An explanation for the siphon phenomenon?
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There is such a phenomenon: the pressure at the high point of the return water in the water-cooled condenser is 3.5 MPa, and its height above the ground is approximately 18 meters. When the drain valve is opened, instead of water spraying outward, air is drawn inwards. How should it be explained? There is another phenomenon: when the exhaust gas absorption system is vented at a high point (50 meters), opening the drain at 15 meters also draws air into the pipe, with the pressure inside the pipe being 20 KPa. How should it be explained? It should all be a siphon effect. How should it be explained theoretically?
Why isn’t anyone answering? Here it is on Baidu! How can the question raised above be explained well? ? ? ? ? ? The principle of siphoning is the same as that of a communicating vessel: the pressure exerted on the liquid inside a sealed container is equal everywhere. The siphon tube is filled with water, without any air; the water level at the inlet side is high, and the outlet is covered with the palm of the hand or some other object. At this point, the pressure inside the tube is equal everywhere. Once everything is in place, the outlet is opened. Although the atmospheric pressure on both sides is equal, the water level at the inlet side is higher and the pressure is greater, which drives the water to flow continuously out of the outlet. The siphon effect is caused by the gravitational force between liquid molecules and the difference in potential energy; in other words, it utilizes the pressure difference in the water column to make the water rise before flowing to lower areas. Since the water surface at the pipe openings is subjected to different atmospheric pressures, water flows from the side with higher pressure to the side with lower pressure, until the atmospheric pressures on both sides are equal and the water levels inside the container become the same; at that point, the flow of water stops. The water in the container can be quickly drawn out using the siphon effect. Of course, gravity also plays an important role in the siphoning process. http://imgsrc.baidu.com/baike/pic/item/4a77b2afcd69dc8e7dd92a5c.jpg In fact, siphoning is not entirely caused by atmospheric pressure; it can occur even in a vacuum. The force that causes a liquid to rise is the cohesive force between the molecules in the liquid. When siphoning occurs, since more liquid flows out of the pipe than flows into it, the gravitational forces on both sides are unbalanced, causing the liquid to continue flowing in one direction. As the liquid flows into the tube, the pressure decreases as it moves higher. If the tube through which the liquid rises is very tall, the pressure will drop to the point where bubbles form inside the tube (composed of air or other gaseous substances), and the operating height of the siphon is determined by the formation of these bubbles. Bubbles break the continuity of the liquid, reducing the force between the gas molecules at either end of the bubble to zero, thereby disrupting the siphon effect; therefore, the tube must be filled with water. At normal atmospheric pressure, the siphon functions better than in a vacuum, as the atmospheric pressure acting on both ends of the tube increases the pressure inside the entire siphon.
Do you know if a broken siphon is related to the diameter of the inlet and outlet pipes of the equipment?
It’s best to draw a simple schematic; based on the principles of chemical engineering, apply Bernoulli’s equation to two cross-sections – if the pressure is lower than the external pressure, fluid will naturally flow inward.
This situation occurs when the difference in diameter between the backflow pipe and the main pipe is too large