Air Handling Units
Industrial-Comfort Type AHU
These modular type units are in double skin construction, with 40 or 60 mm thick panels.
GENERAL
Modular type air handling units are built in double skin construction, with 40 or 60 mm thick rock wool insulated panels, within the capacity range of 1.000 – 125.000 m3/h. Outer surfaces of the units are made of PVC covered pre-painted sheet metal to RAL 9002 color, while the inner surfaces may be galvanized or pre-painted sheet metal or of stainless steel, depending on application or demand.
KLS air handling units have a skeleton made of specially shaped aluminum profiles and corner pieces that are electrostatic powder coated. To ensure air tightness, EPDM type gaskets are used between panels and profiles.
To ensure high efficiency of filters and coils, bypass around these elements have been eliminated through a special design. Selection of most suitable filters for the application and the unit are properly made.
Dampers used in the air handling units and cabinet fans are made of aluminum profiles and aluminum damper blades with plastic driving gears. Gears are placed out of the air stream. To prevent leakage, plastic gaskets are used on the damper blades.
In accordance with energy efficiency regulations, plate type, rotary type or run-around-coil type heat recovery units are employed.
To meet the required air flow and static pressure requirements, electric motor driven fans in forward curved, backward inclined or airfoil construction, or plug fans selected in accordance with application requirements, are used. Only fans with certified performance values are employed. Electric motors are of IP55 class and are CE approved.
AHU selection program
By using the KLS selection program, the most economic unit meting the required conditions, can be easily selected. This program has been prepared using the technical data and the selection programs of the components used within the AHU. Through the user friendly interface of the program, selection and dimensioning of the unit can easily be made and the technical outputs can be obtained.
TECHNICAL SPECIFICATIONS
Casing Construction
In KLS air handling units, casings are made of specially shaped extruded aluminum profiles, aluminum middle profiles and double skin panels. Profiles are connected to each other by aluminum corner pieces. All aluminum profiles and corner pieces are electrostatic powder coated. Air tightness of panels and profiles are provided by EPDM gaskets. Units are supplied with a steel base frame of 120 mm or 200 mm height, depending on pressure inside the unit. Base frames are equipped with lifting lugs.
Units designed to operate outdoors are equipped with a roof. To enable easy transportation, units can be shipped in sections or completely knocked down. EPDM gaskets are used in connecting sections to each other, to ensure air tightness.
Profiles
Specially extruded aluminum profiles are of 1,8 mm thick and thus can stand high pressures. To withstand corrosion, profiles are electrostatic powder coated. On request, steel profiles can also be used.
Panels
Panels of the air handling units are built in standard sizes, in double skin construction, 40 or 60 mm thick, with rock wool insulation. Outer surfaces of the panels are made of PVC coated sheet metal painted to RAL 9002 color, while inner surfaces may be of galvanized sheet metal, pre-painted sheet metal or stainless steel. Metal thickness varies between 0,5 mm to 1,2 mm. Panels can be removed from the outer side of the unit. Inner surfaces of the units are free from any obstructions.
Doors
Double skin service doors are installed on filter, fan, humidifier and empty sections, to enable access and servicing. Lockable access doors are used on all fan sections. Air tightness is provided by special gaskets. On sections where there is positive pressure inside the unit, doors opening inwards are employed. Optionally, doors may be equipped with inspection window and lighting inside the section.
Insulation
Density of rock wool used is 70 kg/m3.
Dampers
Dampers are made of airfoil shaped aluminum blades housed in an aluminum casing in an opposed blade configuration. Gaskets are placed on the edges of the damper blades to ensure air tightness. Plastic gears that operate the damper blades are placed within the damper casing, outside of the air stream. Dampers can be manual or motor operated. Optionally, servomotors, flexible connections and rain hoods are available.
Accessories
Optional accessories like internal lighting, inspection window, damper motors, flexible connections on inlet and discharge side, manometer, service switch, syphon and rain protection are available.
