Part-load is a term used to describe the actual load served by the motor as compared to the rated full-load capability of the motor. Definition. As the fan total pressure, FTP, reflects the full increase in mechanical energy imparted by the fan, Motor efficiency taken at full load. Use of diffusers Case study, final overview with cost c A No. Fan 1 not performing to specification. efficient replacement, you need to determine operating hours, efficiency improvement values, and load. See the “References” section for a starting point. (in.) Generally, efficiency increases and fan size decreases as specific speed increases. fan and represented by the velocity pressure at outlet has, traditionally, been assumed to be a loss of useful energy. Method 1 - Exhaust steam is dry & saturated or superheated. ) Optimize efficiency of the fan system, including the fan, drive, motor, and variable speed drive (i.e. As shown in Figure 1, each FEG band contains a range of fan diameters and their corresponding efficiencies. often used in the calculation of sound pressure levels. Accordingly, we will only reiterate the major equations and concepts here. It is important to remember that electronic humidity meters . Water): Static Fan Efficiency (%): Brake Horsepower (HP): Air Density: … 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. The first thing to consider is what will be moving through the blades. The present regulatory values vary typically between 2 and 3 kW/m3s. Motor part-loads may be estimated through using input power, amperage, or speed measurements. • Fan not pulling full Amps • Fan performance 80% of design • Fan sounded like it was hunting eg in stall • Initial diagnoses was uneven air on conditions due to transition pieces • Damper in front of fans disruption air flow on to blades • Fan selection is ultimately more important than peak efficiency in determining fan power consumed. BASIC FAN LAWS Existing Flowrate (CFM): Existing Static Pressure (in. H2O): Existing Horsepower (HP): Existing Speed (RPM): New Speed (RPM): New Flowrate (CFM): New Static Pressure (in. x number of fans motor efficiency actual power Bhp x watts Bhp ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ EQ-6 2. 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. To check and assess the SFP should be easy and clear also for the building owner, the end user, the inspectors etc. 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. Even with a reduced motor efficiency of 77.8% and drive efficiency of 86%, with adjust-able speed operation the power required by the fan and the VFD is only 2.8 kW. Ambient temperature T a = in grad K Fan output: Stagnation temperature/ambient temperature T 0f /T a = Stagnation pressure/ambient pressure p 0f /p a = Fan nozzle exhaust velocity u ef = m/s 64.7 > 61.43. As SP is increased, HP increases and CFM decreases. 12 ()() BL C D d Dd C =+ ×++ − 2157 4 2. Fin Efficiency and Fin Resistance The general concept of fin efficiency and fin resistance was developed in Chapter 1. New fan-efficiency metrics developed by AMCA International—fan energy index (FEI) and fan electrical power (FEP)—can be used to right-size fans and reduce power consumption in commercial and industrial air systems. With small changes it suffices to take into account all significant energy flows and embodied energy with average primary energy co-efficients. Larger Fans vs. Configurations to Improve Fan System Efficiency 8. 12 Circ in Ts FPM RPM. Basic calculations (manually or by Steam Flex). See Figure 1 for typical units used for the calculations. Seasonal Energy Efficiency Ratio (SEER) The Seasonal Energy Efficiency Ratio is similar to the EER in that its purpose is to represent the efficiency of the unit while in the cooling mode. Calculating energy efficiency potential is dependent on the scale and timeframe of the analysis. Fan Curves Source: ASHRAE Handbook. Fan adiabatic efficiency η f = Fan nozzle adiabatic efficiency η fn = Gas constant (fan nozzle) R f = in J/(Kg K). VSD power Taken as motor full load power ie P ed = 11 Kw • FEI will encourage more efficient fan designs, use of more efficient motors, and direct drives. (min.) It is a measure of the electric power that is needed to drive a fan (or collection of fans), relative to the amount of air that is circulated through the fan(s). As the overall efficiency is > than target efficiency fan is compliant. Max. 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. = ×12 RPM Ts FPM Circ in = ()×. Notes. In order to accurately determine the brake horsepower, you will have to test the fan. FEI addresses a longstanding problem in characterizing fan efficiency, which is that a fan’s peak efficiency often has little relationship to a fan’s actual operat-ing efficiency. Fan calculations: Static fan efficiency: FanBHP CFM SP SE = × 6356× FanTipSpeedFPM RPM Circ in =×. Fan Performance and Selection References Burmeister, L.C., Elements of Thermal-Fluid System Design, ... • Choose a fan that has its peak efficiency at or near your operating point. For a fan discharging directly to atmosphere this is, indeed, the case. At half its rated operating speed, the fan delivers 50% of its rated airflow but requires only 1/8 full-load power. Fan and Pad Greenhouse Evaporative Cooling Systems 2 frequently drift out of calibration and should be checked against standards on a regular basis. • Sometimes will provide data