Coil Face velocity (fpm) 4 GENERAL 1 To calculate unit dimension, each "Module" = 342mm Eg YSM / YBM 40x60 Height : (4x342 + 58 +100)mm Width : (6x342 + 58)mm Eg YDM / YCBM 40x60 Height : (4x342 + 108 + 100)mm Width : (6x342 + 108)mm NOTE : 100mm unit base to be included when calculate for unit height dimension 1.2.1.3 Integral Face and Bypass Coil. •Fraction circuiting (0.25, 0.33, 0.5, 0.75) –Multiple tubes are circuited together to increase tube velocity S. Tredinnick, G. Phetteplace, in Advanced District Heating and Cooling (DHC) Systems, 2016. installing open coil duct heaters into velocities over 1200 feet per minute contact your local INDEECO representative. A long narrow coil has less tubes, welding and manifold than a more square coil making it cheaper to manufacture. WATER VELOCITY FEET PER SECOND (FPS) WATER VELOCITY FPS* = GPM × Factor ÷ Number of Tubes Fed Tube Diameter Factor 5/8 “ OD 1.085 1/2” OD 1.704 3/8” OD 3.050 **As Water Velocity increases, the capacity of a coil increases, but so does the water resistance. desired tube velocity •Number of tubes in coil face is a function of coil height •Tube sizes (3/8”, 1/2”, 5/8”) •Circuiting Options •Full or 1 –All tubes in face have equal full. 1.2.1.2 Forced-Circulation Air-Heating Coil. Certified Characteristics. 8.6.1 Deeper coils for higher ΔT. Local high velocities and moisture tracking causing spillage are best avoided by downstream drainage. Always question unit design and operation if they request 40% This temperature does not include superheat. Face velocity, fin spacing, finned height and latent cooling rate (SHR) are all contributory factors and differing combinations will change these affects. Description The filter media shall be bonded to a sturdy water-resistant coated beverage board filter frame to fit industry standard size filter racks. Design parameters used are: coil face velocity of 2.0 m/s, air inlet relative humidity of 90%, temperature 30 °C, refrigerant enthalpy 351 . This is termed scfm b. When I have had to do this, I always work with a coil company. - arrangement of coil in relationship to the direction of the airflow - minimum and maximum number of rows - minimum and maximum number of tubes per row - minimum and maximum finned length. Active coil face velocity can vary from 100 to 67% of design (440 to 295 fpm/ 2.2 to 1.5 m/s). The direct expansion or the DX type of central air conditioning system is usually used for cooling the small buildings or the rooms on the single floor. All DX evaporator coils and heat pump condenser coils include rifled tube enhancements and refrigerant distributors that ensure proper refrigerant distribution into the coil. Number of circuits Out. The face velocity of air through the coil should range from 400 to 600 feet per minute. VIEW EXISTING RUNS UPLOAD TEST CSV FILE. Selecting a maximum face velocity will determine a minimum face size but the length to height ratio will have effect on cost. The amount of superheat at the exit of the DX coil has been factory set at 10 °F for calculation purposes. This face velocity shall be based on the actual coil face area sans any safing around the coil. Actual face velocity = = 494 fpm. Typical Dry Coil Pressure Drop in inches of H2O at 500 fpm Rows 90 fins/ft 120 fins/ft 150 fins/ft 168 fins/ft Type II – Pleated panel filters 1. Anything higher and you are asking for complications. A heat exchanger, with or without extended surfaces, through which 5. °C) m =outside diameter, (m) 5. The other consequence of dropping airflow is lower overall sensible capacity and therefore a drop in EER and SEER rating. 3.3 Forced-Circulation Air Coil. Filter Face Air Velocity (FPM) 492 Maximum Initial Resistance (Inches W.G.) 372 Heat Exchangers Basics Design Applications Where, k g l = minimum free-flow air area, (m 2) _ = mass flow rate of air through the cooling coil, (kg/s) J _ =dynamic viscosity of air (kg/m.s) _ =thermal conductivity of air (W/m. 1.0 Minimum MERV Rating 8 B. b. coil fin height >36”; tall coils will tend to carryover at lower velocities . Our Daikin E-F (energy-efficient) fins save energy by reducing air pressure drop as much as 33% and lowering fan brake horsepower requirements. Governing equations and methodology The sizing of cooling coil requires solving the two energy equations of the air-side and I could turn the heat on and get delta T and use-btu output x 1.08 /delta T to obtain CFM, then use CFM /area of coil in sqft. Air velocity: For a given cfm of air, a reduction in coil face area increases coil face velocity over the coil tubes. k A dx hPdx T T dx dx (5) and 2, 2,, 1 kx ()0 S kx f kx dT dT hPdA T T dx A dxdxkA (6) or 2, 2 2 (ln ) kx ()0 S dT dTdA mT T dx dx dx (7) where 2 f kx, hP m kA (8) Both P and A kx, are the function of x or a variable cross section. Moving to 300-400 FPM velocity adds a small % first cost but saves big in supply fan HP over life of unit. Entering air wb and db temperature. Glycol % has a drastic negative effect on transfer properties making GPM, coil and piping sizing go up. In the direct expansion or DX types of air central conditioning plants the air used for cooling space is directly chilled by the refrigerant in the cooling coil of the air handling unit. Second, the drain pan in the bottom of the unit for a 96” high coil would be enormous. A coil for use in