Advanced Materials and Technologies Laboratory, Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061-0238, United States.
Langmuir. 2023 Jul 18;39(28):9885-9892. doi: 10.1021/acs.langmuir.3c01123. Epub 2023 Jul 6.
Hydrophobic, lubricant-infused surfaces offer enhanced potential for dew harvesting compared to bare metal substrates due to their water repellent nature. Most of the studies to date examine the condensation effectiveness of the nonwetting surfaces over a short duration and have not considered the durability or performance of the surfaces over extended periods. To address this limitation, the present study experimentally investigates the long-term performance of a lubricant-infused surface subject to dew condensation for 96 h. Condensation rates as well as sliding and contact angles are measured periodically to examine the surface properties and water harvesting potential over time. Due to the narrow time window in which dew harvesting can be conducted in application, the additional collection time gained by shedding droplets at lower nucleation times is explored. It is shown that three phases occur in lubricant drainage, which affect performance metrics relevant to dew harvesting. The first 24 h of condensation induces drainage that has little effect on the adhesion of droplets to the surface and on the additional collection time. The next phase, from about 24 to 72 h, showed steady drainage and a steady decrease in performance. The final 24 h, from about 72 to 96 h of operation, was seen to have little added effect on drainage and therefore on the performance metrics. The study bears significance in the design of surfaces for long-term use in practical water harvesters.
疏水性、润滑剂注入的表面由于其疏水性质，与裸露的金属基底相比，具有更高的露水收集潜力。迄今为止，大多数研究都在短时间内检查了非润湿表面的冷凝效果，而没有考虑表面在长时间内的耐久性或性能。为了解决这一限制，本研究通过实验调查了润滑剂注入表面在 96 小时内露水冷凝的长期性能。定期测量冷凝速率以及滑动和接触角，以检查表面特性和随时间推移的水收集潜力。由于在应用中可以进行露水收集的时间窗口很窄，因此研究了通过在较低成核时间下滴下露水来获得额外的收集时间。结果表明，润滑剂排水过程中发生了三个阶段，这会影响与露水收集相关的性能指标。冷凝的前 24 小时会引起排水，这对液滴在表面上的附着力和额外的收集时间几乎没有影响。接下来的阶段，从大约 24 小时到 72 小时，显示出稳定的排水和性能的稳定下降。在操作的最后 24 小时，从大约 72 小时到 96 小时，几乎没有对排水和因此对性能指标产生额外的影响。这项研究对实际水收集器中用于长期使用的表面设计具有重要意义。
