Its working principle is condensing to achieve the heat transfer.
When the wall temperature is lower than the saturated steam temperature, steam will condense into liquid when in contact with wall phase, at the same time release of the latent heat of vaporization and the heat passed on to the wall, the wall will transfer the heat to the other side, this heat exchange process is called condensation heat transfer.
In general, the single component condensation heat transfer is an efficient heat transfer process, and its heat transfer coefficient is higher than that of the single phase convective heat transfer coefficient of the same fluid.However, the condensation heat transfer coefficient will be greatly reduced because of the condensation of the mixture containing non-condensable gases.
The condensing process of two-phase flow heat transfer is widely used, Such as condensation of gas come from the top of the distillation tower; water vapor condenses to heat air heat exchanger; refrigerant steam condensation, etc.
In the process of condensation of main equipment are involved in tube and shell condenser, air heat exchanger, plate condenser and spiral plate condenser, etc., mainly contains no non-condensable gas distillate, or for the purpose of heating air steam condensation.
The correlation of condensation mechanism is based on a large number of experimental research data and literature data, and all kinds of condensing mechanisms have their application conditions and occasions, which have certain limitations.It is unscientific to oversimplify or use the same correlation in all kinds of condensation.
For example, whether the condensing in the tube or outside the tube, whether gravity control flow or scissors force control flow;whether horizontal or vertical installation;it is not advisable to adopt the same model.In fact, the accuracy of any method is related to its application.
Therefore, when discussing the mechanism of condensation heat transfer, the specific equipment should be combined with the process.