Calculation of Duct Sizing by Equal Friction Method

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Design of Air Condioning Calculating of Cooling Load Total Cooling Load = Hs + Hl where = total heat load(Btu/hr) Hs = Sensible heat(Btu/hr) Hl = latent heat(Btu/hr) Sensible heat Hs = 1.08 q dt where Hs = Sensible heat(Btu/hr) q = air volume flow(cfm) dt = temperature differencr('F) Room to be air conditioned, length = 5m width = 3.8 m Height = m Area = 19.00 Volume Volume = 0.00 air change rate = 6.00 (from table 1) q= 114.00 l/s 1 l/s = 2.119 cfm q= 241.57 cfm utside temperature = 36.00 'C (from table 3) inside temperature = 20.00 'C (from table 2) dt = 16.00 'C dt = 60.80 'F Therefore Hs = 15,862.19 Btu/hr 1Btu/hr = 0.293 Watt Hs = 4,647.62 Watt Table 1-Air Change Rate Type of Building and Room Air Shifts Airflow per hour (1/h) floor area) Animals Sheep Horses Hens Cows Chickens Pigs, sow Piglet Apartments Assembly halls 5~10 Ht (l/s per m 2

Transcript of Calculation of Duct Sizing by Equal Friction Method

Air ConDesign of Air CondioningCalculating of Cooling LoadTotal Cooling LoadHt=Hs + HlwhereHt=total heat load(Btu/hr)Hs=Sensible heat(Btu/hr)Hl=latent heat(Btu/hr)Sensible heatHs=1.08 q dtwhereHs=Sensible heat(Btu/hr)q=air volume flow(cfm)dt=temperature differencr('F)Room to be air conditioned,length=5mwidth=3.8mHeight=mArea=19.00mVolumeVolume=0.00mair change rate=6.00(from table 1)q=114.00l/s1 l/s=2.119cfmq=241.57cfmoutside temperature=36.00'C(from table 3)inside temperature=20.00'C(from table 2)dt=16.00'Cdt=60.80'FThereforeHs=15,862.19Btu/hr1Btu/hr=0.293WattHs=4,647.62WattTable 1-Air Change RateType of Building and RoomAir ShiftsAirflowOutdoorper hour(l/s per m2Airflow(1/h)floor area)(l/s)AnimalsSheep3 per animalHorses40 per animalHens3 per animalCows100 per animalChickens2 per animalPigs, sow60 per animalPiglet15 per animalApartments15 - 20 per personAssembly halls5~1014 per personAuditoriums10 - 15 per personBakeriesProduction8Pastry room6BanksService2~3Archive1Staff2~3Baths5~815Barber Shops15 - 25 per personBars15 - 25 per personBeauty Shops15 - 25 per personBoiler rooms4Bowling Alleys15 - 20 per personCafeterias410 - 15 per personCinemas/Theatres5~107 - 15 per personChemist's shopsSterile room15Laboratory15Packing room4Store1Churches210 - 15 per personClubhouses15 - 25 per personCocktail Lounges15 - 25 per personComputer Rooms15 - 20 per personCourt Houses10 - 15 per personDance halls15 - 30 per personDental Clinics, Offices15 - 20 per personDepartment Stores (cfm/Sq.Ft)0.3Dining Halls10 - 15 per personDrug Shop10 - 15 per personEngine rooms4Exhibition halls10~20Fire Stations15 - 20 per personGarages5~6> 1HospitalsGeneral25 per personTherapy9Operating theatre14Autopsy9HotelsReception15 - 20 per personRoom3IndustriesFactory20 - 30 per personCarpenter work shop2~5Car repair shop4Car repair shop, exhaust outlet60 - 80 per carMechanical work shop3~4Welding12~15Assembly4~5Jails10 - 15 per personJewelry Shop10 - 15 per personLibraries10 - 15 per personLunch Rooms, Luncheonettes10 - 15 per personMunicipal Buildings10 - 15 per