Experimental study on condensation heat transfer of steam on vertical titanium plates with different surface energies

Combined Visualization and Heat Transfer Measurements for Steam Flow Condensation in Hydrophilic and Hydrophobic Mini-Gaps

“…Heat fluxes and heat transfer coefficients in dropwise condensation on flat plates [1,[19][20][21][22] or external tubes [23][24][25][26] have been found to be 5-20 times higher than filmwise condensation for these external flows. Surface properties such as contact angle [27], surface roughness [20,28,29], and droplet state (i.e., Ref.…”

“…[30] or [31]) are essential for promoting dropwise condensation. In order to obtain desired surface properties to form dropwise condensation, surfaces have been modified with surface roughness at multiple length scales [20,29,30,[32][33][34], anisotropic patterns [1,28,35], self-assembled monolayers [36,37], electroplating [38], ion implantation [25], and low-surface-energy material coatings [39]. For external flows, droplet nucleation, growth, coalescence, and departure have been identified as critical parameters of heat transfer performance of dropwise condensation [40][41][42][43][44][45], with decreased thermal resistances for lower droplet sizes [46][47][48].…”

“…Condensers are critical heat exchangers for a wide range of applications, such as power plants, seawater desalination, and chemical processing equipment [1]. In 2014, 86% of electricity in the United States was generated using thermal cycles [2].…”

Flow condensation heat transfer enhancement in a mini-channel with hydrophobic and hydrophilic patterns

“…A film wetted the hydrophilic channel walls, while dropwise condensation at the inlet of the hydrophobic channel yielded a slightly (15%) higher heat flux compared to the hydrophilic tube. In contrast, significant enhancement has been found by promoting dropwise condensation of steam on external tubes and plates, which offered heat flux enhancements of 5 to 20 times that of filmwise condensation under the same conditions [5][6][7][8][9][10][11][12][13].…”

“…Despite larger heat transfer coefficients achieved by researchers at the mini-and micro-scales, few enhancements other than channel shape have been found at the mini-and micro-scale. Dropwise condensation, on external surfaces and in vapor space, offered an order of magnitude enhancement in heat transfer coefficients [5][6][7][8][9][10][11][12][13] but has seldom been applied to internal flows. However, promotion of dropwise condensation in internal condensation would reduce condenser size.…”