Experiment 1 Bernoulli Experiment
First, the purpose of the experiment.
1. Familiar with the concept and mutual conversion relationship of various energies and indenters in fluid flow, and deepen the understanding of Bernoulli's equation.
2. Observe the change law of various energies (or indenters) with flow velocity.
Second, the principle of experiment.
1. When the incompressible fluid flows stably in the pipe, due to the change of pipeline conditions (such as position, pipe diameter, etc.), it will cause the corresponding change and mutual conversion of three kinds of mechanical energy - potential energy, kinetic energy and static pressure energy in the flow process. For an ideal fluid, the sum of the three energies is conserved at any section of the system, although they are not necessarily equal (the law of conservation of mechanical energy).
2. For the actual fluid, due to the internal friction, there is always a part of the mechanical energy of the fluid in the flow that is converted into heat energy with friction and collision and lost. Therefore, for the actual fluid, the sum of the mechanical energy on any two sections is not equal, and the difference between the two is the mechanical loss.
3. The above mechanical energy can be expressed by the liquid level difference in the U-shaped pressure differential gauge, which is called the potential pressure head, dynamic pressure head and static pressure head. When the small hole (i.e., the pressure hole) in the manometer straight pipe is perpendicular to the direction of the water flow, the height of the liquid column (potential pressure head) in the pressure tube is the sum of the static pressure head and the dynamic pressure head. The difference between the sum of the indenter, the static indenter and the dynamic indenter between any two sections is the loss indenter.
Experiment 2 Centrifugal pump performance curve determination
First, the purpose of the experiment.
1.Learn about the construction and operation of centrifugal pumps.
2.Learn and master the determination method of the characteristic curve of centrifugal pump.
Second, the principle of experiment.
The main performance parameters of centrifugal pumps are flow rate Q (also called liquid delivery capacity), head h (also called pressure head), shaft power n and efficiency. The characteristic curves of centrifugal pumps are the relationship curves between q-h, q-n and q-.
Experiment 3 Filtration experiment
First, the purpose of the experiment.
1.Learn about the construction and operation of plate and frame filters.
2.Master the method of measuring the constant pressure filtration constant, and determine the constant pressure filtration constant;Virtual filtrate volume;Virtual filter time.
Second, the basic principle.
For incompressible filter residues, the relationship between the filtrate volume and the filtration time in the case of constant pressure filtration.
Experiment 4: Heat transfer experiment
First, the purpose of the experiment.
A quasi-correlation for determining the convective heat transfer coefficient.
Second, the principle of experiment.
The core problem of convective heat transfer is to calculate the heat transfer coefficient, and the general form of the convective heat transfer criterion correlation formula when the fluid has no phase change is:
Experiment 5: Distillation experiment
First, the purpose of the test.
1.Master the structure of the distillation column.
2.The theoretical number of plates and the efficiency of the distillation column were determined.
Second, the principle of experiment.
1.Theory plates.
2.The number of theoretical plates is found by the graphing method.
3.The whole column efficiency et of the distillation column is the ratio of the theoretical number of plates to the actual number of plates n, i.e.:
et=nt/n
The veneer efficiency of the distillation column can be calculated from the gas phase (or liquid phase) by measuring the concentration change of the plate.
If calculated as a change in liquid phase concentration, it is:
eml=(xn-1-xn)/(xn-1- xn*)
If calculated as a change in gas phase concentration, it is:
emv=(yn-yn+1)/( yn*-yn+1)
Where: the liquid composition of the falling plate of xn-1 --- n-1, molar fraction;
xn --- composition of the liquid descending from the nth plate, molar fraction;
xn*--Composition of the liquid phase equilibrium with the liter steam yn phase on the nth plate, molar fraction;
YN+1--- composition of rising steam in the n+1 plate, molar fraction;
yn--- composition of the nth plate rising steam, molar fraction;
yn* -- composition of the gas phase equilibrium with the descending liquid xn on the nth plate, molar fraction.
Experiment.
6. Absorption experiment
1. Experimental principle.
In this experiment, ammonia is absorbed from an air-ammonia mixture with water. The concentration of ammonia in the gas mixture is very low. The concentration of the resulting solution is also not high. The equilibrium relationship between gas and liquid phases can be considered to obey Henry's law (i.e., the equilibrium line is a straight line in the x-y coordinate system). Therefore, the logarithmic average concentration difference method can be used to calculate the average driving force of mass transfer in the packing layerExperiment 7 Drying experiment
First, the purpose of the experiment.
1.Understand the basic process and working principle of airflow drying equipment.
2.The drying rate curve and mass transfer coefficient of the material under certain drying conditions were determined.
Second, the principle of experiment.
1.Drying characteristic curve.
The drying process is divided into three stages: material preheating stage, constant speed drying stage and reduced speed drying stage.
2.Mass transfer coefficient.
Constant velocity stage: The drying rate u of the constant velocity stage is determined only by the external drying conditions, and the surface temperature of the material is close to the air wet bulb temperature tw.
Drying stage: the shape of the drying rate curve in the drying stage varies with the internal structure of the material and the properties of the moisture contained in it, so the drying curve can only be obtained through experiments, the calculation of the drying time in the reduction stage can be obtained according to the rate curve data, when the drying rate of the reduction stage is approximately proportional to the free water content of the material (x-x*), the drying rate curve can be simplified to a straight line.