In order to solve the unsatisfactory heat and mass transfer in polymer indirect evaporative coolers(IEC)resulting from poor wetting in the wet channels,a nano-coated polypropylene(PP)IEC is proposed,aiming at improving the hydrophilicity.The experiment focused on the hydrophilicity and durability of the nano-coated PP plate,and explored the effect of its water distribution.The results show that the coated PP plate shows good hydrophilicity,and the static contact angle of water can be reduced to less than 10°.Meanwhile,the coating has a good water resistance ability,and the contact angle is stabilized at about 30° after long-term testing by water souring.In addition,under experimental conditions,the nano-coating core can reach above 80%wetting rate in about 1 min.It is also found that the coated PP surface forms a porous structure with water absorption ability,which facilitates the realization of intermittent water spraying in IECs.Under the condition that the wet bulb efficiency remains stable,the coefficient of performance is 54%higher than that of traditional continuous water distribution.
indirect evaporative coolernano-solutionhydrophiliccontact anglewettabilityintermittent water distribution