Air handlimg unit an overview - basic features presentation

AHU

1. Air Handling Unit an Overview

2. Contents Introduction to AHU Classification of AHU Main Components of AHU AHU selection parameters Energy conservation tips

3. What is an AHU ?

4. An Air Handling Unit (AHU) is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning system. An air handler is usually a large metal box containing blower, heating or cooling elements, filter racks or chambers, sound attenuators, mixing box, humidifier and dampers AHU Perform one or more of the functions of circulating, cleaning, heating, cooling, humidifying, dehumidifying and mixing of air. AHU controls following parameters of a space: Temperature Humidity Air movement Air Cleanliness

5. Main Classification of AHU 1. According to Blower Fan arrangement Draw through Blow through 2. According to mounting Floor mounted Ceiling suspended 3. According to structure Horizontal floor mounted Vertical floor mounted 4. According to air conditioning characteristics Fresh air handling unit ( No return air is used) Mixing AHU ( Fresh air + return air) 5. According to decker Single Multi 6. According to medium Chilled water DX type

6. Main Components of AHU Mixing box section Filter section Coil section Blower motor section

7. FILTERS Pre -Filter: - Pre-filter is used for initial filtration of the air from the mixing chamber. Generally we use G-4 Filter which has a filtration of 10 Micron . Bag-Filter: - It is the second stage of air cleaning after pre-filter, the air pass on to bag filter . Generally we use F-9 Filter which has a filtration of 3 Micron.

8. CHILLED WATER COILS Casing material – GI Tube material – Copper Fin material - Aluminium

9. BLOWER MOTOR Belt driven – Centrifugal fan: Forward curve type – Smaller air volume & less static pressure Backward curve type – Larger air volume & higher static pressure Backward curve type are more efficient than forward curve type Belt driven fans have inherent energy losses

10. 2. Direct drive – Plug type Impeller is directly mounted on the driving motor shaft and the entire assembly mounted in a cabinet, which is pressurized by the operation of the fan. The Plug fans are preferred primarily on account of ease of cleanliness and maintenance of fans. As these fans don’t have housing, it is easy to clean the impellers. Compared to centrifugal fans, plug fans offer lower energy consumption and lower operating costs due to less energy loss as there is no belt, pulley etc. Plug Fan uses external VFD

11. 3. EC Fans EC plug fans provide a compact and high efficiency solution for air handling units. The high performance impeller, motor and electronics system are all optimally adjusted to one another, leading to an overall efficiency of well above 60 %. They have in build VFD

12. AHU Selection parameters: Ambient Temperature- Deg.C or Deg. F Total Capacity – TR or BTU/ Hr Sensible Capacity – BTU/ Hr Supply Air- CFM Fresh Air- CFM Entering Coil Temperature- Deg . C or Deg. F Leaving Coil Temperature- Deg . C or Deg. F External Static Pressure- Pa Power Supply-V- Ph -Hz Chilled Water Entering Coil Temperature-Deg. C or Deg. F Chilled Water Leaving Coil Temperature-Deg. C or Deg. F Chilled Water Flow-GPM or L/S The filtration requirement Location -above ceiling or in separate room Some other requirements like body type, casing type, fan type. Fan selection from highest pressure drops in ducts and air inlet outlets. Control selection like it is coming with which types of controls, is it standalone type or can be controlled by BMS only. Discharge type ––upward/downward/side flow

13. Energy conservation opportunities in AHU’s Double skin AHU – PUF body Thermal break profile Opposed blade volume control dampers

14. Thermally insulated ducts both for supply and return air

15. Provide proper insulation of at least 50 mm thickness to chilled water lines using EPS ( expanded polystyrene foam ) with glass fabric cloth covering and mastic sealant coat.

16. Electronic pressure independent type balancing cum control valve (PIBCV) with integrated 2 way modulating control valve in a single body

17. Plug type blower fan and motor of IE3 efficiency with external VFD control Fan speed will be regulated based on the return air temperature

18. Thank you