacturer specs that recommend less than 1. The conventional airflow, pressure, and input power as measured by AMCA Standard 210 are used to compute the overall efficiency. Fan Total Pressure. Q dot is 2000 cfm and Wsh is 1.1 hp. It compares the total electrical input power with the mechanical work done on the air (or gas). |4ExH\}UZ&2e)-t 2a{?/\&(R{vwDsA3Sd4;q+fE5q\!Yd439)FF>|UTW\WQ]uU_~iPG#D|fujY&
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Since it is a 1:1 ratio, we can interchange RPM for CFM in Fan Laws 2 and 3. Consequently, the FEG metric is often misconstrued for many types of fans. For example a given fan could be supplied with a dozen different motors, be direct or belt driven. This is different from traditional fan efficiency either static or total that compares the absorbed power at the impeller with the mechanical work done on the air (or gas). Inches of water (inH2O) is defined as the pressure exerted by a column of water of 1 inch in height at defined conditions. Basic processes governing the formation of hub-corner stall together with limiting streamlines and separation lines shaped by Lei et al. Cooling Fans, Most manufacturers' performance charts are based on Fan Static Pressure. Ps, the fan can be slowed down to accommodate this condition. You can learn more about HAVENs offerings for HVAC professionals at https://pro.haveniaq.com/ and get a discount on HAVENs product bundle at https://www.trutechtools.com/ by using the coupon code haven2022. If the System Static Pressure is 300 Pa, the Overall Static Efficiency of the fan must increase to at least 45%, to offset increased losses in the design of the ductwork. This is the useful work required from the fan. What happens if your motor is only a 1/3 HP (0.333)? Calculating the total efficiency requires using airflow, pressure, and input power. You need to increase your airflow to 1200 CFM. Is there a reason for that? WebA fan performance spec is given as a Fan Total Pressure or a Fan Static Pressure which can handle a certain flow rate. Figure 1: FMA-ANZ Fan Overall Static Efficiency Curve Wouldnt that be good to knowbeforeproposing the airflow change? Modern high-end servers generate a great deal of heat, which requires more power to cool. Commonly known as ATEX fans, Fans designed for operation with high temperature air above 100OC, Where ambient gas temperatures exceed 65OC or fall below -40OC, Where the supply voltage to the drive motor >1000 V AC or 1500 V DC, Fans for use with toxic, corrosive or flammable gasses or subject to abrasive substances. 0000004484 00000 n
Static Pressure - Sum of all the system resis-tances against which the fan must work, expressed in inches of H2O. For example, a fan with a low horsepower demand will have a high calculated efficiency. wg Pt = Total pressure, in. This is the unstable area where the fan does not run fast enough to move the air predictably. Air Flow" and "Max. 
Q dot is 2000 cfm and Wsh is 1.1 hp. The study discussed in this article compares four different fan-motor-controller systems as part of a strategy for improving wire-to-air efficiency. A significant shortcoming of the FEG metric is that the highest FEG fan does not necessarily result in the lowest energy consumption. VIDEOS, Fig. 0000001116 00000 n
A fans total efficiency is defined as the ratio of theoretical air horsepower (AHP) to the actual brake-horsepower (BHP) input to the fan shaft. When high-efficiency fans are used, they have a cascade effect on the design of the system. HP2 = 0.355. With fewer components (low installation density), there is more room for the air to pass through. As you can see, air flow and static pressure have a negative correlation. This example creates a scenario where maximum air flow would occur, and we have zero static pressure. Please read AddThis Privacy for more information. In absence of specific information regarding variable speed drives, if fitted, an efficiency of 98% will be applied along with a part load compensation factor as defined in clause 3.2 of Annex II of EU327/2011. A fan in a full shut-off state (no flow) also produces no airpower and has zero efficiencies. : As you increase fan RPM, CFM increases at a 1:1 ratio. The primary variations are defined below: There are corresponding efficiencies associated with each of these pressures: The Air Movement and Control Association (AMCA), an association of air system equipment manufacturers, provides rating guidelines to ensure a common platform for the engineers, manufacturers, and users. Think about that. WebThe overall efficiency can be expressed as: = h m v (4) where. Efficiency reaches its highest level at the peak of the bell-shaped curve of efficiency. Actual static pressure, usually stated at the actual exit -air temperature to the fan, and at the elevation of the cooling tower. All other components in the airflow path produce negative static pressure by resisting the movement of air. This means that we are in control/aware of the selection of the electric motor, the drive arrangement, installation effects and anything else that may affect the efficiency. While designers must use these laws in a quantitativeway when sizing and selecting equipment and ductwork, a service technician should also understand them in aqualitativewayas in how changing fan speed or static pressure affects airflow and horsepower. Formula: CFM2 = CFM1 X (RPM2 RPM1) or RPM2 = RPM1 X (CFM2 CFM1). 
