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Heat exchangers are one of the most common and important in many industries. When using heat exchangers in dirty applications, the thermal performance of heat exchangers was reduced. Therefore, coatings may be applied to the surfaces of heat transfer for corrosion protection. In this work, tungsten trioxide (WO3) nanoparticles were used with epoxy resin to enhance the performance of heat exchangers. The brass (B-111) samples were coated with the neat epoxy and a solution consisting of epoxy and tungsten trioxide nanoparticles in different proportions by the dip-coating method. All samples were characterized by contact angle measurement, XRD, SEM, EDS, AFM. Heat transfer experiments were carried out at various hot water temperatures and various cold water flow rates. Results show that the tube coated with epoxy contains 1% wt of WO3 nanoparticles has a high overall coefficient of heat transfer and effectiveness compared with a neat epoxy coated tube. The increase in the cold water flow rate contributes to the increment in the heat transfer for these three tubes and increase in the hot water temperature leads to the increment in the heat transfer for a tube without coating and a tube coated with epoxy but a tube coated with epoxy contains 1% wt of WO3 nanoparticles shows a stable behavior. Additionally, the rise in the flow rate of cold water contributes in the decrease in the effectiveness for the three tubes but with the rise in temperature of hot water, a tube without coating and the epoxy coated tube show unstable behavior but the epoxy and 1% wt of WO3 nanoparticles coated tube shows a stable behavior. [ABSTRACT FROM AUTHOR]