in a table rather than in a graph. Specific Fan Power (SFP) is a parameter that quantifies the energy-efficiency of fan air movement systems. Figure 1: Fan-efficiency grades (FEG) defined by AMCA Standard 205. hp to an exhaust fan when operated at its full rated speed. The new FEG metric is a dimensionless index calculated based on fanrating - test data. However, there are two major differences between them. Step 3 compare calculated efficiency with target efficiency. Fan noise 7/12/2000 11.3 Noise Comparison For lowest noise output, fans should always be operated near their peak efficiency point. (For dry air it is around 287.) Outside diameter of fan, duct or transition. minimize total ‘wire-air’ -to losses). O.D. ( .) • Existing fan efficiency metrics are not suitable for ensuring energy savings. This figure can be used to determine the most efficient size and type of fan for a particular application. C = Distance between shaft centers (in.) calculate wet bulb temperature based on the dry bulb temperature and relative humidity. Drive loss is based on full load motor power (11 kW) ie P a = 11 kW. It is not constant for a given fan, but changes with both air flow rate and fan pressure rise. Industrial Fan Types, Blade Profiles, and Particulates. Increased turbulence and tolerance magnification result in smaller fans operating at a reduced Figure 1. Fan Drive Options 10. Oversizing must be avoided, since fan efficiency can decrease significantly if the combination of airflow and pressure rise is not near the combinations giving peak efficiency. (in.) D = Fan sheave dia. Go to Figure 1, page 12 for the descriptions of the various symbols used. PDF | This paper deals with the analysis of jet fan efficiency in road tunnels. Software packages are also available to calculate wet bulb temperatures. These fans have good efficiency near free air delivery and are used primarily in low static pressure, high volume applications. Static Fan Efficiency = Volume (m3/s) * Pressure gain (Pa) / Power input (W) * 100. Once you know those variables, you can make the fan static efficiency calculation to select the right fan. ( .) Multiple-Fan Arrangements 11. For this Smaller Fans. Clean air allows both for the most choices and the most efficient fans. SPECIFIC FAN POWER – a tool for better performance of air handling systems ... calculation, and measuring guidance for installers. 12.8 Ventilation and Air Flow Related Calculations 241 12.9 Combined Thermal and Ventilation Models 246 References 249 Appendix 1 251 Air Leakage Characteristics of Building Components 251 Appendix 2 257 Wind Pressure Coefficient Data 257 Appendix 3 261 AIDA – Air Infiltration Development Algorithm 261 Index 267. H2O): New Horsepower (HP): FAN APPLICATION FORMULAS Fan Brake Horsepower: Flowrate (CFM): Static Pressure at Discharge (in. Stay tuned to be able to search FEI rated fans and use our FEI calculation … Motor Efficiency, Selection, and Management A Guidebook for Industrial Efficiency Programs In the fiercely competitive global marketplace, minimizing operational costs can mean the difference ME Mechanical efficiency (or Total efficiency). can’t we use the simple fan efficiency calculation, rather than something more complicated like FEG? Let’s look at the impact of fan diameter on efficiency. Controlling Fans with Variable Loads 9. Propeller Fan (Axial Fan)—An air moving device in which the air flow is parallel or axial to the shaft on which the propeller is mounted. A profitability calculation should also be made. Mechanical efficiency uses total pressure, which includes the kinetic energy, to calculate the efficiency. Note the efficiency and/or power can also be calculated manually using a steam Mollier chart and steam tables such as Keenan and Keyes. Impulse Turbine Efficiency Calculation Methods with Organic Rankine Cycle Johan E. Dahlqvist Approved 2012-10-16 Examiner Damian Vogt Supervisor Jens Fridh Commissioner Contact person 1 Abstract A turbine was investigated by various methods of calculating its efficiency. • Fan efficiency is highly sensitive to actual operating conditions • Peak fan efficiency for a given model varies little across diameters FEG used in ASHRAE 90.1 has this characteristic Peak fan efficiency for a given model varies slightly with fan speed. He explains the reasons for the need of high-efficiency fans, regulated through international standards like ISO 12759 or the Minimum Energy Performance Standards (MEPS) and In From The Cold Strategy locally in Australia. ptF = fan total pressure, Pa 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. 9 Generalized Fan Curves • These kinds of curves can be used to help choose a fan. Definitions of Fan Power and Fan Efficiency for buildings Simon talks about Fan Efficiency , Fan Input Power and regulations that are associated with this. FanRPM MotorRPM d D =× MotorRPM FanRPM D d =× BL = Belt Length (in.) Mechanical efficiency is a ratio of the total fan power out- put to the power supplied to the fan. d = Motor Sheave dia. AMCA Standard 208-18) for calculating a new metric for fan efficiency: the fan energy index (FEI). ( .) Other Fan Efficiency Options Other Fan Efficiency Options There are numerous other ventilation fan up-grade opportunities to improve efficiency. Bibliography ASHRAE. 10 AIVC Guide to Ventilation.

fan efficiency calculation pdf

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