an air stream whose circulation is caused by a difference in pressure produced by a fan or blower. Figure 4B. d. coil face velocity >550 FPM . Face Pitch is the centerline distance between two consecutive tubes in the coil face… Suction pressure remains low in the active circuit, thus providing a lower fin temperature and leaving air temperature in the active portion of the face. Air velocity for chilled water or DX coils should never be higher than 550 feet/min. Add a new Section 5.12 to specify requirements for finned-tube coils in the air distribution system. c. spiral fins in lieu of plate fin type coils . Super heat %Ref DP/TD. DX CALCULATION. Coil face dimensions In designing an evaporator for a particular requirement, the factor which most influences its dimensions is the volume flow rate of air to be cooled. Face velocity is restricted to 500 fpm (2.5 m/s) to avoid carryover of condensate from the coil. 3 evaporator Coil types ... (Figure 2) is used for face control. If space allows, making coil section larger to reduce velocity. Figure 4A. The maximum face velocity for cooling coils in both custom and emi-customs units shall be limited to 450 FPM. The value of 500 fpm (2.5 m/s) is very commonly used for coil sizing and it works very 0.40 Minimum Rated Final Resistance (Inches W.G.) Coils operating with all or high fresh air content are particularly vulnerable. Positive coil freeze protection must be used in … Traditional Face Split. A good rule of thumb is a minimum of: • 500 feet per minute (fpm) or 2.54 meters per second (mps) for horizontal suction and hot gas lines And, it would be practically “raining” off the top of a coil 96” high. Face velocity (Feet/Min) Pressure drop (ft H2O) Refrigerant flow rate (lbs/hr) Number of circuits In. of face area per hour under peak sensible and peak dew point design conditions , considering both latent load and coil face velocity. 500 10,000 1/2 20.25 10,000 1. The finned height and finned length (face area) of the coil must be chosen to give an acceptable face velocity (volume flow rate divided by face area). Face Pitch. Coil Face Area (Sq. scfm fpm face vel. It is a balance between the desired capacity and the resultant 20 3.3.1 Forced-Circulation Air-Cooling Coil. A face velocity of 500 feet per minute is generally accepted as the most desirable. I provide the specifications: any required dimensions, cooling capacity or heat of rejection, face area, air velocity, etc. Within limits, the … AAON DX coils are designed The number of fins per inch is determined by the allowable air friction loss. Type EF coils are normally furnished with two distributors and two suction connections offer-ing 50% capacity reduction capabilities. Face Control is the simplest form of capacity control. The cooling coil’s air face velocity shall be sized for a nominal air face velocity not to exceed 2.0 m/s (400 fpm) for the present design conditions and 2.5 m/s (480 fpm) for the future growth capacity. The coil company engineers come back with choices available to achieve the design: coil depth, fin spacing, number of passes, etc. To select a coil, the following information must be determined from system requiremenst: a. The actual DX coil furnished for the system was 8 row, 10 fpi, with a face velocity of 440 fpm (2.24 m/s), so it is very near the pressure drop of the coil required for the chilled-water system: DOWNLOAD CSV FILE. Coil choices include water cooling, water heating, steam, booster, evaporator and condenser. DX Coil capacity is inversely proportional to evaporating temperature. The 2.5 m/s rule for sizing cooling coils is adequate to keep water droplets from leaving the outer edge of the discharge side of the coil (carryover). minimum of 6 inches 5 E N 14 06 C 24.00 x 144.00 . Our Daikin Hi-F (high-efficiency) fins maximize heat transfer with less fins to lower your initial cost. casing and headers (a minimum of 10 inches be-yond the leaving face of the coil). face velocity through the coil and ensuring proper drainage are essential to prevent moisture carryover. At part load, only a portion of the coil face remains active. Active coil face velocity can vary from 100 to 50% of design (440 to 220 fpm 2.2 to 1.1 m/s). to obtain face velocity in FPM. A type of Coil which has damper(s) c. leaving air wb and db temperature required. To simplify the equation, the new dependent variable is introduced: www.intechopen.com Under 350 should be … Quantity of standard air to be cooled. to the compressor, a minimum velocity must be maintained in the piping so that sufficient oil is returned to the compressor sump at full and part load conditions. c. Air flow is greater than 25% but less than 50%, two dampers and solenoid valves will open. The drain pan must be elevated to provide free drainage of con-densate and to provide ample space for installation of a trap in the drain line, to overcome pressure in the coil casing. A heat exchanger, with or without extended surfaces, through which either hot water, hot aqueous ethylene or propylene glycol solutions, or steam is circulated for the purpose of sensible heating of a forced-circulation air stream. DX condenser coils are available with multiple rows, up to 22 fins per inch, and can be configured with interlaced or face split circuitry. 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