Saturated vapor When some of the wa化西ter molecules in the gas phase change t厭綠o a liquid state due to a快妹 change in temperature or press睡厭ure, the vapor is called "wet 購亮vapor" when it contains some wat放放er.
Completely gaseous water molecul站相es are called "dry steam暗購".
Saturated vapor is actu去道ally the critical point at w員草hich water molecules change from 個刀liquid to gas.
Steam is one of the mos什快t widely used second音來ary energy sources in production a媽離nd life. Phase transformat美說ion is inevitable in the process of煙去 steam transportation and u路能tilization.
For example, when steam 子山is discharged from a heat source pla花影nt (station), it is superheate師女d. Due to the natural heat dissipa低他tion of steam pipe, s得習team temperature decreases gr微你adually with the increa影商se of conveying dist樂裡ance. At the beginnin時遠g, the superheat of steam 風通decreases, but at a certain 是個point, when the superheat 黑裡drops to 0, the steam presents a cr美道itical saturation state. With the incr科務ease of transmission dist高話ance, the saturated 票錢steam turns into wet steam.
The phase transition occurs讀雪 in the process of transmiss房關ion, so the density compens鐘小ation cannot be carried out by 行數the conventional method of tem妹個perature and pressure c金畫ompensation.
The temperature of wet steam tw物木o-phase flow remains co海高nstant under certain pressure conditi紙從ons, so it is difficult to direct海議ly measure humidity by們廠 combining temperature and p年麗ressure with gas state廠國 equation.
The density and enthalpy of wet steam熱見 will change with the 年信change of humidity, so the acc匠外urate measurement of humidity is the k不熱ey difficulty of wet steam訊懂 measurement.
The state of water in steam
Principle of vapor humidity朋器 measurement based o飛理n optical principle: 睡樂Light will attenuate in the li還北quid phase particle 數月medium of wet vapor, and the 靜數relation between humidity and att嗎微enuation is as follows
Φ:Humidity of wet steam two-phase fl學花ow IO:Attenuating prelight intensity I:Attenuated light inte民做nsity L:Optical path
Wet steam two-phase flow multi-p快人arameter measurement solut計如ion, through the optical頻跳 principle of humidity measuring dev購小ice and general differential pressu她為re or velocity flowmete學吧r combination measurement to ach玩數ieve humidity, mass flow and ent工妹halpy comprehensive online mea頻暗surement of wet steam.
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