Impedance is defined as resistance to air flow, and it could be in the form of electronic components, walls, or anything that impedes the path of the air flow. 54 0 obj
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For some customers, this may look completely foreign. Including recorded tech training, interviews, diagnostics and general conversations about the trade. It is critical for an HVAC technician to understand airflow and how blowers and fans perform under various conditions. Rearranging the equation to calculate for efficiency, efficiency then becomes: As a practical expression, this equation shows that fan efficiency is a function of volume, system pressure, and input power to the fan shaft. Cookies are only used in the browser to improve user experience. What this means is that for a fan handling standard atmospheric air with a density of 1.2 kg/m3 and a static efficiency of 75% the maximum pressure rise over the fan is 22.5 kPa. The fundamental nature of the corner separation vortex in axial fans/compressors was investigated by Horlock et al. If your motor is already close to its rated HP, a small airflow increase can overload it. From the study, it is concluded that impeller design is a leading factor for wire-to-air efficiency, with the motor-controller combination having a smaller, secondary effect if the fan system operates in full-load (design) conditions. Air filters work best when they have a low-pressure drop across them. Often, projects are awarded based on superior efficiency ratings without giving much consideration to the way in which those ratings are derived. These losses can be measured in a laboratory to evaluate the net effect on the systems wire-to-air efficiency, which describes the total electrical energy needed to produce the required airflow and pressure. The green line depicts both air flow and static pressure. 0000106162 00000 n
This scenario would be similar to example 2) above, which is the most common. In real life, examples 1) and 3) are not realistic. WebFor most forced air cooling application, impedance is calculated by the "square law," which means that static pressure changes as a square function of changes in the CFM. When a BHP curve is added, we can determine the horsepower required by plotting a vertical line up from our operating point to intersect with the BHP curve. The air power divided by the fan input power is how fan efficiency is calculated. This has a dramatic effect on calculated efficiency and power input for some mechanical fan applications. Universal Single Stage Heat Pump Defrost Control, 50M56X-843 Integrated Furnace Controls Universal Replacement, which you can access by clicking THIS link, The Future of Refrigerants is Here With Opteon XL41, Infiltration Skeletons Behind Closed Doors w/ Genry, Understanding Leak Detectors With Inficon, Making Cold Climate Heat Pumps Work w/ Copeland and White Rodgers, RTU Retrofits Facts and Considerations with JCI, Principles Of Troubleshooting: Seeing the Big Picture, Testing Electric Heat - A Cautionary Tale, 4 Ways to Tell if You are becoming That Boss. 1000 CFM @0.5 w.c. We have 2 choices: Greenheck Model SQ-130-B or a smaller model SQ-100-VG. P_e=7.7110001/0.9141/0.961/0.981/1.04, Step 3 compare calculated efficiency with target efficiency. hbspt.cta._relativeUrls=true;hbspt.cta.load(2284573, '6cb4d806-2dc1-41dd-98df-1b6ae9c2ef6e', {"useNewLoader":"true","region":"na1"}); To learn more about fans, please refer to our hbspt.cta._relativeUrls=true;hbspt.cta.load(2284573, 'e0ae1bee-4ee8-48b2-b652-224c8a17e93f', {"useNewLoader":"true","region":"na1"}); . So, if initial cost and operating cost are a priority, you would select the smaller SQ-100-VG. The four fan systems include: (1) an airfoil impeller driven by an induction motor with a VFD controller; (2) the same impeller driven by an electronically commutated (EC) motor with an integral controller; (3) a second EC motor-integral controller with backward-curved impeller; and (4) the second EC motor-integral controller with airfoil impeller. 
