Evaporatively cooled heat exchangers are an alternative to air-cooled or water-cooled heat exchangers for heat rejection to the environment. Previous work on an experimental vertical-tube heat exchanger has shown that in many applications the controlling resistance to heat transfer takes place at the air-water interface. To decrease this controlling resistance, heat transfer enhancement techniques must be employed. In this work, the design of coiled wire turbulence promoters for heat transfer enhancement is described. The testing results of two turbulence promoters with different spacings from the wall are presented. The preferred design for minimizing the air pressure drop is identified. The effectiveness of turbulence promoters for heat and mass transfer enhancement, as an alternative way to extend surfaces, is shown.