Original Title: Tunnel Drying Experimental Device, Tunnel Drying Experimental Equipment JGKY-GZ/DD Tunnel Drying Experimental Equipment Overview: The tunnel drying experimental equipment is developed by Beijing Jinggong Science and Education Equipment Co., Ltd. for the teaching experiment of tunnel drying and related disciplines, which is suitable for different types and levels of professional teaching experimental equipment. The main purpose is to improve students'practical ability, ability to analyze and solve problems, and deepen students' perceptual knowledge of theories and concepts in classroom teaching. The purpose of the tunnel drying experiment is to understand the flow, structure and process principle of the airflow atmospheric drying equipment, to master the measurement method of the drying rate curve, and to understand the influence of changing the operating conditions on different drying stages; Product reference picture: The experimental equipment 3D simulation teaching software, on the one hand, can save a lot of time for teachers to write on the blackboard and overcome the problem of reduced class hours; on the other hand, Vividly demonstrate the working principle in the form of animation, display various photos learned, schematic diagrams or circuit diagrams of complex systems, so that students can understand intuitively and understand and apply more easily. Screenshot of tunnel drying 3D simulation software: Expand the full text I. Purpose of the experiment 1. Practice and master the determination method of drying curve and drying rate curve. 。 2. Practice and master the method of measuring the moisture content of materials. 。 3. The critical water content of materials is deepened through experiments. Xc concept and its influencing factors. 4. Practice and master the measurement method of convective heat transfer coefficient between material and air in constant speed drying stage. 。 5. Learn to use the error analysis method to estimate the error of the experimental results 。 II. Contents of the experiment 1． Under the condition of fixed air flow and air temperature, the drying curve, drying rate curve and critical water content of a certain material are measured and drawn. 2． Measure the convective heat transfer coefficient between the material and the air in the constant-speed drying stage. III. Experimental principle When the wet material is in contact with the dry medium, the moisture on the surface of the material begins to gasify and transfer to the surrounding medium. According to the characteristics of medium transfer, the drying process can be divided into two stages. The first stage is a constant-speed drying stage. At the beginning of the drying process, due to the large moisture content of the whole material, the moisture inside the material can quickly reach the surface of the material. At this time, the drying rate is controlled by the gasification rate of the surface moisture of the material, so this stage is called the surface gasification control stage. In this stage, all the heat transferred from the drying medium to the material is used for the gasification of water, the surface temperature of the material remains constant (equal to the wet bulb temperature of hot air), nutsche filter dryer ,jacketed glass reactor, the partial pressure of water vapor on the surface of the material also remains constant, and the drying rate is constant, so it is called constant-rate drying stage. And that second stage is a speed reduction dry stage. When the moisture content of the material reaches the critical moisture content after drying, it enters the stage of deceleration drying. At this time, the moisture content in the material is less, the moisture transfer rate from the interior to the surface of the material is lower than the gasification rate of the moisture on the surface of the material, and the drying rate is controlled by the moisture transfer rate inside the material. This is called the internal migration control phase. As the moisture content of the material gradually decreases, the migration rate of moisture in the material gradually decreases, and the drying rate decreases continuously, so it is called the falling rate drying stage. The main factors affecting the drying rate and critical moisture content in the constant rate section include the type and nature of the solid material, the thickness or particle size of the solid material layer, the temperature, humidity and flow rate of the air, and the relative motion mode between the air and the solid material. The drying rate and critical moisture content in the constant rate section are important data for the study of drying process and the design of dryer. In this experiment, canvas material was dried under constant drying conditions, and the drying curve and drying rate curve were measured and drawn. The purpose was to master the measurement methods and influencing factors of drying rate and critical moisture content in constant speed section. 