Flow and Heat-Transfer Characteristics of Droplet Impingement on Hydrophilic Wires.

It is a common phenomenon that droplets collide with wires in industrial production, and their flow and heat-transfer behavior significantly impact the production efficiency. This article presents an experimental and numerical study on the impact of pure water droplets on hydrophilic stainless-steel wires. The dynamic behavior and solid-liquid heat-transfer law of droplet impacting the wire are emphatically analyzed. The impact position of the droplets has a significant effect on their morphology. Under the condition of low Weber number (We), eccentric impacts tend to cause droplets to separate from the wire. Additionally, both We and wire/droplet size ratio have noticeable effects on the droplet morphology. The smaller the We, the larger the wire/droplet size ratio, and the easier it is for droplets to be captured by wires. Conversely, as We increases and the wire-to-droplet size ratio decreases, some droplets become detached from the wire, primarily exhibiting a single-film falling mode. Furthermore, the impact morphology of droplets is influenced by the Ohnesorge number (Oh). The higher the Oh, the more inclined the droplet to develop a double-film falling mode. There is obvious field synergy in the process of droplet impacting on wire. The maximum heat flux is located at the three-phase contact line, while the minimum heat flux is observed at the bubble interface. The impact position of droplets influences the temperature distribution, although its impact on the magnitude of temperature variation is minimal.

Effect of Non-Coal Heating and Traditional Heating on Indoor Environment of Rural Houses in Tianjin.

In order to understand the effect of the non-coal heating and the traditional coal-fired heating on the indoor environment of the rural houses, the humidity environment and indoor air quality in several households were investigated during the heating period in Beichen District and Wuqing District of Tianjin, China. The results showed that the indoor average temperature for the heating by the electricity and the natural gas was higher than that by the traditional coal fire. The indoor relative humidity for the heating by the electricity and the natural gas was lower than that by the traditional coal fire. The indoor air quality (IAQ) for the heating by the electricity and the natural gas was better than that by the traditional coal fire. For traditional coal-fire heating households, the indoor pollutant emission (CO emission) by using the clean coal was lower than that by using the raw coal. The indoor ventilation rate which was an important parameter for the indoor air quality was generally poor in winter. The total volatile organic compounds (TVOC) emission in the indoors of the coal-fired heating households was generally higher than that of the non-coaled heating households.