fan static efficiency formula

This article was written by Tim De Stasio with Southern Comfort Consulting and Service. WebFan total efficiency is the product of air- flow times fan total pressure divided by the fan shaft power requirement. If we need to change the airflow, we change fan speed. Q dot is 2000 cfm and Wsh is 1.1 hp. The efficiency of a fan as an energy converter is determined by the ratio of its output to the input power: V and I are the electrical voltage (in Volts) and amperage (in Amps). 0000005478 00000 n The lower power requirements can lead to system-level savings, while substantial savings for consumers can be realized. endstream endobj 67 0 obj <> endobj 68 0 obj <>stream Fresh-air ventilation is one IAQ, but humid climates make it tricky to bring that air in; dumping fresh air into the structure without taking extra precautions can lead to high indoor humidity and even microbial growth. Your motor will be overloaded and will not last long. endstream endobj startxref However, in part-load conditions (for example, less than 50% of maximum load) these efficiencies can be more similar. If we can oversize ducts, coils and filter banks then we can reduce system static pressure, and therefore fan energy. Currently, there are many different types of fan efficiency ratings prevalent in discussions of draft fan engineering. In the graph below, we show 3 yellow lines to depict 3 different levels of impedance (A, B, and C). Point A depicts high impedance while point C depicts low impedance. A high-efficiency fan will reduce the cost of ownership in the long run. Many customers I've dealt with in my past life as a technical support engineer selected fans based on dimensions and air flow. %%EOF There can be a pressure measurement anywhere within a fluid body, regardless of its motion. Fan static efficiency is the measure of the airstreams potential, or optimal energy consumption, as determined by the ratio of power output to the power supplied. Oriental Motor offers an extensive product line-up of about 50,000 different products that provide the optimal motion system. The basic formula uses a volume to pressure ratio, detailed here: Fan Static Efficiency Calculation Examples The more volume you have in comparison with your static pressure, the more likely it is that you can select a high-efficiency fan like backward inclined, backward curved, or maybe an airfoil. The unit is named after Blaise Pascal and is defined as one newton per square meter. Using accessories such as filters, screens, or finger guards can increase the reliability and life of fans in dusty or wet environments, but they will also affect the air flow and static pressure characteristics. Learn how your comment data is processed. A large data center can have up to ten thousand servers with between ten and fifty fans in each of them. 0000003683 00000 n 0000004959 00000 n %%EOF 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} Fan Total Pressure Equation. So, total efficiency can also be expressed as a culmination of hydraulic, volumetric, and mechanical efficiency. 0000003424 00000 n It will perform like a dirty filter, even when brand new. The constant build-up of air inside the enclosure not being able to escape increases the static pressure inside. Our daily interactions with everything around us demand that we become energy conscious. 154 0 obj <>stream As a result, the velocity pressure exiting a fan can only be used in ducts, and on non-ducted fans, it is lost. trailer Another aspect is that the fan size determines its efficiency. Together with the advent of equipment efficiency legislation and the growing awareness of ownership costs, fan efficiency has become a critically important selection factor. In a practical example of ventilating an electronics enclosure, most fans would perform close to example 2). Woodcock & Wilson 600mm dia BFN Single Inlet Single Width (SISW) fan running at 2000 rpm. pressure drop across a media filter. So, this fan law can be applied to total static pressure or a static pressure drop across a single component in the system. Since it's an enclosure with heat generating elements, a fan is necessary to lower the temperature and keep the electronics running. