Heat transfer measurement during dropwise condensation using micro/nano-scale porous surface

Unique micro/nano-scale porous surfaces were fabricated on the surfaces of steam condensers to promote dropwise condensation which can exhibit higher heat transfer rate than that of filmwise condensation. Steam condensation tests were conducted to evaluate heat transfer performance of the fabricated micro/nano-scale porous surfaces. The micro/nano-scale porous surfaces were prepared using a self-assembly technique, polymer based thin coatings, and a surface etchings technique. The resulting surface morphologies and the wetting characteristics were investigated using SEM and the liquid contact angle measurements to quantify important parameters for enhancing the dropwise condensation. From visual observations, it was deduced that the micro/nano-scale porous surfaces can effectively initiate dropwise condensation by generating smaller condensates and limiting the growth of 'large' condensate drops and by improving surface renewal rate.