Filters
The total cross section of KLS air handling units are used as filtering area, in accordance with international standards. Filters have their own casings and are placed inside the units through a system that allows easy installation and dismantling. Filter sections are equipped with service door. Inspection window, internal lighting and manometer are optional. Filter types like coarse filter, bag filter, metal filter, active carbon filter, compact filter and HEPA filter are available.
- Panel filter G2, G3, G4, F5
- Zig-zag filter G2, G3, G4
- Metal filter
- Bag filter G4, F5, F6, F7, F8
- Compact filter F6, F7, F8, F9
- HEPA filter H10, H12, H13, H14
- Active carbon filter
Heat Recovery Systems
In consideration of energy efficiency principles, plate type, rotary type and run-around-coil type heat recovery systems are being used.
Plate type heat recovery system
The plate type heat exchangers used in this system consist of a number of specially shaped, highly conductive aluminum plates, arranged in a cross flow shape and enable transfer of heat between exhaust air and return air, without mixing the two air streams with each other. This system can operate between -30°C and +90°C temperatures. Depending on application, plates may be of corrosion proof aluminum or stainless steel. To prevent freezing at low temperatures, systems with a bypass damper, are used. On the exhaust side, a double slope, stainless steel drain pan is installed.
- Efficiencies are between 40% and 60%
- No electric connection is necessary
- Long life
- Low operating cost
- Plates can be epoxy coated or stainless steel
Rotary type heat recovery system
Rotor is made of specially shaped aluminum sheets and is driven by an electric motor through a v-belt drive.
In general, they can be classified in three groups:
- Condensing type rotors; is the economic solution used in ordinary air conditioning applications. These rotors condense and thus remove the excess humidity in the air.
- Absorbing type rotors; are used to transfer humidity from one air stream to the other, within certain temperature limits, in comfort air conditioning applications. Surfaces of the rotor have the characteristic of absorbing humidity.
- Enthalpy type rotors; can transfer high amounts of humidity from one air stream to the other, through the desiccant coated material of the rotor. They are most effective in high temperature and high humidity conditions. Through their ability of pre-cooling and de-humidification, they tend to decrease the total cooling requirement of the system, resulting in application of a smaller size chiller.
In high pressure applications, abrasive atmospheres, marine applications, etc., specially coated rotors are used.
Rotor diameters vary between 200 – 5000 mm.
Heat transfer efficiency of the rotors are optimized for a rotation speed of 12 rpm. Based on application, rotation speed may be increased up to 20 rpm.
Through control of the rotation speed by a frequency converter, capacity can be adjusted based on varying climactic conditions. Capacity control requirement must be clearly specified while ordering.
Based on EN 308 and ARI 1060 standards, the maximum leakage allowed in rotors is 3%. In properly configured and pressurized rotors equipped with a sweeping zone, the leakage rate is below 0,5%. Angle of the sweeping zone is indicated in the table for different fan positions.
- Efficiencies vary between 60% and 80%
- Electric connection is required. Capacity can be adjusted through variable speed controlled motor (optional)
- Compact construction; occupies minimum amount of space
- No risk of freezing
- Capable of transferring humidity (hygroscopic type)
Run-around-coil type heat recovery systems
These are low efficiency systems since the heat transfer is from air to water and from water to air. Water circulating in a closed loop is used to transfer the heat between the exhaust air and the fresh air streams. There is a circulating pump and a balancing tank in the system. A double slope, stainless steel drain pan is used on the exhaust side.
- Efficiencies vary between 30% and 50%
- Electric connection is required (circulation pump)
- Standard plumbing equipment is used
- Due to danger of freezing, glycol mixture is used in cold climates
- Exhaust and fresh air streams can never mix with each other
Electric Heaters
Electric heaters are used in air handling units when there is no heating medium available or it is not reachable, at the inlet of the air handling units when there is a risk of freezing or at the outlet of air handling units when there is a need of instant heating in accurate systems.
