NEBB Fundamental Formulas

Transcription

1 Approved NEBB - May 1, 17 Page 1 of 8 Version 1.3 A = Area (ft²) IP, (m²) SI M = Mass (lb) IP, (kg) SI ACH = Air Changes per Hour ma = Mixed Air Ak = Effective Area m = meter (metre) AV = Average m³/s = Volumetric Flow: Cubic Meters Per Second BHP = Brake Horsepower (IP) HP NLA = No Load Amperage BP = Brake Power (SI) kw NPSHA = Net Positive Suction Head Available Btu = British Thermal Unit oa = Outside Air Btu/h = Btuh = BTUH = BTU/Hour % oa = % of Outside Air = Center Distance (used in belt formula) Ω = Ohm C = Degrees Celsius, C P = Pressure C = Friction Loss Coefficient (For Duct Fittings) Pa = Atmospheric Pressure CCF = Cubic Feet Pab = Absolute Pressure (Atmospheric Pressure + Gauge Pressure) CFM = Volumetric Flow: Cubic Feet Per Minute Pa = Pascals, Pressure SI Cp = Specific Heat π = 3.14 Cv = Flow Constant (IP) ρ = Density (lb/ft³) IP, (kg/m³) SI d = Diameter (in.) IP, (mm) SI Δ = Difference or Change (Final - Initial) dimp = Impeller Diameter E = Volts Eff = Efficiency EP = Pump Efficiency PD = Sheave Pitch Diameter P = Pressure at Pump Centerline ppm = parts per million psi = Pounds Per Square Inch psia = Pounds Per Square Inch Absolute psig = Pounds Per Square Inch Gauge Pvp = Absolute Vapor Pressure Q (flow) = Volumetric Fluid Flow Rate: (i.e. CFM, GPM, m³/s, l/s, etc.) F = Degrees Fahrenheit, F Q (heat) = Heat Flow Rate (BTU/Hour) IP, (W or kw) SI f = Friction Factor R = Rankin = Degrees Rankin, R FLA = Full Load Amps r = Radius (in) IP, (mm) SI fpm = Feet per Minute (fpm) % ra = % of Return Air ft = Foot R = Resistance g = Acceleration of Gravity ra = Return Air gal = Gallons rad = Radians GPM = Gallons Per Minute (GPM) RH = Relative Humidity h = Enthalpy (BTU/lb dry air) IP, (kj/kg dry air) SI RPM = Revolutions Per Minute H = Head (in wc, ft wc, psi) IP, (Pa, kpa) SI Rvalue = Thermal Resistance Hg = Mercury s = second hma = Mixed Air Enthalpy SHR = Sensible Heat Ratio hoa = Outside Air Enthalpy SME = Sash Movement Effect Performance Rating (SME-XX yyy) HP = Horsepower SP = Static Pressure hr = Hour Sp Gr = Specific Gravity (for water use 1.) hra = Return Air Enthalpy T = Temperature HT = Height (in) IP, (mm) SI Ta = Absolute Temperature (46 + T) or R I = Amps Tma = Mixed Air Temperature J = Joules Toa = Outside Air Temperature K = Kelvin, K TP = Total Pressure Kv = Flow constant (SI) Tra = Return Air Temperature kg = Kilogram TS = Tip Speed (fpm) IP, (m/s) SI kj = Kilojoule U = Heat Transfer Coefficient kpa = Kilopascal µ = viscosity, dynamic kw = Kilowatt = Watts V = Velocity l = Liter (Litre) VP = Velocity Pressure l/s = Volumetric Flow: Liters Per Second W = Watt lb = Pounds WD = Width (in) IP, (mm) SI lm = Lumens wg = wc = water gauge = water column ln = natural log WHP = Water Horsepower (IP) LG = Length (in) IP, (mm) SI WP = Water Power (SI) lx = Lux ω = Humidity Ratio (lb or grains of water/lb of dry air) (g H2O/kg dry air)

