ME Mechanical efficiency (or Total efficiency). Let’s look at the impact of fan diameter on efficiency. C = Distance between shaft centers (in.) Software packages are also available to calculate wet bulb temperatures. Mechanical efficiency uses total pressure, which includes the kinetic energy, to calculate the efficiency. It is not constant for a given fan, but changes with both air flow rate and fan pressure rise. These fans have good efﬁciency near free air delivery and are used primarily in low static pressure, high volume applications. Fan adiabatic efficiency η f = Fan nozzle adiabatic efficiency η fn = Gas constant (fan nozzle) R f = in J/(Kg K). Multiple-Fan Arrangements 11. (min.) efficient replacement, you need to determine operating hours, efficiency improvement values, and load. 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. Increased turbulence and tolerance magnification result in smaller fans operating at a reduced Figure 1. The present regulatory values vary typically between 2 and 3 kW/m3s. 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. Mechanical efficiency is a ratio of the total fan power out- put to the power supplied to the fan. 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. ) Optimize efficiency of the fan system, including the fan, drive, motor, and variable speed drive (i.e. The new FEG metric is a dimensionless index calculated based on fanrating - test data. 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. For this It is important to remember that electronic humidity meters . minimize total ‘wire-air’ -to losses). BASIC FAN LAWS Existing Flowrate (CFM): Existing Static Pressure (in. 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. (in.) d = Motor Sheave dia. Calculating energy efficiency potential is dependent on the scale and timeframe of the analysis. 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. ( .) • FEI will encourage more efficient fan designs, use of more efficient motors, and direct drives. Fan Drive Options 10. Fin Efficiency and Fin Resistance The general concept of fin efficiency and fin resistance was developed in Chapter 1. At half its rated operating speed, the fan delivers 50% of its rated airflow but requires only 1/8 full-load power. Water): Static Fan Efficiency (%): Brake Horsepower (HP): Air Density: … 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. Use of diffusers Case study, final overview with cost c A No. 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. Fan calculations: Static fan efficiency: FanBHP CFM SP SE = × 6356× FanTipSpeedFPM RPM Circ in =×. 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. 12 Circ in Ts FPM RPM. often used in the calculation of sound pressure levels. See the “References” section for a starting point. 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. AMCA Standard 208-18) for calculating a new metric for fan efficiency: the fan energy index (FEI). Accordingly, we will only reiterate the major equations and concepts here. 10 AIVC Guide to Ventilation. • Sometimes will provide data in a table rather than in a graph. D = Fan sheave dia. ( .) Definitions of Fan Power and Fan Efficiency for buildings Simon talks about Fan Efficiency , Fan Input Power and regulations that are associated with this. Clean air allows both for the most choices and the most efficient fans. Other Fan Efficiency Options Other Fan Efficiency Options There are numerous other ventilation fan up-grade opportunities to improve efficiency. Configurations to Improve Fan System Efficiency 8. See Figure 1 for typical units used for the calculations. Drive loss is based on full load motor power (11 kW) ie P a = 11 kW. (in.) x number of fans motor efficiency actual power Bhp x watts Bhp ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ EQ-6 2. hp to an exhaust fan when operated at its full rated speed. With small changes it suffices to take into account all significant energy flows and embodied energy with average primary energy co-efficients. 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. 12 ()() BL C D d Dd C =+ ×++ − 2157 4 2. A profitability calculation should also be made. 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). = ×12 RPM Ts FPM Circ in = ()×. 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. Stay tuned to be able to search FEI rated fans and use our FEI calculation … The first thing to consider is what will be moving through the blades. fan and represented by the velocity pressure at outlet has, traditionally, been assumed to be a loss of useful energy. (For dry air it is around 287.) Once you know those variables, you can make the fan static efficiency calculation to select the right fan. Motor part-loads may be estimated through using input power, amperage, or speed measurements. 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. Definition. O.D. Bibliography ASHRAE. As shown in Figure 1, each FEG band contains a range of fan diameters and their corresponding efficiencies. ( .) Fan Curves Source: ASHRAE Handbook. 64.7 > 61.43. calculate wet bulb temperature based on the dry bulb temperature and relative humidity. FanRPM MotorRPM d D =× MotorRPM FanRPM D d =× BL = Belt Length (in.) As the fan total pressure, FTP, reflects the full increase in mechanical energy imparted by the fan, 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 Figure 1: Fan-efficiency grades (FEG) defined by AMCA Standard 205. Smaller Fans. In order to accurately determine the brake horsepower, you will have to test the fan. • Existing fan efficiency metrics are not suitable for ensuring energy savings. • 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 9 Generalized Fan Curves • These kinds of curves can be used to help choose a fan. Notes. Motor Efficiency, Selection, and Management A Guidebook for Industrial Efficiency Programs In the fiercely competitive global marketplace, minimizing operational costs can mean the difference Motor efficiency taken at full load. As SP is increased, HP increases and CFM decreases. Basic calculations (manually or by Steam Flex). However, there are two major differences between them. H2O): New Horsepower (HP): FAN APPLICATION FORMULAS Fan Brake Horsepower: Flowrate (CFM): Static Pressure at Discharge (in. Generally, efficiency increases and fan size decreases as specific speed increases. 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. As the overall efficiency is > than target efficiency fan is compliant. 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. SPECIFIC FAN POWER – a tool for better performance of air handling systems ... calculation, and measuring guidance for installers. Note the efficiency and/or power can also be calculated manually using a steam Mollier chart and steam tables such as Keenan and Keyes. 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. Industrial Fan Types, Blade Profiles, and Particulates. Method 1 - Exhaust steam is dry & saturated or superheated. Outside diameter of fan, duct or transition. This figure can be used to determine the most efficient size and type of fan for a particular application. To check and assess the SFP should be easy and clear also for the building owner, the end user, the inspectors etc. Fan 1 not performing to specification. Max. Specific Fan Power (SFP) is a parameter that quantifies the energy-efficiency of fan air movement systems. 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. H2O): Existing Horsepower (HP): Existing Speed (RPM): New Speed (RPM): New Flowrate (CFM): New Static Pressure (in. Fan and Pad Greenhouse Evaporative Cooling Systems 2 frequently drift out of calibration and should be checked against standards on a regular basis. Fan noise 7/12/2000 11.3 Noise Comparison For lowest noise output, fans should always be operated near their peak efficiency point. • Fan selection is ultimately more important than peak efficiency in determining fan power consumed. Static Fan Efficiency = Volume (m3/s) * Pressure gain (Pa) / Power input (W) * 100. For a fan discharging directly to atmosphere this is, indeed, the case. • 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. Larger Fans vs. VSD power Taken as motor full load power ie P ed = 11 Kw can’t we use the simple fan efficiency calculation, rather than something more complicated like FEG? Step 3 compare calculated efficiency with target efficiency. Controlling Fans with Variable Loads 9.
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