personMuseums10 - 15 per personSmithies6~7KitchensSmall20 - 40Large10~20< 7 m215> 7 m220Industrial in general25 - 30Gas ovens550/m2 outside wallElectric ovens300/m2 outside wallGrill table400/m2 outside wallFrying pan300Boiling pan 100 l100Boiling pan 200 l200Coffee machine60Refrigerated cabinet7~10Cooling and freezer room0.3 - 0.5Store2~4Laundries10~15Lavatories5~1010Night Clubs15 - 25 per personBuilding / RoomAir Change RatesMalls10 - 15 per person- n -Motels15 - 20 per person(AC/Hr.)OfficesModule3~815 - 20 per personAll spaces in generalmin 4Landscape20 per personAttic spaces for cooling12 - 15Conference room15 - 30 per personAuditoriums8 - 15Lecture room10 - 15 per personBanks4 - 10Dining hall15 - 20 per personBarber Shops6 - 10Staff, changing clothes8~12Bars20 - 30Dining room8~10Beauty Shops6 - 10Resting room15 per personBoiler rooms15 - 20Police Stations15 - 20 per personBowling Alleys10 - 15Post Offices15 - 20 per personCafeterias12 - 15Precision Manufacturing15 - 20 per personChurches8 - 15Restaurants5~101015 - 20 per personClubhouses20 - 30Retail Stores (cfm/Sq.Ft)0.3Cocktail Lounges20 - 30SchoolsClassroom4~510 - 15 per personComputer Rooms15 - 20Shops20 per personCourt Houses4 - 10Shopping Centers10 - 15 per personDental Centers8 - 12Sports halls3~4Department Stores6 - 10Supermarkets10 - 15 per personDining Halls12 -15Swimming pools5~10Dining rooms hotels5Taverns15 - 25 per personDress Shops6 - 10Town Halls15 - 20 per personDrug Shops6 - 10Winter ConditionEngine rooms4 - 6Table 2-Inside TemperatureFactory buildings, ordinary2 - 4Type of Heated roomsTemperatureFactory buildings, fumes and moisture10 - 15oFoCFire Stations4 - 10Bars6418Foundries15 - 20Bathrooms7222Galvanizing plants20 - 30Bedrooms6418Garages repair20 - 30Changing rooms7222Garages storage4 - 6Churches6418Homes, night cooling10 - 18Cloakrooms6116Jewelry shops6 - 10Classrooms6820Kitchens15 - 60Corridors6116Laundries10 - 15Dining rooms6820Libraries, public4Dressing rooms7021Lunch Rooms12 -15Exhibition halls6418Luncheonettes12 -15Factories, sedentary work6418Nightclubs20 - 30Factories, light work6116Malls6 - 10Factories, heavy work5513Medical Centers8 - 12Gyms5915Medical Clinics8 - 12Halls, assembly6418Medical Offices8 - 12Halls, entrance6116Mills, paper15 - 20Hotel rooms7021Mills, textile general buildings4Laboratories6820Mills, textile dyehouses15 - 20Lecture rooms6820Municipal Buildings4 - 10Libraries6820Museums12 -15Living rooms7021Offices, public3Museums6820Offices, private4Offices6820Police Stations4 - 10Operating theatres7524Post Offices4 - 10Prisons6418Precision Manufacturing15 - 50Recreation rooms6418Pump rooms5Restaurants6418Restaurants8 - 12Shops6418Retail6 - 10Stores5915School Classrooms4 - 12Swimming baths8127Shoe Shops6 - 10Waiting rooms6418Shopping Centers6 - 10Wards6418Shops, machine5Warehouses6116Shops, paint15 - 20Summer ConditionShops, woodworking5Table 3-Inside TemperatureSubstation, electric5 - 10Outside dry bulbInside air conditions withSupermarkets4 - 10temperaturedew point constant at 14oCTown Halls4 - 10oCoC maxoC min%Taverns20 - 30352718.544Theaters8 - 