What is Insulation material?
An insulation material is any substance that slows the transfer of heat by conduction, convection, or radiation, acting as a barrier to reduce heat loss or gain and maintaining stable indoor temperatures.
Why Duct Thermal Insulation is required?
Duct Thermal Insulation Material used for Air-conditioning Ducts
Elastomeric Rubber Insulation / Nitrile Butadiene Rubber (NBR)
Polyolefin (Cross Linked Polyethylene foam – XLPE)
Fiber Glass
Mineral Wool
Expanded Polystyrene (EPS) – Thermocol
Polyurethane foam (PUF)
How to calculate Insulation material Thickness for A/C ducts?
STEP-01 : SELECT THE INSULATION MATERIAL TYPE
Nitrile Butadiene Rubber Insulation material
STEP-02 : FIND OUT THE THERMAL CONDUCTIVITY & EXTERNAL SURFACE COEFFICIENT OF THE INSULATION MATERIAL
For Nitrile rubber insulation
Thermal Conductivity (k) : 0.038 W/m 0C
External Surface coefficient (h) : 9 W/m2 0C
STEP-03 : COLLECT AMBIENT CONDITION OF THE PARTICULAR CITY
For Example Chennai ambient condition for Monsoon season
Ambient Dry Bulb Temperature (Tamb) : 28.3 0C
Surrounding air Wet Bulb Temperature (Twb) : 26.00 0C
Surrounding air Dew Point Temperature (Tdp) : 22.28 0C
Surrounding air Relative Humidity (RH) : 80%
STEP-04 : CHECK THE SUPPLY AIR TEMPERATURE TRAVELLED INSIDE THE DUCT
Air Temperature inside the duct (Tcold) : 12 0C
How to calculate Insulation material Thickness for A/C ducts ?
The duct thermal insulation thickness is calculated to prevent condensation using the following equation (applicable where ducts are installed inside the building)
X = (k/h) * [(Tdp – Tcold) / (Tamb – Tdp)]
X = (k/h) * [(Tdp – Tcold) / (Tamb – Tdp)]
= (0.038/9) * [ ( 22.28 – 12) / ( 28.30 – 22.28)]
= 0.0042 * [ (10.28) / (6.02) ]
= 0.00717 m
X = 7.17 mm (Required insulation thickness)
Selected Insulation thickness is 9mm
(Standard Insulation thickness available in the market)