2 Approved NEBB - May 1, 17 Page 2 of 8 Version 1.3 Airflow & Velocity Equations QVA TP VP SP V 4 VP V 96 VP QV x A TP VP SP V 1.66 VP V VP Q6 ACH LG x WD x HT Area πd 2 πr HT WD Area / 144 Area HT x WD π HT ACH Q 36 LG x WD x HT Area πd 2 1,, πr 1,, HT WD Area / 1,, Area Air Temperature Equations HT WD π HT 2 1,, R 46 K 273 T % T % T h % h % h % T T T T % Q 4.CFM h Q 6CpρCFM T Q 1.8CFM T Heat Transfer Calculations h h h h Q 1.2 l s h Q Cpρ l s T Q 1.23 l s T Q.69CFM Q 484 CFM Q 3. l s SHR Q Q Q A U Fan Equations Q Q Q Q A U CFM CFM RPM RPM P CFM P CFM BHP CFM BHP CFM Tip Speed TS πdrpm 12 l s l s m s P l s P l s m s kw l s kw l s rad s rad s m s m s m s m s Tip Speed TS πdrpm 6

3 Approved NEBB - May 1, 17 Page 3 of 8 Version 1.3 Sheave Equations RPM PD RPM PD RPM RPM PD PD Fan Belt Length 21.7 PD PD PD PD 4 Electrical Equations Power EI IE Ω 1 kw Watts ΩEI 1 HP 746 Watts 1 Watt Btu/hr Power Equations PFPower Factor BHP EIPFEff 746 PFPower Factor kw EIPF EIPFEff1.732 BHP 746 PFPower Factor.8 & Eff.9; if not given BHP HP I NLA. FLA NLA. FLA FLA E E Fan HP CFM TP SpGr 66 Eff Resistance kw E I PF Series Circuit: total resistance: Ω R R R R R R E I E I Parallel Circuit: total resistance: Ω R R R R R Voltage Drop I R Conversions kilowatts Kw Btu / hr 3413 horsepower HP Btu / hr 4 joules Btu / hr.948 kilogram calories Btu / hr tons of cooling chiller Btu / hr tons of cooling cooling tower Btu / hr gallons U.S. water pounds U.S. lb millimeters inches U.S..4 centimeters inches U.S. 2.4 bar pounds per square inch PSI 14. inches of water pounds per square inch PSI.36 inches of Mercury Hg pounds per square inch PSI.491

4 Approved NEBB - May 1, 17 Page 4 of 8 Version 1.3 Hydronic Pump Equations GPM GPM RPM RPM l s l s m s m s rad s rad s GPM GPM d d H GPM H GPM BHP GPM BHP GPM WHP GPM H SpGr 396 SpGr 1., unless given, EP use.7 if not given BHP GPM H SpGr 396 EP SpGr 1., unless given, EP use.7 if not given EP % WHP BHP Hydronic Calculations m s m s m H h H m h BP m s BP m s d d rad s rad s rad s rad s WP 9.81 m s H SpGr WP l s H SpGr 2 EP % BP WP EP WP BP Coil P: GPM GPM P P Coil P: m h m h P P GPM SpGr C P K m h SpGr P GPM C P SpGr SpGr 1., unless given, EP use.7 if not given P SpGr GPM C SpGr 1., unless given, EP use.7 if not given m h C P SpGr SpGr 1., unless given, EP use.7 if not given m P SpGr h SpGr 1., unless given, EP use.7 if not given K NPSHA P P V 2g P P Heat Transfer Calculations h ρ ρ h Boiler Calculations Output Btu Input Btu %Eff Fire Rate Input Btu Fuel Btu Boiler Operating Cost Fire Rate hrs Burned $Cost gal Btu lb of water T

