Experimental analysis of dropwise condensation heat transfer on a finned tube: Impact of pitch size

Abstract

Condensation is one of the essential processes in diverse industries due to its widespread use in various industrial applications such as power generation, water desalination, and air conditioning. Much research has been conducted to achieve better efficiencies and better heat transfer performances in condensers in the past decades. Condensation is divided into dropwise and filmwise based on the surface free energy, surface roughnesses, and condensate characteristics. This study investigated the influence of the 1-Octadecanethiol coating on vertically grooved copper tube’s condensation heat transfer characteristics. The hydrophobic surfaces have been created using self-assembled monolayers (SAMs) on the pure copper tubes (99.9% Cu). Moreover, four different pitch sizes of 1.5, 2, 2.5, and 3.5 mm have been implemented on the surface. Finally, the heat flux and the heat transfer coefficient as functions of logarithmic mean temperature difference are reported in the result section. For validation, the results obtained from the experiment were compared with available data in the literature, and an acceptable agreement was achieved. According to the results, it was found that the 1.5-mm pitch size has the highest heat flux, and the 3.5-mm pitch size has the lowest heat flux. Additionally, it can be inferred that the maximum heat flux of 696.71 kW/m2 was attributed to the 1.5-mm pitch size for logarithmic mean temperature differences of 64.3 K, which is approximately 1.24 times higher compared to the plain tube.