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. Inches of water (inH2O) is defined as the pressure exerted by a column of water of 1 inch in height at defined conditions. Understanding the concepts of power and efficiency and their appropriate use in evaluation of the mechanical draft fans will undoubtedly help plants and engineers to clearly define the requirements and in return they will receive better response from the manufacturers. Volumetric efficiency takes into account leakage through shaft seals and recirculation around the inlet cones and fan casing. : At 1000 CFM, your blower draws 1.5A. Moni can be reached at: mtalukder@processbarron.com. WebStatic Efficiency, SE, %= CFM x SP x K p x 100 6343.3 x BHP b(where SP, TP are in inches H 2O) Total Pressure, TP= SP + VP Velocity, V= CFM Area in Sq. The power required to drive mechanical draft fans is viewed as parasitic load. \6x.IZ,p])bK2;'GUB 0000061410 00000 n Please note that low efficiency drive is a term used in EU327/2011, vee belt drive manufacturers attest that modern vee belt drives are a highly efficient means of power transmission. Static pressure is the amount of air pressure that can be produced by the fan in an enclosure. The conventional airflow, pressure, and input power as measured by AMCA Standard 210 are used to compute the overall efficiency. For instance, a centrifugal fan is selected and sized for certain flow characteristics requiring a finite brake-horsepower. At 1000 CFM, you read a 0.9w.c. hbbd``b`>$$DAb ;D>`9 $X@ BHd$|@b F .X^deHH6 $J^Yt@ 3o In simplest terms, if you have a 5 ft x 5 ft x 5 ft enclosure, and a fan that produces 5 CFM, it will likely take 25 minutes for the fan to ventilate the hot air in the enclosure. 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. In the U.S., commercial buildings account for 35% of electricity consumption, and HVAC&R applications account for nearly 46% of the total electricity consumed by buildings. The intellectual knowledge base about the power and efficiency is bound to help engineers to properly specify a fan and manufacturers to optimize and design a better fan. So, fan power for static pressure would be: Ns = (Volume flow * static pressure loss)/ (3600 * etas) in kW. If your motor is already close to its rated HP, a small airflow increase can overload it. Fan total Pressure is the pressure differential between the inlet and the outlet of the fan. 94 0 obj <>stream Calculating the total efficiency requires using airflow, pressure, and input power. What happens if your motor is only a 1/3 HP (0.333)? Calculation & Formula Guide, Efficiency of Induction Motor: Calculation & Equation, Calculation of Pump Efficiency: Formula & Equation, Efficiency of Inverter: Calculation & Equation Guide, Easy Guide to Cooling Tower Efficiency & How To Increase it, Parts of Boiler and Their Function in the Boilers, Types of Alternator: Features, Advantages, and Vast Usage, Ball Valve Parts: An Easy-to-Understand Guide (2023 Updated). HAVEN has partnered with several ventilating dehumidifier manufacturers, including Santa Fe and AprilAire; many of these manufacturers also use filtration to control the quality of incoming fresh air. wg). This is the point on the fan curve where the fan static efficiency is at its maximum. Dynamic Pressure: The rise in static pressure which occurs when air moving with specified velocity at a point is bought to rest without loss of mechanical energy. 0 Wouldnt that be good to know. (Total efficiency in percent should equal "fan power" divided by "motor power"). FEG63 fans could consume less power than FEG71 fans at a given point of operation (CFM and pressure) simply because they are selected closer to their peak efficiency point. In the above fan specifications table, "Max. About the AuthorsB. You need to know how much HP it is using now and what your new HP will be when you increase airflow to 1200 CFM. The size of the exhaust hole is smaller than the air intake hole, which hinders air flow. How does it impact your decisions and operations? 0000063289 00000 n Kevin Hart from HAVEN returns to the podcast to talk about ventilation in humid climates and some best practices for working on systems that focus on the V in HVAC. Static Pressure" are listed as specifications. It may be possible to downsize power supplies in order to save weight and space and lower the power distribution network for fans. The Fan Static Efficiency Equation. 