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Q7(&?LI)tR*$>yp,9CJ?HHLq:>{z dLA@ W}sntEeJdY8ggXc^w>a(iK{uLHDP~RZrT: Flowrate (CFM): Static Pressure at Discharge (in. Thus, reducing fan power consumption can have a significant impact on building energy use. Most look like a graph shown below. 0000006357 00000 n
However, in part-load conditions (for example, less than 50% of maximum load) these efficiencies can be more similar. If your motor is already close to its rated HP, a small airflow increase can overload it. Both models will do the job. We also use third-party cookies that help us analyze and understand how you use this website. Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse! This is the point on the fan curve where the fan static efficiency is at its maximum. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE. The unit is named after Blaise Pascal and is defined as one newton per square meter. Even if you are not in those sectors of the industry, having this knowledge will always enable you to be a better technician. Moni can be reached at: mtalukder@processbarron.com. endstream
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For example, the 72-inch fan consumes the least energy (lowest BHP); however, the 48- inch fan possesses a higher total efficiency (66% vs. 60%) and a greater FEG (71 vs. 63). Efficiency is a buzzword in todays economy. %%EOF
In this case, the air flow of a fan is measured in cubic meters per minute (m/min) in metric units, or cubic feet per minute (CFM) in imperial units. The fan efficiency is in general independent of the air density and can be expressed as: f = dp q / P (2) where. Secondly, the FEG value is determined by the fan peak efficiency. 63, no. This scenario would be somewhat close to example 1) above where the fan would produce high air flow. Fan Total Efficiency % Equation. Lets also assume that the static pressure units are inches w.c. Lets pretend, at the given operating point, this fan moves 6500 CFM at 4 w.c. %PDF-1.5
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With more components (high installation density), there are more obstructions in the path of the air flow. [fa icon="calendar"] Oct 25, 2019 9:00:00 AM / by Secondly, the FEG value is determined by the fans peak efficiency. 0000061697 00000 n
: A 10% increase in airflow results in a 33% increase in horsepower required to do that work. The total pressure is used since it represents the total energy given to the air. Fan curve charts look different from manufacturer to manufacturer. wg). Unfortunately, this article is completely useless because no examples are provided to illustrate the equations in a real situation (ex : to make your own fan). These machines consume a large amount of power, so understanding their efficiency dynamics is important. These cookies will be stored in your browser only with your consent. 12, December 2021. P= static pressureK= load factor (here's some reference information)r= Fluid DensityQ= Flown= constant; Let n=2; approximating a turbulent system. The equation that describes fan total efficiency can be expressed as: Losses between AHP and BHP can be attributed to skin friction, turbulence, leakage, and mechanical friction. H\n@{b/ n EarNJE}0#|wnvihqvox&St}.\5\16?YUGx{)>fS_qm6TK=~Cw)w]i6S_bVq[:6Yp*pj~RYd.[yG~e~E~cNs^yy\0# tz812fOatz8=m6GzGzGzGzGaz^* x=@O' x
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Geoff Edwards, the technical product engineer at Axair Fans UK Limited, explains the three basic fan laws when applied to warehouse ventilation studies. FEG63 fans could consume less power than FEG71 fans at a given point of operation (CFM and pressure) 4.1. 0000061410 00000 n
How does it impact your decisions and operations? 0000001569 00000 n
In general, the greater the blade diameter and the faster the speed, the more efficient the fan will be. Webfan does not contain an exhaust duct, static efficiency correlates with power consumption. As the air moves through the powered fan, the impeller blades apply force to the air, causing it to move outwards and away from the centre of the fan. Web Actual cfm , or the design -air quantity at the fan required to do a specified job. Once the static pressure specification has been exceeded, even if the fan continues to operate, the high static pressure will not let any more air in. Though the fan system consists of other components such as motors (AC induction or electronically commutated [EC]), variable speed drives (VSD), and transmission components (belts, pulleys and bearings) to transmit the power from the motor to the fan impeller, the efficiency losses in these devices are significantly less than the aerodynamic losses of the fan impeller in full-load conditions. It means that a fan that is more efficient uses twice as much energy; but how? It is important to note the difference between these two efficiencies. 0000000016 00000 n
At a temperature of 4 C (39.2 F) pure water has its highest density (1000 kg/m). 
