MIXING TEE EFFECTIVENESS
CFD ANALYSIS OF MIXING TEE
INTRODUCTION:
In this project CFD simulation is done using ANSYS Workbench for the short mixing tee and long mixing tee.In which hot fluid and cold fluid are mixed and compair the result of this mixing tee.
CASE 1:
For case 1,CFD analysis of short mixing tee is carried out using ANSYS Workbench. CAD model of short mixing tee is imported to ANSYS Spaceclaim as shown in figure.
meshing for short mixing tee is done using ANSYS mesher.element size for mesh is 10.19 mm.Default setting is taken for mesh generation.Meshed model is shown in figure below.
A mesh metric that identifies elements according to their quality was employed.it is shown that most of element have high quality in range of 0.70 to 0.90.so it is acceptable quality.
then for hot air velocity 3 m/s and for cold air 6 m/s is given as per momentum ratio 2 is given.simulation is run and result obtained.
CASE 2 :
for case 2,CFD analysis of long mixing tee is carried out in ANSYS WORKBENCH.Cad model of long mixing tee is imported to ANSYS spaceclaim as shown in figure.
Model is meshed using Ansys mesher with element size 13.85 mm and default setting.meshed model is shown in figure.
A mesh metric that identifies quality of the elements was employed.most of the elements are in range of 0.7 to 0.9.so it is acceptable for solve.it is shown in figure below.
now simulation is run and result obtained for hot air velocity is 3 m/s and for cold air 6 m/s with momentum ratio 2.
CASE 3:
For case 3,CFD analysis of short mixing tee is carried out using ANSYS Workbench. CAD model of short mixing tee is imported to ANSYS Spaceclaim as shown in figure.
meshing for short mixing tee is done using ANSYS mesher.element size for mesh is 10.19 mm.Default setting is taken for mesh generation.Meshed model is shown in figure below.
A mesh metric that identifies elements according to their quality was employed.it is shown that most of element have high quality in range of 0.70 to 0.90.so it is acceptable quality.
then for hot air velocity 3 m/s and for cold air 12 m/s is given as per momentum ratio 4 is given.simulation is run and result obtained.
COMPARISION OF CASES:
|
CASE NO. |
CELL COUNT |
AVERAGE OUTLET TEMPERATURE |
NUMBER OF ITERATION FOR CONVERGENCE |
|
1. |
12834 |
290.64 K |
229 |
|
2. |
15613 |
290.72 K |
245 |
|
3. |
12657 |
291 K |
450 |
RESULT:
CONVERGENCE PLOT:
Ansys fluent is used to solve this problem.For all 3 cases result is obtained and convergence plot is given below.Boundary condition is taken for case 1.short mixing tee 3 m/s velocity for hot air and 6 m/s is taken for cold air as momentum ration is given 2.hybrid initialization is taken for this solution and maximum iteration given as 300.solution is convered about 229 iteration as shown in figure below.for case 2. long mixing tee boundary condition is taken same as case 1.solution is converged after 245 iteration. and for case 3 short mixing tee boundary condition is taken as 3 m/s velocity for hot air and 12 m/s for cold air with momentum ratio 4 .solution is converged after 450.
CASE 1 short mixing tee(momentum ratio=2)
CASE 2 long mixing tee(momentum ratio=2)
CASE 3 short mixing tee(momentum ratio=4)
TEMPERATURE CONTOUR:
for all 3 cases cutplane along the pipe as shown in figure below and coloured by temperature.for case 1 short mixing tee temperature is not uniform where for case 3 temperature is uniform as momentum ratio is incresed for short mixing tee.As length of pipe is increased temperature becomes uniform at outlet as shown in figure for case 2.
CASE 1. short mixing tee(momentum ratio=2)
CASE 2. long mixing tee(momentum ratio=2)
CASE 3. short mixing tee(momentum ratio=4)
VELOCITY :
For all 3 cases cutplane is shown with velocity.For case 1.short mixing tee maximum velocity is about 4.96 m/s wheres for case 2 and 3 velocity are 7.71 m/s and 14.085 m/s.When momentum is less for short mixing tee mixing is not proper.As momentum ratio increased mixing is done properly as shown in figure.
CASE 1 short mixing tee(momentum ratio=2)
CASE 2. long mixing tee(momentum ratio=2)
CASE 3. short mixing tee(momentum ratio=4
CONCLUSION:
From the result we clonclued that when the length of the pipe increased the mixing of fluid is better and heat transfer is better and when momentum ratio increased for short mixing tee the mixing of fluid is good.