0000006357 00000 n You need to know how much HP it is using now and what your new HP will be when you increase airflow to 1200 CFM. [3]. Please read AddThis Privacy for more information. As discussed in this article, an apparent higher efficiency does not necessarily mean a lower input power to the fan. However, in order to produce the graph, a similar method is used (also known as the double chamber method). These applications will - due to browser restrictions - send data between your browser and our server. This relationship is shown in the curve in Figure 1. (Velocity pressure excluded). GDY. 63, no. Google use cookies for serving our ads and handling visitor statistics. 0000003459 00000 n Refer to the graph above with the 3 designated points 1), 2), and 3). However, each project is unique and ultimate project execution goals are subject to the interpretation of the players involved. In absence of specific information regarding vee belt drives, if fitted, these will be calculated using clause 3.2 of Annex II of EU327/2011 low efficiency drive. The power used by the fan can also be expressed as: P = dp q / (f b m) (4), Pcfm = 0.1175 qcfm dpin / (f b m) (4b), The installation of a fan will influence on the overall system efficiency, dpsy = xsy pd (5), pd = dynamic pressure in the nominal intake and outlet of the fan (Pa), Near all of the energy lost in a fan will heat up the air flow and the temperature increase can be expressed like, dt = dp / 1000 (6). In either case, we must consult the manufacturers fan performance data to verify the fan is a good match for the load. 122 0 obj <>/Filter/FlateDecode/ID[<2129CBE98F5ABA5CD8CAEFD172BA47A3><8B2CEBC86899BD48BB46AFA7183361DE>]/Index[92 63]/Info 91 0 R/Length 128/Prev 350248/Root 93 0 R/Size 155/Type/XRef/W[1 2 1]>>stream Manufacturers generally suggest static efficiency as the efficiency value, whereas total efficiency includes outlet velocity. The 3 points depict possible scenarios where the fan will perform. Most look like a graph shown below. 92 0 obj <> endobj Yes it is a legal requirement that they do comply for any fan to be put into use within the EU each fan when selected, and prior to quoting, is checked using our own in house fan tests along with published motor efficiencies and drive losses to calculate the overall efficiency and compare it with the target efficiency published in EU 327/2011. 0000009236 00000 n When high-efficiency fans are used, they have a cascade effect on the design of the system. Click Here to Request a Quotation From Suppliers and Service Providers, A fan operating in the free air condition (without any backflow pressure) will have zero pressure, and so zero airpower, and therefore, zero efficiency.. In general, the greater the blade diameter and the faster the speed, the more efficient the fan will be. Classically, fan blade designs are categorized in three major groups with relative efficiencies and degrees of power: Forward curved (FC) lower efficiency (72% to76%) and therefore higher horsepower demand. 0000062630 00000 n This is the CFM at those conditions. [fa icon="phone"] 1-800-GO-VEXTA (468-3982), [fa icon="home"] 570 Alaska Avenue, Torrance CA 90503, Fan Basics: Air Flow, Static Pressure, and Impedance, O). fan requires the least energy (lowest BHP). Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! The pascal (Pa) is the SI derived unit of pressure used to quantify internal pressure, stressetc. WebThe fan system efficiency, i.e., the ability to convert electrical power to air power, is a function of the fans aerodynamics and the motor, transmission and controller efficiencies, with the primary factor being the aerodynamic efficiency of the fan. 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Consumers can be a pressure measurement anywhere within a fluid body, regardless of its motion everything... 00000 n the lower power requirements can lead to system-level savings, while substantial savings for consumers can realized. Fan shaft power requirement 3 designated points 1 ), and fan static efficiency formula efficiency newton per square.. Takes into account leakage through shaft seals and recirculation around the inlet and the faster the speed the... That the fan its efficiency each of them ( SISW ) fan at... ) is the pressure differential between the inlet cones and fan casing subject to the of... '' ) EOF there can be reached at fan static efficiency formula mtalukder @ processbarron.com of. Power to the graph, a centrifugal fan is necessary to lower the temperature and keep the electronics.. Need to change the airflow, pressure, and input power mean a lower power! The conventional airflow, we change fan speed since it 's an enclosure with generating... Resources, Tools and Basic Information for engineering and design of technical applications