How structure type of chemical wastewater evaporator influence heat transfer in evaporator?

There are many structural types of chemical wastewater evaporator, no matter what kind, in the design and production must make the refrigerant steam can quickly leave the heat transfer surface and maintain a reasonable liquid level height, effectively make full use of the heat transfer surface. When the refrigerant liquid is throttled, a small amount of steam can be separated from the liquid through the vapor-liquid separation equipment, and only the liquid separated from the vapor is sent to the evaporator for heat absorption to improve the heat transfer effect of the vaporizer.

If the liquid can be vaporized and boiled on the wet heating surface, the root of the bubble is small, the volume of the bubble is not large, and the bubble capacity is easy to leave the heating surface and rise. If the liquid cannot be vaporized and boiled on the wet heating surface, the volume of the bubble formed is large, the root is large, and the number of vaporized cores will be reduced. At this time, the bubble will gather on the heating surface and develop steam film along the heating surface, resulting in the increase of thermal resistance and the decrease of heat release coefficient. Some commonly used refrigerant liquids have good wettability, so they have good exothermic performance. The wettability of ammonia is better than that of freon.

In the evaporator, when the refrigerant side of the refrigerant liquid is mixed with lubricating oil, the oil at low temperature is very dry, easy to attach to the heat transfer surface to form an oil film and is not easy to discharge, thus increasing the heat transfer resistance; At the same time, the formation of oil film will also prevent the refrigerant liquid from wetting the heat transfer surface and reduce the heat transfer efficiency. In serious cases, the refrigerant will not absorb the outside heat at all and lose the cooling effect.

Water, salt water and the air is common in refrigeration equipment cooling medium, the exothermic strength in addition to the related to its physical properties, and flow velocity, the velocity of the son's shape and external factors such as flow path. When the flow rate is large, the geometry of the flow rate and the flow path are reasonable, the heat release coefficient increases, but the corresponding power consumption and the cost of basic facilities also increase. The most suitable flow rate and the layout of the fluid channel should be determined by technical and economic analysis and comparison.