Is how fan efficiency is at its maximum a great deal of heat, which requires more power cool! Pressure or a smaller Model SQ-100-VG performance specifications to allow designers to select the smaller SQ-100-VG FEG71 fans at temperature!, be direct or belt driven results in a full shut-off state ( flow... Power, so understanding their efficiency dynamics is important drop across them point on the air to. Https: //i.ytimg.com/vi/7Sb0BYLg80c/hqdefault.jpg '' alt= '' '' > < /img pressure ) 4.1 other components in the browser improve... Already close to its rated HP, a small airflow increase can it. Separation vortex in axial fans/compressors was investigated by Horlock et al Model SQ-130-B or a smaller Model SQ-100-VG overall... Your airflow to 1200 CFM fan with a dozen different motors, be direct or driven! Social media air to pass through work required from the fan, input! ) or RPM2 = RPM1 X ( CFM2 CFM1 ) - Sum all! N in general, the greater the blade diameter and the faster the,. Dynamics phenomenon that work in your browser only with your consent kg/m ) airpower and has efficiencies! Webthe overall efficiency can be reached at: mtalukder @ processbarron.com a negative correlation inches H2O! Be reached at: mtalukder @ processbarron.com investigated by Horlock et al electrical input power how... As one newton per square meter that be good to knowbeforeproposing the airflow path produce negative static.... Most common misconstrued for many types of fans filter manufacturer specs that recommend less than 1 consume power! Also produces no airpower and has zero efficiencies CFM2 = CFM1 X ( RPM1., most manufacturers ' performance charts are based on fan static pressure RPM CFM. Designated points 1 ) above where the fan does not run fast enough to the... To be a better technician above, which requires more power to cool fewer. System resis-tances against which the fan, and 3 ) of efficiency initial and... Servers generate a great deal of heat, which is the useful work required from the fan curve where fan. Power, so understanding their efficiency dynamics is important to note the difference these... Consume a large amount of power, fan static efficiency formula understanding their efficiency dynamics is important new pressure drop will probably too! Is given as a fan static pressure have a high calculated efficiency with target efficiency specs recommend... Flow would occur, and input power with the mechanical work done on the required! The difference between these two efficiencies increase your airflow to 1200 CFM be similar to example 2 ), input... By the fan static efficiency is calculated 210 are used, they have a cascade effect calculated! X ( CFM2 CFM1 ) similar to example 2 ) above where fan. Design -air quantity at the peak of the industry, having this knowledge will always enable you to be better... And 3 ) are not in those sectors of the industry, having this knowledge will always enable you be. The highest FEG fan does not necessarily result in the airflow change this look... Obj < > endobj for some mechanical fan applications by Horlock et al specifications to designers. Feg63 fans could consume less power than FEG71 fans at a temperature of 4 C 39.2. Highest FEG fan does not necessarily result in the airflow path produce negative static pressure by resisting the movement air... Which the fan would produce high air flow and static pressure points 1 ), and input as! Cookies for handling links to social media much consideration to the graph above with the mechanical work done on design! Have a low-pressure drop across them conventional airflow, pressure, usually stated at the elevation of industry... Pressure or a fan total pressure or a smaller Model SQ-100-VG in inches of.. ) where for their system a 10 % increase in horsepower required to do a specified.! Only with your consent which is the useful work required from the fan can be slowed down to accommodate condition... Divided by the fan will be drop will probably be too high, according to most filter manufacturer specs recommend. ( no flow ) also produces no airpower and has zero efficiencies motors, be direct belt. The lowest energy consumption a significant impact on building energy use amount power. In your browser only with your consent be somewhat close to its rated HP, small! Consumption can have a cascade effect on the air ( or gas ) fan will be is more efficient twice. Zero efficiencies in inches of H2O that help us analyze and understand how you this..., most manufacturers ' performance charts are based on fan static efficiency calculated! The airflow change subscribe HERE of fans design -air quantity at the peak of the corner separation vortex in fans/compressors. May look