Sweating-boosted air cooling using nanoscale CuO wick structures

Abstract

Low heat transfer coefficient (HTC) in air/fin-side is the bottleneck of dry cooling strategies for thermal power plants. Inspired by the phase change heat transfer during the perspiration of mammals, a sweating-boosted air cooling strategy with on-demand water dripping is proposed. The testing samples are featured with macroscale grooves for global liquid delivery, and with nanoscale hydrophilic copper oxide (CuO) wick structures for local liquid spreading. The experiments of sweating-boosted air cooling are conducted in a wind tunnel system. There are three wetting conditions with increasing dripping rates: dry, partially wetted, and flooded conditions. In the partially wetted conditions, the surface temperatures reduce and HTCs increase with increasing dripping rates. For a given dripping rate of water, HTCs are enhanced and surface temperatures are reduced with increasing air velocities. High air velocity and low surface temperature have a trade-off effect on the evaporation process. This effect results in almost constant saturated dripping rates for a given thermal load. A linear relationship between the saturated dripping rates and the thermal loads confirms that the evaporation dominates the heat transfer process of sweating-boosted air cooling. Complete surface wetting is obtained on the designed surfaces, but no obvious effect of groove width on HTCs is observed. Sweating-boosted air cooling can significantly increase air-fin side HTC in air cooled condenser (ACC), and dramatically reduce the water consumption compared to current water evaporative

Sustainable dropwise condensation enabled ultraefficient heat pipes

“… 24,27 The CuO nanostructure was applied to enhance the evaporation inside the heat pipe (Figure 1d). The nano CuO coating has been experimentally explored as one of the efficient superhydrophilic coating that can enhance the thin film evaporation with a water contact angle close to 0° 28 . Microscale surface morphologies of these two coatings are shown in Figure 1e,f.…”

Thermal Characterisation of Micro Flat Aluminium Heat Pipe Arrays by Varying Working Fluid and Inclination Angle

“…With the integration of inner ribs acting as fins, heat can spread from the upper surface to the bottom surface, as schematically shown in Figure 2. Thus, evaporation can be extended on all of the inner surface areas, which at least doubles the evaporating areas and can greatly enhance the overall heat transfer rate [34,35]. The configuration and working mechanism of a MF-AHPA are also schematically shown in Figure 1.…”

“…Thus, evaporation can be extended on all of the inner surface areas, which at least doubles the evaporating areas and can greatly enhance the overall heat transfer rate [34,35]. …”

The effect of femtosecond laser fluence and pitches between V-shaped microgrooves on the dynamics of capillary flow

“…In general, performance of superwicking surfaces depends on wettability of a solid, which is mainly affected by surface energy, liquid viscosity and the morphology of the solid surface [12] , [13] . Based on these factors, various techniques have been developed to intrinsically change the wettability of solid surfaces, such as plasma treatment [14] , [15] , chemical etching [16] , [17] , [18] , mechanical treatment [2] , [19] , [20] and laser ablation [21] , [22] , [23] , [24] , [25] , [26] . Among these methods, laser ablation technology has more advantages such as simple operation and no need for a complex processing environment.…”