1. Determination of drying rate ： 2. Dry basis water content of materials ： 3. Measurement of Convective Heat Transfer Coefficient in Constant Speed Drying Stage ： 4. Calculation of Actual Volume Flow of Air in Dryer ： IV. Basic information of the experimental device 1． Basic information of the experimental device Tunnel size: length 1.16 m, width 0.190 m, height 0.24 m Heating power: 500 w-1500 w Air flow: 1-5m3/min Drying temperature: 40-120 ℃ Weight sensor indicator: measuring range (0-200 G);. Dry bulb thermometer, wet bulb thermometer display: measuring range (0-150 ℃) Thermometer indicator at orifice flowmeter: measuring range (0-100 ℃) Orifice Meter Differential Pressure Transmitter and Display: Range (0-10 Kpa) The absolute error of electronic stopwatch is 0.5 second. 2. Instrument panel diagram of tunnel dryer experimental device (See Figure 2) Fig. 2 Panel Diagram of Tunnel Dryer Experimental Device 3． Flow diagram of tunnel dryer experimental device (see Fig. 1) Fig. 1 Flow Diagram of Tunnel Dryer Experimental Device 1-Exhaust gas discharge valve; 2-Exhaust gas circulation valve; 3-Air inlet valve; 4-Tunnel dryer; 5-Fan; 6-Dry material; 7-Weight sensor; 8-Dry bulb thermometer; 9-Orifice flowmeter; 10-Wet bulb thermometer; 11-Air inlet thermometer; 12-Heater; 13-Dry bulb temperature display control instrument; 14- Wet-bulb temperature indicator; 15- Inlet temperature indicator; 16- Flow differential pressure indicator; 17- Weight indicator; V. Experimental operation method Manual operation 1. The material will be dried (Canvas) is soaked in water, and the beaker containing the gauze of the wet bulb thermometer is filled with water. 2. Butterfly valve for adjusting the suction of the blower 3 Start the fan after reaching the full open position. 3. Through the exhaust valve Turn on the heating power supply after the exhaust gas recirculation valve 1 and exhaust gas recirculation valve 2 regulate the air to the specified flow. Set the dry bulb temperature in the intelligent instrument, and the instrument will automatically adjust to the specified temperature. 4. At air temperature . Read and record the weight of the bracket measured by the weight sensor under the condition of stable flow. 5. Fully wetted dry material (Canvas) 6 is fixed on the weight sensor 7 and placed parallel to the air flow. 6. Under the stable condition of system ? Record the weight loss of the dried material every 3 minutes during the drying time until the weight of the dried material is no longer significantly reduced. 7. Air flow and air temperature can be varied ? Repeat the above experimental steps and record the relevant data. 8. At the end of the experiment ? Turn off the heating power supply first, and turn off the fan power supply and the main power supply after the dry bulb temperature drops to normal temperature. Everything is restored. VI. Precautions 1. The weight sensor has a range of The accuracy is relatively high, so be sure to handle with care when placing dry materials, so as not to damage or reduce the sensitivity of the weight sensor. 2. The heating device can only be turned on when there is air flowing through the dryer ? To avoid damage to the heater due to dry firing. 3. The dry material shall be fully wetted, but no water shall drip down. Otherwise, the accuracy of the experimental data will be affected. 4． Do not change the settings of the smart meter while the experiment is in progress. VII. Examples of experimental data processing (for reference only) 1. Results of the commissioning experiment See Table 1 for commissioning test data, and the symbols in the table are as follows: S-drying area m2; GC-absolute dry material quantity G; R-reading of air flowmeter kPa; To-dryer inlet air temperature ℃; t-dry bulb temperature of the place where the sample is placed ℃; Tw-wet bulb temperature of the place where the sample is placed ℃; GD-weight of the sample support frame G; GT-total weight of the material to be dried and the supporting frame G; G-weight of the material to be dried G; T-accumulative drying time S; X-dry basis water content of material kg water/kg absolutely dry material; XAV-the average moisture content of the material to be dried between two records, kg water/kg dry material; U ─ drying rate kg water/ (s · m2) 2． Data calculation example: Take the data of group I and I + 1 in Table 1 as an example. The drying curve X-T curve is plotted with X and T data,cbd crystallization equipment, as shown in Fig. 3. The drying rate curve U-X curve is plotted with U and XAV data, as shown in Fig. 4. Convective heat transfer coefficient from air to material surface in constant velocity state Take the experimental data in Table 1 as an example for calculation. i＝1 i＋1＝2 GT，i＝201.1[g] GT，i＋1＝199.5[g] GD＝101.3[g] From formula (1) and (2): Gi = 99.8 [G] Gi + 1 = 98.2 [G] GC = 30.6 [G] From formula (3) and (4): Xi = 2.2614 [kg water/kg dry material] Xi + 1 = 2.2092 [kg water/kg dry material] From formula (5): XAV = 2.2353 [kg water/kg dry material] S＝2×0.145×0.082=0.02378[m2] Ti＝0 [s]， Ti＋1＝180 [s] From formula (6): U = 3.738 × 10-4 [kg water/ (s · m2)] 3. Experimental data record sheet and related images Table 1 Experimental data records and collation results Fig. 3 Drying Curve of Experimental Device Fig. 4 Drying Rate Curve of Experimental Device See related products for details: M. Bjhjwy. Com/A1.html "> Reynolds Experiment Platform m. Bjhjwy. Com/A2.html" > Bernoulli Experiment M. Bjhjwy. 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