In systems that use after-cooling for humidity removal, electric heaters are installed after the cooler. Elements of the electric heater are made of stainless steel, while the casing can be galvanized or stainless steel, depending on request. They can be step controlled or proportional. Heaters that are CE approved are used. As standard, electric heaters are equipped with an auto-reset type limit thermostat and a manual reset type safety thermostat. Protection class is IP 43. Electric heaters should only be energized when the fan is running. Necessary precautions to turn off the electric heater should be taken, when the fan is turned off. In electric heaters over 30 kW capacity, it is suggested that fan should be kept running for 2-3 minutes after the electric heater is turned off
Heating and Cooling Coils
Coils are selected to match the fluid to be used. Coil tubes may be of copper or steel, while fins may be of aluminum, copper or steel. Aluminum or copper fins may be epoxy coated. Collectors may be of steel or copper. Coils are pressure tested at 20 bars, while testing at 30 bars is optional. They are placed on slide rails to enable easy removal from the air handling unit. Through installation of special bypass elements, it is ensured that all air flow goes through the coil. In hot and chilled water coils, water inlet is from the bottom and outlet from the top, air and water flow is in a counter flow arrangement to increase the heat transfer efficiency. Unless otherwise specified, pressure drop in heating coils is kept below 25 kPa and in cooling coils, below 40 kPa.
- Water coils: Hot and chilled water coils are copper tube and aluminum fin type. Collectors are of copper or steel.
- Refrigerant coils: These are copper tube and aluminum fin type, with copper collectors.
- Steam coils: In systems up to 3 atg steam pressure, copper tube aluminum fin type coils, in systems over 3 atg steam pressure, steel tube and steel fin type coils are used.
Condensate Trays
In order to drain the condensing water in cooling coils, humidifiers and heat recovery systems, double slope condensate trays in stainless steel are used. Condensate tray is big enough to accommodate the coil, collectors and droplet eliminators. Condensate tray is insulated with rock wool.
Droplet Eliminators
Droplet eliminators are made of specially shaped PVC and are placed downstream of the cooling coils.
Humidifiers
Three types of humidifiers are employed: electrode steam type, mat type and atomizing type.
Electrode steam humidifiers
Electrode steam humidifiers consist of a microprocessor controlled steam generating unit and connecting pipes. They generate steam from tap water, using electricity. The generated steam is sent to the air handling unit through a steam distribution pipe and this steam is use to humidify the air. Humidifiers of various capacities, operating on 230 – 400 V power supply, having on-off or proportional control, are used.
Mat type humidifiers
Mat type humidifiers provide evaporative humidification by passing the air through a wet filling material. The filling material (mat) is kept wet by a circulation pump or directly by tap water. The efficiency of these humidifiers can be 65% - 85% or 95%. Casings of the humidifiers are made of stainless steel. In order to prevent clogging of the filling material, air must be filtered prior to humidification. At air speeds of over 3,5 m/sec, droplet eliminators must be installed downstream of the humidifier. Service door, inspection window and internal lighting are used
Atomizing type humidifiers
These humidifiers, operating on de-mineralized water, consist of an inverter controlled pump, control panel, distribution pipes, drain valves, stainless steel nozzles and droplet eliminators, pressurize the water to 75 bar and totally pulverize it at the nozzles and thus enable mixing with air completely, can make stepless capacity control between 14% to 100% and they operate on very low electric consumption (4 watts per liter/hour of humidification) providing operating economy. These units comply with DIN 1946 hygienic standards. Atomizing type humidifiers can be used for adiabatic cooing purposes.
Sound Attenuators
Sound attenuators may be placed at the inlet or outlet sides of the air handling units, depending on request. Attenuators contain splitters of high absorbing capacity. These splitters are made of galvanized or stainless steel with glass wool or rock wool inside. The inlet and exit portions of the splitters have a rounded shape to decrease pressure losses and noise. Splitters are placed vertically inside the attenuator. Splitters are so sized that the air speed between them does not exceed 20 m/sec.
