# Study on the Influence of Different Factors on Pneumatic Conveying in Horizontal Pipe
## 4 Simulation Results and Analysis
### Simulation Results and Analysis of Different Mass Flow Rates  
In order to study the influence of mass flow rate on the conveying characteristics of particles, the mass flow rate of other working conditions is set to 0.4 kg/s, 0.6 kg/s, or 0.8 kg/s based on the benchmark working conditions, and the control variable method is used for simulation analysis. The simulation results are as follows. Figure 9a is the fluid  
Figure 8: Velocity and pressure drop change curve with conveying wind speed. (**a**) Variation of average value of final stable velocity with conveying wind speed; (**b**) Variation of pipe pressure drop with conveying wind speed. dynamic pressure cloud diagram under different mass flow rates in the sampling section. Figure 9b shows the cloud diagram of particle mass concentration changes under different mass flow rates in the sampling section. It can be seen from Figure 9 that the overall dynamic pressure in the pipe does not change much with the increase of particle mass flow rate. From the specific value, the maximum value of dynamic pressure in the pipe increases, while the minimum value decreases, showing different changing trends. The increase of particle mass flow rate means that the number of particles in the pipeline increases. However, the conveying wind speed is unchanged, that is, the total energy transferred to the particles by the wind is unchanged. When the number of particles increases, the energy obtained by each particle will decrease, and the dynamic pressure is small, resulting in a small particle velocity. The number of particles suspended in the high-speed zone is little, the kinetic energy of each particle is larger, and the dynamic pressure is larger. As can be clearly seen from the picture, with the increase of particle mass flow rate, the particle mass concentration in the pipeline also increases, which is in line with the actual situation. From the perspective of the low-speed zone, when the particle mass flow rate increases at the rate of 0.2 kg/s, the increment of particle mass concentration is 73, 60, and 180 respectively, that is, when the particle mass flow rate increases from 0.6 kg/s to 0.8 kg/s, the particle mass concentration changes the most, at this time, the porosity of particles is small, and the collision between particles increases, and it will lead to the increase of breakage in actual transportation. Figure 10 shows the relationship between the average velocity of particles in the 0.5 m pipes length in the three zones with time under different mass flow rates. It can be seen from Figure 10 that under the condition of a certain conveying wind speed, the increase of particle mass flow rate has almost no effect on the time for the first particle to arrive at the sampling section, but has an impact on the time for the particle group to reach stability in the 0.5 m long sampling section, that is, the greater the particle mass flow rate, the longer the time for dynamic equilibrium. It can also be seen from the figure that the influence of particle mass flow rate on the average velocity of particle groups in the high-speed zone is lower than that in the low-speed zone. Figure 11a shows the average value of the final stable velocity of the particles in the three zones with the change of the mass flow rates, it can be seen from Figure 11a that in the stability of the conveying stage, with the increase of particle mass flow rate, the average stable speed in the high-speed zone decreases by 1.56, the transition zone decreases by 2.62, and the low-speed zone decreases by 2.97. The overall changes are small, but the change in the high-speed region is the smallest, indicating that the mass flow rate has a greater impact on the low-speed zone when other conditions remain unchanged. Figure 9: Distribution cloud diagram of fluid dynamic pressure and solid mass concentration under different mass flow rates. (**a**) Fluid dynamic pressure cloud diagram, Pa; (**b**) particle mass concentration cloud diagram, kg/m\({}^{3}\).