Thanks for the reply. Indeed the note is specific. I have misquoted the note and the correct note is "Vendor to consider 10% extra margin on surface area by increasing air quantity". By this i understand 1. First design heat exchanger without any margin. BY this we know the required surface area for design condition. 2. Increase air flow rate with outlet temperature of air and other side (GW) open. By this require surface area increase and this increased area can be compared with case 1 to get 10% additional area. Let me know you view.
Edited by dattatray kolte, 23 March 2019 - 06:06 AM.