1532261846Turbine rooms, electric5 - 10292517.852Warehouses2272417.551Waiting rooms, public4242317.257212217571 dm3(litre)/s = 10-3 m3/s = 3.6 m3/h = 0.03532 ft3/s = 2.1189 ft3/min (cfm) = 13.200 Imp.gal (UK)/min = 15.852 gal (US)/min = 792 Imp. gal (UK)/hLatent heatHl=0.68 q dwwhereHl=Latent heat(Btu/hr)q=air volume flow(cfm)dw=humidity ratio difference(lb.water/lb dry air)outside humidity ratio=46.00(lb.water/lb dry air)inside humidity ratio=40.00(lb.water/lb dry air)dw=6.00(lb.water/lb dry air)ThereforeHl=985.59Btu/hr1Btu/hr=0.293WattHl=288.78WattThereforeTotal Cooling LoadHt=Hs + HlHt=16,847.78Btu/hrHt=4,936.40Watt4.94KWPressure Loss for Heat Load

VentilationDesign of Ventilationroom 1room 2room3Room 1length=5mwidth=4mheightv3mVolume=60.00mair change rate=12.00(from table 1)Flowrate of Airto be handled=720m/hr0.20m/secVelocity thgh Grille=2.30m/sec(from table 3)Area of Grille=0.09mopen only 50%=0.17mSize of Grille=0.45 x 0.45m=450 x 450mmVelocity inside duct=3.00m/sec(from table 2)Area of Duct=0.07mSize of Duct(1-2)=300 x 250mm(from Fig 1)Length=20.00mFriction Loss=0.40Pa/m(from Fig 2)Friction loss in duct (1-2)=8.00Pa-----------------Eq(1)Friction loss in Duct Component= =40.41Pa-----------------Eq(2)(where =1.23) kg/mdamper=5.00Pa-----------------Eq(3)Room 2length=6mwidth=5mheightv3mVolume=90.00mair change rate=12.00(from table 1)Flowrate of Airto be handled=1080m/hr0.30m/secVelocity thgh Grille=2.30m/sec(from table 3)Area of Grille=0.13mopen only 50%=0.26mSize of Grille=0.55 x 0.55m=550 x 550mmVelocity inside duct=3.00m/sec(from table 2)Area of Duct=0.10mSize of Duct(3-4)=400 x 250mm(from Fig 1)Length=20.00mFriction Loss=0.30Pa/m(from Fig 2)Friction loss in duct (3-4)=6.00Pa-----------------Eq(4)Friction loss in Duct Component= =40.41Pa-----------------Eq(5)(where =1.23) kg/mDamper5.00Pa-----------------Eq(6)Room 3length=8mwidth=5mheightv3mVolume=120.00mair change rate=12.00(from table 1)Flowrate of Airto be handled=1440m/hr0.40m/secVelocity thgh Grille=2.30m/sec(from table 3)Area of Grille=0.17mopen only 50%=0.35mSize of Grille=0.6 x 0.6m=600 X 600mmVelocity inside duct=3.00m/sec(from table 2)Area of Duct=0.13mSize of Duct(3-5)=600 x 250mm(from Fig 1)Length=20.00mFriction Loss=0.25Pa/m(from Fig 2)Friction loss in duct (3-5)=5.00Pa-----------------Eq(7)Friction loss in Duct Component= =41.51Pa-----------------Eq(8)(where =1.23) kg/mDamper5.00Pa-----------------Eq(9)flowrate in duct(1-3)=0.70m/secVelocity inside duct=5.00m/sec(from table 2)Size of Duct(1-3)=600 x 300mm(from Fig 1)Length=20.00mFriction Loss=0.70Pa/m(from Fig 2)Friction loss in duct (1-3)=14.00Pa-----------------Eq(10)flowrate in duct(0-1)=0.90m/secVelocity inside duct=6.00m/sec(from table 2)Size of Duct(1-3)=800 x 300mm(from Fig 1)Velocity thgh Louvre=2.30m/secArea of Louvre=0.39mopen only 50%=0.78mSize of Louvre=1.0 X 0.8m=1000x800mmLength=20.00mFriction Loss=0.80Pa/m(from Fig 2)Friction loss in duct (0-1)=16.00Pa-----------------Eq(11)Louver10.00Pa-----------------Eq(12)ThereforeTotal Friction Loss in longest Ducting System=91.51Pa=91.51N/mTotal Fan capacity=0.90m/sec=3240m/hr @92Patable 1- recommended velocity in ductCircular equivalent diameter - de (mm)LocationVelocity(m/s)DuctDuct side - b (mm)Computer Rooms15 - 20side - aCourt Houses4 - 10mm100150200250300400500600800100012001400160018002000Dental Centers8 - 12100109133152168183207227Department Stores6 - 10150133164189210229261287310Dining Halls12 -15200152189219244266305337365Dining rooms hotels5250168210246273299343381414470Dress Shops6 - 10300183229266299328378420457520574Drug Shops6 - 10400207260305343378437488531609674731Engine rooms4 - 6500227287337381420488547598687762827886Factory buildings, ordinary2 - 46003103654144575315986567558409149801041Factory buildings, fumes and moisture10 - 158004144705206096877558759761066114612191286Fire Stations4 - 101000517574674762840976109311961289137314511523Foundries15 - 2012006207318279141066119613121416151115981680Galvanizing plants20 - 3014007818869801146128914161530163517321822Garages repair20 - 30160093910411219137315111635174918541952Garages storage4 - 6180010961286145115981732185419682073Homes, night cooling10 - 182000152316801822195220732186Jewelry shops6 - 10Kitchens15 - 60Laundries10 - 15Libraries, public4Lunch Rooms12 -15Luncheonettes12 -15Nightclubs20 - 30Malls6 - 10Medical Centers8 - 12Medical Clinics8 - 12Medical Offices8 - 12Mills, paper15 - 20Mills, textile general buildings4Mills, textile dyehouses15 - 20Municipal Buildings4 - 10Museums12 -15Offices, public3Offices, private4Police Stations4 - 10Post Offices4 - 10Precision Manufacturing15 - 50Pump rooms5Restaurants8 - 12Retail6 - 10School Classrooms4 - 12Shoe Shops6 - 10Shopping Centers6 - 10Shops, machine5Shops, paint15 - 20Shops, woodworking5Substation, electric5 - 10Supermarkets4 - 10Town Halls4 - 10Taverns20 - 30Theaters8 - 15Turbine rooms, electric5 - 10Warehouses2Waiting rooms, public4table 2-VelocityType of DuctComfort SystemsIndustrial SystemsHigh Speed SystemsMain ducts4 - 7 m/s8 - 12 m/s10 - 18 m/sMain branch ducts3 - 5 m/s5 - 8 m/s6 - 12 m/sBranch ducts1 - 3 m/s3 - 5 m/s5 - 8 m/sTable 3-VelocityServiceVelocity - vPublic buildingsIndustrial plantm/sft/minm/sft/minAir intake from outside2.5 - 4.5500 - 9005.0-6.01000 - 1200Heater connection to fan3.5 - 4.5700 - 9005.0-7.01000 - 1400Main supply ducts4.0 - 7.01000 - 15006.0-12.01200 - 2400Branch supply ducts1.0 - 3.0500 - 6004.5 - 9900 - 1800Supply registers and grilles1.2 - 2.3250 - 4501.5 - 2.5350 - 500Low level supply registers0.8 - 1.2150 - 250Main extract ducts4.5 - 8.0900 - 15006.0-12.01200 - 2400Branch extract ducts2.5 - 3.0500 - 6004.5 - 9900 - 1800Figure 1-Rectangular Duct with VelocityFigure 2- Friction losstable 4- Minor loss in Duct ComponentComponent or FittingMinor Loss CoefficientRoom 1Room 2Room 390o bend, sharp1.390o bend, with vanes0.790o bend, rounded, radius/diameter duct 10.2545o bend, sharp0.545o bend, rounded, radius/diameter duct 10.05T, flow to branch(applied to velocity in branch)0.30.30.3Exit to room1111Entry from room0.5Reduction, tapered0Enlargement, abrupt(due to speed before reduction)(v1= velocity before enlargement and v2 = velocity after enlargement)(1 - v2 / v1)2Enlargement, tapered angle < 8'(due to speed before reduction)(v1= velocity before enlargement and v2 = velocity after enlargement)0.15 (1 - v2 / v1)2Enlargement, tapered angle > 8'(due to speed before reduction)(v1= velocity before enlargement and v2 = velocity after enlargement)(1 - v2 / v1)2Grilles, 0.7 ratio free area to total surface3Grilles, 0.6 ratio free area to total surface4Grilles, 0.5 ratio free area to total surface6666Grilles, 0.4 ratio free area to total surface10Grilles, 0.3 ratio free area to total surface20Grilles, 0.2 ratio free area to total surface507.37.37.5

Thomas Thein:20 mComfort Systems

Equal FrictionVentilation SystemsEqual Friction MethodDateProjectroom1room 2room 3With Circular DuctSectionDuct Length (m)Air flowrate (m3/s)Duct Diameter (m)Velocity (m/s)Friction Loss (Pa/m)Frictionloss (Pa)Minor Loss Coefficients ()Minor Loss (Pa)Pressure Loss Damper (Pa)Total Pressure Loss (Pa)Pressure Loss Path 0-1-2 (Pa)Pressure Loss Path 0-1-3-4 (Pa)Pressure Loss Path 0-1-3-5 (Pa)0-1200.90.54.60.480.08.08.08.08.01-2200.20.32.80.487.329.35.042.342.31-3200.70.53.60.360.66.66.66.63-4200.30.42.40.367.320.85.031.831.83-5200.40.452.50.247.523.710.037.737.750.346.452.3Type of DuctComfort SystemsIndustrial SystemsHigh Speed SystemsMain ducts4 - 7 m/s8 - 12 m/s10 - 18 m/sMain branch ducts3 - 5 m/s5 - 8 m/s6 - 12 m/sBranch ducts1 - 3 m/s3 - 5 m/s5 - 8 m/sComponent or FittingMinor Loss CoefficientRoom 1Room 2Room 390o bend, sharp1.390o bend, with vanes0.790o bend, rounded, radius/diameter duct 10.2545o bend, sharp0.545o bend, rounded, radius/diameter duct 10.05T, flow to branch(applied to velocity in branch)0.30.30.3Exit to room1111Entry from room0.5Reduction, tapered0Enlargement, abrupt(due to speed before reduction)(v1= velocity before enlargement and v2 = velocity after enlargement)(1 - v2 / v1)2Enlargement, tapered angle < 8'(due to speed before reduction)(v1= velocity before enlargement and v2 = velocity after enlargement)0.15 (1 - v2 / v1)2Enlargement, tapered angle > 8'(due to speed before reduction)(v1= velocity before enlargement and v2 = velocity after enlargement)(1 - v2 / v1)2Grilles, 0.7 ratio free area to total surface3Grilles, 0.6 ratio free area to total surface4Grilles, 0.5 ratio free area to total surface6666Grilles, 0.4 ratio free area to total surface10Grilles, 0.3 ratio free area to total surface20Grilles, 0.2 ratio free area to total surface507.37.37.5Circular equivalent diameter - de (mm)DuctDuct side - b (mm)side - amm10015020025030040050060080010001200140016001800200010010913315216818320722715013316418921022926128731020015218921924426630533736525016821024627329934338141447030018322926629932837842045752057440020726030534337843748853160967473150022728733738142048854759868776282788660031036541445753159865675584091498010418004144705206096877558759761066114612191286100051757467476284097610931196128913731451152312006207318279141066119613121416151115981680140078188698011461289141615301635173218221600939104112191373151116351749185419521800109612861451159817321854196820732000152316801822195220732186

Comfort Systems