How is the steam ejector evacuated?

The principle of steam ejector is an ejector that uses steam as the working fluid to operate, although various specific purpose steam ejectors seek different purposes (such as steam jet vacuum pumps require the maximum injection coefficient at a specific injection pressure, or require a specific injection medium flow to achieve a minimum injection vacuum; Steam jet heat pumps, on the other hand, require the maximum compression ratio that can be achieved under a specific operating pressure or working load), but their basic working principle is similar, that is, the working steam is accelerated in the Laval nozzle to form a supersonic jet, and the pilot fluid is sucked into the mixing chamber due to the shear interaction with the working steam, and then gradually forms a single-homogeneous mixed fluid, which is decelerated and compressed to a fixed back pressure after a diffusion section and discharged from the ejector
。 The characteristics of steam ejector vacuum are that the flow rate at the throat is not the fastest, and the pressure is not low, on the contrary, the pressure in the throat section rises sharply and the speed drops sharply from the above figure steam ejector structure and fluid diagram, it can be seen that the throat section changes faster
than other parts of the diffuser.
Similarly, in the contraction section, the pressure gradually rises, the speed gradually decreases, and the change in the
expansion section is even more self-evident.
It can be concluded that the fluid in the entire diffuser section is a process of rising pressure and decreasing fluid velocity, and the throat section changes the fastest, but whether it is compressible fluid or incompressible fluid, the law of conservation of energy is applicable to any interface of the diffuser, including the throat section, the greater the flow rate of the steam, the smaller the inevitable pressure energy or potential energy, that is, the pressure energy or potential energy of the steam continues to increase on the entire diffuser The kinetic energy continues to decrease, and only the throat section changes the fastest as to the role of the throat segment and the contraction section can be understood as The function of the diffuser section is to increase the kinetic energy of the steam into pressure energy, and the saturated vapor pressure of the steam after pressurization rises, so that it can be all condensed in the water cooler behind the hose section due to the sharp pressurization effect of shortening the length of the diffuser section correspondingly reducing the size of this evaluator and reducing the material.
The original basis for steam ejector evacuation is the classical law of conservation of energy, and the kinetic energy of the kinetic energy of the dynamic steam generates negative pressure at the nozzle to absorb the medium of low energy, so that they are mixed energy exchange in the throat, and the large energy drives the small energy to finally enter the next stage together, and the sum of the energy is consistent
.