5 Approved NEBB - May 1, 17 Page of 8 Version 1.3 Metric Equivalents acceleration m/s 2 meters per second squared 1m/s ft/sec 2 m 3 /s cubic meters per second 1 m 3 /s cfm airflow volumetric flow rate l/s liters per second 1 l/s 2.12 cfm m 3 /hr cubic meters per hour 1 m 3 /hr.89 cfm area m 2 square meter 1 m ft 2 mm 2 square millimeters 1 mm 2.16 in 2 atmospheric kpa kilopascals 1.3 kpa in Hg psi pressure Bar Barometers 1 Bar kpa 29.3 in Hg 14.4 psi m meter 1 m ft distance. length, or distance m meter 1 m in mm millimeter 1 mm.39 in lighting intensity lx Lux 1 lx.93 fc lm/m 2 Lumens/square meter 1lm/m fc pressure kpa kilopascals Pascals 1 kpa.296 in Hg.14 psi Pa Pascals 1 Pa.4 in wg temperature C degrees Celsius C F 32 / 1.8 velocity m/s meters per second 1 m/s fpm volume m 3 cubic meters 1 m 3.31 ft 3 1 Btu Energy required to heat 1 lb of H2O from 39 F to 4 F 1 CCF Btu 1 ft inches 12 1 ft wc.434 psi 1 ft Hg.89 psi inches ft x 12 1 mm Hg. in wc 1 in Hg ft 1 kw/hr 3413 Btu 1 lbmoisture 7 grains 1 psi 2.7 ft wc 1 psi in wc 1 psi 2.36 in Hg 1 Ton refrigeration Btu/hr Atmospheric. Press in Hg or psi Density of Air Std.7 lb/ft 3 Density of Water Std 62.4 lb/ft 3 or 7.49 gal/ft 3 or 8.33 lb/gal One foot of mercury Hg column.89 lb/in 2 psi One inch of mercury Hg column 13.6 inches in wg 1.13 ft wg Specific Heat Cp of dry air.24 Btu/lb x 68 F Specific Heat Cp ice. Btu/lb x 68 F Specific Heat Cp vapor.4 Btu/lb x 68 F Specific Heat Cp water 1. Btu/lb x 68 F Specific Volume of Air Std ft 3 /lb

6 Approved NEBB - May 1, 17 Page 6 of 8 Version PSYCHROMETRIC CHART BAROMETRIC PRESSURE inches of Mercury SENSIBLE HEAT TOTAL HEAT.2.1 ENTHALPY HUMIDITY RATIO ENTHALPY - BTU PER POUND OF DRY AIR Linric Company Psychrometric Chart, h W Qs Qt SATURATION TEMPERATURE - F 9% 6 8% 7% 6% % 4% % % % RELATIVE HUMIDITY DRY BULB TEMPERATURE - F SPECIFIC VOLUME ft³/lb OF DRY AIR 8 WET BULB TEMPERATURE - F 14. % % 8% 6% 4% 2% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND OF DRY AIR DEW POINT - F VAPOR PRESSURE - INCHES OF MERCURY ENTHALPY - BTU PER POUND OF DRY AIR

7 Approved NEBB - May 1, 17 Page 7 of 8 Version SENSIBLE HEAT RATIO = Qs / Qt PSYCHROMETRIC CHART - METRIC NORMAL TEMPERATURE SI Units SEA LEVEL BAROMETRIC PRESSURE: 1.3 kpa 1 WET BULB TEMPERATURE - C SENSIBLE HEAT TOTAL HEAT ENTHALPY HUMIDITY RATIO h W Qs Qt ENTHALPY - KJ PER KILOGRAM OF DRY AIR % 8%.84 7% 6% % 4% % %.86 % RELATIVE HUMIDITY.9.88 VOLUME - CUBIC METER PER KG DRY AIR % % 8% RELATIVE HUMIDITY 6% 4% 2% HUMIDITY RATIO - GRAMS MOISTURE PER KILOGRAM DRY AIR VAPOR PRESSURE - MM OF MERCURY SENSIBLE HEAT RATIO = Qs / Qt - - DEW POINT TEMPERATURE - C ENTHALPY - KJ PER KILOGRAM OF DRY AIR DRY BULB TEMPERATURE - C

8 Air Density Correction Factors (US Units) Standard Air Density (Sea Level & 7 F) =.7 lb/ft in Hg Altitude (ft) Sea Level Barometer (in Hg) (in wg) Air Temperature F Water Temperature F Feet head differential per inch Hg differential Altitude (m) Barometer Air Temperature C Water Temperature C (kpa) Air Density Correction Factors (Metric Units) Standard Air Density (Sea Level & C) = 1.4 kg/m 1.3 kpa Sea Level Approved NEBB - May 1, 17 Page 8 of 8 Version 1.3