Study On Dynamic Pressure Rise Measurement And Frosting Characteristic In Freeze-drying

Vacuum freeze drying is the process of moisture's sublimation and desorption dries in the condition of low temperature and vacuum. The measure and control of the inteifacial temperature of the sublimation have important meaning on preventing the freezing-dry materiel's dissolving and dent and increasing the velocity of dryness in whole hog. The technique of dynamic pressure rise measurement is a non-contacting measure method which is only belong to freeze-dry and it has more unexampled merits that others doesn't have. The technique of dynamic pressure rise measurement can not only measure the interfacial temperature but also supervise the process of freezing-dry. It can exactly reflect the concluding time of freezing-dry; because of this the technique of dynamic pressure rise measurement has an important meaning in process of heat and mass transfer. In the next place, the problem of the frosting under the low pressure is always difficulty and hotspot in researching. For water-catcher optimize design, the frost's density and the heat conductivity is very important. In this paper there are some points:(1) Set up the math model of the technique of dynamic pressure rise measurement and the means to deal with the data regression; Analyze the restricting condition of the technique of dynamic pressure rise measurement via experimental research on solid materiel and liquid materiel; Set up the relationship among of leak-ratio of freeze-dry room, the capacity of taking out gas of vacuum pump, the lowest temperature limit of dynamic pressure rise measure and the errors of measure. Supply theory according for implementing the technique of dynamic pressure rise measurement and freeze-dryer's design.(2 ) Independently develop software system of dynamic pressure rise measurement actualized on freeze-dryer.(3) Carry out frosting experiment under low-pressure and get frost density; by observing and analyzing experimental data, bring forward that water-catcher's frost has double-deck configuration under low-pressure, the one which closes to the surface has smaller heat conductivity, and make heat conduct become worse; Carry through experiments measure and account the heat conductivity for this double-deck configuration; Establish the bases of water-catcher's optimize design.