Mixing efficiency
#Objective of this challenge:
To compare the Cell count , Outlet temperature and the number iteration for convergence for different cases with different length of tee and different momemtum ratios.
#Introdution to Mixing Tee:
Mixing Tee is also called as the T-joint because it splits the flow and the angle between them is `90^(o) C`. For example if we want to air conditioned the room and if the AC provides the chilled air at `10^(o)C`, this is very much cold as per the human comfort , human comfort temperature is around `16^(o) -25^(o) C`. In order to maintain temperature in this range, we use T-joint , where the hot air around `25^(o)-35 ^(o) C` enters from Horizontal inlet and the cold air enters from the vertical inlet mixes with each other to give the ideal temperature at the outlet. In order to calculate the effectiveness of the mixing we calculate Standard deviation of temperature at the outlet , a high Standard deviation means the mixing is not proper ,whereas the low standard deviation means the mixing is proper. Effectiveness in the mixing also depends on the momentum ratio , where momentum ratio is given by `
`M.R = V_(hotair) /V_(coldair)``
and on the length of the mixing tee.
#Mixing Tee CAD model:
#Results obtained during simulation Via ANSYS:
A) Case 1:
- Short mixing tee with hot inlet velocity of 3m/s.
- Momentum ratio of 2.
The results are as follows:
1.Residuals:
2. Standard deviation of temperature:
3. Temperature at the outlet:
4.Temperature Capture on a cut plane:
5.Velocity Capture on the Cut plane:
B) Case 2:
- Long mixing tee with hot inlet velocity of 3m/s.
- Momentum ratio of 2.
Results are as follows:
1.Residuals:
2. Standard deviation of temperature:
3. Temperature at the outlet:
4.Temperature Capture on a cut plane:
5.Velocity Capture on the Cut plane:
C) Case 3:
- Short mixing with hot inlet velocity of 3 m/s.
- Momentum ration of 4.
Results are as follows:
1.Residuals:
2. Standard deviation of temperature:
3. Temperature at the outlet:
4.Temperature Capture on a cut plane:
5.Velocity Capture on the Cut plane:
#Comparison between all the cases:
Assumptions:
1.Hot inlet temperature = `25^(o) C`
2.Cold inlet Termperaturee = `10^(o) C`
#Conclusion:
1. larger tee with momentum ratio of 2 , has a standard deviation of 0.5 degree celcius which is smaller than the small tee length with same momentum ratio , which means that larger the length, smaller is the standard deviation ,hence mixing is good.
2. Increasing the momentum ratio to 4 in small tee also reduces the standard deviation as compared to small tee with momentum ratio of 2, therefore by increasing the momentum ratio helps us to achive proper mixing.