Project: To analyze the variation of mixing effectiveness of a mixing tee on the basis of momentum ratio.

Project: To analyze the variation of mixing effectiveness of a mixing tee on the basis of momentum ratio.

Project Introduction: Mixing Tees utilizes a specifically engineered internal geometry to efficiently mix two fluid streams into one combined stream. These mixing tees are specifically designed for high pressure applications. Steady state simulations were performed on different geometries of mixing tee with different momentum ratios and mixing effectiveness and final average temperature of the stream was observed.

Different Cases Studied

	Mixing Tee Type	Hot Inlet Velocity (m/s)	Momentum Ratio
Case 1	Short	3	2
Case 2	Long	3	2
Case 3	Short	3	4

Momentum Ratio : Cold Inlet Velocity/ Hot Inlet Velocity

3-D Design of Mixing Tee

Short Type Mixing Tee

Long Type Mixing Tee

Mesh

Mixing Tee Short

Mixing Tee Long

Case Set up

For all the three cases under consideration, viscous model with K-epsilon realizable type model with standard wall functions has been taken.

Boundary Conditions

Initial Boundary Condition Parameters:

1. Temperature of Cold Air is taken as 10 degree celsius

2. Temperature of Hot Air is taken as 25 degree celsius

3. Fluid is taken as Air with its standard properties with gauge pressure as zero

Convergence Plots

Case 1 Mixing Tee Short with hot air inlet velocity 3 m/s and momentum ratio 2

a) Residual Plots

b) Area Weighted Average

The average temperature at outlet after reaching steady state is around 19.95 degree celsius.

c) Standard Deviation

The standard deviation of temperature for the case under consideration after reaching steady state is 1.3 degree celsius.

Case 2: Mixing Tee Long with hot air inlet velocity 3 m/s and momentum ratio 2

a) Residual Plot

b) Area Weighted Average Temperature

The average temperature obtained at outlet after attaining steady state is 19.98 degree celsius.

c) Standard Deviation Temperature

The standard deviation in outlet temperature after reaching the steady state is around 0.85 degree celsius.

Case 3 Mixing Tee short with hot air velocity 3 m/s and momentum ratio 4

a) Residual Plot

b) Area Weighted Average of Temperature at outlet

The average temperature at outlet of case under consideration is 17.5 degree celsius.

c) Standard Deviation Temperature

The standard deviation in outlet temperature of case under consideration is close to 1.2 degree celsius.

Temperature and Velocity Contours

Case 1

a) Temperature Contour

b) Velocity Contour

Case 2

a) Temperature Contour

b) Velocity Contour

Case 3

a) Temperature Contour

b) Velocity Contour

Results

S.NO	Cases	Number of Cells	No. of Iterations	Avg. outlet Temperature
1	CASE 1	14247	250	19.95
2	CASE 2	17771	210	19.98
3	CASE 3	14247	250	17.5

Conclusion

1. After carrying out the steady state simulations of the various cases of Mixing tee, it has been observed that variation of length has negligible effect on the outlet temperature of air. This may be due to uniform temperature distribution as evident from temperature and velocity contours of CASE 1 and CASE 2

2. It has also been observed that on increasing the cold air inlet velocity , the outlet air temperature changes drastically as evident from CASE 1 and CASE 3. Thus, on increasing the momentum ratio, the mixing effectivness increases considerably.