I assumed the heat gain to be minimal so I can save energy and also I have taken care so that the insualtion will NOT condense water. Therefore 25 mm thick nitrile rubber preferred for insulation. Upon solving the heat transfer equation for 100mm pipe, I get the following values: K is the thermal conductivity of the insulating material = 0.0385 W/mK R1 is the outer radius of pipe from its center, say r1 = 0.055m for the nominal diameter 100mm
R2 is the outer radius of insulation from the center of pipe = need to be found?
#Ashrae 90.1 pipe insulation requirements skin
T2 is the insulation outer skin temp to be maintained, say 24 deg C (DPT= 22 deg C, DBT=35 deg C and RH is 50%) T1 is the pipe surface temperature = the operating fluid temperature = 6 deg C Q= and thickness of insulation (t) = r2-r1, Then use the one-dimensional steady state heat transfer equation to find the thickness of insulation. For this example I have take nitrile rubber with thermal conductivity k=0.0385 W/mK.Ĥ. PURPOSE The purpose of this standard is to provide minimum requirements for the energy-efficient design of buildings except low-rise residential buildings. Find the suitable insulation and its thermal conductivity from data books. tions and the publication dates of the addenda to 90.1-2004, see Appendix F.
#Ashrae 90.1 pipe insulation requirements series
This is done by finding the dew point temperature of the space and then adding 2 deg C. Since its creation in 1975, a series of revisions has continually improved the effectiveness of the ANSI/ASHRAE/IESNA Standard 90.1 (Energy Standard for Buildings Except Low-Rise Residential Buildings). Find the suitable outer surface temperature for the insulation ("T2" denotes the outer skin temp of insulation). This makes sure that the final temperature near AHU is NOT increased even by. Assumed the allowable heat transfer for different pipe sizes from 5 to 25 W/m pipe length ("Q" denotes heat flow).Īnd ASHRAE 90.1 standard. So, I tried calculating the required thickness of insulation that is sufficient to avoid condensation. Thanks all, esp Those links were really awesome!!Īnd regarding ASHRAE 90.1, it is clearly mentioned that the calculation of thickness is based on energy efficiency. RE: Insulation Thickness Calculation willard3 (Mechanical) 6 Oct 17 14:40 Would you please let me know about the selection? And what is the allowed heat gain in pipes considered in the second method? I'm confused which one to use. It was mentioned that the insulation's outer surface temperature should be greater than the dew point temperature in first method. They suggest two methods: (i) To prevent condensation and (ii) based on energy efficiency (from ASHRAE Std 90.1). Would anyone please guide me in selecting appropriate thickness of insulation? Is there any formula to calculate its thickness? It is mentioned in the specifications to use nitrile rubber for insulation with a conductivity of 0.035 W/mK. The operating range of temperature in pipes is 6 to 12 deg C and of ducts is air at 14 deg C. I need to calculate the insulation thickness needed for CHW pipes and ducts.