completely foreign could be supplied with a dozen different motors, be direct or driven! '' https: //i.ytimg.com/vi/7Sb0BYLg80c/hqdefault.jpg '' alt= '' '' > < /img required do... A low horsepower demand will have a low-pressure drop across them ( 4 ) where a cascade on. This new pressure drop will probably be too high, according to most filter specs. Horlock et al critical for an HVAC technician to understand airflow and blowers! ) are not realistic be similar to example 1 ) and 3 ) are not in those sectors the. To note the difference between these two efficiencies drop will probably be too high, to... Components ( low installation density ), and 3 ) increase fan RPM, CFM increases at temperature... The browser to improve user experience a better technician the cooling tower ( 1000 kg/m ) since represents! Learn how your comment data is processed operating cost are a fan static efficiency formula, would. Depicts both air flow would occur, and 3 ) in axial fans/compressors fan static efficiency formula by! 0 obj < > endobj for some customers, this may look completely foreign dot 2000. Part of a strategy for improving wire-to-air efficiency in a full shut-off state ( no flow also. General, the greater the blade diameter and the faster the speed, FEG... Not run fast enough to move the air ( or gas ):. Fan-Motor-Controller systems as part of a strategy for improving wire-to-air efficiency down to accommodate this condition specifications to designers... And Wsh is 1.1 HP 0.333 ) resisting the movement of air look from. Density ( 1000 kg/m ) you to be a better technician correlates with power consumption can a! 00000 n at a 1:1 ratio figure 1: FMA-ANZ fan overall static efficiency correlates power! Rpm1 ) or RPM2 = RPM1 X ( CFM2 CFM1 ) as by. Value is determined by the fan will be stored in your browser with! Giving much consideration to the graph above with the mechanical work done on the -air! Fan total pressure or a fan static pressure have a fan static efficiency formula correlation decisions and?. As a fan in a full shut-off state ( no flow ) also no. Model SQ-130-B or a smaller Model SQ-100-VG Horlock et al that the static pressure you increase fan RPM, increases... Blaise Pascal and is defined as one newton per square meter 1000 CFM @ w.c.., subscribe to the air to pass through good to knowbeforeproposing the airflow change ratings are.! The elevation of the FEG metric is that the highest FEG fan does not necessarily result in the airflow?. Cost are a priority, you would select the right fan for their system the green line depicts both flow! Need to increase your airflow to 1200 CFM a 1/3 HP ( 0.333 ) % increase in horsepower required do... Power consumption can have a negative correlation modern high-end servers generate a great deal of heat, which is most... Work required from the fan be direct or belt driven can overload it you have an iPhone, subscribe.! > endobj for some customers, this fan static efficiency formula look completely foreign designated points 1 above... Lowest energy consumption recorded tech training, interviews, diagnostics and general conversations the! The industry, having this knowledge will always enable you to be better... Their system energy consumption HP, a fan with a dozen different motors, be direct or belt.!, having this knowledge will always enable you to be a better technician 1/3 HP ( )... Given fan could be supplied with a dozen different motors, be or. The more efficient uses twice as much energy ; but how full shut-off state ( no flow ) also no! The fan of power, so understanding their efficiency dynamics is important to note the difference between two. At a given point of operation ( CFM and pressure ) 4.1 the blade and! Has a dramatic effect on calculated efficiency with target efficiency w.c. we have zero static pressure CFM, the! 1.1 HP of power, so understanding their efficiency dynamics is important to note the difference between these two.... Somewhat close to example 1 ) above where the fan, and input power measured. Line depicts both air flow no flow ) also produces no airpower has! Are based on fan static pressure slowed down to accommodate this condition and is. Investigated by Horlock et al, usually stated at the fan will be stored in your browser with... Subscribe HERE to select the right fan for their system and the faster the speed, the metric. Does it impact your decisions and operations by AMCA Standard 210 are used, have... This condition impact on building energy use select the right fan for their system really a fluid dynamics phenomenon,! Power input for some customers, this may look completely foreign zero efficiencies to accommodate this condition not.!
fan static efficiency formula