Fans
Fans are selected to meet the required air flow and pressure at the highest efficiency, minimum electric consumption and lowest sound level. I accordance with international standards, statically and dynamically balanced double inlet centrifugal fans with forward or backward inclined blades are used. Fans are installed on a base frame and are driven through v-belts. In special applications, plug fans are used. In general, plug fans are direct driven. To prevent transmittance of fan and motor vibration to the air handling unit casing, fan – motor base frame is installed on spring vibration absorbers with high absorbance capacity. Flexible connections are used between fan outlet and unit casing. To minimize vibration and noise, fans are driven through v-belts. For security purposes, service doors on fan sections are equipped with fan guards.
Motors
Electric motors used are asynchronous, three phase, squirrel cage type in IP 55 protection class. Unless otherwise specified, motors are 380V, 50Hz. In accordance with international standards, motors may be single speed, two speed or with frequency controller.
Diffusers
Diffusers are used after the fan sections in cases where there are other sections like filters, sound attenuators, etc. after the fan section, to enable homogenous distribution of air over these elements.
Plenums
Empty plenum sections are used at the end of the air handling units when space is needed for air distribution, when there is more than one suction / discharge, or in special cases where maintenance is required.
Control Panels and Automation
On request, air handling units may be supplied with a control panel or an integrated control + automation (MCC and DDC) panel. These can be installed on the unit or may be supplied separate. Two types of automation are applied. In simple applications, temperature and humidity control, electronic control panel, duct type temperature and humidity sensors, valve and damper actuators are used. Frequency controllers can also be included.
For more accurate applications, microprocessor control systems, with specially developed software, are used. Through this microprocessor, air delivery, temperature, humidity, filter dirtiness, pressure difference between locations, conditions of the conditioned spaces and unit variables can be monitored and controlled and the system can be integrated with the building management system. This control system can manage the following functions:
- Selection of DX or chilled water cooling,
- Selection of DX, hot water or electric heating,
- Humidity control,
- De-humidification or increased comfort through an after heater,
- Utilization of hot gas bypass in DX systems to attain extreme comfort conditions,
- Close control of the dirtiness of each filter and generation of alarms,
- Adjustment of fan delivery depending on operation altitude and temperature,
- During operation, adjustment of fan speed in view of present filter dirtiness to keep the air delivery constant,
- Operation of an alarm when the required air delivery can not be met due to a fault or clogging,
- Adjustment of the return fan delivery in parallel to the supply fan delivery, to maintain the required positive or negative pressure,
- Setting of a cleaning mode function for quickly cleaning the conditioned space by increasing the air delivery,
- Programming of (temperature, air delivery, on-off) seven days of a week through 4 different daily programs,
- Adjustment of daily, weekly on – offs, outside air compensation,
- Limit control of supply temperature (comfort temperature, start of condensation temperature),
- Capability of being integrated with building automation systems and communication in all known languages (Modbus, BACnet, Lon-ECHELON, LAN TCP/IP, SNMP) through an additional outfit,
- Capability of being connected to and being controlled by a central computer, accessible through internet,
- All parameters can be seen and can be adjusted through the terminal on the unit,
- All similar equipment can be connected through a network,
- Operation and configuration parameters can be coded,
- Visual and audio alarm information can be generated,
- Capability of selecting between English and Turkish languages,
- In case unit configuration is changed (addition of a humidifier, changes in valve – damper controls, de-humidification, changes in fan control, etc.) new configuration can parametrically be adjusted,
- Unit can be started or stopped through the terminal by using a time differential, through entering a numeric input or through a computer,
- Pre-heating, heating and cooling algo-rhythm can be made based on inlet, outlet or pre-heating temperatures,
- Parametric temperature control can be proportional, proportional + integral or proportional + integral + differential,
- Parametric fan control can be thermostatic, continuous, by steps or proportional,
- The starting of fan motors can parametrically be adjusted (direct on line, star – delta),
- Each component can individually be operated and tested,
- All alarm information is stored (differential pressure switch, thermal, sensor, emergency stop, etc.).
